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Four-membered Chelate Ring (four-membered + chelate_ring)

Distribution by Scientific Domains

Chemistry	100%

Selected Abstracts

Variable Coordination Modes of Benzaldehyde Thiosemicarbazones , Synthesis, Structure, and Electrochemical Properties of Some Ruthenium Complexes

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 29 2008
Swati Dutta
Abstract Reaction of benzaldehyde thiosemicarbazones [H2LR, where H2 stands for the two protons, the hydrazinic proton, and the phenyl proton at the ortho position, with respect to the imine function and R (R = OCH3, CH3, H, Cl, and NO2) for the para substituent] with [Ru(PPh3)2(CO)2Cl2], carried out in refluxing ethanol, afforded monomeric complexes of type [Ru(PPh3)2(CO)(HLR)(H)]. The crystal structure of the [Ru(PPh3)2(CO)(HLNO2)(H)] complex was determined. The thiosemicarbazone ligand is coordinated to the ruthenium center as a bidentate N,S-donor ligand forming a four-membered chelate ring. When the reaction of the thiosemicarbazones with [Ru(PPh3)2(CO)2Cl2] was carried out in refluxing toluene, a family of dimeric complexes of type [Ru2(PPh3)2(CO)2(LR)2] were obtained. The crystal structure of [Ru2(PPh3)2(CO)2(LCl)2] was determined. Each thiosemicarbazone ligand is coordinated to one ruthenium atom, by dissociation of the two protons, as a dianionic tridentate C,N,S-donor ligand, and at the same time the sulfur atom is also bonded to the second ruthenium center. 1H NMR spectra of the complexes of both types are in excellent agreement with their compositions. All the dimeric and monomeric complexes are diamagnetic (low-spin d6, S = 0) and show intense absorptions in the visible and ultraviolet regions. Cyclic voltammetry of the [Ru(PPh3)2(CO)(HLR)(H)] and [Ru2(PPh3)2(CO)2(LR)2] complexes show the ruthenium(II),ruthenium(III) oxidation within 0.48,0.73 V vs. SCE followed by a ruthenium(III),ruthenium(IV) oxidation within 1.09,1.47 V vs. SCE. Potentials of both the oxidations are found to correlate linearly with the electron-withdrawing character of the substituent R. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]

Poly[(acetone)tetraaqua[,6 -ethyl (dichloromethylene)diphosphonato][,5 -ethyl (dichloromethylene)diphosphonato]tribarium(II)]

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2009
Jonna Jokiniemi
The novel title compound, [Ba3(C3H5Cl2O6P2)2(C3H6O)(H2O)4]n, has a polymeric two-dimensional network structure which lies parallel to the (10) plane. The asymmetric unit consists of three independent Ba2+ ions, two of them eight-coordinated and the third nine-coordinated, and two independent ethyl (dichloromethylene)diphosphonate(3,) ligands, one acetone ligand and four aqua ligands. The coordination environments around the BaO8 polyhedra are best described as bicapped trigonal prismatic, while the BaO9 polyhedron is in a distorted tricapped trigonal prismatic geometry. The two diphosphonate ligands adopt different coordination modes. Both ligands chelate three metal cations, but one is coordinated to six metal cations in total and forms two six-membered and one four-membered chelate ring, while the other is coordinated to five metal cations in total and forms one six-membered and two four-membered chelate rings, the fifth unsubstituted O atom remaining uncoordinated. [source]

Directed anisotropy in bis(acetato-,2O,O,)diaquazinc(II) at 110 and 250,K

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 2 2009
Martin Lutz
The molecule of the title compound, [Zn(C2H3O2)2(H2O)2], is located on a twofold axis in the crystal structure. The displacement parameters and the thermal expansion of the crystal show significant anisotropy. This is explained by the two-dimensional hydrogen-bonded structure, with only very weak interactions perpendicular to it. Besides the overall molecular motion, there are internal vibrations, which cause the Zn,O(carboxylate) bonds to fail the Hirshfeld rigid-bond test. It is shown that this can be interpreted in terms of the steric strain in the four-membered chelate ring due to the bidentate carboxylate coordination. [source]