Chemistry of π-complexes derived from [(Ph 3P) 2Pt(η 3-CH 2CCPh)](O 3SCF 3). Interconversion between η 3-alkoxoallyl and η 3-oxoallyl complexes and between η 3-aminoallyl and η 3-iminoallyl complexes

Abstract

The η 3-alkoxoallyl complexes of platinum ( 2a– c: RMe ( a), Et ( b), i-Pr ( c)) derived from [(Ph 3P) 2Pt(η 3-CH 2CCPh)] + ( 1) and ROH are dealkylated by OMe − to form the η 3-oxoallyl complex (Ph 3P) 2Pt(η 3-CH 2C(O)CHPh) ( 3). Reactions of 3 with Et 3O + and (MeO) 2SO 2 regenerate the η 3-alkoxoallyl complexes 2a, b. Treatment of 1 with H 2O affords binuclear [((Ph 3P) 2Pt(η 3- (CH 2)(CHPh)C)) 2O] 2+ ( 4), which is converted to 3 upon treatment with two equivalents of OMe −. The η 3-aminoallyl complexes [(Ph 3P) 2Pt(η 3-CH 2C(NHR)CHPh)] + ( 6), obtained from 1 and RNH 2 (R p-MeC 6H 4NH 2, p-O 2NC 6H 4NH 2), react with LiPh to afford the η 3-iminoallyl complexes (Ph 3P) 2Pt(η 3-CH 2C(NR)CHPh) ( 7). Complexes 7 are protonated by HBF 4 and alkylated by (MeO) 2SO 2 to yield 6 and [(Ph 3P) 2Pt(η 3-CH 2C(NRMe)CHPh)] + ( 8), respectively. The complex [(Ph 3P) 2Pt(η 3-CH 2C(NMe 2)CHPh)] + ( 5) undergoes fluxional behavior at ambient temperatures in solution, and this behavior is ascribed to rotation about the CNMe 2 bond. The reported chemistry is rationalized by η 3-allyl and metallacyclic resonance hybrid properties of 2– 8.