Triamidoamine-supported zirconium phosphido complexes, (N 3 N)ZrPRR 0 (N 3 N=N(CH 2 CH 2 -NSiMe 3 ) 3 3-; R = alkyl, aryl; R 0 = 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 CdO, CdN, CtN, and CdS functionalities into the Zr-P bond. Molecular structures of the insertion products (N 3 N)ZrNdC(PHCy)Ph (4), (N 3 N)ZrNdC(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.
The iridium-catalyzed arene C-H borylation reaction of benzylic amines has been developed, which inverts the typical steric-controlled product distribution to provide ortho-substituted boronate esters. Picolylamine was found to be an ideal ligand to replace 4,4'-di-tert-butylbipyridine to induce the directing effect. Preliminary experiments are consistent with a mechanism involving dissociation of one amine of the hemilabile diamine ligand.
Triamidoamine-supported zirconium complexes catalyze the heterodehydrocoupling of primary phosphines with silane and germanes. In this catalysis, P-Si or P-Ge products are observed exclusively with no competitive P-P bond formation. Phosphido complexes (N3N)ZrPHR (N3N = N(CH2CH2NSiMe3)33-, R = Ph, 2; Cy, 3) were observed to be the catalyst resting state, and complex 2 was structurally characterized.
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