STABILIZATION OF MONOOXOMOLYBDENUM(V) COMPLEXES [MoO(SR)4]1− USING PEPTIDE THIOLATO AND BULKY AROMATIC THIOLATO LIGANDS

Abstract

Abstract Mononuclear monooxomolybdenum(V) peptide complexes having hydrophobic amino acid residues adjacent to Cys residue, [MoO(Z-cys-Val-OMe)4]1− and [MoO(Z-cys-Pro-Leu-cys-OMe)2]1−, exhibit large A|| values (54.2×10−4 cm−1 and 56.6×10−4 cm−1, respectively) in the EPR spectra. Other monooxomolybdenum(V) complexes having bulky thiolato ligands, [NEt4][MoO(tmbt)4] (tmbt = 2,4,6-trimethylbenzenethiolato) and [NEt4][MoO(tipbt)4] (tipbt = 2,4,6-triisopropylbenzenethiolato), have been prepared. These have a covalent Mo=O bond as evidenced by the EPR (large A|| of 57.6×10−4 cm−1), and high v(Mo–O) (944 cm−1) from Raman spectroscopy on the latter complex). Electrochemical reduction of these complexes results in removal of the oxo ligand.