Synthesis and crystal structure of the first trinuclear chloride-bridged platinum(II) complex with mutually perpendicular co-ordination planes: cyclo-tri-µ,-chloro-tris[chloro(1-hydroxy-1-imino-2,2-dimethylpropane)platinum(II)]-dichloromethane (0.5/1)

Abstract

The first trinuclear chloride-bridged platinum(II) compound has been obtained by disproportionation of cis-[{PtCl₂[HNC(OH)C(CH₃)₃]₂}₂]1. Two compounds result from the disproportionation, which contain one and three amide molecules per platinum atom (compounds 2 and 3 respectively). Compound 2, which crystallizes from dichloromethane as orange hexagonal prisms, contains discrete molecules of [{PtCl₂[HNC(OH)C(CH₃)₃]}₃]. The co-ordination geometry of each metal centre is square planar; two cis positions are occupied by bridging chloride ions, and a terminal chloride and the nitrogen atom of an amide ligand (iminol form) complete the co-ordination sphere. The co-ordination planes of the three platinum atoms are mutually perpendicular with a dihedral angle of 99.2(2)°. The structure is strongly related to that of the β form of PtCl₂(Pt₆Cl₁₂ molecules). Compound 2 incorporates exactly one half of the Pt₆Cl₁₂ cube and saturates the vacant co-ordination sites, made available by splitting of the bridges across the two halves of the cube, with amide ligands. The complex, as a whole, assumes a calyx-type shape and two molecules of complex take up one molecule of solvent (CH₂Cl₂).