The interaction of copper(II) with S-methylcysteine. Crystal and molecular structure of bis(S-methyl-L-cysteinato)copper(II)

Abstract

Crystals of a copper(lI) complex of S-methyl- cysteine, bis(S-methyl-L-cysteinato)copper(II), have been grown from a solution on the surface of a solid copper(II) hydroxysalt. They are monoclinic, space group P2 1, with a=13.265(8), b=5.036(3), c= 9.571(6) Å, β=97.55° and Z=2. The crystal structure was determined from diffractometer data and refined by the full-matrix least-squares technique to a final R=0.045 and R w=0.052 for 921 observed refiections. The structure consists of Cu(S-methyl-L- cysteine) 2 units with an approximately square planar trans coordination of copper(II) by two O(carboxylate) and two N(amino) atoms. These units are linked by two weak additional CuO(carboxylate) bonds to form a two-dimensional polymer. There is no interaction of copper(ll) with the ether sulfur of the ligand; overall features of the structure are very similar to that of the analogous cadmium complex. In accordance with the interpretation of infrared data, weak intermolecular hydrogen bonds of the type NH···O with N···O distances ranging from 2.94 Å to 3.10 Å are observed.