Nucleophilic Addition of Secondary Phosphines to Cationic Dienyl Tricarbonyliron Complexes: A novel Route to Optically Active Phosphines.

Abstract

Secondary phosphines such as HPPh2 and to the cationic iron dienyl complex [η5 -(1R)-ethylnopadienyl)Fe-(CO)3 ]+ (1) by nucleophilic addition. The phosphonium salt initially formed is readily deprotonated to yield an optically active tertiary phosphine [(n4 -(1 R)-ethylnopadienePPh2 )Fe(CO)3 ] (2b). A similar reaction also occurs with [C6 H7 Fe-(CO)3 ]+ (3) and [C7 H9 Fe(CO)3 ]+ (4) to give [(C6 H7 PPh2 )Fe(CO)3 ] (5) and [(C7 H9 PPh2 )Fe(CO)3 ] (6) in good yields. The mechanism of formation of these novel phosphines is discussed. Complex 2 b crystallizes in the space group P21 21 21 (no. 19); 5 crystallizes in the space group P21 /c (no. 14). Like other monodentate optically active phosphines, 2 b is capable of coordinating to transition metal complexes. It forms palladium complexes on reaction with [{μ-chloro(allyl)palladium}2 ] as well as with [{μ-chloro[(N,N-dimethylamino-kN-2-methyl)phenyl-kC]palladium}2 ] (11). The latter reaction product crystallizes in the space group P31 (no. 144).