A STUDY ON THE PALLADIUM(II) METHIONINE-2,6-DIMETHYL-4H-PYRAN-4-ONE SYSTEM

The methionine (Met) complexes [PdX2L].dmp (X = Cl, Br or 1; L = D-, L - or DL-Met; dmp = 2,6-dimethyl-4H-pyran-4-one) have been prepared in benzene by reaction of palladium dihalides with methionine in the pres ence of an excess of dmp, whereas in dichloromethane the corresponding [PdX2L] adducts have been isolated. The crystal structure of [PdI2(DL -Met)].dmp was determined by X-ray crystallography and refined to a fi nal R of 0.065, based on 1720 observed reflections. The crystal is mon oclinic, P2(1)/c, with a = 11.851(3), b = 14.953(3), c = 11.303(2) ang strom, beta 109.94(4)-degrees. The Pd is co-ordinated by two I and one chelate Met ligand in a distorted square-planar geometry. Relevant bo nd distances are: Pd-I 2.594(2) and 2.621(2) angstrom, Pd-S 2.318(4) a ngstrom and Pd-N 2.08(1) angstrom. The dmp molecule is bound to the me thionine carboxyl by a hydrogen bond.