Abstract
Clusters formed from borates and phosphates have been used as catalysts and desiccants in pigments (patents). These clusters are described by the formula (RCOOMO)3X. (MOX, M = Ni or Co and X = P(O) or B). When used with a cocatalyst (BF3OEt2 and Al(i-Bu)3), these complexes polymerize butadiene to 1.4-polybutadiene with a greater than 95% conversion to the cis microstructure. Although much is known about producing suitable cis-polymer, almost no details are understood concerning the catalyst itself. The objective of this work is to synthesize and study the structured and physical properties of the clusters containing borate and phosphate, especially those where Co(II) and Ni(II) are present. The poly(metal phosphinates) have been extensively investigated because of their potential in a variety of high temperature applications including coatings and grease thickeners. The presence of paramagnetic transition metal sites throughout the polymeric lattice holds potential for the propagation of magnetic exchange. In this work new cobalt phosphinate polymers have been synthesized and characterized. These linear chain polymers also provide interesting examples of low-dimensional magnetic exchange. Two forms of [Co(OPPj2O2)]n have been crystallized from a DMF solution with, various co-solvents. Crystals suitable for X -ray diffraction demonstrated for the first time the existence of two isomeric coordination polymers with the same metal ion and phosphinate ligands. The temperature-dependent magnetic susceptibility data for both isomers showed that the OPO bridges provide a path for an antiferromagnetic exchange interaction. The pyridine adduct [Co(OPPh2O)2 (py)]n has been synthesized and characterized by X-ray crystallography. The crystal structure of the pyridine adduct showed that the polymeric structure retained its double phosphinate bridges with the pyridine ligands oriented trans to each other. The crosslinking polymer [Co(OPPh2O)2 (bpy)]n has been synthesized and characterized by X-ray crystallography. The crystal structure of the crosslinking polymer demonstrated that the chains are bridged by 4.4/-bipyridyl units bound to each side of the cobalt atom s forming a two-dimensional polymer.
Liu, Shu-Jen (1993). New oxygen bound transition metal clusters and coordination polymers-borates, phosphates and diphenylphosphinates of CoII and NiII. Texas A&M University. Texas A&M University. Libraries. Available electronically from
https : / /hdl .handle .net /1969 .1 /DISSERTATIONS -1530776.