Crystal and molecular structure of the anion phosphido-di-μ-carbonyltetradecacarbonyl hexacobaltate(1 -) in its tetraphenylphosphonium salt

The tetraphenylphosphonium salt of the anion [Co6P(CO)16]- crystallizes in the monoclinic space group P21/c, with unit cell dimensions a = 10.115(4), b = 21.233(9), c = 20.585(8) Å, β = 91.76(6)°, and Z = 4. The structure has been determined by direct methods from X-ray single-crystal counter data and refined by least-squares calculations to R = 0.059 for 4698 significant diffraction intensities. The anion contains an open array of metal atoms consisting of four triangles linked in a chain sorrounding a semi-interstitial phosphide atom. The nine CoCo bond distances fall into three classes: four have mean values of 2.574 Å, an other four have mean values of 2.656 Å, and one, very long, has a value of 2.934(2) Å. The phosphorus atom lies in an exposed position so that it is coordinated to all six metals, with CoP bonds in the range 2.165-2.268(2) Å. Of the 16 carbonyl groups 14 are terminally bound (mean CoC and CO distances 1.78 and 1.14 Å) and two are symetrically bridging (mean CoC and CO distances 1.90 and 1.17 Å, respectively). © 1983.