Alternating Ferro/Antiferromagnetic Copper(II) Chain Containing an Unprecedented Triple Formato/Hydroxido/Sulfato Bridge.

The first example of a triple formato/hydroxido/sulfato (FHS) bridge for any metal is reported in compound [Cu2(bpym)(OH)(HCO2)(SO4)(H2O)2]·3H2O (1). Its structure shows the presence of alternating triple FHS bridges and 2,2'-bipyrimidine (bpym) ones. Although in the initial synthesis the sulfate anions were introduced accidentally, here we report the rational synthesis and the magnetic properties of this compound. The magnetic properties show that 1 is an alternating ferro/antiferromagnetic (F/AF) chain compound with predominant antiferromagnetic interactions and were fit to an alternating F/AF S = (1)/2 chain with g = 2.103, JAF = -139 cm(-1), and JF = 116 cm(-1) (α = JF/|JAF| = 0.83). Th…

Combined study of anion recognition by a carbazole-based neutral tripodal receptor in a competitive environment

Anion recognition studies have been carried out on a series of neutral synthetic receptors in which carbazole-2-carboxamide has been used as building block. Different ligands which include one to three carbazole units in their structure have been prepared. Binding experiments have been performed under competitive conditions in DMSO and DMSO-water solutions. The tripodal receptor offered a better host-guest association due to the synergistic effect of a well arranged set of hydrogen bonds. A selective response towards the biologically important pyrophosphate anion has been achieved. This selectivity is enhanced when studies are carried out with an increasing water content, which gets as high…

Regio-specific synthesis of new 1-(tert-butyl)-1H-pyrazolecarboxamide derivatives

Regio-specific and non-regiospecific condensation reactions on 1,3-dicarbonyl compounds rendered 1,3,5-trisubstituted pyrazoles. Herein, the control of regio-specificity was a significant improvement in pyrazole research. A high yield acylation of poorly nucleophilic aryl amines, which resulted in mono- or diacylated products depending on the reaction conditions, is described. As a result, a library of potentially bioactive compounds was obtained. Fil: Ruatta Merke, Santiago Matías. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas; Argentina Fil: Murguia, Marcelo Cesar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Co…

ChemInform Abstract: Switchable Palladium-Catalyst Reaction of Bromomethyl Sulfoxides, CO, and N-Nucleophiles: Aminocarbonylation at Csp3versus Oxidative Carbonylation of Amines.

Pd2(dba)3/ Xantphos-catalyzed coupling of the sulfoxides (I) and (V) with amines and carbon monoxide allows a new and efficient access to amides of type (IV) and (VI).

Structure and photoreactivity of stable zwitterionic group 6 metal allenyls

The synthesis and mechanistic study of the unprecedented reactivity of a series of zwitterionic η(1)-metal allenyls are reported.

Synthesis of oxaspiranic compounds through [3 + 2] annulation of cyclopropenones and donor–acceptor cyclopropanes.

The Sc(OTf)3-catalyzed [3 + 2]-annulation reaction between cyclopropenones and donor–acceptor cyclopropanes is described. The process leads directly to the formation of 4-oxaspiro[2.4]hept-1-ene derivatives in good to excellent reaction yields. Density functional theory calculations suggest that the [3 + 2]-annulation pathway is strongly preferred over the possible [3 + 3]-process.

Host–Guest Chemistry: Oxoanion Recognition Based on Combined Charge‐Assisted C−H or Halogen‐Bonding Interactions and Anion⋅⋅⋅Anion Interactions Mediated by Hydrogen Bonds

Several bis-triazolium-based receptors have been synthesized and their anion-recognition capabilities have been studied. The central chiral 1,1'-bi-2-naphthol (BINOL) core features either two aryl or ferrocenyl end-capped side arms with central halogen- or hydrogen-bonding triazolium receptors. NMR spectroscopic data indicate the simultaneous occurrence of several charge-assisted aliphatic and heteroaromatic C-H noncovalent interactions and combinations of C-H hydrogen and halogen bonding. The receptors are able to selectively interact with HP2 O7 (3-) , H2 PO4 (-) , and SO4 (2-) anions, and the value of the association constant follows the sequence: HP2 O7 (3-) >SO4 (2-) >H2 PO4 (-) . The …

Unprecedented Palladium-Catalyzed Cross-Coupling Reaction of α-Bromo Sulfoxides with Boronic Acids

[reaction: see text] A new Suzuki-type palladium-catalyzed reaction of boronic acids with alpha-bromo sulfoxides has been developed using a protocol similar to the well-documented reaction of boronic acids with aryl halides. Both cross-coupling and homocoupling processes were observed. The best yields in cross-coupling products were obtained when the presence of oxygen was carefully excluded using degassed solvents. The oxidative addition palladium complex intermediate could be isolated and characterized by X-ray single-crystal diffraction.

ChemInform Abstract: Asymmetric Synthesis of Fluorinated Amino Macrolactones Through Ring-Closing Metathesis.

The synthesis of new chiral fluorinated amino and azamacrolactones of types 1 and 2 is described. A ring-closing metathesis (RCM) reaction constitutes the key step in this methodology, which uses fluorinated amino alcohols 7 as starting materials. The influence of the CF2 group, which is located in the alpha-position relative to the carbon bearing the amino group, on the efficiency of the RCM reaction is noteworthy. This method allows for the preparation of the desired fluorinated macrolactones in excellent yields.

Cooperative H-bonds, π⋯π and anion⋯π interactions as driving forces in the construction of novel Cu(II) bis(imidazol-2-yl) supramolecular 3D frameworks

Abstract Two new Cu(II) complexes with bis(2-imidazolyl) based ligands, with the formula [Cu(BIM)2(SCN)2]·2H2O (BIM = bis(2-imidazol-2-yl)methane) and [Cu(HBIMAM)2(OH2)2](BF4)4·2H2O (BIMAM = bis(2-imidazol-2-yl)methylaminomethane) have been synthesized and characterized. Both compounds contain mononuclear entities as molecular building blocks (MBBs); neutral [Cu(BIM)2(SCN)2] in compound 1 and cationic [Cu(HBIMAM)2(OH2)2]4+ in compound 2. The coordination around the metal atoms shows a tetragonally-elongated octahedral geometry (CuN4S2 and CuN4O2 chromophores). The Q-band EPR spectra of both compounds are indicative of an essentially d x 2 - y 2 ground state for copper(II) ions. The analysis…

Dual Role of Vinyl Sulfonamides as N -Nucleophiles and Michael Acceptors in the Enantioselective Synthesis of Bicyclic δ-Sultams

ChemInform Abstract: Novel Strategy for the Synthesis of Fluorinated β-Amino Acid Derivatives from Δ2-Oxazolines.

Abstract Racemic and chiral non-racemic β-fluoroalkyl-β-amino acid derivatives have been prepared in two steps starting from 2-alkyl-Δ2-oxazolines and fluorinated imidoyl chlorides. Subsequent chemoselective reduction of the C-masked β-enamino acid derivatives initially formed provided the target β-amino acids. The process takes place with total chemoselectivity, high yields and satisfactory diastereoselectivity.

ChemInform Abstract: Selective “One-Pot” Synthesis of Functionalized Cyclopentenones.

Reaction of squaric acid derivatives with vinyl magnesium bromide followed by treatment with trifluoroethanol allows a new and stereoselective access to functionalized cyclopentenones of type (III)/ (V).

Novel strategy for the synthesis of fluorinated β-amino acid derivatives from Δ2-oxazolines

Abstract Racemic and chiral non-racemic β-fluoroalkyl-β-amino acid derivatives have been prepared in two steps starting from 2-alkyl-Δ2-oxazolines and fluorinated imidoyl chlorides. Subsequent chemoselective reduction of the C-masked β-enamino acid derivatives initially formed provided the target β-amino acids. The process takes place with total chemoselectivity, high yields and satisfactory diastereoselectivity.

Fluorescence Quenching in BODIPYs Having Ir‐ and Rh‐Tethered Complexes

The effect of Rh- and Ir-centers on the optical properties of the BODIPY core has been studied. To this end, novel metal complexes tethered to BODIPY have been prepared through an easy and versatile procedure using N-directed C–H activation reactions. The organometallic moiety has a tremendous influence on the emissive properties of the BODIPY fragment. A photoinduced electron transfer (PET) mechanism is suggested to be the main mechanism responsible for the suppression of the BODIPY fluorescence emission in the newly formed dyads. The efficiency of the PET depends on both the distance between the chromophores in the dyad and the nature of the transition metal (Rh vs. Ir).

[(Pyridylcarbonyl)pyridyl]triazolopyridines, Useful Ligands for the Construction of Polynuclear Coordination Compounds – Synthesis, Crystal Structure and Magnetic Properties of a Novel Tetranuclear Copper(II) Cubane

A new tetranuclear cubane Cu4O4 complex has been synthesised from assembly of CuII ions and the polydentate ligand (pyridin-2-yl){6-([1,2,3]triazolo[1,5-a]pyridin-3-yl)pyridin-2-yl}methanone. Crystallographic analysis indicates that the Cu4O4 unit has an S4 symmetry. The magnetic properties have been analysed using the H = –2Σi,jJijSiSj spin Hamiltonian. Two distinct coupling constants, 2J1,3 = –37.4 cm–1 and 2J1,2 = –2.6 cm–1, obtained from the fitting of the experimental data have been rationalised on the basis of a density functional study of magnetostructural correlations in cubane complexes containing the Cu4O4 core. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

The product of a regiospecific and stereoselective ene-reaction of a polycyclic terpenoid system

The X-ray structure of di­methyl (Z)-[(8aS,2R,4aR,4bR)-8a-methoxy­carbonyl-1,4a,7-tri­methyl-8-oxo-2,3,4,4a,4b,5,8,8a,9,10-deca­hydro­phenanthren-2-yl]-2-butenedioate, C25H32O7, confirmed its relative configuration. The structure shows the bend in the molecular skeleton as found for similar compounds. Weak intermolecular C—H⋯O interactions have been found in the crystal.

Ion pair recognition receptor based on an unsymmetrically 1,1'-disubstituted ferrocene-triazole derivative.

The ferrocene-triazole derivative 4, available from 1,1'-bis(diazido)ferrocene by sequential functionalization through click-type chemistry and the Staudinger reaction, is elaborated as a lab-on-a-molecule for the selective sensing of HP(2)O(7)(3-) and Hg(2+). Receptor 4 behaves as a ratiometric fluorescent probe for HP(2)O(7)(3-) with a good selectivity over other anions, whereas in the presence of Hg(2+) it modifies the fluorescent emission of the pyrene unit, acting as a selective on-off fluorescent sensor for Hg(2+) with a low detection limit. The most salient feature of compound 4 is its behavior as an excellent electrooptical ion pair recognition receptor able to simultaneously recogn…

Synthesis and characterization of a Cu(II) complex of 2-benzylmercapto-5- methyl-1,3,4-thiadiazole (C10H10N2S 2)

A Cu(II) complex of 2-benzylmercapto-5-methyl-1,3,4-thiadiazole was synthesized and characterized. The crystal structure of the copper complex and the free ligand were determined by single-crystal X-ray diffraction at room temperature: {[Cu(C10H10N2S2) 2(Cl)2], P1 triclinic, a = 8.1450(2) Å, b = 8.1690(2) Å, c = 10.8180(3) Å, α = 97.4040(12)°, β = 101.6270(11)°, γ = 116.1431(14)°; C10H10N2S2 ligand, Pbca orthorhombic, a = 8.7938(7) Å, b = 9.6491(7) Å, c = 25.3552(18) Å}. The metal complex framework consists of discrete units that provide crystalline stability through a network of van der Waals contacts. The Cu(II) is coordinated by two chloride ions and two 2-benzylmercapto-5-methyl-1,3,4- …

On the Use of Metal Purine Derivatives (M=Ir, Rh) for the Selective Labeling of Nucleosides and Nucleotides

The reactions of neutral or cationic IrIII and RhIII derivatives of phenyl purine nucleobases with unsymmetrical alkynes produce new metallacycles in a predictable manner, which allows for the incorporation of either photoactive (anthracene or pyrene) or electroactive (ferrocene) labels in the nucleotide or nucleoside moiety. The reported methodology (metalation of the purine derivative and subsequent marker insertion) could be used for the postfunctionalization and unambiguous labeling of oligonucleotides.

Synthesis and structural characterization of novel tetranuclear organotitanoxane derivatives.

Synthesis of the novel titanoxane compounds, [(TiCl)(TiOH){(Ti)[μ-(η(5)-C(5)Me(4)SiMe(2)O-κO)](2)(μ-O)}(2)(μ-O)] (4) and [{Ti[μ-(η(5)-C(5)Me(4)SiMe(2)O-κO)](μ-O)}(4)] (5) by controlled reaction of the dinuclear titanium oxo complex [{Ti{μ-(η(5)-C(5)Me(4)SiMe(2)O-κO)}Cl](2)(μ-O)] (1) with 2 equiv of LiOH is reported. Complex 4 is innovative and remarkable. It is one of the rare known examples of tetranuclear stable terminal hydroxo titanium complexes, with an open-chained structure, which coincides with the transient metal monohydroxo proposed in the stepwise pathway employed to justify the formation of the hexanuclear complex [{Ti[μ-(η(5)-C(5)Me(4)SiMe(2)O-κO)](μ-O)}(6)] (3) from 1. (1)H DO…

Competitive gold-activation modes in terminal alkynes: an experimental and mechanistic study.

The competition between π- and dual σ,π-gold-activation modes is revealed in the gold(I)-catalyzed heterocyclization of 1-(o-ethynylaryl)urea. A noticeable effect of various ligands in gold complexes on the choice of these activation modes is described. The cationic [Au(IPr)](+) (IPr=2,6-bis(diisopropylphenyl)imidazol-2-ylidene) complex cleanly promotes the π activation of terminal alkynes, whereas [Au(PtBu3 )](+) favors intermediate σ,π species. In this experimental and mechanistic study, which includes kinetic and cross-over experiments, several σ-gold, σ,π-gold, and other gold polynuclear reaction intermediates have been isolated and identified by NMR spectroscopy, X-ray diffraction, or …

Switchable palladium-catalyst reaction of bromomethyl sulfoxides, CO, and N-nucleophiles: aminocarbonylation at Csp3 versus oxidative carbonylation of amines.

The palladium-catalyzed reaction of α-bromomethyl sulfoxides, carbon monoxide, and N-nucleophiles follows different reaction pathways according to the catalytic system and the reaction conditions. The Pd-xantphos catalyst affords high yields of α-sulfinyl amides by an aminocarbonylation process and is the first example of this type of transformation for a nonbenzylic sp(3)-hybridized carbon. On the other hand, the oxidative carbonylation of amines occurs with α-bromomethyl sulfoxides, carbon monoxide, and catalytic Pd(PPh(3))(4) under aerobic conditions, yielding ureas and oxalamides from either primary or secondary amines. The reaction with ambident nucleophiles such as amino alcohols was …

Gold(I)-catalysed cascade reactions in the synthesis of 2,3-fused indole derivatives.

A gold(I)-catalysed hydroaminative/arylative cascade for the efficient synthesis of a variety of indole-fused skeletons has been developed. Factors controlling the catalyst loading required in these transformations involving 1,3-unsubstituted indole intermediates have been revealed, allowing isolation of an unprecedented 1,3-dimetallated 3H-indole gold complex characterized by X-ray diffraction.

Synthesis, Structure and Conformation of Partially-Modified Retro- and Retro-Inversoψ[NHCH(CF3)]Gly Peptides

Partially modified retro- (PMR) and retro-inverso (PMRI) psi[NHCH(CF(3))]Gly peptides, a conceptually new class of peptidomimetics, have been synthesized in wide structural diversity and variable length by aza-Michael reaction of enantiomerically pure alpha-amino esters and peptides with enantiomerically and geometrically pure N-4,4,4-trifluorocrotonoyl-oxazolidin-2-ones. The factors underlying the observed moderate to good diastereocontrol have been investigated. The conformations of model PMR-psi[NHCH(CF(3))]Gly tripeptides have been studied in solution by (1)H NMR spectroscopy supported by MD calculations, as well as in the solid-state by X-ray diffraction. Remarkable stability of turn-l…

Effect of a κ1-Bonded-M-1,2,3-triazole (M = Co, Ru) on the Structure and Reactivity of Group 6 Alkoxy (Fischer) Carbenes

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.inorgchem. 6b02957. NMR data for the synthesized compounds, electrochemical data of azides 2 and 4 (PDF) Computational details and cif files containing crystal data for 3a and 5b (CIF1, CIF2)

Correction: A C(π-hole)⋯Cl–Zn tetrel interaction driving a metal–organic supramolecular assembly

Correction for ‘A C(π-hole)⋯Cl–Zn tetrel interaction driving a metal–organic supramolecular assembly’ by Carmen Ramírez de Arellano et al., CrystEngComm, 2020, 22, 6979–6982, DOI: 10.1039/D0CE01272F.

Stable Methylene- and Oxo-Bridged Monocyclopentadienyl Titanium Compounds. Molecular Structure of {Ti[μ-(η5-C5Me4SiMe2-O)]Me}2(μ-CH2)

Thermolysis of {Ti[μ-(η5-C5Me4SiMe2-O)]Me2}2 affords the methylene-bridged titanium compound {Ti[μ-(η5-C5Me4SiMe2-O)]Me}2(μ-CH2), concurrent with the evolution of methane, the first example of a fu...

Diastereoselective Insertion of Isocyanide into the Alkyl−Metal Bond of Methylbenz[ e ]indenyl ansa ‐Zirconocene Complexes

Alkylation of ansa-zirconocene [Zr{(η5-C5H5)SiMe2(MBI)}Cl2] (MBI = η5-2-Me−C13H7) with MgRCl gave the dimethyl complex [Zr{(η5-C5H5)SiMe2(MBI)}Me2], but unresolvable mixtures containing mono-alkylated compounds were obtained when bulkier alkyls were used. However pure dialkyl complexes [Zr{(η5-C5H5)SiMe2(MBI)}R2] (R = CH2Ph, CH2SiMe3) were easily obtained using K(CH2Ph) and Li(CH2SiMe3) as alkylating agents. Diastereoselective insertion into the MBI-unprotected Zr−R bond was observed when all of these dialkyl complexes were treated with 2,6-xylyl isocyanide to give the iminoacyl compounds [Zr{(η5-C5H5)SiMe2(MBI)}R{CR[η2-N-(2,6-xylyl)]}] (R = Me, CH2Ph, CH2SiMe3). All of the new complexes we…

A novel dinuclear manganese(II) compound incorporating two bis(imidazolyl) based ligands with single μ2-η1:η1-carboxylato bridges. Molecular and crystal structure and magnetic properties of [Mn2Cl(BIP)(HBIMAM)(H2O)5]Cl3·4H2O (BIP=3,3-di(2-1H-2-imidazolyl)propanoate; BIMAM=N-methyldi(1H-2-imidazolyl)methanamine)

Abstract This paper reports the synthesis, X-ray structure and magnetic characterization of [Mn 2 Cl(BIP) (HBIMAM)(H 2 O) 5 ]Cl 3 ·4H 2 O a novel dinuclear manganese(II) incorporating two related bis(imidazolyl)-based ligands, BIP (3,3-di(2-1 H -2-imidazolyl)propanoate) and BIMAM ( N -methyldi(1 H -2-imidazolyl)methanamine). The metal atoms in the dinuclear entity are bridged by a μ 2 -η 1 :η 1 carboxylate group (from the propionate arm of the BIP ligand) acting in an anti – anti coordination bridging mode, with an intramolecular Mn⋯Mn distance of 6.47 A. The coordination around the Mn(II) ions shows a distorted octahedral geometry for both MnClN 2 O 3 and MnN 2 O 4 chromophores. Between th…

Synthesis and characterization of new 1,4 and 1,5-disubstituted glucopyranosyl 1,2,3-triazole by 1,3-dipolar cycloaddition

Abstract A series of 1,4 and 1,5-disubstituted 1-(β- d -glucopyranosyl)-1,2,3-triazoles has been prepared in an efficient manner with excellent yields using the intermolecular 1,3-dipolar cycloaddition of 1-azido-2,3,4,6-tetra-O-acetyl-β- d -glucopyranose 2 to a variety of substituted alkynes phenylacethylene 3, propargyl alcohol 4, 2-butyn-1,4-diol, 5, 3-propargylbenzimidazole 6 and propargylpyrazole 7 in toluene. The reaction takes place with the formation of both 4- and 5-regioisomers.

Single Heteroatom Fine-Tuning of the Emissive Properties in Organoboron Complexes with 7-(Azaheteroaryl)indole Systems

The application of organoboron compounds as light-absorbing or light-emitting species in areas as relevant as organic electronics or biomedicine has motivated the search for new materials which contribute to the progress of those applications. This article reports the synthesis of four-coordinate boron complexes based on the unexplored 7-(azaheteroaryl)indole ligands. An easy synthetic approach has enabled the fine-tuning of the electronic structure of the organoboron species by modifying a heteroaromatic component in the conjugated system. Furthermore, a comprehensive characterization by X-ray diffraction, absorption and emission spectroscopy, both in solution and in the solid state, cycli…

Triazole vs. triazolium carbene ligands in the site-selective cyclometallation of o-carboranes by M(iii) (M = Ir, Rh) complexes

Ir(iii) and Rh(iii)-mediated site-selective cage B-H and C-H bond activation in o-carboranylmethyl derivatives has been achieved. The selectivity of the reaction is related to the electron donating properties of the ligand. 1,2,3-Triazole-derivatives use the N2 position of the triazole ring to direct the selective o-carborane B-H bond activation, whereas the corresponding triazolylidene derivatives lead to the cage C-H bond activation with complete site-selectivity.

X-Ray characterization of 3-methyl-6,8-di(2-pyridyl)-[1,2,3]triazolo[5',1':6,1]pyrido[2,3-d]pyrimidine

Abarca Gonzalez, Belen. Belen.Abarca@uv.es ; Ballesteros Campos, Rafael, Rafael.Ballesteros@uv.es ; Chadlaoui, Mimoun, michad@alumni.uv.es ; Ramirez de Arellano Sanchez, Maria del Carmen, Ramirezdearellano@uv.es

Sequential Reactions of Alkynes on an Iridium(III) Single Site

Sequential insertion of terminal alkynes on IrIII cyclometalated complexes allow the formation of novel metallapolycycles in a controlled and efficient manner. ortho-Methylarylethynyl derivatives led to an unprecedented cascade combination of three fundamental processes (C−C bond formation, C(sp3)−H activation, and reductive coupling) on a single IrIII center, in a process compatible with functionalized biomolecules and photoactive substrates. The reaction with tert-butylacetylene led to a [6,5,4]-polycycle that incorporates an iridacyclobutenylidene in its structure. The sequence is a multicomponent reaction in which the metal not only promotes the different steps but also determines their…

Synthesis, Structure and Anion Sensing Properties of a Dicationic Bis(imidazolium)-Based Cyclophane

The preparation and sensing properties of a tetracyclic cyclophane receptor containing two imidazolium rings as anion binding sites and two fluorene rings as fluorescent signaling units, are reported. The receptor behaves as a selective fluorescent chemosensor molecule for inorganic phosphates. H-NMR spectroscopical data clearly indicate the simultaneous occurrence of charge-assisted aromatic and aliphatic C−H noncovalent interactions. PCM/DFT calculations have been carried out to predict the structures of the complexes formed with one and two molecules of PF , HPO and HPO .

Palladium-catalyzed Suzuki-Miyaura reaction involving a secondary sp3 carbon: studies of stereochemistry and scope of the reaction.

Palladium-catalyzed C--C bond formation involving secondary sp3-hybridized carbon is described. These reactions occur with secondary 1-bromoethyl arylsulfoxides and different arylboronic acids, to produce the corresponding arylated sulfoxides in moderate to high yields and with complete stereospecificity. Despite the presence of beta hydrogens in the substrate, the competitive beta-hydride elimination is not a significant side reaction when coordinating solvents are used. The reported cross-coupling involves secondary C(sp3)--C(sp2) bond formation: this is the first time that a mechanistic study has been carried out with such substrates. The reaction proceeds with inversion of configuration…

NHC-Stabilized Gold(I) Complexes: Suitable Catalysts for 6-exo-dig Heterocyclization of 1-(o-Ethynylaryl)ureas

3-Substituted 1-(o-ethynylaryl)ureas 1 selectively undergo either 6-exo-dig or 5-endo-dig cyclization (to give 4-methylene-3,4-quinazolin-2-ones 2 or indoles 3, respectively) depending on the choice of the metal, ligand, and reaction conditions. The best results (up to 96% yield) in the preparation of the hydroamination products 2 are achieved with the highly bulky NHC-stabilized cationic gold(I) complex [Au(IPr)](+). Conversely, ureas bearing an internal alkyne lead to the 5-endo-dig cyclization mode regardless of the gold(I) complex employed. Whereas the nature of the substituent at N-3 does not have any influence on the regiochemistry observed, it does, in some cases, affect the efficien…

Early transition metal derivatives stabilised by the phenylenediamido 1,2-C6H4(NCH2tBu)2 ligand: Synthesis, characterisation and reactivity studies: Crystal structures of [Ta{1,2-C6H4(NCH2tBu)2}2Cl] and [Zr{(1,2-C6H4(NCH2tBu)2}(NMe2)(μ-NMe2)]2

Abstract Li 2 [1,2-C 6 H 4 (NCH 2 t Bu) 2 ] reacts with one equiv of [TiCl 4 (THF) 2 ] in refluxing toluene to give the chelate compound [Ti{1,2-C 6 H 4 (NCH 2 t Bu) 2 }Cl 2 (THF)] ( 1 ), isolated as a black product, while the reaction of the dilithio diamido salt with one equiv of [ZrCl 4 (THF) 2 ] in refluxing toluene affords the dinuclear zirconium derivative [Zr{1,2-C 6 H 4 (NCH 2 t Bu) 2 }Cl(THF)(μ-Cl)] 2 ( 2 ), obtained as an orange solid. Treatment of the dilithio diamido salt with TaCl 5 in a 2:1 molar ratio in toluene yields [Ta{1,2-C 6 H 4 (NCH 2 t Bu) 2 } 2 Cl] ( 3 ) as a red product. The reaction of 1,2-C 6 H 4 (NHCH 2 t Bu) 2 with [Zr(NMe 2 ) 4 ] in toluene at room temperature …

Asymmetric synthesis of fluorinated cyclic beta-amino acid derivatives through cross metathesis.

The asymmetric synthesis of several fluorinated cis-2-aminocycloalkane carboxylic acids (cis-2-ACACs) with a cross metathesis (CM) reaction as the key step has been carried out, constituting the first time a metathesis protocol has been undertaken with fluorinated imidoyl chlorides. Subsequent chemoselective hydrogenation of the olefin moiety, Dieckmann condensation, and stereoselective reduction of the iminic double bond afforded the corresponding beta-amino esters with several ring sizes. The asymmetric version of the process was achieved by using (-)-8-phenylmenthol as a chiral auxiliary.

Bis(3,5-dimethylpyrazol-1-ato) zirconium complexes as precursors for ethylene polymerisation upon activation with MAO: Syntheses, characterisation and X-ray molecular structure of [Zr(η2-3,5-Me2Pz)2Cl2(η1-3,5-Me2PzH)2]·(3,5-Me2PzH) and [Zr(η2-3,5-Me2Pz)2(CH2Ph)2] (3,5-Me2Pz=3,5-dimethylpyrazol-1-ato)

Abstract The bis(3,5-dimethylpyrazol-1-ato) zirconium complex [Zr(η2-3,5-Me2Pz)2(NMe2)2(NHMe2)2] (2) is obtained by treatment of [Zr(NMe2)4] with 2 equiv. of 3,5-dimethylpyrazole 1. The reaction of the [ZrCl4(THF)2] adduct with 2 equiv. of the potassium salt of 1 affords the dichloro derivative [Zr(η2-3,5-Me2Pz)2Cl2]n (3), while reaction with 4.1 equiv. of 1 in the presence of 2.1 equiv. of NEt3 affords the dichloro pyrazole adduct [Zr(η2-3,5-Me2Pz)2Cl2(η1-3,5-Me2PzH)2] (4). Treatment of [Zr(CH2Ph)4] with 2 equiv. of 1 gives the dibenzyl complex [Zr(η2-3,5-Me2Pz)2(CH2Ph)2] (5) via alkane elimination. Compound 4 presents fluxional behaviour in CDCl3 solution, which was studied and quantified…

Regiospecific and stereoselective ene reaction of the A-ring methylcyclohexene moiety of polycyclic terpenoid systems with dimethyl acetylenedicarboxylate

Polycyclic terpenoid compounds with a methylcyclohexene moiety at the A-ring, such as 1 and 7, give a regio- and stereoselective ene reaction when heated at low temperatures with dimethyl acetylenedicarboxylate. The structure and stereochemistry of the compound formed in the case of 1, e.g. 5, is determined by X-ray analysis.

Exploiting 1,4-naphthoquinone and 3-iodo-1,4-naphthoquinone motifs as anion binding sites by hydrogen or halogen-bonding interactions

We describe here the utilization of 1,4-naphthoquinone and 3-iodo-1,4-naphthoquinone motifs as new anion binding sites by hydrogen- or halogen-bonding interactions, respectively. These binding sites have been integrated in bidentate ester based receptors. Emission experiments reveal that both receptors selectively recognize sulfate anions, which induced a remarkable increase of a new emission band attributed to the formation of π-stacking interactions between two 1,4-naphthoquinone units. Absorption spectroscopy and mass spectrometry indicate the disruption of the ester group of the 1,4-naphthoquinone based receptor in the presence of HP2O73−, H2PO4−, F−, AcO− and C6H5CO2− and in the haloge…

Efficient ultraviolet-light energy dissipation by an aromatic ketone.

Experimental evidence on the efficiency of 2,2'4,4'-tetramethoxybenzil for UV-light energy dissipation is provided. This non-phenolic aromatic ketone has a low energy triplet which quickly decays to the ketone ground state, thus avoiding the generation of undesirable reactive species. El Moncef, Abdelkarim, elmonab@alumni.uv.es ; Cuquerella Alabort, Maria Consuelo, Chelo.Cuquerella@uv.es ; Zaballos Garcia, Elena, Elena.Zaballos@uv.es ; Ramirez de Arellano Sanchez, Maria del Carmen, Carmen.Ramirezdearellano@uv.es ; Stiriba, Salah Eddine, Salah.Stiriba@uv.es ; Perez Prieto, Julia, Julia.Perez@uv.es

An Entry to Mixed NHC-Fischer Carbene Complexes and Zwitterionic Group 6 Metal Alkenyls

The addition of NHCs to α,β-unsaturated Cr(0) and W(0) (Fischer) carbene complexes is strongly dependent on the electrophilicity of the carbene carbon. Electrophilic alkoxy-carbene complexes quantitatively react with NHCs to yield stable zwitterionic (racemic) Cr(0) - and W(0) -alkenyls with total regio- and E-stereoselectivity. Less electrophilic aminocarbenes react with NHCs to promote the displacement of a CO ligand and yield "mixed" NHC/Fischer biscarbenes in a process that is unprecedented in group 6 metal-carbene chemistry. In fact, the compounds prepared, are some of the scarce examples of Fischer bisylidenes reported in the literature. The electrochemistry of the zwitterionic Cr(0) …

Palladium-Catalyzed Reaction of Boronic Acids with Chiral and Racemic ?-Bromo Sulfoxides.

Palladium-catalyzed cross-coupling reactions of racemic α-bromo sulfoxides with boronic acids are carried out in either aqueous or nonaqueous medium with formation of a new C sp3−C sp2 bond. The arylation of chiral α-bromo sulfoxides occurs without racemization. The cross-coupling reaction is general and gives high yields with arylboronic acids substituted with either donor or acceptor groups but gives poor results with heteroarylboronic acids. The best yields are obtained using degassed solvents and CsF instead of aqueous base. The use of aqueous base and the presence of oxygen favor the homocoupling side reaction.

Selective "one-pot" synthesis of functionalized cyclopentenones.

Double addition (1,2-1,4) of vinyl magnesium bromide to squaric acid derivatives allows the preparation of polyoxygenated cyclopentenones (8) in a "one-pot" procedure. The reaction occurs through the intermediate formation of octatetraenes (6). Protonation of this latter intermediate at -78 °C with TFE occurs selectively at the vinyl CH(2) closer to the metallic centers. DFT studies of the cyclization step justify the observed diastereoselectivity.

Electrocatalytic Behavior of Tetrathiafulvalene (TTF) and Extended Tetrathiafulvalene (exTTF) [FeFe] Hydrogenase Mimics

TTF- and exTTF-containing [(μ-S2)Fe2(CO)6] complexes have been prepared by the photochemical reaction of TTF or exTTF and [(μ-S2)Fe2(CO)6]. These complexes are able to interact with PAHs. In the absence of air and in acid media an electrocatalytic dihydrogen evolution reaction (HER) occurs, similarly to analogous [(μ-S2)Fe2(CO)6] complexes. However, in the presence of air, the TTF and exTTF organic moieties strongly influence the electrochemistry of these systems. The reported data may be valuable in the design of [FeFe] hydrogenase mimics able to combine the HER properties of the [FeFe] cores with the unique TTF properties

Synthesis of substituted piperidines by enantioselective desymmetrizing intramolecular aza-Michael reactions.

An organocatalytic enantioselective intramolecular aza-Michael reaction has been described for the first time in a desymmetrization process employing substrates different from cyclohexadienones. By using 9-amino-9-deoxy-epi-hydroquinine as the catalyst and trifluoroacetic acid as a co-catalyst, a series of enantiomerically enriched 2,5-and 2,6-disubstituted piperidines have been obtained in good yields and with moderate diastereoselectivity. Depending on the catalyst/co-catalyst loading ratio, either the major or the minor diastereoisomer of the final piperidine products was achieved with high levels of enantioselectivity. Finally, some mechanistic insights have been considered by means of …

Remote Control by π-Conjugation of the Emissive Properties of Fischer Carbene-BODIPY Dyads.

The synthesis, structure, and complete characterization of mono- and bimetallic dyads joining Fischer carbene complexes and BODIPY chromophores are reported. In these organometallic species, the Fischer carbene complex is attached to the BODIPY moiety through a p-aminophenyl group linked at the C8 carbon atom of the BODIPY core. The photophysical properties, namely the corresponding UV/vis absorption and emission spectra of these new metal-carbene complexes, are analyzed and discussed. It is found that whereas the absorption of the considered dyads strongly resembles that of the parent 4-anilinyl-substituted BODIPY, the fluorescence emission is significantly reduced in these species, very l…

Mono- and Bimetallic Zwitterionic Chromium(0) and Tungsten(0) Allenyls

A series of stable chiral (racemic), formally neutral, zwitterionic mono- and bimetallic M(CO)5[C(OEt)═C═CR(NHC)] (M = Cr, W) σ-allenyls are ready available by the addition of N-heterocyclic carbenes (NHCs) to Cr(0) and W(0) alkynyl Fischer carbene complexes. Different classes of NHCs, (e.g., 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene, 1,3-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene, and their six- and seven-membered analogues and 1,3-bis(dimethyl)imidazol-2-ylidene) were employed as nucleophiles in these C-C bond-forming reactions yielding the novel complexes in essentially quantitative yields. A systematic experimental and computational study of the electronic properties of the C…

ChemInform Abstract: Regiospecific and Stereoselective Ene Reaction of the A-Ring Methylcyclohexene Moiety of Polycyclic Terpenoid Systems with Dimethyl Acetylenedicarboxylate.

Properties of a triazolopyridine system as a molecular chemosensor for metal ions, anions, and amino acids.

The characteristics as a chemosensor of the compound 3-methyl-6,8-di(2-pyridyl)-[1,2,3]triazolo[5',1':6,1]pyrido[2,3-]pyrimidine (1) have been analyzed. Interaction with Cu(2+) produces a quenching of the fluorescence, while interaction with Zn(2+) leads to a quenching of the fluorescence followed by a bathochromic shift. The crystal structure of the Zn(1)(H(2)O)(3)(ClO(4))(2) x H(2)O complex shows the coordination of Zn(2+) through the terpyridine moiety. The octahedral site is completed by three water molecules. Interactions of the Zn(2+) complex with the anions sulfate, nitrate, nitrite, and dihydrogenphosphate in ethanol produce hypsochromic shifts and restoration of the fluorescence wh…

The selective synthesis of metallanucleosides and metallanucleotides: a new tool for the functionalization of nucleic acids.

Nucleobases team up: the efficient and selective preparation of purine-derived metallanucleosides, metallanucleotides, and metalladinucleotides having M-C bonds (M=Ir(III), Rh(III)) is reported for the first time. The results presented may be applied to the synthesis of functionalized nucleic acids, or DNA/RNA-modified segments.

The Reaction of 4-Amino-2-oxazolines with Isocyanates and Isothiocyanates. Synthesis and X-Ray Structures of Polysubstituted 2-Imidazolidinones, 1,3-Oxazolidines and 1,3-Thiazolidines.

Abstract Reactions of 4-alkylamino-2-phenyl-2-oxazolines 1 with isocyanates and isothiocyanates provide unprecedented efficient and regioselective heterocycle–heterocycle transformations. Compounds 1 reacted rapidly with tosyl isocyanate yielding directly 3-alkyl-4-benzamido-1-tosyl-2-imidazolidinones 4 in almost quantitative yields. The corresponding ureido intermediates 2 were not isolable species. However, the reactions with non-sulfonylated isocyanates or isothiocyanates were slower, leading to the expected ureido and thioureido derivatives 5, which were easily and efficiently transformed to either polysubstituted 2-imino-1,3-oxazolidine or 2-imino-1,3-thiazolidine hydrochlorides 7, res…

Triazole-Containing [FeFe] Hydrogenase Mimics: Synthesis and Electrocatalytic Behavior

Through a Cu-catalyzed Huisgen cycloaddition between terminal alkynes and azides (CuAAC) reaction, azide [(μ-SCH2)2N(4-N3C6H4)Fe2(CO)6] has demonstrated to be a robust and versatile reagent able to...

ChemInform Abstract: NHC-Stabilized Gold(I) Complexes: Suitable Catalysts for 6-exo-dig Heterocyclization of 1-(o-Ethynylaryl)ureas.

Under the optimized gold catalysis, the less favored and more challenging 6-exo-dig cyclized products are formed in yields up to 96% from ureas bearing a terminal alkyne at the ortho-position.

New Fluorinated 1,3-Vinylogous Amidines as Versatile Intermediates: Synthesis of Fluorinated Pyrimidin-2(1H)-ones.

The condensation of the azaenolates derived from readily available ketimines with fluorinated nitriles offers an efficient and straightforward entry to new fluorinated 1,3-vinylogous amidines. These versatile compounds, in turn, react with triphosgene to yield new fluorinated pyrimidin-2(1H)-ones in high yields.

Oxygenation of Alkane C−H Bonds with Methyl(trifluoromethyl)dioxirane:  Effect of the Substituents and the Solvent on the Reaction Rate

[Chemical reaction: See text] The mechanism of the oxygenation of alkane C-H bonds with methyl(trifluoromethyl)dioxirane (1a) is studied through the effect of the substituent and solvent on the rate of oxygenation of 2-substituted adamantanes (2). The results suggest a remarkable electron deficiency at the reacting carbon atom in the transition state leading to the regular oxygenation products. The linearity of the Hammett plot reveals that the reaction mechanism does not change within a range of 0.15-0.67 units of sigma(I). A change in the solvent does not affect the distribution of the products, indicating a through-bond transmission of the substituent effect as the origin of the deactiva…

Asymmetric Synthesis of New β,β-Difluorinated Cyclic Quaternary α-Amino Acid Derivatives

The synthesis of new beta,beta-difluorinated cyclic quaternary alpha-amino acid derivatives 1 in which a ring-closing metathesis reaction (RCM) constitutes the key step is described. The approach employs imidoyl chlorides 3 as fluorinated building blocks, and the overall process involves the stereoselective creation of a quaternary stereocenter. Complete selectivity was achieved when (R)-phenylglycinol methyl ether was used as chiral auxiliary, allowing for the preparation of new six-membered cyclic fluorinated alpha-amino acids as single enantiomers.

Synthesis and characterization of monomeric siloxo palladium(II) complexes: crystal structure of [Pd(tmeda)(C6F5)(OSiPh3)]

Abstract Mononuclear palladium-hydroxo complexes of the type [Pd(N–N)(C6F5)(OH)] [(N–N)=2,2′-bipyridine (bipy), 4,4′-dimethyl-2,2′-bipyridine (Me2bipy), or N,N,N′,N′-tetramethylethylenediamine (tmeda)] react with silanols HOSiR3 in toluene giving the corresponding siloxo complexes [Pd(N–N)(C6F5)(OSiR3)]. The X-ray crystal structure of [Pd(tmeda)(C6F5)(OSiPh3)] has been determined. In one of the two molecules in the asymmetric unit there is an intramolecular interaction by phenyl–pentafluorophenyl π-stacking.

Diastereoselective synthesis of antiquorin and related polyoxygenated atisene-type diterpenes

Abstract A diastereoselective approach to polyoxygenated atisene-type diterpenes starting from (S)-(+)-carvone is described. The key steps used in the preparation of the atisene framework are an intramolecular Diels–Alder reaction, an intramolecular diazoketone cyclopropanation, an endocyclic cyclopropane ring cleavage and the regioselective reduction of an allylic bromide by a low-valent chromium species. The synthesis of natural atisanes antiquorin (1), atis-16-ene-3,14-dione (3), atis-16-ene-2,3,14-trione (8) and 3β-hydroxy-atis-16-ene-2,14-dione (9) following this approach is presented. Also described is the synthesis of 18-hydroxy-atis-16-ene-3,14-dione (5), the structure erroneously a…

Mononuclear and binuclear copper(II) complexes with bis(2-imidazolyl)(bis(methoxycarbonyl)methylmethane) (BIBM), a tripodal bis(imidazole) based ligand. Synthesis, crystal structure and magnetic Characterization of [Cu(BIBM)2](ClO4)2 and [{Cu(BIBM)(H2O)}2(μ1,2,3,4-C2O4)](C4O4)·6H2O

Two new Cu(II) complexes with bis(2-imidazolyl) (bis(methoxycarbonyl)methylmethane) (BIBM), a tridentate bis(imidazole) based ligand with the formula [Cu(BIBM) 2 ](ClO 4 ) 2 ( 1 ) and [{Cu(BIBM)(H 2 O)} 2 (μ 1,2,3,4 -C 2 O 4 )](C 4 O 4 )·6H 2 O ( 2 ) have been synthesized and characterized. Compound 1 shows mononuclear cationic [Cu(BIBM) 2 ] 2+ units and perchlorate ions. The coordination around the Cu(II) ion shows a tetragonally-elongated octahedral geometry. The BIBM ligand acts as a k 3 -N,N’,O tripodal ligand, through two imidazole N atoms and a weak Cu–O(carboxymethyl) axial interaction. In the crystal structure cations and anions connect through H-bonds generating linear chains. Line…

Synthesis of 1,3,5-Trisubstituted Hydantoins by Regiospecific Domino Condensation/Aza-Michael/O→N Acyl Migration of Carbodiimides with Activated α,β-Unsaturated Carboxylic Acids.

[reaction: see text] Carbodiimides and suitably activated alpha,beta-unsaturated carboxylic acids react effectively to afford a vast array of 1,3,5-trisubstituted hydantoins by means of a regiospecific domino condensation/aza-Michael/N--O acyl migration. The reaction works well in very mild conditions (20 degrees C, dichloromethane) with fumaric acid derivatives bearing an electron-withdrawing group in the beta position. Good results have been obtained also with less activated substrates bearing only one electron-withdrawing group in the beta position, using more polar solvents (acetonitrile, DMF), and in the presence of a base (2,4,6-trimethylpyridine). Reactions with asymmetric carbodiimi…

A Concise, Asymmetric Synthesis of Tetramic Acid Derivatives

[reaction: see text] A simple, asymmetric synthesis of tetramic acid derivatives is described in this paper. The key step is a carbonyl transfer from carbonyldiimidazole (CDI) to alpha-diimines (I) to form N-alkyl-4-alkylamino-5-methylenepyrrol-2-ones (II). In turn, these compounds can be easily transformed into tetramic acid derivatives (III) in two additional steps.

2,4,5-Trimethylimidazolium Scaffold for Anion Recognition Receptors Acting Through Charge-Assisted Aliphatic and Aromatic C–H Interactions

A series of two-armed 2,4,5-trimethylimidazolium-based oxoanion receptors, which incorporate two end-capped photoactive anthracene rings, being the central core an aromatic or heteroaromatic ring, has been designed. In the presence of HP2O7(3-), H2PO4(-), and SO4(2-) anions, (1)H- and (31)P NMR spectroscopical data clearly indicate the simultaneous occurrence of several charge-assisted aliphatic and aromatic C-H noncovalent interactions, i.e., significant downfield shifts were observed for the imidazolium C(2)-CH3 protons, the methylene N-CH2 protons, and the inner aromatic proton or the outer heteroaromatic protons. Density functional theory calculations confirm the occurrence of these non…

Palladium-catalyzed reaction of boronic acids with chiral and racemic alpha-bromo sulfoxides.

Palladium-catalyzed cross-coupling reactions of racemic alpha-bromo sulfoxides with boronic acids are carried out in either aqueous or nonaqueous medium with formation of a new C sp(3)-C sp(2) bond. The arylation of chiral alpha-bromo sulfoxides occurs without racemization. The cross-coupling reaction is general and gives high yields with arylboronic acids substituted with either donor or acceptor groups but gives poor results with heteroarylboronic acids. The best yields are obtained using degassed solvents and CsF instead of aqueous base. The use of aqueous base and the presence of oxygen favor the homocoupling side reaction.

An efficient synthesis of uracil derivatives from 2-alkyl-Δ2-oxazolines and nitriles

An efficient and convenient synthesis of new fluorinated and non-fluorinated uracils is described herein. The condensation of nitriles with enolates generated from 2-alkyl-Δ 2 -oxazolines (I) affords fluorinated β-enamino acid derivatives, which react with triphosgene to give an isomeric mixture of oxazolopyrimidinones. These can then be easily transformed into a single C-6 pyrimidindione derivative through reaction with a suitable nucleophile.

Electrochemical synthesis of 2-arylimino-4,5-di(2-furyl)-1,3-dioxoles and (E)-1,2-di(2-furyl)vinylene bis(N-arylchloroformimidates). HF and B3LYP computational study of the topomerization mechanism of aryliminodioxoles

Abstract Cathodic reductions of 2,2′-furils in the presence of N-arylcarbonimidoyl dichlorides lead to 2-arylimino-4,5-di(2-furyl)-1,3-dioxoles in high yields, along with minor amounts of (E)-1,2-di(2-furyl)vinylene bis(N-arylchloroformimidates). HF and B3LYP density functional theory methods have been applied to the determination of molecular geometries and to study the topomerization mechanism of aryliminodioxoles. The molecular structure of (E)-1,2-di(2-furyl)vinylene bis[N-(2-chloro-4-methylphenyl)chloroformimidate] has been determined by X-ray crystallography and compared with the calculated structure.

ChemInform Abstract: Electrochemical Synthesis of 2-Arylimino-4,5-di(2-furyl)-1,3-dioxoles and (E)-1,2-Di(2-furyl)vinylene Bis(N-arylchloroformimidates). HF and B3LYP Computational Study of the Topomerization Mechanism of Aryliminodioxoles.

Abstract Cathodic reductions of 2,2′-furils in the presence of N-arylcarbonimidoyl dichlorides lead to 2-arylimino-4,5-di(2-furyl)-1,3-dioxoles in high yields, along with minor amounts of (E)-1,2-di(2-furyl)vinylene bis(N-arylchloroformimidates). HF and B3LYP density functional theory methods have been applied to the determination of molecular geometries and to study the topomerization mechanism of aryliminodioxoles. The molecular structure of (E)-1,2-di(2-furyl)vinylene bis[N-(2-chloro-4-methylphenyl)chloroformimidate] has been determined by X-ray crystallography and compared with the calculated structure.

Asymmetric synthesis of fluorinated amino macrolactones through ring-closing metathesis

The synthesis of new chiral fluorinated amino and azamacrolactones of types 1 and 2 is described. A ring-closing metathesis (RCM) reaction constitutes the key step in this methodology, which uses fluorinated amino alcohols 7 as starting materials. The influence of the CF2 group, which is located in the alpha-position relative to the carbon bearing the amino group, on the efficiency of the RCM reaction is noteworthy. This method allows for the preparation of the desired fluorinated macrolactones in excellent yields.

Semisynthetic roxburghin tetramethyl ether

The title molecule, (E)-2,3′,4,5-tetramethoxystilbene, C18H20O4, is virtually planar. The angle between the two benzene rings is 4.06 (6)°. The intermolecular interactions present in the structure are weak. There are C—H...O hydrogen bonds and C—H...π-electron ring interactions. The molecules are ordered into planes that are parallel to (overline{1}01). The distance between adjacent planes is about 3.3 Å and therefore π–π electron interactions between the aromatic planes are also plausible.

A C(π-hole)⋯Cl-Zn tetrel interaction driving a metal-organic supramolecular assembly

A brominated pyrimidinyl triazolopyridine ligand (bptpy) forms a C(π-hole)⋯Cl-Zn tetrel interaction that plays a determining role in the formation of supramolecular layers through chain assembly in 18 membered metallacycle [(ZnCl2)2(μ-bptpy)2] crystals. Supramolecular chains are formed through C-H⋯X interactions. The observed interactions are supported by DFT calculations using model dimers. This journal is

Hydrogen bonding versus π-stacking in ferromagnetic interactions. Studies on a copper triazolopyridine complex

Magnetic susceptibility measurements show weak ferromagnetic exchange between the copper(II) ions of a novel triazolopyridine derivative [Cu(TPT)(H2O)2(BF4)](BF4)·2H2O (TPT = 3-{6-([1,2,3]triazolo[1,5-a]pyrid-3-yl)-2-pyridyl}-[1,2,3]triazolo[1,5-a]pyridine). Mononuclear [Cu(TPT)(H2O)2(BF4)]+ entities are connected through O–H⋯F, C–H⋯F and π⋯π interactions to give a 3D framework. Ferromagnetic properties are discussed on the basis of the interactions network.

Cationic Cyclopentadienyl Phenylenediamido Titanium Species Generated by Reaction of TiCpR[1,2-C6H4(NCH2t-Bu)2]R (CpR = η5-C5H5, η5-C5Me5; R = CH3, CH2Ph) with B(C6F5)3. X-ray Molecular Structure of Ti(η5-C5Me5)[1,2-C6H4(NCH2t-Bu)2][μ-MeB(C6F5)3]

The reaction of TiCpR[1,2-C6H4(NNp)2]R with the Lewis acid B(C6F5)3 in noncoordinating solvent affords the new zwitterionic species TiCpR[1,2-C6H4(NNp)2)][μ-RB(C6F5)3]. When the reaction is performed in dichloromethane, the [μ-RB(C6F5)3]- anion is displaced by solvent molecules, giving ionic products in which the anion is not coordinated. The cyclopentadienyl zwitterionic complexes TiCp[1,2-C6H4(NNp)2)[μ-RB(C6F5)3] decompose via ligand scrambling between boron and titanium to give the neutral titanium complex TiCp[1,2-C6H4(NNp)2](C6F5) along with the byproduct RB(C6F5)2. In contrast, the pentamethylcyclopentadienyl analogues TiCp*[1,2-C6H4(NNp)2][μ-RB(C6F5)3] evolve through C−H activation t…

The Role of Organic Fluorine in the Supramolecular Assembly of Halogenated β-Hydroxysulphoxides Diastereomers

A series of optically pure γ-halogenated β-hydroxysulphoxides containing two stereogenic centers have been prepared, and the X-ray crystal structures have been determined. The conformational behavior in the solid state and the crystal packing of the different β-hydroxysulphoxide diastereoisomers have been determined. The intermolecular and intramolecular interactions present have been studied in both halogenated and nonhalogenated β-hydroxysulphoxides to establish the influence of the halogen atom in the supramolecular structure. The main intermolecular hydrogen bond OH···OS is always present and produces molecular chains. Self-assembly of these chains includes weak CH···F, C−F···F−C, and C…

Identification of the Iodination and Bromination Products of 3-Hydroxybenzaldehyde: Preparation of 5-Hydroxy-2-iodobenzaldehyde

The monohalogenation products of 3-hydroxybenzaldehyde (1) are useful synthons for the preparation of more complex molecules.1–4 For example, the introduction of a halogen allows the use of a Suzuk...

A new family of "clicked" estradiol-based low-molecular-weight gelators having highly symmetry-dependent gelation ability.

Reported herein is the discovery of a novel family of "clicked" estradiol-based LMWGs whose gelation ability highly depends on the gelator symmetry. These LMWGs that gel different organic solvents in the presence of H(2)O even at concentrations as low as 0.04 wt% are readily accessible using "click" chemistry.

[1,2,3]Triazolo[1,5-a]pyridine derivatives as molecular chemosensors for zinc(ii), nitrite and cyanide anions

Three recently prepared tridentate ligands TPF, TPS and TPT, based on the triazolopyridine–pyridine nucleus possessing fluorescent properties, have been tested as chemosensors for metal ions. A particular response is obtained in the case of ZnTPT+2. The Zn2+ TPT 1 : 1 complex has proved to be an efficient chemosensor for anions especially nitrite and cyanide.

A novel coordination polymer with an unusual [3×2] oblique copper(II) grid: [Cu2(HBIMAM)2(C4O4)3(H2O)2]n·2nH2O [BIMAM=bis(imidazol-2-yl)methylaminomethane]. X-ray structure and magnetic characterization

Abstract This paper reports the synthesis, X-ray structure and magnetic characterization of [Cu2(HBIMAM)2(C4O4)3(H2O)2]n·2nH2O [BIMAM = bis(imidazol-2-yl)methylamino methane]. This compound is made of infinite chains – running along the [1 1 0] direction – with copper ions bridged by μ1,3-squarato ligands. Furthermore, these chains are further cross-linked through additional squarate anions (with the same μ1,3-bis(monodentate) bridging mode) to generate two-dimensional sheets parallel to the ab plane. There are inter-chains links every two copper atoms in a chain, forming an unusual (3 × 2) oblique copper(II) grid. Magnetic susceptibility measurements in the range 2–300 K show weak antiferr…

Revisiting the photochemical synthesis of [FeFe]-hydrogenase mimics: reaction optimization, mechanistic study and electrochemical behaviour

The photoreaction of [(μ-S)2Fe2(CO)6] and alkenes or alkynes has been optimized to readily obtain functionalized [FeFe]-hydrogenase mimics. Irradiation under low CO pressure in THF produces the corresponding photo-adducts in good/acceptable (alkenes/alkynes) yields, with retention of the starting olefin stereochemistry. DFT-calculations provide plausible reaction pathways in both, singlet and triplet states. The DFT-calculation based in the singlet state is energetically more favorable. The electrochemical behavior of the synthesized compounds is also presented, including studies in acidic media. The electrochemical properties of the products vary in the presence of a double bond (cycloaddi…

Experimental and theoretical insights in the alkene-arene intramolecular π-stacking interaction

Chiral acrylic esters derived from biomass were developed as models to have a better insight in the aryl-vinyl π-stacking interactions. Quantum chemical calculations, NMR studies and experimental evidences demonstrated the presence of equilibriums of at least four different conformations: π-stacked and face-to-edge, each of them in an s-cis/s-trans conformation. The results show that the stabilization produced by the π-π interaction makes the π-stacked conformation predominant in solution and this stabilization is slightly affected by the electron density of the aromatic counterpart. Fil: Corne, Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológi…

New Fluorinated Peptidomimetics through Tandem Aza-Michael Addition to α-Trifluoromethyl Acrylamide Acceptors: Synthesis and Conformational Study in Solid State and Solution

A range of partially modified retro (PMR) psi[NHCH(2)] peptide mimetics containing a hydrolytically stable CH(2)CH(CF(3))CO unit have been synthesized. The first kind of peptidomimetics is obtained from the highly efficient aza-Michael addition of different amines to alpha-trifluoromethyl acrylamide acceptors. Subsequent deprotection of the amino group furnishes the key common intermediate for the synthesis of other families of peptidomimetics: dipeptides, tripeptides, peptidomimetics containing a urea moiety, and structures containing two units of alpha-trifluoromethyl-beta(2)-alanine. Finally, a conformational study of several of the newly synthesized peptidomimetics, performed with the a…

Insertion of One, Two, and Three Molecules of Alkyne into the Pd−C Bond of Ortho-palladated Primary and Secondary Arylalkylamines

The ortho-metalated complex [Pd2{κ2(C,N)-C6H4CH2CH2NHMe-2}2(μ-Br)2] (1) can be prepared by refluxing a 1:1 mixture of Pd(OAc)2 and N-methylphenethylamine in acetonitrile, followed by addition of an excess of NaBr. Complex 1 reacts with PPh3 to give the mononuclear derivative [Pd{κ2(C,N)-C6H4CH2CH2NHMe-2}Br(PPh3)] (2). The cationic complex [Pd{κ2(C,N)-C6H4CH2CH2NHMe-2}(py)2]ClO4 (3) can be obtained by reacting 1 with AgClO4 and pyridine. The previously reported complex [Pd2{κ2(C,N)-C6H4CH2NHCH2Ph-2}2(μ-Br)2] (A) reacts with PhC≡CCO2R (R = Me, Et) to give the monoinserted derivatives [Pd2{κ2(C,N)-C(Ph)═C(CO2R)C6H4CH2NHCH2Ph-2}2(μ-Br)2] (R = Me (4a), Et (4b)). These dimers react with neutral l…

[3.3]Ferrocenophanes with guanidine bridging units as multisignalling receptor molecules for selective recognition of anions, cations, and amino acids.

The synthesis, electrochemical, and optical properties of a new [3.3]ferrocenophane framework in which two ferrocene subunits, with similar electronic environments, are linked through two substituted guanidine moieties, are reported. The receptors 4-7 have been prepared in good yields by the reaction of bis(carbodiimide) 3 with primary amines. This architecture is exceptionally "tunable" because a variety of "legs" may be appended to the basic [3.3]ferrocenophane scaffold to give a wide range of signaling units. These receptors show remarkable ion-sensing properties, due to the presence of a redox active unit (ferrocene), and an amphoteric binding site (guanidine). In this nitrogen-rich str…

CCDC 1440542: Experimental Crystal Structure Determination

Related Article: Miguel A. Sierra, Alba D. Merinero, Elena A. Giner, Mar Gómez-Gallego, Carmen Ramírez de Arellano|2016|Chem.-Eur.J.|22|13521|doi:10.1002/chem.201601735

CCDC 1045718: Experimental Crystal Structure Determination

Related Article: Gong M. Chu, Israel Fernández, Andrés Guerrero-Martínez, Carmen Ramírez de Arellano and Miguel A. Sierra|2016|Eur.J.Inorg.Chem.||844|doi:10.1002/ejic.201501283

CCDC 1485045: Experimental Crystal Structure Determination

Related Article: Elena A. Giner, Alicia Santiago, Mar Gómez-Gallego, Carmen Ramírez de Arellano, Rebecca C. Poulten, Michael K. Whittlesey, and Miguel A. Sierra|2015|Inorg.Chem.|54|5450|doi:10.1021/acs.inorgchem.5b00492

CCDC 1045717: Experimental Crystal Structure Determination

Related Article: Gong M. Chu, Israel Fernández, Andrés Guerrero-Martínez, Carmen Ramírez de Arellano and Miguel A. Sierra|2016|Eur.J.Inorg.Chem.||844|doi:10.1002/ejic.201501283

CCDC 1440541: Experimental Crystal Structure Determination

Related Article: Miguel A. Sierra, Alba D. Merinero, Elena A. Giner, Mar Gómez-Gallego, Carmen Ramírez de Arellano|2016|Chem.-Eur.J.|22|13521|doi:10.1002/chem.201601735

CCDC 2026029: Experimental Crystal Structure Determination

Related Article: Carmen Ramírez de Arellano, Rosa Adam, Rafael Ballesteros-Garrido, Belen Abarca, Rafael Ballesteros, Ibon Alcorta, José Elguero, Emilio Escrivà|2020|CrystEngComm|22|6979|doi:10.1039/D0CE01272F

CCDC 1960548: Experimental Crystal Structure Determination

Related Article: Sergio Aguado, Luis Casarrubios, Carmen Ramírez de Arellano, Miguel A. Sierra|2020|RSC Advances|10|29855|doi:10.1039/D0RA06002J

CCDC 1054408: Experimental Crystal Structure Determination

Related Article: Alexandra R. Rivero , Israel Fernández , Carmen Ramírez de Arellano , and Miguel A. Sierra|2015|J.Org.Chem.|80|1207|doi:10.1021/jo502292y

CCDC 1440540: Experimental Crystal Structure Determination

Related Article: Miguel A. Sierra, Alba D. Merinero, Elena A. Giner, Mar Gómez-Gallego, Carmen Ramírez de Arellano|2016|Chem.-Eur.J.|22|13521|doi:10.1002/chem.201601735

CCDC 626412: Experimental Crystal Structure Determination

Related Article: Antonio Abad, Consuelo Agulló, Ana C. Cuñat, Ignacio de Alfonso Marzal, Antonio Gris, Ismael Navarro, Carmen Ramírez de Arellano|2007|Tetrahedron|63|1664|doi:10.1016/j.tet.2006.11.083

CCDC 952797: Experimental Crystal Structure Determination

Related Article: Marta Valencia, Mamen Martín-Ortiz, Mar Gómez-Gallego, Carmen Ramírez de Arellano, Miguel A. Sierra|2014|Chem.-Eur.J.|20|3831|doi:10.1002/chem.201304091

CCDC 1829500: Experimental Crystal Structure Determination

Related Article: Marta Guerola, Marcos Escolano, Gloria Alzuet-Piña, Enrique Gómez-Bengoa, Carmen Ramírez de Arellano, María Sánchez-Roselló, Carlos del Pozo|2018|Org.Biomol.Chem.|16|4650|doi:10.1039/C8OB01139G

CCDC 1915911: Experimental Crystal Structure Determination

Related Article: Encarnación Navarro-García, María D. Velasco, Fabiola Zapata, Antonio Bauzá, Antonio Frontera, Carmen Ramírez de Arellano, Antonio Caballero|2019|Dalton Trans.|48|11813|doi:10.1039/C9DT02012H

CCDC 1535717: Experimental Crystal Structure Determination

Related Article: Elena A. Giner, Mar Gómez-Gallego, Alba D. Merinero, Luis Casarrubios, Carmen Ramírez de Arellano, Miguel A. Sierra|2017|Chem.-Eur.J.|23|8941|doi:10.1002/chem.201701100

CCDC 1884097: Experimental Crystal Structure Determination

Related Article: Alba D. Merinero, Alba Collado, Luis Casarrubios, Mar Gómez-Gallego, Carmen Ramírez de Arellano, Antonio Caballero, Fabiola Zapata, Miguel A. Sierra|2019|Inorg.Chem.|58|16267|doi:10.1021/acs.inorgchem.9b02813

CCDC 1449799: Experimental Crystal Structure Determination

Related Article: Miriam Más-Montoya, Laura Usea, Arturo Espinosa Ferao, María F. Montenegro, Carmen Ramírez de Arellano, Alberto Tárraga, José N. Rodríguez-López, and David Curiel|2016|J.Org.Chem.|81|3296|doi:10.1021/acs.joc.6b00265

CCDC 1915912: Experimental Crystal Structure Determination

Related Article: Encarnación Navarro-García, María D. Velasco, Fabiola Zapata, Antonio Bauzá, Antonio Frontera, Carmen Ramírez de Arellano, Antonio Caballero|2019|Dalton Trans.|48|11813|doi:10.1039/C9DT02012H

CCDC 1536882: Experimental Crystal Structure Determination

Related Article: Elena A. Giner, Mar Gómez-Gallego, Luis Casarrubios, María C. de la Torre, Carmen Ramírez de Arellano, Miguel A. Sierra|2017|Inorg.Chem.|56|2801|doi:10.1021/acs.inorgchem.6b02957

CCDC 1469282: Experimental Crystal Structure Determination

Related Article: Carlos J. Gómez-García, Emilio Escrivà, Samia Benmansour, Juan J. Borràs-Almenar, José-Vicente Folgado, and Carmen Ramírez de Arellano|2016|Inorg.Chem.|55|2664|doi:10.1021/acs.inorgchem.6b00105

CCDC 893127: Experimental Crystal Structure Determination

Related Article: Francisco Otón , María del Carmen González , Arturo Espinosa , Carmen Ramírez de Arellano , Alberto Tárraga , and Pedro Molina|2012|J.Org.Chem.|77|10083|doi:10.1021/jo301570u

CCDC 743200: Experimental Crystal Structure Determination

Related Article: Abdelkarim El Moncef, M. Consuelo Cuquerella, Elena Zaballos, Carmen Ramírez de Arellano, Abdeslem Ben-Tama, Salah-Eddine Stiriba and Julia Pérez-Prieto|2010|Chem.Commun.|46|800|doi:10.1039/B915792A

CCDC 952795: Experimental Crystal Structure Determination

Related Article: Marta Valencia, Mamen Martín-Ortiz, Mar Gómez-Gallego, Carmen Ramírez de Arellano, Miguel A. Sierra|2014|Chem.-Eur.J.|20|3831|doi:10.1002/chem.201304091

CCDC 1536511: Experimental Crystal Structure Determination

Related Article: Santiago Matías Ruatta, Marcelo César Murguía, Carmen Ramírez de Arellano, Santos Fustero|2017|Tetrahedron Lett.|58|2441|doi:10.1016/j.tetlet.2017.05.029

CCDC 1061399: Experimental Crystal Structure Determination

Related Article: Ana Gimeno, Alejandra Rodríguez-Gimeno, Ana B. Cuenca, Carmen Ramírez de Arellano, Mercedes Medio-Simón, Gregorio Asensio|2015|Chem.Commun.|51|12384|doi:10.1039/C5CC04606H

CCDC 1469281: Experimental Crystal Structure Determination

Related Article: Carlos J. Gómez-García, Emilio Escrivà, Samia Benmansour, Juan J. Borràs-Almenar, José-Vicente Folgado, and Carmen Ramírez de Arellano|2016|Inorg.Chem.|55|2664|doi:10.1021/acs.inorgchem.6b00105

CCDC 1884096: Experimental Crystal Structure Determination

Related Article: Alba D. Merinero, Alba Collado, Luis Casarrubios, Mar Gómez-Gallego, Carmen Ramírez de Arellano, Antonio Caballero, Fabiola Zapata, Miguel A. Sierra|2019|Inorg.Chem.|58|16267|doi:10.1021/acs.inorgchem.9b02813

CCDC 952796: Experimental Crystal Structure Determination

Related Article: Marta Valencia, Mamen Martín-Ortiz, Mar Gómez-Gallego, Carmen Ramírez de Arellano, Miguel A. Sierra|2014|Chem.-Eur.J.|20|3831|doi:10.1002/chem.201304091

CCDC 1839885: Experimental Crystal Structure Determination

Related Article: Cristina Mulet, Marcos Escolano, Sebastián Llopis, Sergio Sanz, Carmen Ramírez de Arellano, María Sánchez‐Roselló, Santos Fustero, Carlos del Pozo|2018|Adv.Synth.Catal.|360|2885|doi:10.1002/adsc.201800548

CCDC 1471182: Experimental Crystal Structure Determination

Related Article: Gong M. Chu, Andrés Guerrero-Martínez, Carmen Ramírez de Arellano, Israel Fernández, and Miguel A. Sierra|2016|Inorg.Chem.|55|2737|doi:10.1021/acs.inorgchem.5b02448

CCDC 1824868: Experimental Crystal Structure Determination

Related Article: María Frutos, Mar Gómez-Gallego, Elena A. Giner, Miguel A. Sierra, Carmen Ramírez de Arellano|2018|Dalton Trans.|47|9975|doi:10.1039/C8DT02296H

CCDC 953983: Experimental Crystal Structure Determination

Related Article: Ana Gimeno, Ana B. Cuenca, Samuel Suárez-Pantiga, Carmen Ramírez de Arellano, Mercedes Medio-Simón, Gregorio Asensio|2014|Chem.-Eur.J.|20|683|doi:10.1002/chem.201304087

CCDC 1824870: Experimental Crystal Structure Determination

Related Article: María Frutos, Mar Gómez-Gallego, Elena A. Giner, Miguel A. Sierra, Carmen Ramírez de Arellano|2018|Dalton Trans.|47|9975|doi:10.1039/C8DT02296H

CCDC 1910411: Experimental Crystal Structure Determination

Related Article: Emilio Escrivà, José-Vicente Folgado, Amparo Sancho, Rosa Ortíz, Lourdes Perelló, Carmen Ramírez de Arellano|2019|Polyhedron|171|137|doi:10.1016/j.poly.2019.06.054

CCDC 2026030: Experimental Crystal Structure Determination

Related Article: Carmen Ramírez de Arellano, Rosa Adam, Rafael Ballesteros-Garrido, Belen Abarca, Rafael Ballesteros, Ibon Alcorta, José Elguero, Emilio Escrivà|2020|CrystEngComm|22|6979|doi:10.1039/D0CE01272F

CCDC 1449800: Experimental Crystal Structure Determination

Related Article: Miriam Más-Montoya, Laura Usea, Arturo Espinosa Ferao, María F. Montenegro, Carmen Ramírez de Arellano, Alberto Tárraga, José N. Rodríguez-López, and David Curiel|2016|J.Org.Chem.|81|3296|doi:10.1021/acs.joc.6b00265

CCDC 1535716: Experimental Crystal Structure Determination

Related Article: Elena A. Giner, Mar Gómez-Gallego, Alba D. Merinero, Luis Casarrubios, Carmen Ramírez de Arellano, Miguel A. Sierra|2017|Chem.-Eur.J.|23|8941|doi:10.1002/chem.201701100

CCDC 953982: Experimental Crystal Structure Determination

Related Article: Ana Gimeno, Ana B. Cuenca, Samuel Suárez-Pantiga, Carmen Ramírez de Arellano, Mercedes Medio-Simón, Gregorio Asensio|2014|Chem.-Eur.J.|20|683|doi:10.1002/chem.201304087

CCDC 1536881: Experimental Crystal Structure Determination

Related Article: Elena A. Giner, Mar Gómez-Gallego, Luis Casarrubios, María C. de la Torre, Carmen Ramírez de Arellano, Miguel A. Sierra|2017|Inorg.Chem.|56|2801|doi:10.1021/acs.inorgchem.6b02957

CCDC 1824869: Experimental Crystal Structure Determination

Related Article: María Frutos, Mar Gómez-Gallego, Elena A. Giner, Miguel A. Sierra, Carmen Ramírez de Arellano|2018|Dalton Trans.|47|9975|doi:10.1039/C8DT02296H

CCDC 1514944: Experimental Crystal Structure Determination

Related Article: Raul Blasco, Carmen Ramírez de Arellano, Juan F. Sanz-Cervera|2017|Org.Prep.Proced.Int.|49|265|doi:10.1080/00304948.2017.1320924

CCDC 1910410: Experimental Crystal Structure Determination

Related Article: Emilio Escrivà, José-Vicente Folgado, Amparo Sancho, Rosa Ortíz, Lourdes Perelló, Carmen Ramírez de Arellano|2019|Polyhedron|171|137|doi:10.1016/j.poly.2019.06.054

CCDC 952794: Experimental Crystal Structure Determination

Related Article: Marta Valencia, Mamen Martín-Ortiz, Mar Gómez-Gallego, Carmen Ramírez de Arellano, Miguel A. Sierra|2014|Chem.-Eur.J.|20|3831|doi:10.1002/chem.201304091

CCDC 893839: Experimental Crystal Structure Determination

Related Article: Emilio Escrivá, Lucía Soto, Juan Server-Carrió, Carlos J. Gómez-García, Guillermo Mínguez Espallargas, Nailette Ruiz, Amparo Sancho, Julia García-Lozano, Carmen Ramírez de Arellano|2013|Polyhedron|56|90|doi:10.1016/j.poly.2013.03.016