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

Sequential bond dissociation energies of Co(CO)(x)(+) (x = 1-5) have b een determined in collision-induced dissociation (CID) experiments wit h Xe using guided-ion beam mass spectrometry. Analysis of the CID thre sholds provides the following 0 K bond dissociation energies: D-0[(COC o+-CO] = 0.78 +/- 0.05 eV, D-0[(COCo+-CO] = 0.78 +/- 0.06 eV, D-0[(COC o+-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, consis tent with a previous determination. The values here, along with the es tablished 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. Th e 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 bon d energies are compared with those of other metals and discussed in te rms of the electronic structure of the complexes.