SEQUENTIAL BOND-ENERGIES OF CR(CO)X+, X=1-6

The sequential bond energies of Cr(CO)x+, x = 1-6, are determined by c ollision-induced dissociation in a guided ion beam tandem mass spectro meter. Values for the 0 K bond energies (in eV) are determined to be D (Cr+-CO) = 0.93 +/- 0.04, D[(CO)Cr+-CO] = 0.98 +/- 0.03, D[(CO)2Cr+-CO ] = 0.56 +/- 0.06, D[(CO)3Cr+-CO] = 0.53 +/- 0.08, D[(CO)4Cr+-CO] = 0. 64 +/- 0.03, and D[(CO)5Cr+-CO] = 1.35 +/- 0.08. The sum of these bond dissociation energies, 4.99 +/- 0.14 eV, is in good agreement with li terature thermochemistry. The observation that the relative bond stren gths vary nonmonotonically with the number of ligands is discussed in terms of spin conservation and ligand field theory. The bond energy fo r Cr+-Xe is also determined as 0.7 +/- 0.1 eV and compared with values for other transition metal ion rare gas species.