0000000000077235
AUTHOR
Luca Russo
Evidence of the Facile Hydride and Enolate Addition to the Imine Bond of an Aluminum−Salophen Complex
The isolation of complexes 2 and 3, unambiguously characterized by single-crystal X-ray diffraction, demonstrates that nucleophilic additions to the aluminum-coordinated imino bond of salophen complex 1 can be achieved under very mild conditions.
Titelbild: Direct CH Metalation with Chromium(II) and Iron(II): Transition-Metal Host / Benzenediide Guest Magnetic Inverse-Crown Complexes (Angew. Chem. 18/2009)
Chrom und Eisen als die neuesten Erganzungen des Konzepts der alkalimetallvermittelten Metallierung stellen J. Klett, R. E. Mulvey et al. in ihrer Zuschrift auf S. 3367 ff. vor. Das elektropositivere Natrium ist wesentlich fur die Reaktion, doch das weniger elektropositive Chrom oder Eisen ist es, das Benzol tatsachlich deprotoniert. Diese neuartige Reaktivitat kann mit einem Schachspiel verglichen werden, bei dem die Konigin (Na) dem Konig Schach bietet und der Springer (Cr, Fe) Matt setzt.
A modular "toolbox" approach to flexible branched multimacrocyclic hosts as precursors for multiply interlocked architectures.
Tetralactam macrocycles can be functionalized by a variety of cross-coupling reactions. A modular “toolbox” strategy is presented that allows 1) several tetralactam macrocycles to be covalently connected with each other or with a central spacer, 2) the macrocycles to be substituted with or connected to different chromophores, and 3) metal-coordination sites to be attached to the macrocycles. With this approach a series of different oligo-macrocyclic hosts was obtained with great structural diversity and enormous potential for further functionalization. Rotaxanes made on the basis of these macrocycles have been synthesized to demonstrate their utility in building more complex supramolecular …
Zinc-salophen complexes as selective receptors for tertiary amines
Zinc-salophen compounds 1-3 incorporating in the given order 1,2-diaminobenzene, 2,3-diaminonaphthalene, and 9,10-diaminophenantrene moieties were synthesised. Their binding properties toward a series of tertiary amines were assessed by UV-Vis and fluorescence spectroscopy in chloroform solution. Unprecedented selectivities of quinuclidine vs. triethylamine higher than 105 were recorded, thereby revealing the dramatic influence of steric effects on axial coordination of tertiary amines. X-Ray diffraction analyses showed that in the solid state compound 2 is dimeric, but its 1 : 1 quinuclidine complex is monomeric. Strong indications were obtained that both free receptors and their amine add…
catena-Poly[benzyltriethylammonium [tri-μ-thiocyanato-κ4N:S;κ2S:N-cadmate(II)]]
The title compound, {[(C6H5CH2)N(C2H5)3][Cd(SCN)3]}n, contains benzyltriethylammonium cations lying between one-dimensional chains of stoichiometry {[Cd(SCN)3]−}n. Each Cd2+ ion is 3N,3S-hexacoordinated by thiocyanate ligands in an octahedral arrangement. The asymmetric unit contains one cation and one anion.
Three 2,5-dialkoxy-1,4-diethynylbenzene derivatives
2,5-Diethoxy-1,4-bis[(trimethylsilyl)ethynyl]benzene, C20H30O2Si2, (I), constitutes one of the first structurally characterized examples of a family of compounds, viz. the 2,5-dialkoxy-1,4-bis[(trimethylsilyl)ethynyl]benzene derivatives, used in the preparation of oligo(phenyleneethynylene)s via Pd/Cu-catalysed cross-coupling. 2,5-Diethoxy-1,4-diethynylbenzene, C14H14O2, (II), results from protodesilylation of (I). 1,4-Diethynyl-2,5-bis(heptyloxy)benzene, C24H34O2, (III), is a long alkyloxy chain analogue of (II). The molecules of compounds (I)–(III) are located on sites with crystallographic inversion symmetry. The large substituents either in the alkynyl group or in the benz…
Bis[(trimethylsilyl)methyl]manganese: Structural Variations of Its Solvent-Free and TMEDA-, Pyridine-, and Dioxane-Complexed Forms
First synthesized in 1976 and recently taking on a new significance as a key precursor to heterobimetallic alkali-metal-manganese(II) complexes, bis[(trimethylsilyl)methyl] manganese has been structurally characterized by X-ray crystallography. It forms a polymeric chain structure of formula [{Mn(CH2SiMe3)(2)}(infinity)], 1, in which distorted tetrahedral, spiro Mn atoms are linked together via mu(2)-bonding alkyl ligands. The structure is notable for displaying two distinct categories of Mn-C bond lengths with a mean size differential of 0.225 angstrom and for being the first fully crystallographically characterized polymeric manganese(II) dialkyl compound. Magnetic measurements of 1 indic…
Hierarchical, Lithium‐Templated Assembly of Helicate‐Type Complexes: How Versatile Is This Reaction?
Catechol ligands that bear carbonyl functions such as esters or aldehydes in the 3-position (1a–c-H2) form triple-stranded, helicate-type complexes [Li3(1a–c)6Ti2]– with titanium(IV) and the corresponding double-stranded compounds [Li2(1a–c)4B2] with boron(III) in hierarchical, lithium-templatedprocesses. The related 8-hydroxyquinoline ligands 2a,b-H can be used for the formation of similar complexes[Li3(2a,b)6M2]+ with cobalt(II), nickel(II), or zinc(II). A prerequisite for the formation of the lithium-bridged dimers is a negative charge of the mononuclear complexes, which are able to electrostatically attract the lithium cations and thus compensate the repulsion between the cations. (© Wi…
Generation of [2×2] Grid Metallosupramolecular Architectures from Preformed Ditopic Bis(acylhydrazone) Ligands and through Component Self‐Assembly
Ditopic bis(acylhydrazone) ligands, derived from the reactions of carbohydrazides with 2-phenylpyrimidine-4,6-dicarbaldehyde and designed for grid formation with octahedrally coordinating transition-metal ions, exhibit a varied coordination chemistry depending upon the degree of their deprotonation. The neutral acylhydrazones are relatively poor ligands and are seemingly involved in multiple, labile complexation equilibria varying with the solvent and the particular metal salt in solution; nevertheless, grid complexes of different forms can be isolated in the solid state. Although only limited study has been made of the singly deprotonated ligands, grid species appear to be much more readil…
cis-Aquabis[bis(diphenylphosphino)ethane-κ2 P,P′]chlororuthenium(II) hexafluorophosphate dichloromethane sesquisolvate hemihydrate
In the title compound, [RuCl(C26H24P)2(H2O)]PF6·1.5CH2Cl2·0.5H2O, the complex RuII cation is in a slightly distorted octahedral environment, chelated by two bis(diphenylphosphino)ethane ligands, with a water molecule and a chloride anion in a mutually cis geometry completing the coordination.
Sodium-mediated manganation: direct mono- and dimanganation of benzene and synthesis of a transition-metal inverse-crown complex.
Inside out approach: Twofold deprotonation of benzene by a sodium monoalkyl bisamido manganate(II) reagent derived from BuNa, 2,2,6,6-tetramethylpiperidine, and Mn(CH2SiMe3)2 has produced the first inverse-crown complex in which the transition-metal atoms are incorporated in the host (see X-ray structure, blue N, green Na, purple Mn). Variable-temperature magnetization measurements show that the complex is antiferromagnetic.
cis-[Bis(diphenylphosphino)ethane-κ2P,P′]dichlororuthenium(II) dichloromethane disolvate
The title compound, cis-[RuCl2(C26H24P2)2]·2CH2Cl2, was obtained as an unexpected product from our attempts to prepare new ruthenium molecular wires using organic bridging ligands. Three solvates and a solvent-free structure of the isomeric complex with the chloride anions in a trans geometry have already been reported, while the cis isomer has been described only in solution studies prior to this work.
Tuning the Basicity of Synergic Bimetallic Reagents: Switching the Regioselectivity of the Direct Dimetalation of Toluene from 2,5‐ to 3,5‐Positions
Meta-meta metalation: Remarkably, toluene can be directly dimanganated or dimagnesiated at the 3,5-positions using bimetallic bases with active Me3SiCH2 ligands (see scheme, blue). In contrast, n-butyl ligands lead to 2,5-metalation (red). tmp=2,2,6,6-tetramethylpiperidide.
cis-Diazido[bis(diphenylphosphino)methane-κ2P,P′]ruthenium(II) dichloromethane 0.42-solvate
Submitted by António Freitas (amsf@uma.pt) on 2019-06-13T13:44:22Z No. of bitstreams: 1 cis-Diazidobis(diphenylphosphino)methane-j2PP000ruthenium(II) dichloromethane 0.42-solvateJoãoRodrigues.pdf: 167616 bytes, checksum: 2ba0b7a76027be3eda26ce11d43fec66 (MD5) Made available in DSpace on 2019-06-13T13:44:22Z (GMT). No. of bitstreams: 1 cis-Diazidobis(diphenylphosphino)methane-j2PP000ruthenium(II) dichloromethane 0.42-solvateJoãoRodrigues.pdf: 167616 bytes, checksum: 2ba0b7a76027be3eda26ce11d43fec66 (MD5) Previous issue date: 2006 info:eu-repo/semantics/publishedVersion
Three-Component Entanglements Consisting of Three Crescent-Shaped Bidentate Ligands Coordinated to an Octahedral Metal Centre
3,3'-biisoquinoline ligands (biiq) L, bearing aromatic substituents on their 8 and 8' positions, have been used to generate interwoven systems consisting of three crescent-shaped ligands disposed around an octahedral metal centre. Mono-ligand complexes of the type [ReL(CO)3py]+ (py: pyridine) have also been prepared, leading to sterically non-hindering complexes in spite of the endotopic nature of the chelate used. The three-component entanglements have been prepared by using either FeII or RuII as gathering metal centre. The synthetic procedure is simple and efficient, affording fully characterised complexes as their PF6 or SbCl6 salts. X-ray crystallography clearly shows that the crescent…
Anion Receptors Based on a Quinoline Backbone
2-Amido-8-urea substituted quinoline derivatives are potent receptors for the binding of halide or benzoate anions in chloroform. The selectivity and affinity of the receptors for fluoride can be tuned by variation of the substituents at the receptor side chains. Computational considerations show that the cleft of the receptors provides space for effective binding of F–, but not bigger anions.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Can tongue position and cervical ROM affect postural oscillations? A pilot and preliminary study
The tongue is considered an important part of the postural system, so it is fundamental to understand how it can interfere with the humans’ postural oscillations. The aim of this preliminary investigation is to understand the effects of different tongue position and cervical ROM on postural oscillations measured in a stabilometric test. Thirteen voluntary subjects were recruited (30.8 ± 9.7 yrs.; 173.6 ± 14.9 cm; 72.6 ± 15.6 kg) and tested in three different random tongue conditions: comfortable tongue position (CT), palatal spot position (ST) and low tongue position (LT). All tests were performed with open eyes. Stabilometric test were performed with a pressure platform. In addition, the c…
Synthesis, characterization and solid-state photoluminescence studies of six alkoxy phenylene ethynylene dinuclear palladium(II) rods
A rare family of six discrete binuclear [PdCl(PEt3)2] phenylene ethynylene rods with alkoxy side chains (methoxy, ethoxy and heptoxy) have been developed, and their solid-state photoluminescence results have been presented and discussed. The shorter bridging ligands are of the general formula H–CuC– C6H2(R)2–CuC–H, where R = H, OCH3, OC 2H5, and OC7H15, whereas the longer ones are based on H– CuC–C6H4–CuC–C6H2(R)2–CuC–C6H4–CuC–H, where R = OCH3, OC 2H5. These ligands display increasing length in both the main dimension (backbone length) as well as the number of carbons in the side chains (R, alkoxide side chain) that stem from the central phenylene moiety. The X-ray crystal structures of tw…
A novel global postural alteration? Qualitative assessment of hallux valgus and swallowing disorder in human posture: A preliminary investigation on the incidence during age span for promoting psycho-physical and postural well-being
Hallux Valgus (HV) and Swallowing Disorder (SD) are two multifactorial postural and biomechanical alterations. It is very important to look for the incidence of these two conditions in order to promote psycho-physical and postural well-being. Our study aimed to clinically assess the presence of HV and SD in a large group with different ages spans. Fours skilled professionals performed the assessment following clinical criteria. A total of 61 volunteers subjects (163.5 ± 14.1 cm; 59.7 ± 15.7 kg; 22.9 ± 13.2 yrs.) were selected for the study. The 51% of the sample showed the HV alteration, 30% and 73% respectively for male and female. Regarding ages cluster, the HV was present in 44% under 20…
Dimerization of (+)-Lysergic Acid Esters
Dimer isomer mixtures, characterized by a bridgehead C8-C8' bond, (6a-7a; 6b-7b) were obtained from (+)-lysergic acid methyl or ethyl ester (1b; 1c) in a solution of methanol or ethanol. The isomers were separated, and their structures were determined by detailed NMR measurements and X-ray analysis. Density functional theory was applied to provide insight into the reaction mechanism. Based on an extended examination and the theoretical calculations, a plausible reaction sequence leading to dimers is also presented. The proposed mechanism has been verified by detecting the formation of the superoxide radical anion (O 2 * -).
Brown bear behaviour in human-modified landscapes: The case of the endangered Cantabrian population, NW Spain
Large carnivores are recolonizing parts of their historical range in Europe, a heavily modified human landscape. This calls for an improvement of our knowledge on how large carnivores manage to coexist with humans, and on the effects that human activity has on large carnivore behaviour, especially in areas where carnivore populations are still endangered. Brown bears Ursus arctos have been shown to be sensitive to the presence of people and their activities. Thus, bear conservation and management should take into account potential behavioural alterations related to living in human-modified landscapes. We studied the behaviour of brown bears in the Cantabrian Mountains, NW Spain, where an en…
E-Ring extended estrone derivatives: introduction of 2-phenylcyclopentenone to the estrone D-ring via an intermolecular Pauson–Khand reaction
Abstract An expedient synthetic route to E-ring extended estrone derivatives is reported. Estrone-derived cyclopentenones were accessed by an intermolecular Pauson–Khand (PK) cycloaddition. It was found that electron donating and withdrawing substituents in the arylalkyne increased and decreased the yields of PK products, respectively. The stereochemistry of the products was elucidated by X-ray and NMR studies.
A new hydrogen bonding motif involved in self-recognition in the solid state by functionalised macrocycles
Self-recognition within the crystal lattices of three functionalised macrocycles results in the formation of arrays of remarkably similar hermaphroditic pairs of macrocycles. In the case of two of the macrocycles containing acylhydrazine substituents, a hitherto unknown recognition pattern is found in the interaction of the hydrazine moiety with crown-ether oxygen atoms.
Sodium Congener of the Classical Lithium Methylchromate Dimer: Synthetic, X-ray Crystallographic, and Magnetic Studies of Me8Cr2[Na(OEt2)]4
One of the milestone structures in the development of transition-metal complexes with metal metal bonds of multiple bond order was the lithium methylchromate dimer Me8Cr2[Li(donor)](4) (donor = THF or Et2O). Using a simple salt metathesis reaction mixing this compound with sodium tert-butoxide, the sodium congener Me8Cr2-[Na(OEt2)]4 has been synthesized as a green crystalline compound and isolated in 51% yield. Its solid-state structure was determined by single-crystal X-ray diffraction. Exhibiting exact crystallographic C-4h symmetry, this heavier alkali-metal chromate structure is also dimeric, formally comprising a (Me8Cr4)(4-) tetranionic core with four peripheral Na+ cations carrying s…
Cover Picture: Direct CH Metalation with Chromium(II) and Iron(II): Transition-Metal Host / Benzenediide Guest Magnetic Inverse-Crown Complexes (Angew. Chem. Int. Ed. 18/2009)
Chromation and ferration are the latest additions to the concept of alkali-metal-mediated metalation, as described by J. Klett, R. E. Mulvey, and co-workers in their Communication on page 3317 ff. While the more electropositive sodium is essential for the reaction, it is the less electropositive chromium or iron that actually performs deprotonation of benzene. This novel reactivity can be likened to a game of chess in which the queen (Na) holds the king in check, while the knight (Cr, Fe) scores checkm(etal)ate.
Direct C-H metalation with chromium(ii) and iron(ii): transition- metal host/benzenediide guest magnetic inverse-crown complexes
Check M(etal)ate: The chessboard and the figures represent a special reaction in which different low-polarity metals can metalate arenes directly when they are brought into the right position. In a combination of queen (sodium) and knight (chromium or iron), it is possible for the knight (usually the weaker piece) to make a direct deadly hit on the king (benzene) in this game of elemental chess. Fil: Alborés, Pablo. Johannes Gutenberg Universitat Mainz; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Carrella, Luca M.. Johannes Gutenberg Universitat Mainz; Alemania Fil: Clegg, William. University of Newcastle; Reino Unido Fil: García Álvarez, Pablo. Univ…
Solution stoichiometry determines crystal stoichiometry in halogen-bonded supramolecular complexes
The behavior of the methylisonicotinate (MINC) building block as halogen bonding-acceptor module has been investigated in the solid state. Both the N and the O atoms of MINC interact with the iodine atoms of 1,4-diiodotetrafluorobenzene (DITFB) giving rise to N⋯I and O⋯I interactions. Hierarchy between these interactions allows the control of the composition and thus the structure of the supramolecular complex, according to the composition of the reaction mixture. A structure based on an infinite chain and a trimeric supermolecule have been obtained starting from a 1 ∶ 1 MINC/DITFB stoichiometry or by using a large excess of MINC, respectively. While the former structure shows simultaneous …
Structural and Magnetic Insights into the Trinuclear Ferrocenophane and Unexpected Hydrido Inverse Crown Products of Alkali‐Metal‐Mediated Manganation(II) of Ferrocene
With the aim of introducing the diisopropylamide [NiPr(2)](-) ligand to alkali-metal-mediated manganation (AMMMn) chemistry, the temperature-dependent reactions of a 1:1:3 mixture of butylsodium, bis(trimethylsilylmethyl)manganese(II), and diisopropylamine with ferrocene in hexane/toluene have been investigated. Performed at reflux temperature, the reaction affords the surprising, ferrocene-free, hydrido product [Na(2)Mn(2) (mu-H)(2){N(iPr)(2)}(4)]2 toluene (1), the first Mn hydrido inverse crown complex. Repeating the reaction rationally, excluding ferrocene, produces 1 in an isolated crystalline yield of 62 %. At lower temperatures, the same bimetallic amide mixture leads to the manganati…
CCDC 882325: Experimental Crystal Structure Determination
Related Article: João Figueira, Wojciech Czardybon, José Carlos Mesquita, João Rodrigues, Fernando Lahoz, Luca Russo, Arto Valkonen, Kari Rissanen|2015|Dalton Trans.|44|4003|doi:10.1039/C4DT00493K
CCDC 882324: Experimental Crystal Structure Determination
Related Article: João Figueira, Wojciech Czardybon, José Carlos Mesquita, João Rodrigues, Fernando Lahoz, Luca Russo, Arto Valkonen, Kari Rissanen|2015|Dalton Trans.|44|4003|doi:10.1039/C4DT00493K