Excited levels of iron, nickel and cobalt obtained by activation of metal carbonyls at 11.8 ev

Energy Disposal in the Photodissociation of Co(CO)3NO near 225 nm

“…The average adiabatic BDE in Co(CO) 3 NO determined here is larger than that average M−CO BDE for two first-row transition-metal carbonyls, Fe(CO) 5 and Ni(CO) 4 , as determined by collisionally induced dissociation. , In this case, it is likely because the BDE of a linear metal−nitrosyl bond, as is found in Co(CO) 3 NO, is larger than the BDE of a metal−carbonyl bond . The estimate of the average adiabatic BDE found in these experiments (36.2−38.6 kcal/mol) is significantly narrower than the range of possible values for average BDEs determined by Hellner et al from the vacuum UV photolysis of Co(CO) 3 NO (36.9−43.7 kcal/mol) . Rayner et al find that a one-photon photolysis of Co(CO) 3 NO at 248 nm forms CoCO.…”

“…This indicates that the average adiabatic metal-ligand BDEs for the dissociation of two carbonyls and the nitrosyl is 38 kcal/mol. However, Wang et al 3 argue that 248-and 266-nm photolyses of Co(CO) 3 NO form Co(CO) 2 , citing the work of Hellner et al 8 and suggesting that 248-nm photolysis to form CoCO provides little excess energy for the photoproducts. Their revised assignment of the primary one-photon product would raise the sum of the adiabatic BDE of one Co-CO bond and the Co-NO bond to 107 kcal/mol and the average BDE for these two bonds to 54 kcal/mol.…”

“…6 Hellner et al have studied the vacuum UV photodissociation of Fe-(CO) 5 , Ni(CO) 4 , and Co(CO) 3 NO by observing the emission of excited metal atoms. 8 They used these data to estimate the total bond dissociation energies in each of the compounds. This contribution uses dispersed fluorescence (DF) and fluorescence excitation (FE) spectroscopies to study an apparent two-photon photodissociation of Co(CO) 3 NO near 225 nm.…”

“…Further REMPI experiments investigating the bare Co atom following photodissociation , found that the Co product distribution depended on the size of a substituted ligand and the laser power near 450 nm . Hellner et al have studied the vacuum UV photodissociation of Fe(CO) 5 , Ni(CO) 4 , and Co(CO) 3 NO by observing the emission of excited metal atoms . They used these data to estimate the total bond dissociation energies in each of the compounds.…”

Metal-atom fluorescence from the quenching of metastable rare gases by metal carbonyls

“…In addition to this work, this unique pathway to metal atoms and ions, as well ·as to the more expected carbonyl fragments, has been observed from iron and some other carbonyls, from methods including multiphoton excitation (Engelking, 1980;Duncan et al, 1979;Karny et al, 1978), vacuum ultraviolet photon photolysis in a bulb (Hellner et al, 1979(Hellner et al, , 1981 or in a beam (Hor~k, 1982; Hor~k and Winn, to be published), and recent work in our laboratory has shown that electron impact also yields iron fluorescence. 1…”