Preparation and 31P NMR studies of platinum complexes of some chiral, bidentate phosphines

Abstract

Two chiral diphosphines of formula RN(P(C 6H 5) 2, S-peap and S-alap, have been prepared from S-α-phenethylamine and the ethyl ester of S-alanine, respectively. Their syntheses, and the preparation of the achiral diphosphine beap, N, N′-bis(diphenylphosphino)- N, N′-dibenzylethylenediamine, are described. Platinum complexes of these bidentate ligands of formula Pt(chelate)CH 3Cl and [Pt(chelate)CH 3(X)]ClO 4 (X  acetone; p-YC 5H 4N, when Y  CH 3, C 2H 5, CHO, CO 2CH 3, H and N(CH 3) 2; and a series of monodentate, Group V donor ligands, P(C 2H 5) 3, P(C 3H 7) 3, P(C 8H 17) 3, PCH 3(C 6H 5) 2, P(CH 3) 2C 6H 5, P(C 6H 5) 3, P(C 6H 11)(C 6H 5) 2, P(C 6H 11) 2C 6H 5, P(C 6H 11) 3, P(C 6H 5) 2N(C 2H 5) 2, As(C 6H 5) 3 and Sb(C 6H 5) 3) have been prepared and their 1H and 31P NMR parameters recorded. The cationic pyridine complexes show a correlation of the ϱ values of the para substituent to some of the 31P chemicals shifts and coupling constants. The steric and electronic properties of the diphosphine ligands have been investigated by comparing their 31P NMR parameters with those of analogous complexes containing (+)-diop and S, S-chiraphos.