INTERMEDIATES IN THE PALLADIUM-CATALYZED REACTION OF 1,3-DIENES, .6. A SOLID-STATE NMR SPECTROSCOPIC INVESTIGATION OF BUTADIENE COMPLEXES OF NICKEL, PALLADIUM AND PLATINUM

The structure of the (1,3-butadiene)M(R2PC2H4PR2) compounds (M = Ni, Pd, Pt; R = Pr(i), Bu(t), Cy) in the solid-state have been investigated by C-13 and P-31 CP/MAS NMR spectroscopy. The bonding mode adopted by the diene is dependent upon the nature of the metal: the palladium compounds contain an eta-2-diene molecule, the nickel compound where R is cyclohexyl contains an eta-4-diene molecule whereas the Pr(i)2PC2H4PPr(i)2-stabilized platinum compound contains a platinacyclopentene ring. The crystal structures of (eta-2-1,3-C4H6)Pd(Cy2PC2H4PCy2) and (eta-4-1,3-C4H6)Ni(Cy2PC2H4PCy2) have been confirmed by X-ray diffraction.