PREPARATION AND REACTIONS OF (PI-ALLYL)PALLADIUM AND (PI-ALLYL)PLATINUM CARBONATE COMPLEXES

The tertiary-phosphine-coordinated Pd(0) complexes Pd(styrene)L2 (L = PMe3, PMe2Ph, PMePh2) react readily with allylic carbonates (methyl 2-methylallyl carbonate and allyl ethyl carbonate) in THF to afford cationic (pi-allyl)palladium complexes having an alkyl carbonate anion [(pi-allyl)PdL2]+[OCOOR]- (allyl = 2-MeC3H4, R = Me, L = PMe3 (1a), PMe2Ph (1c), PMePh2 (1d); allyl = C3H5, R = Et, L = PMe3 (1b)). Complexes 1a-1d are extremely moisture sensitive and readily react with water to give the corresponding hydrogen carbonate complexes [(pi-allyl)PdL2]+[OCOOH]-. X-ray analysis of the hydrogen carbonate complex (2a) derived from 1a has revealed that 2a has a dimeric structure, in which two [(eta(3)-2-MeC3H4)Pd(PMe3)2]+[OCOOH]- units are associated with each other by hydrogen bonds between the hydrogen carbonate anions. Crystal data for 2a: C11H26O3P2Pd, a = 12.055 (2) angstrom, b = 14.497 (2) angstrom, c = 9.602 (2) angstrom, beta = 97.93 (1)-degrees, monoclinic, P2(1)/a, Z = 4. Treatment of 1a with active hydrogen compounds including 2,4-pentanedione, dimethyl malonate, and cyclohexanone gives the allylation products, whereas 1a reacts with CO to afford methyl 3-methyl-3-butenoate together with methyl 2-methylallyl ether. Preparation of related (pi-allyl)platinum carbonate complexes [(eta(3)-2-MeC3H4)Pt(PMe3)2]+[OCOOR]- (R = Me (3), H (4)) are reported.