Search results for "complex"
showing 10 items of 5889 documents
Inclusion complexes of Cethyl-2-methylresorcinarene and pyridine N-oxides: breaking the C–I⋯−O–N+ halogen bond by host–guest complexation
2016
C ethyl-2-Methylresorcinarene forms host–guest complexes with aromatic N-oxides through multiple intra- and intermolecular hydrogen bonds and C–H⋯π interactions. The host shows conformational flexibility to accommodate 3-methylpyridine N-oxide, while retaining a crown conformation for 2-methyl- and 4-methoxypyridine N-oxides highlighting the substituent effect of the guest. N-Methylmorpholine N-oxide, a 6-membered ring aliphatic N-oxide with a methyl at the N-oxide nitrogen, is bound by the equatorial −N–CH3 group located deep in the cavity. 2-Iodopyridine N-oxide is the only guest that manifests intermolecular N–O⋯I–C halogen bond interactions, which are broken down by the host resulting i…
Mono- and Bimetallic Zwitterionic Chromium(0) and Tungsten(0) Allenyls
2015
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…
Bimetallic ruthenium-tin chemistry: synthesis and molecular structure of arene ruthenium complexes containing trichlorostannyl ligands
2010
A series of neutral, anionic and cationic arene ruthenium complexes containing the trichlorostannyl ligand have been synthesised from SnCl2 and the corresponding arene ruthenium dichloride dimers [(η6-arene)Ru(μ2-Cl)Cl]2 (arene = C6H6, PriC6H4Me). While the reaction with triphenylphosphine and stannous chloride only gives the neutral mono(trichlorostannyl) complexes [(η6-C6H6)Ru(PPh3)(SnCl3)Cl] (1) and [(η6-PriC6H4Me)Ru(PPh3)(SnCl3)Cl] (2), the neutral di(trichlorostannyl) complex [(η6-PriC6H4Me)Ru(NCPh)(SnCl3)2] (3) could be obtained for the para-cymene derivative with benzonitrile as additional ligand. By contrast, the analogous reaction with the benzene derivative leads to a salt compose…
Fluoroquinolone–metal complexes: A route to counteract bacterial resistance?
2014
Abstract Microbial resistance to antibiotics is one of the biggest public health threats of the modern world. Antibiotic resistance is an area of much clinical relevance and therefore research that has the potential to identify agents that may circumvent it or treat resistant infections is paramount. Solution behavior of various fluoroquinolone (FQ) complexes with copper(II) in the presence and absence of 1,10-phenanthroline (phen) was studied in aqueous solution, by potentiometry and/or spectrophotometry, and are herein described. The results obtained showed that under physiological conditions (micromolar concentration range and pH 7.4) only copper(II):FQ:phen ternary complexes are stable.…
An Octanuclear Metallosupramolecular Cage Designed To Exhibit Spin-Crossover Behavior.
2018
By employing the subcomponent self-assembly approach utilizing 5,10,15,20-tetrakis(4-aminophenyl)porphyrin or its zinc(II) complex, 1H-4-imidazolecarbaldehyde, and either zinc(II) or iron(II) salts, we were able to prepare O-symmetric cages having a confined volume of ca. 1300 Å3 . The use of iron(II) salts yielded coordination cages in the high-spin state at room temperature, manifesting spin-crossover in solution at low temperatures, whereas corresponding zinc(II) salts led to the corresponding diamagnetic analogues. The new cages were characterized by synchrotron X-ray crystallography, high-resolution mass spectrometry, and NMR, Mössbauer, IR, and UV/Vis spectroscopy. The cage structures…
Synthesis of a labile sulfur-centred ligand, [S(H)C(PPh2S)2]−: structural diversity in lithium(i), zinc(ii) and nickel(ii) complexes
2016
A high-yield synthesis of [Li{S(H)C(PPh2S)2}]2 [Li2·(3)2] was developed and this reagent was used in metathesis with ZnCl2 and NiCl2 to produce homoleptic complexes 4 and 5b in 85 and 93% yields, respectively. The solid-state structure of the octahedral complex [Zn{S(H)C(PPh2S)2}2] (4) reveals notable inequivalence between the Zn-S(C) and Zn-S(P) contacts (2.274(1) Å vs. 2.842(1) and 2.884(1) Å, respectively). Two structural isomers of the homoleptic complex [Ni{S(H)C(PPh2S)2}2] were isolated after prolonged crystallization processes. The octahedral green Ni(ii) isomer 5a exhibits the two monoprotonated ligands bonded in a tridentate (S,S',S'') mode to the Ni(ii) centre with three distinctl…
A new tetranuclear copper(I) complex based on allyl(5-phenyl-1,3,4-thiadiazol-2-yl)azanide ligand: Synthesis and structural characterization
2015
Abstract By means of alternating current electrochemical technique a new tetranuclear crystalline copper(I) complex [Cu I 4 ( L − ) 4 ] ( L − – allyl(5-phenyl-1,3,4-thiadiazol-2-yl)azanide ion) has been obtained and characterized by X-ray single crystal diffraction ( Sp. gr. I 4 1 / a ) and Raman spectroscopy. The metal center adopts linear arrangement, composed of one thiadiazole N atom from the one L − anion and one azanide N atom of the other L − ligand. A bridged Cu atoms stitch four L − ligands into the firstly observed tetranuclear copper(I) azanide complex with intramolecular Cu(I)⋯Cu(I) interactions at the distance of 2.7451(6) A. Molecular structure and Raman spectrum of the compo…
Self-assembly of metallosupramolecular rhombi from chiral concave 9,9'-spirobifluorene-derived bis(pyridine) ligands.
2014
Two new 9,9’-spirobifluorene-based bis(4-pyridines) were synthesised in enantiopure and one also in racemic form. These ligands act as concave templates and form metallosupramolecular [(dppp)2M2L2] rhombi with cis-protected [(dppp)Pd]2+ and [(dppp)Pt]2+ ions. The self-assembly process of the racemic ligand preferably occurs in a narcissistic self-recognising manner. Hence, a mixture of all three possible stereoisomers [(dppp)2M2{(R)-L}2](OTf)4, [(dppp)2M2{(S)-L}2](OTf)4, and [(dppp)2M2{(R)-L}{(S)-L}](OTf)4 was obtained in an approximate 1.5:1.5:1 ratio which corresponds to an amplification of the homochiral assemblies by a factor of approximately three as evidenced by NMR spectroscopy and m…
Iron(III) bis(pyrazol-1-yl)acetate based decanuclear metallacycles: synthesis, structure, magnetic properties and DFT calculations
2016
The synthesis, structural aspects, magnetic interpretation and theoretical rationalizations for a new member of the ferric wheel family, a decanuclear iron(III) complex with the formula [Fe10(bdtbpza)10(μ2-OCH3)20] (1), featuring the N,N,O tridentate bis(3,5-di-tert-butylpyrazol-1-yl)acetate ligand, are reported. The influence of the steric effect on both the core geometry and coordination mode is observed. Temperature dependent (2.0–300 K range) magnetic susceptibility studies carried out on complexes 1 established unequivocally antiferromagnetic (AF) interactions between high-spin iron(III) centers (S = 5/2), leading to a ground state S = 0. The mechanism of AF intramolecular coupling was…
A Density Functional Study of Open-Shell Cyclopentadienyl−Molybdenum(II) Complexes. A Comparison of Stabilizing Factors: Spin-Pairing, Mo−X π Bonding…
2000
International audience; The dissociation of PH3 from the 18-electron system CpMoX(PH3)3 to afford the corresponding 16-electron CpMoX(PH3)2 fragment has been investigated theoretically by density functional theory for X = H, CH3, F, Cl, Br, I, OH, and PH2. The product is found to prefer a triplet spin state for all X ligands except PH2, the singlet−triplet gap varying between 1.7 kcal/mol for OH to 8.7 kcal/mol for F. The Mo−PH3 bond dissociation energy to the 16-electron ground state varies dramatically across the series, from 4.5 kcal/mol for OH to 23.5 kcal/mol for H, and correlates with experimental observations on trisubstituted phosphine derivatives. Geometry-optimized spin doublet Cp…