STRUCTURE AND BONDING IN TRANSITION-METAL CARBONYLS AND NITROSYLS .4. MOLECULAR-STRUCTURE OF RUTHENIUM PENTACARBONYL DETERMINED BY GAS-PHASE ELECTRON-DIFFRACTION

The molecular structure of ruthenium pentacarbonyl has been investigated by gas-phase electron diffraction. The effect of single-double multiple scattering on the structural parameters was taken into account. The diffraction data are consistent with a molecule of trigonal-bipyramidal symmetry with the axial Ru—C bonds slightly shorter than the equatorial. With assumption of D3hsymmetry for the molecule, values for some of the more important distance (r/Å) and root-mean-square amplitude (lα/Å) parameters with estimated uncertainties (2σ) are 〈rα(Ru−C)〉 = [2r(Ru−Cax) + 3rα(Ru−Ceq)]/5 = 1.953 (3), Δrα(Ru−C) = rα(Ru−Cax) − rα(Ru−Ceq) = −0.021 (21), 〈rα(C≡O)〉 = 1.126 (2), ΔrαC≡O) = 0 (assumed), rg(Ru−Cax) = 1.950 (9), r(Ru−Ceq) = 1.969 (3), rg(C≡O) = 1.143 (2), l(Ru−Ceq) = l(Ru−Cax) − 0.002 = 0.070 (5), and l(C≡O) = 0.042 (3). The multiple scattering from the molecule was found to be small. The quality of the fit was improved by allowance for the effect of multiple scattering, but the parameter values changed only slightly. © 1990, American Chemical Society. All rights reserved.