SYNTHESIS AND FLUXIONAL BEHAVIOR, INCLUDING A COMPARATIVE-ANALYSIS OFTHE PD-N BOND RUPTURE, OF NEW CHIRAL COMPLEXES OF PALLADIUM(0) AND -(II) WITH A RIGID (AMINOFERROCENYL)PHOSPHINE LIGAND - CRYSTAL-STRUCTUREOF THE 2 ROTAMERS OF A PALLADIUM(0) MALEIC-ANHYDRIDE COMPLEX

The (aminoferrocenyl)phosphine ligand sphino-2,1'-(1-dimethylaminoprop anediyl)ferrocene, 1, was used to synthesize new palladium(0) and -(II ) complexes. The reaction of Pd-2(dba)(3). CHCl3 with 1 in the presenc e of the electron-withdrawing olefins dimethylfumarate (DMFU) and male ic anhydride (MA) gave the new complexes Pd(1)(DMFU) (2) and Pd(1)(MA) (3). The allyl complex [Pd(eta(3)-2-Me-C3H4)(1)]Tf (4) was obtained f rom the reaction of 1 with [Pd(eta(3)-2-Me-C3H4)(Cl)](2) in the presen ce of AgTf. In solution all these compounds exist as mixtures of two d iastereomers, with either the alkene or the allyl group differently or iented with respect to the aminophosphine ligand. The orientation of t hese ligands in the major isomers has been determined by means of NOEs . Alkene rotation takes place in complexes 2 and 3 with free energies of activation Delta G(340)double dagger = 73.1 kJ mol(-1) (2) and Delt a G(368)double dagger = 79.9 kJ mol(-1) (3), respectively. These barri ers are compared with those of some analogous ferrocenyl aminophosphin e ligands, PPFA -dimethylaminoethyl)-1-diphenylphosphinoferrocene) and PTFA endo-(alpha-dimethylamino)tetramethyleneferrocene) complexes. Fo r 3, the alkene rotation leads to isomer interconversion, while the ob served isomerization of 2 must proceed via an olefin face exchange. So me experiments in relation to the nature of this process are discussed . Starting from PdRR'L' precursors and 1 or PPFA, other Pd(II) derivat ives of formulas PdRR'(1), R = Cl, R' = Me, L' = cod, 5; R = R' = Me, L' = tmeda, 6; R = R' = C6F5, L' = cod, 7, or PdClMe(PPFA), 8, were pr epared. For 5 and 8, only the isomers with the methyl group trans to n itrogen were obtained. The Pd-N bond rupture in the new complexes of 1 and in similar derivatives of PPFA and PTFA has been analyzed by vari able-temperature H-1 NMR studies, and in some cases a line shape analy sis has been carried out. The influence of the ferrocenyl aminophosphi ne and ancillary ligands as well as of the oxidation state of the pall adium center on this process is discussed. The molecular structures of both rotamers of 3, present in the same crystal, were determined by X -ray structure analysis.