Pd(II) and Pt(II) D-penicillamine complexes. Crystal structure of a tridentate D-penicillamine cluster of Pd(II)

Complexes of formula [M-2(D-Pen(-))(2)Cl-2], where M = Pd or Pt and D-Pen(-) = D-penicillaminate were synthesized and characterized by the usual spectroscopic methods. Red crystals suitable for X-ray study were obtained, after several days, from the mixture of K2PdCl4/D-Penicillamine solutions. The crystals were identified as [Pd-3(Pen(2)-)(3)].7/8KCl.19/8H(2)O. The structure shows four chemically but not crystallographically equivalent trinuclear clusters in the cell. Three D-penicillamine molecules act as divalent anions in tridentate fashion between three palladium atoms forming neutral units. Each S atom bridges two palladium atoms inside the molecular units. Potassium and chloride ions are curiously distributed along the crystallographic units contributing, together with the water molecules, to the stability of the crystal. The capacity of the penicillamine to act as tridentate ligand can be related to the capacity to capture toxic metals. (C) 1998 Elsevier Science Ltd. All rights reserved.