Structural Evidence for Pnictogen-Centered Lewis Acidity in Cationic Platinum-Stibine Complexes Featuring Pendent Amino or Ammonium Groups †

As part of our continuing interest in the chemistry of cationic antimony Lewis acids as ligands for late transition metals, we have now investigated the synthesis of platinum complexes featuring a triarylstibine ligand substituted by an o-[(dimethylamino)methyl]phenyl group referred to as Ar(N). More specifically, we describe the synthesis of the amino stibine ligand Ph(2)SbAr(N) (L) and its platinum dichloride complex [LPtCl]Cl which exists as a chloride salt and which shows weak coordination of the amino group to the antimony center. We also report the conversion of [LPtCl]Cl into a tricationic complex [LHPt(SMe(2))](3+) which has been isolated as a tris-triflate salt after reaction of [LPtCl]Cl with SMe(2), HOTf and AgOTf. Finally, we show that [LHPt(SMe(2))][OTf](3) acts as a catalyst for the cyclization of 2-allyl-2-(2-propynyl)malonate.