Document Detail

Gas-Phase Reaction Studies of Dipositive Hafnium and Hafnium Oxide Ions - Generation of the Peroxide HfO(2)(2+).
MedLine Citation:
PMID:  23186013     Owner:  NLM     Status:  Publisher    
ABSTRACT Fourier transform ion cyclotron resonance mass spectrometry was used to characterize the gas-phase reactivity of Hf dipositive ions, Hf2+ and HfO2+, towards several oxidants: thermodynamically facile O-atom donor N2O, ineffective donor CO, and intermediate donors O2, CO2, NO, and CH2O. The Hf2+ ion exhibited electron transfer with N2O, O2, NO and CH2O, reflecting the high ionization energy of Hf+. The HfO2+ ion was produced by O-atom transfer to Hf2+ from N2O, O2 and CO2, and the HfO22+ ion by O-atom transfer to HfO2+ from N2O; these reactions were fairly efficient. Density functional theory revealed the structure of HfO22+ as a peroxide. The HfO22+ ion reacted by electron transfer with N2O, CO2, and CO to give HfO2+. Estimates were made for the second ionization energies of Hf (14.5 ± 0.5 eV), HfO (14.3 ± 0.5 eV), and HfO2 (16.2 ± 0.5 eV ), and also for the bond dissociation energies, D[Hf2+-O] = 686 ± 69 kJ mol-1 and D[OHf2+-O] = 186 ± 98 kJ mol-1. The computed bond dissociation energies, 751 and 270 kJ mol-1, respectively, are within these experimental ranges. Additionally, it was found that HfO22+ oxidized CO to CO2 and is thus a catalyst in the oxidation of CO by N2O; and that Hf2+ activates methane to produce a carbene, HfCH22+.
Célia Lourenço; Maria Del Carmen Michelini; Joaquim Marçalo; John Knight Gibson; M Conceição Oliveira
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-11-28
Journal Detail:
Title:  The journal of physical chemistry. A     Volume:  -     ISSN:  1520-5215     ISO Abbreviation:  J Phys Chem A     Publication Date:  2012 Nov 
Date Detail:
Created Date:  2012-11-28     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9890903     Medline TA:  J Phys Chem A     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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