Structural properties and electron transfer reactivity of NX3/NX3+ (X=H, F) coupling systems

Qiao, Sun, Yuxiang, Bu, Mei, Qin and Keli, Han (2005) Structural properties and electron transfer reactivity of NX3/NX3+ (X=H, F) coupling systems. Journal of Molecular Structure: THEOCHEM, 714 2-3: 165-174. doi:10.1016/j.theochem.2004.09.043

Author Qiao, Sun
Yuxiang, Bu
Mei, Qin
Keli, Han
Title Structural properties and electron transfer reactivity of NX3/NX3+ (X=H, F) coupling systems
Formatted title
Structural properties and electron transfer reactivity of NX3/NX3+ (X=H, F) coupling systems
Journal name Journal of Molecular Structure: THEOCHEM   Check publisher's open access policy
ISSN 0166-1280
Publication date 2005-02-14
Year available 2004
Sub-type Article (original research)
DOI 10.1016/j.theochem.2004.09.043
Open Access Status Not Open Access
Volume 714
Issue 2-3
Start page 165
End page 174
Total pages 10
Place of publication Amsterdam, Netherlands
Publisher Elsevier
Language eng
Subject 03 Chemical Sciences
0306 Physical Chemistry (incl. Structural)
Abstract Mesoporous cobalt phosphide (meso-CoP) was prepared by the phosphorization of ordered mesoporous cobalt oxide (meso-Co3 O4 ). The electrical conductivity of meso-CoP is 37 times higher than that of nonporous CoP, and it displays semimetallic behavior with a negligibly small activation energy of 26 meV at temperatures below 296 K. Above this temperature, only materials with mesopores underwent a change in conductivity from semimetallic to semiconducting behavior. These properties were attributed to the coexistence of nanocrystalline Co2 P phases. The poor crystallinity of mesoporous materials has often been considered to be a problem but this example clearly shows its positive aspects. The concept introduced here should thus lead to new routes for the synthesis of materials with high electronic conductivity.
Formatted abstract
The geometries and vibrational frequencies of NH3, NH3+, NF3, NF3+ as well as their encounter complexes ((NH3⋯NH3)+ and (NF3⋯NF3)+) are calculated using DFT and ab initio methods at 6-311++G** basis set level. This paper also discusses the inapplicability of DFT methods in predicting the dissociation energy curves, especially for the systems at large contact distance, due to the ‘inverse symmetry breaking’ problem. Finally, the contact distance dependence of the activation energy, the coupling matrix element and the electron-transfer rate has been analyzed at MP2/6-311++G** level. For the NX3/NX3+ (X=H, F) coupling systems, electron transfer occurs chiefly over a range of contact distance, 2.00 Å<RN–N<5.00 Å. The optimum contact distances for the largest rates of electron transfer are 2.25 Å for NH3/NH3+ system, and 2.22 Å for NF3/NF3+ system. The corresponding maximum electron transfer rates are 1.94×106 s−1 (NH3/NH3+) and 1.64×1011 s−1 (NF3/NF3+), respectively. In addition, it should be noted that the increase of the substituents attracting electrons to the active N centers favor electron transfer.
Keyword DFT calculations
Electron transfer reactivity
Activation energy
Coupling matrix element
MP2 calculations
Contact distance dependence analysis
Q-Index Code C1
Institutional Status UQ
Additional Notes Available online 19 December 2004

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