(1,2-BIS(DIPHENYLPHOSPHINO)ETHANE)(ETA(3)-1-ARYLALLYL)PALLADIUM TETRAFLUOROBORATES - DISTRIBUTION OF THE POSITIVE CHARGE-DENSITY BY CORRELATION OF NMR CHEMICAL-SHIFTS WITH HAMMETT SUBSTITUENT CONSTANTS

C-13 NMR differences of chemical shifts (delta(X) - delta(H)) of allyl carbon atoms in a series of (1,2-bis(diphellylphosphino)ethane)(eta(3)-1-(4-X-phenyl)allyl)palladium tetrafluoroborates, X ranging from NO2 to OMe, correlate very well (r > 0.994) with sigma Hammett constants. However, P-31 NMR differences of the ligand cis and traits phosphorus atoms correlate well with sigma and with sigma(+), respectively. These data indicate that the positive charge density of the cation is localized mainly in the P-Pd-P region.