Reactivity of Alkyne Insertion and Catalytic Activity of Five‐ and Six‐Membered Cyclometalated Phosphine Complexes of Iridium

Reactions of three aryl‐substituted phosphines with [Cp*IrCl 2 ] 2 afforded the corresponding five‐membered or six‐membered cyclometalated iridium complexes ( 2 or 5 , 6 ) via an intramolecular C(sp 2 )–H bond activation. Insertion reactions of the five‐membered cycloiridated complex 2 with PhC≡CPh and PhC≡CCOPh resulted in the corresponding five‐membered and six‐membered doubly cycloiridated complexes 7 and 8 , the formation of which presumably went through the vinylidene rearrangement of alkynes followed by 1,1‐insertion; while the reactions of the six‐membered cyclometalated complexes 5 , 6 with PhC≡CPh or PhC≡CCOPh gave the corresponding eight‐membered cycloiridated complexes 9 – 12 by 1,2‐insertion. The hydrosilylation of imines catalyzed by five‐ or six‐membered P‐containing cycloiridated complexes were studied, and the results proved that the six‐membered cycloiridated complex 5 can be used as an efficient catalyst, which was applied for the hydrosilylation of various imines, especially aldimines. Molecular structures of complexes 9 , 10 and 12 were determined by X‐ray diffraction.