Amine, imine, and aminocarbene complexes of platinum(II)

Abstract

Solutions of the chloride-bridged binuclear platinum complexes [Pt2(µ-Cl)2Cl2L2](L = PMe2Ph or PBu3) readily react with the amines NH2Ph, 4-NO2C6H4NH2, 3-MeOC6H4NH2, NHPh2, or NH2Me to produce trans-[PtCl2(am)L] in the presence or absence of phenylethyne. The imines PhCHNPh, PhCHNMe, 2-MeC6H4CHNPh, or Ph2CNH also react with [Pt2(µ-Cl)2Cl2L2] to produce the analogous N-bonded imine complexes, but reactions of the amines NHEt2 or NH2But with the binuclear compounds lead to additional platinum-containing compounds resulting from ligand redistribution reactions. The complexes of NH2Ph, 4-NO2C6H4NH2, 3-MeOC6H4NH2, and NHPh2 react with phenylethyne over several days at ambient temperature to yield aminocarbene complexes cis-[PtCl2{C(NR1R2)CH2Ph}L](R1R2= H, Ph; H, C6H4NO2-4; H, C6H4OMe-3; or Ph2). Treatment of the imine complexes or any of the other amine complexes with PhCCH, however, led only to decomposition. 2-Aminophenylethyne reacts rapidly with [Pt2(µ-Cl)2Cl2L2] to produce the cyclic carbene complex cis-[PtCl2{[graphic omitted]H}L] in only 1 h, and although the amine-N complexes were observed in solution as transients they were not isolated. Treatment of the carbene complexes with tertiary phosphine, L, leads to cationic complexes trans-[PtCl{C(NR1R2)CH2Ph}L2]Cl. Both the uncharged and cationic aminocarbene compounds are less reactive than their alkoxycarbene analogues, and show no reaction with Cl– and little tendency towards H/D exchange with CD3OD. Hydrogen-1, 13C, and 31P n.m.r. spectroscopic parameters for the complexes are reported and related to the likely solution conformations.