Publication Details (including relevant citation information):
Todd W. Graham, Angela Llamazares, Robert McDonald,† and Martin Cowie Organometallics, 1999, 18 (17), 3502
Reaction of (η5-C5H4(CH2)nPPh2)2MCl2 (n = 1, M = Ti (1), Zr (2); n = 2, M = Ti (3), Zr (4)) with [RhCl(CO)2]2 at −80 °C and under conditions of high dilution yields the tetranuclear products [(μ-η5:η1-C5H4(CH2)nPPh2)2MCl2RhCl(CO)]2 (n = 2, M = Ti (5), Zr (6); n = 1, M = Ti (7), Zr (8)). Molecular weight measurements, mass spectral data, and the X-ray structures of 5b (one isomer of 5) and of 7 confirm the tetranuclear formulations. Compounds 5b and 7 are shown to have two parallel Rh(I) square planes, in which these metals are approximately 11.88 and 9.01 Å apart, respectively, each bridged by the metallodiphosphine ligands, (η5-C5H4(CH2)nPPh2)2TiCl2, which are in trans positions at each Rh. The larger metallodiphosphine ligand (n = 2) gives rise to additional flexibility in compounds 5 and 6, yielding two isomers of each, which appear to differ by a twist of the titanocene dichloride moiety about the metallodiphosphine backbone. Reaction of compound 1 with (COD)PdCl2 gives the analogous Ti/Pd tetranuclear product [(μ-η5:η1-C5H4CH2PPh2)2TiCl2PdCl2]2, which is assumed, on the basis of spectral similarities, to have a structure like those of 7 and 8.
Address (URL): http://pubs.acs.org/doi/abs/10.1021/om990280v