Electrochemical and ESR studies of molybdenum-sulfur donor complexes. One-electron reduction of [cis-bis(N,N-dialkyldithiocarbamato)dinitrosyl]molybdenum and -tungsten complexes

Abstract

cis-M(R,dtc),(NO), complexes (M = M o o r W, R = Me, Et, i-Pr, n-Bu, Bzl, pyr) undergo a reversible one-electron reduction t o give t h e radical anion M(R,dtc),(NO);. E S R studies have shown t h a t t h e unpaired electron is delocalized over both nitrosyl groups. N o metal hyperfine couplings were observed. Analysis of frozen-solution E S R spectra of M o ( E t , d t ~ ) , ( ' ~ N 0 ) , a n d [Mo(Et,dtc),(NO),]- has yielded anisotropic g and nitrogen hyperfine tensors for these complexes. I n addition, t h e angle between the N O vectors remains essentially unchanged upon reduction of Mo(Et,dtc),(NO),. The s e observations strongly support the molecular orbital description of M(R$tc),(NO)<. Here, the unpaired electron resides in a dinitrosyl-based molecular orbital which possesses virtually no metal d-orbital character and which is close t o nonbonding between the two N O groups.