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Ligand Geometry (ligand + geometry)

Distribution by Scientific Domains

Chemistry	100%

Selected Abstracts

Electronic and Magnetic Properties of Bimetallic Ytterbocene Complexes: The Impact of Bridging Ligand Geometry

CHEMISTRY - A EUROPEAN JOURNAL, Issue 2 2008
Christin
Abstract Bimetallic ytterbocene complexes with bridging N-heterocylic ligands have been studied extensively in recent years due to their potential applications ranging from molecular wires to single-molecule magnets. Herein, we review our recent results for a series of ytterbocene polypyridyl bimetallic complexes to highlight the versatility and tunability of these systems based on simple changes in bridging ligand geometry. Our work has involved structural, electrochemical, optical, and magnetic measurements with the goal of better understanding the electronic and magnetic communication between the two ytterbium metal centers in this new class of bimetallics. [source]

Change in electronic structure in a six-coordinate copper(II) complex accompanied by an anion order/disorder transition

ACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2010
Colin A. Kilner
A variable-temperature crystallographic study of [Cu(LOH)2][ClO4]2·2(CH3)2CO [LOH = 2,6-bis(hydroxyiminomethyl)pyridine] between 30 and 300,K is presented. The complex exhibits an unusual electronic structure at room temperature with a {}1 ground state, corresponding to an axially compressed ligand coordination geometry about the copper ion. This reflects a suppression of the pseudo-Jahn,Teller distortion that is normally shown by copper(II) compounds with this ligand geometry [Halcrow et al. (2004). New J. Chem.28, 228,233]. On cooling the compound undergoes an abrupt structural change at 157,±,3,K, that does not involve a change in the space group (P), but causes significant changes to c and the unit-cell angles. This reflects a conformational rearrangement of the complex dication, towards a more typical pseudo-Jahn,Teller elongated coordination geometry. This occurs concurrently with a crystallographic ordering of one of the two perchlorate anions, and a significant displacement of the two lattice acetone molecules. The transformation involves displacements of up to 0.5,Å in the non-H atoms of the structure at 30,K, compared with their positions at 300,K. The change in coordination geometry of the complex around 157,K is reflected in a small reduction in its magnetic moment near that temperature. [source]

PRODRG: a tool for high-throughput crystallography of protein,ligand complexes

ACTA CRYSTALLOGRAPHICA SECTION D, Issue 8 2004
Alexander W. Schüttelkopf
The small-molecule topology generator PRODRG is described, which takes input from existing coordinates or various two-dimensional formats and automatically generates coordinates and molecular topologies suitable for X-ray refinement of protein,ligand complexes. Test results are described for automatic generation of topologies followed by energy minimization for a subset of compounds from the Cambridge Structural Database, which shows that, within the limits of the empirical GROMOS87 force field used, structures with good geometries are generated. X-ray refinement in X-PLOR/CNS, REFMAC and SHELX using PRODRG -generated topologies produces results comparable to refinement with topologies from the standard libraries. However, tests with distorted starting coordinates show that PRODRG topologies perform better, both in terms of ligand geometry and of crystallographic R factors. [source]