Tetranuclear, early-late heterobimetallic complexes bridged by the bifunctional phosphinoalkylcyclopentadienyl ligands [Ph2P(CH2)(n)C5H4](-) (n=1,2)

Reaction of (eta(5)-C5H4(CH2)(n)PPh2)(2)MCl2 (n = 1, M = Ti (1), Zr (2); n = 2, M = Ti(3) Zr(4)) with [RhCl(CO)(2)](2) at -80 degrees C and under cond itions of high dilution yields the tetranuclear products [(mu-eta(5):eta(1) -C5H4(CH2)(n)PPh2)(2)MCl2RhCl(CO)](2) (n = 2, M = Ti (5), Zr (6); n = 1, M = Ti (7), Zr (8)). Molecular weight measurements, mass spectral data, and t he X-ray structures of 5b (one isomer of 5) and of 7 confirm the tetranucle ar formulations. Compounds 5b and 7 are shown to have two parallel Rh(I) sq uare planes, in which these metals are approximately 11.88 and 9.01 Angstro m apart, respectively, each bridged by the metallodiphosphine ligands, (eta (5)-C5H4(CH2)(n)PPh2)(2)TiCl2, which are in trans positions at each Rh. The larger metallodiphosphine ligand (n = 2) gives rise to additional flexibil ity in compounds 5 and 6, yielding two isomers of each, which appear to dif fer by a twist of the titanocene dichloride moiety about the metallodiphosp hine backbone. Reaction of compound 1 with (COD)PdCl2 gives the analogous T i/Pd tetranuclear product [(mu-eta(5):eta(1)-C5H4CH2PPh2)(2)TiCl2PdCl2](2), which is assumed, on the basis of spectral similarities, to have a structu re like those of 7 and 8.