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

Secondary phosphines such as HPPh 2 and to the cationic iron dienyl complex [η 5 ‐(1 R )‐ethylnopadienyl)Fe‐(CO) 3 ] + ( 1 ) by nucleophilic addition. The phosphonium salt initially formed is readily deprotonated to yield an optically active tertiary phosphine [( n 4 ‐(1 R )‐ethylnopadienePPh 2 )Fe(CO) 3 ] ( 2b ). A similar reaction also occurs with [C 6 H 7 Fe‐(CO) 3 ] + ( 3 ) and [C 7 H 9 Fe(CO) 3 ] + ( 4 ) to give [(C 6 H 7 PPh 2 )Fe(CO) 3 ] ( 5 ) and [(C 7 H 9 PPh 2 )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 P 2 1 2 1 2 1 (no. 19); 5 crystallizes in the space group P 2 1 / 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 P 3 1 (no. 144).