A study on the palladium(II)–methionine–2,6-dimethyl-4H-pyran-4-one system

Abstract

The methionine (Met) complexes [PdX₂L]·dmp (X = Cl, Br or I; 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 presence of an excess of dmp, whereas in dichloromethane the corresponding [PdX₂L] adducts have been isolated. The crystal structure of [Pdl₂(DL-Met)]·dmp was determined by X-ray crystallography and refined to a final R of 0.065, based on 1720 observed reflections. The crystal is monoclinic, P2₁/c, with a= 11.851(3), b= 14.953(3), c= 11.303(2)Å, β 109.94(4)°. The Pd is co-ordinated by two I and one chelate Met ligand in a distorted square-planar geometry. Relevant bond distances are: Pd–I 2.594(2) and 2.621(2)Å, Pd–S 2.318(4)Å and Pd–N 2.08(1)Å. The dmp molecule is bound to the methionine carboxyl by a hydrogen bond.