COLLISION-INDUCED DISSOCIATION STUDIES OF CO(CO)(X)(+), X=1-5 - SEQUENTIAL BOND-ENERGIES AND THE HEAT OF FORMATION OF CO(CO)(4)

Sequential bond dissociation energies of Co(CO)(x)(+) (x = 1-5) have been determined in collision-induced dissociation (CID) experiments with Xe using guided-ion beam mass spectrometry. Analysis of the CID thresholds provides the following 0 K bond dissociation energies: D-0[(COCo+-CO] = 0.78 +/- 0.05 eV, D-0[(COCo+-CO] = 0.78 +/- 0.06 eV, D-0[(COCo+-CO] = 0.85 +/- 0.12 eV, D-0[(COCo+-CO] = 1.58 +/- 0.09 eV, and D-0[Co+-CO] = 1.80 +/- 0.07 eV. The ligand exchange reaction of CoCO+ + Xe provides a Co+-Xe bond energy, D-0(Co+-Xe) = 0.80 +/- 0.14 eV, consistent with a previous determination. The values here, along with the established heats of formation for Co+ and CO and the ionization energy of Co(CO)(4), indicate that the 298 K heat of formation of Co(CO)(4)(+) is 256 +/- 18 kJ/mol and that of Co(CO)(4) is -551 +/- 20 kJ/mol. The latter value can be used to determine that D-298[(CO)(4)Co-Co(CO)(4)] = 83 +/- 29 kJ/mol. The trends in the sequential cobalt carbonyl bond energies are compared with those of other metals and discussed in terms of the electronic structure of the complexes.