X-ray and NMR study of the structural features of SCS-pincer metal complexes of the group 10 triad

Abstract

SCS-pincer metal complexes [MX(SCS)] (SCS = [2,6-(RSCH2)2C6H3]−; R = Ph: PhSCS; R = Me: MeSCS; M = Pd, Pt, Ni) have been synthesized via mild and tolerant oxidative addition procedures. The complexes have been characterized by 1H and 13C NMR spectroscopy and X-ray crystal structure determination. Interestingly, the crystal structures of [NiBr(MeSCS)] 4, [PdBr(MeSCS)] 5, [PtBr(MeSCS)] 6, and [PtBr(PhSCS)] 8 each have a unit cell with a unique set of independent [MBr(RSCS)] molecules; each of these structures has a different conformation of the five-membered ortho-chelate ring (including the configuration of the coordinated S-center) in the solid state. The temperature-dependent 1H NMR resonance patterns of these complexes in solution were related to structural features encountered in the solid state and allowed us to assign all dynamic processes (rac/meso isomerizations) that occurred in solution.