Structure and Physical Properties of Bridging Chalcogenide Cluster Complexes

点击翻译按钮获取中文摘要

The purpose of this research project is the synthesis of deltahedral metal cluster complexes by the condensation of trinuclear molybdenum and tungsten chalcogenide clusters, and the X-ray structural study of the products to elucidate the relationships between the oxidation states and the M-M bond distances and the distortion of the cluster frameworks; molecular orbital calculation and the electronic spectra and magnetism. The main targets have been the molecular cluster complexes having the same cluster skeletons as those of the superconducting Chevrel phase compounds.We have established the synthesis of the hexanuclear cluster complexes [Mo_6X_8(PEt_3)_6] (X = S, Se) by the reductive dimerization of [Mo_3X_4Cl_4(PEt_3)_5]. The reduction with sodium amalgam formed one-electron reduced cluster complexes and the structures of these four complexes have been solved by X-ray. The Mo-Mo bond distances for the selenium derivatives are longer than those of the sulfur analogs. The neutral cluster complexes have regular octahedral frameworks, whereas the reduced ones are slightly distorted. The results have corrected a previous theory for the solid state Chevrel compounds concerning the distortion of the octahedra. The tungsten analogs of the Chevrel model compounds have also been prepared.The condensation of [Mo_3X_4Cl_4(PEt_3)_5] with M(cod)_2 (M = Ni, Pt) formed pentanuclear cluster complexes, [Mo_3Ni_2X_4Cl_4(PEt_3)_5] and [Mo_3Pt_2S_4Cl_4(PEt_3)_6]. The molybdenum-nickel cluster has a square-planar and the molybdenum-platinum cluster has a ladder structure.