Si−H Bond Activation by Electrophilic Phosphinidene Complexes

The terminal electrophilic phosphinidene complex [CpFe(CO)2{PN-i-Pr2}][AlCl4] (2), generated via chloride abstraction from [CpFe(CO)2{P(Cl)N-i-Pr2}] (1), reacts with primary, secondary, and tertiary silanes to form the silyl phosphine complexes [CpFe(CO)2{P(H)(SiR3)N-i-Pr2}][AlCl4] (3, SiR3 = SiPhH2; 4, SiR3 = SiPh2H; 5, SiR3 = SiEt3), in which the phosphinidene has inserted into the Si−H bond. A computational study shows that the insertion is concerted and has a triangular transition state. The silyl phosphine complexes 3, 4, and 5 are very susceptible to nucleophilic attack, which leads to P−Si bond cleavage and formation of the bridging phosphido complex [{CpFe(CO)}2(μ-CO){μ-P(H)N-i-Pr2}][AlCl4] (6).