CRYSTAL AND MOLECULAR STRUCTURE OF POTASSIUM SALT OF HEXANUCLEAR CARBONYL COBALTATE [CO6(CO)14]4-

The crystal and molecular structure of the potassium salt of the tetradecacarbonylkhexacobaltate tetraanion K4[Co6(CO)14]·6 H2O has been determined by tridimensional X-ray data measured by counter methods. The structure has been refined by least squares of F down to an R factor of 0.06. The salt crystallizes in the monoclinic space group C52h = P2 1 n with the following cell constants: a = 12.00(1) Å, b = 10.04(1) Å, c = 12.00(1) Å, β = 90.0° (1), there are 2 formula units per cell. The structure is composed of a tetragonal body centered packing of anions with the cavities occupied by potassium ions and water molecules. The anion [Co6(CO)14]4- possesses an inversion center and contains an octahedral cluster of metal atoms surrounded by 14 CO groups; 6 of them are linearly bonded one for each cobalt atom and the other 8 CO groups are triply bridged on all the octahedral faces. The metal atoms cluster and its CO's environment deviate from the holosymmetry OOh. When all the distortions are taken into account the anion can be assigned the symmetry S6. The CoCo mean distance is 2.50 Å; the CoC and the CO distances are 1.70 Å and 1.17 Å for linearly bonded groups; for triply bridged groups the CoC distances are scattered in the range 1.89(1)-2.31(1) Å, the CO mean distance is 2.21 Å. © 1969.