First chelate complexes of 4-mercapto-1-methylpiperidine. Synthesis and characterization of [{M(μ-SC₅H₉NMe)X}₂] (M = Pd^II, X = Cl, Br, or I; M = Pt^II, X = Br or I). Crystal and molecular structure of [{Pt(μ-SC₅H₉NMe)Br}₂]

The reaction of 4-mercapto-1-methylpiperidine in the presence of NEt3 with palladium(II) and platinum(II) halides or treatment of complexes [M(SC5H9NHMe)2][MX4] (M = Pd or Pt; X = Cl, Br, or I) with the same base has led to complexes [{M(μ-SC5H9NMe)X}2] (M = Pd, X = Cl, Br, or I; M = Pt, X = Br or I). When M = Pt and X = Br, crystals are monoclinic, space group P21/a, with a = 13.236(8), b = 9.280(8), c = 14.823(5) Å, and β = 92.00(4)°. The crystal structure consists of chemically independent dinuclear molecules, where each ligand is terdentate and simultaneously S,N-chelating and μ-S bridging. One bromine atom completes the co-ordination around each platinum. The metal environment is approximately square planar, both S2PtNBr planes generating a dihedral angle of 125.24°. There is no metal-metal bonding. Based on the i.r. and 1H n.m.r. spectra, the same structure is proposed for the remaining complexes.