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H2O Ligands (h2o + ligand)

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Chemistry100%

Selected Abstracts

Six-coordinate Co2+ with imidazole, NH3, and H2O ligands: Approaching spin crossover

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 6 2007
Ann M. Schmiedekamp
Abstract Octahedral, six-coordinate Co2+ can exist in two spin states: S = 3/2 and S = 1/2. The difference in energy between high spin (S = 3/2) and low spin (S = 1/2) is dependent on both the ligand mix and coordination stereochemistry. B3LYP calculations on combinations of neutral imidazole, NH3, and H2O ligands show that low-spin isomers are stabilized by axial H2O ligands and in structures that also include trans pairs of equatorial NH3 and protonated imidazole ligands, spin crossover structures are predicted from spin state energy differences. Occupied Co d orbitals from the DFT calculations provide a means of estimating effective ligand strength for homoleptic and mixed ligand combinations. These calculations suggest that in a labile biological system, a spin crossover environment can be created. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 [source]

A novel two-dimensional framework based on unprecedented cadmium(II) chains

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 2 2009
Jie Qin
The bent ligand 4-[(1H -1,2,4-triazol-1-yl)methyl]benzoic acid (HL) has been used to create the novel two-dimensional coordination polymer poly[,2 -aqua-,2 -chlorido-{,2 -4-[(1H -1,2,4-triazol-1-yl)methyl]benzoato}cadmium(II)], [Cd(C10H8N3O2)Cl(H2O)]n, under hydrothermal reaction of HL with cadmium chloride. The crystallographically unique Cd atom is seven-coordinated in an approximately pentagonal,bipyramidal environment of two carboxylate O atoms, two water O atoms, two Cl atoms and one triazole N atom. A notable feature is the presence of zigzag ...Cd...Cd... inorganic chains, in which neighboring CdII ions are doubly bridged by pairs of ,2 -Cl atoms and ,2 -H2O ligands in an alternating fashion. To the authors' knowledge, this is the first example containing this bridging mode in a cadmium(II) framework. The chains are connected to one another through the bridging L, ligand into a two-dimensional undulating network. All of the two-dimensional nets stack exactly together in an ,AA, stacking sequence along the crystallographic b axis. Neighboring layers are further linked into a three-dimensional framework via interlayer hydrogen-bonding interactions. [source]