Structural chemistry of dihalogenopalladium(II) and platinum(II) complexes of heteroleptic N,S- and N,Se-donor ligands based on the 2-organochalcogenomethylpyridine motif

The structural chemistry of dihalogenopalladium(II) and platinum(II) complexes of 2-organochalcogenomethylpyridine ligands is described. Complexes with a methyl group in the 6-position of the pyridyl ring, 6-MepyCH2ER, form dimeric complexes [trans-PdX2(μ-6-MepyCH2SePh-N,Se)]2 (X = Br (1), I (2)) or mononuclear complexes trans-PdI2(6-MepyCH2SR-N)2 (R = Me (5), Ph (6)). Absence of a 6-methyl substituent results in the bidentate configuration observed for PdI2(pyCH2SePh-N,Se) (3) and PdI2(4-MepyCH2SMe-N,S) (4). Related platinum(II) complexes are mononuclear including PtCl2(6-MepyCH2SPh-N,S) (8) as an analogue of trimeric [trans-PdCl2(μ-6-MepyCH2SPh-N,S)]3. Differences between palladium and platinum appear to result from a combination of steric and electronic factors.