CYCLOHEPTATRIENYL-BRIDGED HETERODIMETALLIC COMPLEXES - SYNTHESIS, FLUXIONAL BEHAVIOR, AND X-RAY CRYSTAL-STRUCTURE OF [FE(CO)3(MU-ETA(3)-ETA(2)-C7H7)PD(ETA(5)-C5H5)]

The reaction of [(eta3-C7H7)Fe(CO)3]- with [(eta4-C8H12)PdL]+ leads to the formation of [Fe(CO)3(mu-C7H7)PdL]. When L = C3H5, the known complex [Fe(CO)3(mu-eta3:eta4-C7H7)Pd(eta3-C3H5)] is obtained. When L = C5H5, the reaction gives the title compound. In solution the molecule is fluxional in the H-1- and C-13-NMR time scale and exhibits both metal migration and carbonyl group scrambling processes. The spectroscopic data and X-ray crystal structure show that this is the first case of a bridging cycloheptatrienyl metal-metal bonded complex having an uncoordinated double bond in the ring and detectable low-temperature limiting H-1- and C-13-NMR spectra. Crystal data for [Fe(CO)3(mu-eta3:eta2-C7H7)Pd(eta5-C5H5)]: monoclinic, space group P2(1)/n, a = 8.772(2) angstrom, b = 10.308(6) angstrom, c = 16.078(3) angstrom, beta = 93.38(4)degrees, V = 1451(1) angstrom3, Z = 4, R = 0.019, R(w) = 0.024 based on 1929 reflections with I > 3sigma(I).