Experimental and theoretical studies on Nb{sub 4}C{sub 4}{sup 0+}. Reactivity and structure of the smallest cubic niobium-carbon cluster

Journal Article · Wed Apr 12 04:00:00 EDT 1995 · Journal of the American Chemical Society

DOI:https://doi.org/10.1021/ja00119a020· OSTI ID:41834

Yeh, C S; Byun, Y G; Afzaal, S; Kan, S Z; Lee, S; Freiser, B S ^[1]; Hay, P J ^[2]

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1. Purdue Univ., West Lafayette, IN (United States)
2. Los Alamos National Lab., NM (United States)

Nb{sub 4}C{sub 4}{sup +}, one of the smallest cubic crystallite structures (2x2x2) of the transition metal-carbon cluster family, is studied with the use of a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer equipped with a compact supersonic source. Nb{sub 4}C{sub 4}{sup +} reacts with oxygen to form Nb{sub 4}C{sub 2}{sup +} and, presumably, 2CO. No higher order reactions are observed to proceed by elimination of one or two CO molecules. Taken together with other experiments, these results suggest that 8 eV < D(Nb{sub 4}C{sub 2}{sup +}-C{sub 2}) < 10 eV and D(Nb{sub 4}C{sub 4}{sup +}-C{sub 2}) > 10 eV. In addition, this cluster ion is also found to react with both water and methanol through two competitive pathways which are dependent on the background Ar cooling gas. The reactions with water and methanol proceed with efficiencies of 3.98 and 2.7%, respectively. In the absence of cooling gas, abstraction to form Nb{sub 4}C{sub 4}OH{sup +} and Nb{sub 4}C{sub 4}OCH{sub 3}{sup +} from water and methanol, respectively, dominate and suggest D(Nb{sub 4}C{sub 4}{sup +}-OH) {<=} D(H-OH) = 119 kcal/mol and D(Nb{sub 4}C{sub 4}{sup +}-OCH{sub 3}) nearly equals D(H-OCH{sub 3}) = 104 kcal/mol. Both of these product ions are observed to attach a maximum of 3 more solvent molecules at longer reaction times. 45 refs., 7 figs., 4 tabs.

• Sponsoring Organization: USDOE
• DOE Contract Number: FG02-87ER13766
• OSTI ID: 41834
• Journal Information: Journal of the American Chemical Society, Journal Name: Journal of the American Chemical Society Journal Issue: 14 Vol. 117; ISSN JACSAT; ISSN 0002-7863
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
40 CHEMISTRY
ACTIVATION ENERGY
CARBON
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
DISSOCIATION
ELECTRONIC STRUCTURE
EXCITED STATES
HARTREE-FOCK METHOD
ION PAIRS
MASS SPECTRA
METHANOL
MOLECULAR IONS
MOLECULAR STRUCTURE
NIOBIUM COMPOUNDS
WATER