N-phosphanylamidine ligands and their catalytic activity in the hydroformylation of 1-octene and styrene

摘要

Pyridine-based N-phosphanylamidine ligands i-Pr_2N-C(pyr)N- PR_2 (R = Ph (3), i-Pr (4)) were synthesized and fully characterized by NMR spectroscopy and X-ray crystallography. Mononuclear rhodium complexes 7 and 8 were obtained in one step from the [RhCl(COD)]_2 dimer and the monodentate ligands 1 and 2. Their single-crystal X-ray diffraction studies revealed the structural adaptive behavior of the monodentate N-phosphanylamidine ligands 1 and 2 upon k~1-P coordination mode in rhodium(I) complexes with the imino nitrogen atom of the amidine function which behaves as a "universal joint". Compounds 1-4 were evaluated as ligands in the 1-octene and styrene hydroformylation reactions. The results obtained are encouraging and represent the first report on the use of N-phosphanylamidine ligands of the type R″_2N-C(R′)N-PR_2 in catalytic reactions.