Bond energies in dicobalt octacarbonyl and bromo- and chloro-methylidynetricobalt enneacarbonyls

Abstract

Using a solution calorimetric method at 298.15 K, the standard enthalpies of formation of crystalline [Co₃(CBr)(CO)₉], [Co₃(CCl)(CO)₉], and [Co₂(CO)₈] have been determined as –284.3 ± 2.2, –283.5 ± 2.4, and –298.9 ± 1.2 kcal mol^–1 respectively. The enthalpies of sublimation of the compounds were determined by effusion manometry as 23.8 ± 0.4. 28.1 ± 0.6, and 15.6 ± 0.8 kcal mol^–1 respectively. Bond energies have been derived from the gas-phase enthalpies of formation and their structural implications are discussed.