Norbornadiene complexes of molybdenum(II) and their transformation to a catalyst for ring-opening metathesis polymerization: DFT calculations - X-ray crystal structure of a new norbornadiene complex [MoCl(GeCl3)(CO)(3)(eta(4)-nbd)]

摘要

Photolysis of [Mo(CO)(4)(eta(4)-nbd)] (nbd = norbomadiene) in n-heptane solution containing GeCl4 leads to the formation of a sevencoordinate compound with a direct Mo - Ge bond, [MoCl(GeCl3)(CO)(3)(eta(4)-nbd)] (1). The molecular structure of compound 1 has been established by single-crystal X-ray diffraction studies. Similarly to the previously investigated heterobimetallic complexes of molybdenum(II), [MoCl(SnCl3)(CO)(3)(eta(4)-nbd)] (2) and [MoCl(SnCl3)(CO)(2)(NCMe)(eta(4)-nbd)] (3), the molybdenum - germanium compound 1 initiates the ring-opening metathesis polymerization (ROMP) of nbd. Density functional theory calculations at the B3LYP level have been performed to understand the mechanism of the rearrangement of the eta(4)-nbd ligand to the species initiating the ROMP reaction in the coordination sphere of the molybdenum(II) complexes 2 and 3, which together with complex I are representative examples of experimental complexes in which such a transformation takes place. (c) 2007 Elsevier B.V. All rights reserved.