Overcoming Kinetic Inertness via Transmetalation: Nickel-Mediated Synthesis of Sulfonamide-Functionalized Pd^II and...

A transmetalation strategy has been developed to access sulfonamide-functionalized palladium(II) and platinum(II) dithiocarbamate complexes that are inaccessible through direct functionalization due to the kinetic inertness of these metals. While kinetically labile nickel(II) dithiocarbamates readily undergo sulfonamide insertion into Ni^II-S bonds, the corresponding Pd^II and Pt^II complexes are resistant to direct functionalization. To circumvent this limitation, Ni^II complexes bearing preinstalled sulfonamide modifications were employed as transmetalation precursors. Two families of chelate complexes were obtained: N,S,S,S-tetradentate complexes with one sulfonamide fragment and N,S,S,N-tetradentate complexes featuring two sulfonamide moieties. The procedure was scaled to gram quantities. The versatility of this methodology was demonstrated through the synthesis of ML(NSCN) (M = Pd, Pt) species containing cyclometalated N^∧S or N^∧C ligands (L). X-ray crystallographic analysis of 19 structures revealed characteristic inequivalent C-S bond lengths (averaging 1.76 Å vs 1.71 Å across all structures) and partial C-N double bond character, consistent with significant contributions from both dithiocarbamate and thioureide resonance structures. This work provides a general and scalable route to sulfonamide-functionalized Group 10 metal dithiocarbamate complexes that cannot be accessed by direct methods.