Decomposition of Molybdenum Hexacarbonyl

Abstract

THE publication of results by Clougherty¹ and by Kaye² of the preparation of face-centred cubic molybdenum monocarbide, and by Goldschmidt³ of the preparation of face-centred cubic ditungsten carbide, have led us to re-examine the face-centred cubic dimolybdenum carbide reported by Lander and Germer⁴. They observed its formation while trying to plate metallic substrates maintained at 300° to 475° C with molybdenum, formed by the pyrolysis of molybdenum hexacarbonyl in the presence of partial pressures of carbon monoxide ranging from 0.02 to 0.22 torr. The deposit had a face-centred cubic structure with a cell edge of 4.14 Å and was believed to be Mo₂C, although full chemical analyses were not reported. They suggested it was isostructural with the Mo₂ N phase reported by Hägg⁵, which is believed to have a rock salt structure with a defective anion sublattice. A phase, identified as face-centred cubic Mo₂C, has been noted by Kuo⁶ as a precipitate in high-speed steels, although no lattice parameter was reported.