Solution, structural and catalytic studies of neutral MCl2 (M = Pd, Pt) complexes of the N/E mixed-donor ligands 2-(RECH2)C5H4N (RE = MeS, PhS, MeSe)

The reaction of MCl 2 (M = Pd, Pt) with one mole-equivalent of L [L = 2-(MeSCH 2)C 5H 4N (L 1), 2-(PhSCH 2)C 5H 4N (L 2), 2-(MeSeCH 2)C 5H 4N (L 3)] in MeCN gave the monomeric complexes [MCl 2L] in good yields, Single-crystal X-ray diffraction studies of [MCl 2L 2] confirmed the complexes to be monomeric with square-planar geometry about the metal centre. Variable-temperature NMR spectroscopy showed that the complexes undergo fluxional processes in solution, which were confirmed, by DFT calculations, to be (E)-pyramidal inversion at the chalcogen centre rather than ring-flip or (E)-dissociation processes. The calculations showed that the barrier to inversion increases in the order S