Synthesis of a library of iridium-containing dinuclear complexes with bridging PNNN and PNNP ligands (BL), [LM(mu-BL)M ' L ']BF4. 2. Preparation, basic coordination properties, and reactivity of the carbonyl complexes

摘要

A series of dinuclear carbonyl complexes with PNNP and PNNN ligands, [(L)M(PNNX)M'(L)]BF4 (X = P, N; M(L), M'(L') = Ir(CO)(2), Rh(CO)(2), Pd(allyl)), have been prepared by carbonylation (1 atm) of the corresponding cod complexes, and the Rh/Ir complexes have been further converted to mu-eta(1):eta(2)-acetylide complexes, where effective pi-back-donation to the acetylide ligand is essential to stabilize them. On the basis of the stability of the acetylide complexes, the pi-donating ability of the metal fragment in the PNNX system is estimated to be (P,N)Rh > (P,N)Ir > (N,N)M. The dinuclear PNNX complexes catalyze alkyne hydrogenation, alkene hydroformylation, and allylation of aniline with allyl alcohol, and, for the allylation, a dinuclear mechanism involving activation of allyl alcohol by interaction with a CO ligand is proposed.