Insertion Reactions and Catalytic Hydrophosphination by Triamidoamine-Supported Zirconium Complexes

Triamidoamine-supported zirconium phosphido complexes, (N 3 N)ZrPRR′ (N 3 N = N(CH 2 CH 2 NSiMe 3 ) 3 3−; R = alkyl, aryl; R′ = R, H), have been shown to catalyze the hydrophosphination of terminal alkynes as well as that of symmetric aryl and alkyl carbodiimides. A mechanism based on insertion of the substrate into the Zr−P bond is proposed on the basis of competition experiments and model examples of stoichiometric insertion reactions of polar, small-molecule substrates possessing C═O, C═N, C≡N, and C═S functionalities into the Zr−P bond. Molecular structures of the insertion products (N 3 N)ZrN═C(PHCy)Ph ( 4 ), (N 3 N)ZrN═C(PPh 2 )Ph ( 5 ), and (N 3 N)ZrPhNC(O)PPh 2 ( 11 ), as well as (N 3 N)Zr[η 2 ( N,N )-( i PrN) 2 C(PPh 2 )] ( 9 ), a key intermediate in the catalytic hydrophosphination of carbodiimides, have been determined.