Synthesis, structural characterization and cis-trans isomerization of novel (salicylaldiminato)platinum(II) complexes.

The reaction of cis-[PtCl₂(dmso)] with the salicylaldimine ligand, N-(2-hydroxybenzylidene)-2,6-di-isopropylaniline, LA in the presence of sodium acetate in methanol produced both cis- and trans-[PtClLA(dmso)], 1a and 1b. An analogous reaction for the less bulky ligand, N-(2-hydroxybenzylidene)aniline LB produced only cis-[PtClLB(dmso)], 2. The reactions of these dmso complexes with triphenylphosphine also yielded complexes with different geometries depending on the nature of the salicylaldiminato ligand. Thus the cis-trans isomerization of cis-[PtClLA(PPh₃)] 3a was investigated both experimentally and computationally, and a tetrahedral transition state was detected in this process. A good agreement of the experimental activation parameters with those determined theoretically using DFT was obtained. LA was also reacted with [PtClMe(cod)] in methanol to yield the corresponding salicylaldiminato complex 6 in which the methyl group is cis to the imine nitrogen. X-ray crystal structures of some compounds obtained are reported.