Abstract
Two series of asymmetric ferrocene diphosphines, namely the dppf-type ligands R(2)PfcPPh(2) (protected as BH3 adducts; fc = ferrocene-1,10-diyl) and their semi-homologous counterparts R(2)PfcCH(2)PPh(2) (both in free and BH3-protected form), with diverse PR2 groups (R = cyclohexyl, isopropyl and tert-butyl), were prepared and further converted into the respective phosphine selenides, R2P(Se)fcP(Se)Ph-2 and R2P(Se) fcCH(2)P(Se)Ph-2, which were in turn used to evaluate the electronic properties of these diphosphines through (1)J(SeP) coupling constants. When reacted with [PdCl2(MeCN)(2)] or [PdCl2(cod)] (cod = cycloocta-1,5-diene), the dppf-type ligands exclusively afforded the chelate complexes [PdCl2(R(2)PfcPPh(2)-kappa P-2,P')], whereas the more flexible, homologous ligands produced mixtures mainly containing the similar chelate complexes [PdCl2(R(2)PfcCH(2)PPh(2)-kappa P-2,P')] and the P,P'-bridged dimers [PdCl2(m(P,P')-R(2)PfcCH(2)PPh(2))]2.