Unimolecular Decomposition of Negative Ions Formed from the Transition-Metal Carbonyls of Ni, Fe, Cr, Mo, and W

Abstract

Negative-ion mass spectra and dissociative electron-capture energetics for the principal metal-containing ions have been determined for nickel tetracarbonyl, iron pentacarbonyl, chromium hexacarbonyl, molybdenum hexacarbonyl, and tungsten hexacarbonyl. These data are utilized in the first application of the statistical theory of mass spectra to describe the unimolecular decompositions of negative ions. The mechanism proposed for the formation of the various M(CO)x− ions is an ion-pair production process followed by a series of consecutive ionic-unimolecular decomposition reactions involving the elimination of CO groups.

Low‐energy electron interactions with tungsten hexacarbonyl – W(CO)6

“…The high‐energy resonance is associated with cleavage of four CO groups from W(CO) 6 , i.e., reaction (4). Again, in this case, the resonance position differs from that of Winters and Kiser, who reported a resonance located at 7.5 eV.…”

“…The reaction channel (2) associated with cleavage of two CO groups has a threshold at 0.9 eV and three resonances are present in the ion yield curve at 1.8 and 3.3 eV, and a weak resonance at approximately 7.6 eV. The fragment ion W(CO) 4 – was also reported by Winters and Kiser . However, only one resonance for the reaction channel (2) at 2.6 eV was mentioned by that group.…”

Chemical Bonds Dissociation Energy

“…Surprisingly, it is these "negative" kinetic energy of an electron observed experimentally, as show in Fig.2. The "negative" kinetic energy of an electron (AE<0) is the 4 This is a consequence of the identity of elementary particles. .…”

“…This process simulates the addition of an electron in the electron attachment 4 , and thus, the BDE values corresponding to a number of values for the BDEs of the PI processes must occur in the DEA process, i.e. 4.03 eV, 3.46 eV, 2.13 eV, 1.31 eV, and 1.07 eV.…”

“…The interaction of lowenergy electrons with W(CO) 6 was, however, discussed in a much earlier paper. [4] Our interest here is with the predominantly sequential detachment of a CO ligand from W(CO) 6 , as well as presenting a comparison of the chemical bond dissociation energy BDE(W−CO) as calculated with the EI and DEA processes.…”