Heterobimetallic nickel(II) complexes of ferrocenyldithiophosphonates. Molecular structures of [{FcP(OR)S2}2Ni] [Fc = Fe(?5-C5H4)(?5-C 5H5), R = Et, Pri, Bus, Bu i]

Abstract

The reaction of 2,4-diferrocenyl-1,3-dithiadiphosphetane 2,4-disulfide [FcPS(µ-S)]2 [Fc = Fe(?5-C5H 4)(?5-C5H5)] with alcohols ROH gave the corresponding ferrocenyldithiophosphonic acids [FcPS(OR)(SH)], which were treated in situ with Ni(CH3COO)2·4H 2O in acetic acid to yield the square-planar heterobimetallic trinuclear complexes [{FcP(OR)S2}2Ni] (R = Me (1), Et (2), Pri (3), Bus (4) and Bui (5)). Compounds 1-5 were characterized by elemental analysis, MS, NMR (1H, 13C and 31P), IR spectroscopy, and 2-5 also by X-ray crystallography. Cyclovoltammetric studies on the heterobimetallic nickel(II) complexes 1-5 showed irreversible reduction to unstable nickel(I) complexes and an irreversible two-electron oxidation of the sulfur-containing nickel fragments, followed by a reversible one-electron oxidation of the two ferrocenyl groups.