Insertion Reactions and Catalytic Hydrophosphination by Triamidoamine-Supported Zirconium Complexes

Triamidoamine-supported zirconium phosphido complexes, (N3N)ZrPRR′ (N3N = N(CH2CH2NSiMe3)33−; 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 (N3N)ZrNC(PHCy)Ph (4), (N3N)ZrNC(PPh2)Ph (5), and (N3N)ZrPhNC(O)PPh2 (11), as well as (N3N)Zr[η2(N,N)-(iPrN)2C(PPh2)] (9), a key intermediate in the catalytic hydrophosphination of carbodiimides, have been determined.