Complexes of molybdenum(V) and molybdenum(IV) with dithiocarbamates derived from α-amino acids. Reaction kinetics in organic solvents

Abstract

The reaction between dithiocarbamate derivatives of α-amino acids (glycine, alanine, α-amino-butyric acid, norvaline, valine, norleucine, leucine and isoleucine) and sodium molybdate in acid medium leads to the formation of molybdenum(V) complexes with the general formula [Mo 2O 3)dtc a.a.) 4]·2H 2O (a.a = amino acid). The complexes were characterized by elemental analysis, FT-IR and uv-vis spectroscopies and XPS. They are binuclear complexes with a linear oxygen bridge, the dithiocarbamate moiety acting as a bidentate ligand and thus yielding a distorted octahedral coordination for the metal cation. In organic solvents, these compounds undergo a chemical transformation, yielding complexes with the general formula [MoO(dtc a.a.) 2], whose synthesis is also described. These complexes were characterized using the same experimental techniques as above. The kinetics of transformation in organic media were studied, proposing a multi-step reaction mechanism, and the rate constants have also been determined.