I-F-2 Ab Initio Study of the Isomers: HNNSi, HSiNN, and HNSiN

Fernando R. ORNELLAS (Sao Paulo Univ. and IMS) and Suehiro IWATA

[Bull. Chem. Soc. Jpn. 70, 2057 (1997)]

This work reports new structural, energetics, and vibrational frequency data for three isomers on the potential energy surface [H,Si,N,N] calculated at the UHF, MP2, and CCSD(T) /6-311G(2d) levels of theory. Similarly to SiNN, conventional methods fail to predict a thermodynamic stability for the isomer HSiNN. However, at the CCSD(T) level, the species HSiNN was found to lie 13.63 kcal/mol lower in energy than HNNSi; the isomer HNSiN was located 47.62 kcal/mol above the global minimum. Inclusion of zero-point energies causes the isomer HSiNN and its dissociation products HSi and N2 to be about isoenergetic, what makes its detection plausible only at low temperatures.


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