Monometallic, homo- and hetero-bimetallic complexes based on redox active tris(3,5-dimethylpyrazolyl)borato-molybdenum and -tungsten nitrosyls. Part 4. The effects of ligating atom type on the reduction potentials of monometallic complexes

Abstract

The complexes [M(NO)(L)X(Y)][L = tris(3,5-dimethylpyrazolyl)borate; M = Mo, X = Cl, Y = OPh; M = W, X = Cl, Y = SPh; or M = W, X = Y = NC4H4, OPh, or SPh] have been prepared and characterised. The electrochemical properties of these compounds were investigated by cyclic voltammetry and compared with those of others in the series [M(NO)(L)X(Y)](M = Mo or W; X = Cl, Y = OPh, NHPh, or SPh; or X = Y = NC4H4, OPh, NHPh, or SPh). It was found that the thiophenolate complexes reduced at slightly more anodic potentials than their phenolate analogues while the arylamide complexes reduced at significantly more cathodic potentials. In general the tungsten complexes reduced at potentials ca. 0.45 V more cathodic than their molybdenum analogues.