Cycloheptatrienyl-bridged heterodimetallic complexes: Synthesis, fluxional behavior, and X-ray crystal structure of [Fe(CO)3(μ-η3:η2-C7H 7)Pd(η5-C5H5)]

The reaction of [(η3-C7H7)Fe(CO)3]- with [(η4-C8H12)PdL]+ leads to the formation of [Fe-(CO)3(μ-C7H7)PdL]. When L = C3H5, the known complex [Fe(CO)3(μ-η3:η4-C7H 7)Pd(η3-C3H5)] is obtained. When L = C5H5, the reaction gives the title compound. In solution the molecule is fluxional in the 1H- and 13C-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 1H- and 13C-NMR spectra. Crystal data for [Fe(CO)3(μ-η3:η2-C7H 7)Pd(η5-C5H5)]: monoclinic, space group P21/n, a = 8.772(2) Å, b = 10.308(6) Å, c = 16.078(3) Å, β = 93.38(4)°, V = 1451(1) Å3, Z = 4, R = 0.019, Rw = 0.024 based on 1929 reflections with I > 3σ(I). © 1993 American Chemical Society.