ACETYLENE ISOMERIZATION BY MANGANESE(I) - PREPARATION AND STRUCTURE OF (C5H5)2MN2(CO)4CCH2

The multistep synthesis of Cp2Mn2(CO)4(μ-CCH2), from CpMn(CO2)(THF) and acetylene, is described. The crystal structure of the compound has been determined in order to firmly establish the formal 1, 2-hydrogen migration and to evaluate the degree to which the hydrocarbon unsaturation does or does not interact with the metals. The complex crystallizes in space group P21/c with a = 8.788(3) Å, b = 12.817(5) Å, c = 13.974(6) Å, and β = 112.17 (3)°. Refinement of 2302 reflections collected at -130 °C led to a final R index of 0.075 and a final weighted R index of 0.090. Both hydrogen atoms of the bridging ligand were refined in order to establish the rotational conformation of this ligand. The CCH2 ligand symmetrically bridges a Mn-Mn bond of length 2.759 (2) Å. The carbon-carbon bond length, 1.308 (10) Å, is typical of bond order 2, but there is an 11° twist of the CCH2 ligand about the double bond. © 1979, American Chemical Society. All rights reserved.