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

Abstract

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.