Synthesis and crystal structure of a novel cyclic trinuclear platinum(II) complex, [Pt3(L-HMet)3]·H2O (H3Met = methionine)

Abstract

Reaction of L-methionine hydrochloride [H₄Met]Cl with 1 equivalent of K₂[PtCl₄] under basic conditions (pH 12.36) in aqueous solution gave pale yellow crystals of [Pt₃(L-HMet)₃]·H₂O, as evidenced by X-ray crystallography: monoclinic, space group P2₁, a= 8.396(2), b= 8.331(2), c= 16.872(2)Å, β= 94.11(1)°, Z= 2. The structure was refined to R=R′= 0.075 for 3791 reflections with I < 3.00σ(I). It reveals a cyclic trinuclear platinum(II) complex with bridging amido nitrogens and an approximate three-fold axis of symmetry. Each Pt^II has roughly square-planar geometry with nitrogen, sulfur co-ordination from one methionine, and nitrogen, oxygen co-ordination from a second methionine.