The structure of nonacarbonyl-μ3-methylidyne-triangulo-tricobalt. X-ray and neutron diffraction studies

Abstract

The titlecompound, Co3(CO)9CH , crystallizes in space group P1 (Z = 2). The unit-cell dimensions determined from neutron diffraction data at 102 K are a = 7.936(2), b = 13.656(4), c = 6.856 (2).A, a = 101.60 (2), fl = 109.34 (2) and y = 93.96 (2) °. The structure was solved by Patterson methods with X-ray diffraction data obtained at room temperature, and further refined with low-temperature X-ray and neutron diffraction data. R(F) (neutron) = 0.037 for 3781 observations. The molecule possesses an idealized Cap point symmetry. Three Co(CO)a groups and a CH group form a distorted tetrahedron. The high resolution of the present study reveals significant differences between the axial and equatorial Co-C bond lengths, the average Co-C distances for these being respectively 1.837(2) and 1.798 (1)/~. The C-H bond distance as determined by neutron diffraction is 1.084 (1) ,/~. The Co neutron scattering length has been refined to a value of 2.48 (2) fm.