Low-Temperature Vapor Pressures of W-, Cr-, and Co-Carbonyls

摘要: Low-temperature vapor pressures of three metal carbonyls—W(CO) 6, Cr(CO)6, and Co2(CO)8—were determined using the gravimetric torsion effusion method. The W(CO)6 ranged from 10-5 to 10-4 kPa in a temperature range 265 288 K, those Cr(CO)6 10-3 266 272 K. Both these monomer carbonyls were virtually free disproportionation during vaporization, measured molecular weights compounds very close actual values. vaporization behavior Co2(CO)8 exhibited complex behavior, it decomposed cobalt at room temperature, vacuo. decomposition (dimer) metallic Co did not occur below ~278 but dimer disproportionated other forms, suggested by differences weight vaporizing gas species 229 g/mol as compared an value 342 g/mol. It is proposed that dimer, Co2(CO)8, undergoes partial tetramer [Co4(CO)12], [Co2(CO)8], CO gas. each above-mentioned carbonyls, average effusing gases, mechanisms for carbonyl, equilibrium constants reactions, their enthalpies, entropies, Gibbs energies are presented.