FACILE INTRA-MOLECULAR METALATION OF TRI-TERT-BUTYLPHOSPHINE IN PALLADIUM(II) HYDRIDE COMPLEXES

Palladium(II) hydrides trans-PdH(X)(P-t-Bu3)2 (I) when X=Cl or CF3COO), prepared by the oxidative addition of HX to bis(tri-tert-butylphosphine)palladium(0), have been shown to undergo facile intramolecular metalation in solution producing complexes of the type PdX(P-t-Bu2CMe2CH2)(P-t-Bu3) (II). These complexes (II) when kept in dichloromethane or benzene solution lose 1 molar equiv of phosphine to give the bridged dimeric complexes [PdX(P-t-Bu2CMe2CH2)]2 (III). Complex III (where X=Cl) is also obtained from the reaction of tri-tert-butylphosphine with PdCl2(NCPh)2 in CH2C12. Sodium. borohydride reduction of complexes I, II, or III in ethanol invariably produces bis(tri-tert-butylphosphine)palladium(0). Reaction of n-butyllithium with PdH(X)(P-t-Bu3)2 in n-hexane also gives the palladium(0) complex. The chloride bridge of complex III can be split by a variety of ligands (e.g., pyridine, Ph3As, Ph3P, Et3P, Ph2MeP, i-Pr3P, t-Bu2MeP, Cy3P, and (C7H7)3P) to give mononuclear species of the type trans-PdCl(P--Bu2CMe2CH2)(L). © 1979, American Chemical Society. All rights reserved.