Gold(III) Adducts with Chiral Pyridinyl-Oxazolines. Synthesis, Reactivity of the Coordinated Ligands, and Structural Characterizations

Novel gold(III) pyridinyl-oxazolilie cationic complexes [A U(pyox(R))Cl-2[X] [pyox(R) 2-(pyridin-2-yl)-4,5-dihydrooxazole, with R = Pr-i, Bn, and (R)-4-phenyl-2-(pyridin-2-yl)-4,5-dihydrooxazole; X = PF6, AuCl4, or mixtures of the two anions] were synthesized and Structurally characterized. Reaction of the adducts with NaOAc ill aqueous Solution afforded the neutral complexes [Au(N,N',O)Cl] of the deprotonated ligands N-(1-hydroxy-3-R-2-yl)pyridine-2-carboxamide (R = Pr-i, Ph), N,N'H,OH, resulting from ring-opening of the bound pyox ligand by hydroxide ions and incorporation of hydroxide into the ring-opened products. Reaction of [Au(N,N',0)Cl] (R = Pr-i) with FIX (X = Cl, BF4, OTf) in aqueous Solution resulted in protonation of the coordinated alkoxo, group and its displacement from the coordination sphere to give the adducts [Au(N,N', OH)ClX] (X = OTf, Q or the aquo complex [Au(N,N',OH)(OH2)Cl](+) (X = BF4). Crystal structure characterizations were carried out on both [Au(N,N',O)Cl] and [Au(N,N',OH)Cl-2] (R = Pr-i). Equimolar mixtures of the ring-opened derivative [Au(N,N',OH)Cl] (R = Pr-i) and either silver salts or HBF4 Were found to promote, Under Mild conditions, polymerization of styrenes.