Synthesis and Pd(II) Complexes of an Unsymmetric and Flexible Ferrocene Bisphosphine

Abstract

To expand the family of flexible homologated analogs of 1,1′‐bis(diphenylphosphino)ferrocene, the unsymmetric bisphosphine 1‐(diphenylphosphino)‐1′‐[2‐(diphenylphosphino)ethyl]ferrocene ( 1 ) was prepared and examined as a ligand in Pd(II) complexes. The compound was obtained by hydrophosphination of 1‐(diphenylphosphino)‐1′‐vinylferrocene ( 2 ) and was further converted to the corresponding bis(phosphine selenide) ( 3 ). While the reactions of 1 with [PdCl 2 (cod)] and [(L NC )Pd(MeCN) 2 ](ClO 4 ) (cod = cycloocta‐1,5‐diene, L NC = [2‐(dimethylamino)methyl]phenyl) were unselective and yielded no defined product, cleavage of the dimeric precursor [(L NC )Pd(μ‐Cl)] 2 cleanly produced the P,P′‐bridged palladium(II) complex [(μ(P,P′)‐ 1 ){Pd(L NC )Cl} 2 ] ( 4 ). These experiments suggested that 1 has a decreased ability to form chelate complexes, typical of the more rigid dppf. Compounds 1 , 3 , and 4 were characterized by spectroscopic methods, elemental analysis, and single‐crystal X‐ray diffraction, and the electrochemical properties of 1 and the dipalladium complex 4 were investigated using cyclic voltammetry.