Nitromethylene (H-C-NO[sub 2]). A comparison of the lowest lying triplet and singlet states of a highly unconventional carbene

Journal Article · Wed Jul 14 04:00:00 EDT 1993 · Journal of the American Chemical Society; (United States)

DOI:https://doi.org/10.1021/ja00067a040· OSTI ID:5845102

Bolton, E E; Schaefer, III, H F ^[1]

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1. Univ. of Georgia, Athens (United States)

The lowest lying triplet and single states of nitromethylene were studied with ab initio quantum mechanical methods employing large basis sets and high levels of theory. The lowest triplet state is predicted to have a planar C[sub s] symmetry structure. The lowest singlet state displays C[sub s] symmetry at the self-consistent field (SCF) and at the two-configuration self-consistent field (TCSCF) level of theory but shows C[sub 1] symmetry at correlated levels of theory. With a basis set of triple-[zeta] plus double polarization (TZ2P) quality and using the configuration interaction method including all single and double excitations (CISD), the zero point vibrational energy (ZPVE) corrected energy separation between the two electronic states is 3.5 kcal/mol, with the triplet state lying lower. However, Davidson corrected energies and single point energies at CISD geometries using the coupled cluster method including all single and double excitations (CCSD) suggest that the singlet state is about 7 kcal/mol lower in energy than the triplet state. The inclusion of f functions at the SCF level of theory showed little effect on the geometry of nitromethylene. 48 refs., 6 figs., 9 tabs.

• DOE Contract Number: FG09-87ER13811
• OSTI ID: 5845102
• Journal Information: Journal of the American Chemical Society; (United States), Journal Name: Journal of the American Chemical Society; (United States) Vol. 115:14; ISSN JACSAT; ISSN 0002-7863
• Country of Publication: United States
• Language: English

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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
661100 -- Classical & Quantum Mechanics-- (1992-)
664100 -- Theory of Electronic Structure of Atoms & Molecules-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
74 ATOMIC AND MOLECULAR PHYSICS
CARBENES
DATA
ELECTRONIC STRUCTURE
ENERGY LEVELS
EXCITED STATES
INFORMATION
MECHANICS
NUMERICAL DATA
QUANTUM MECHANICS
RADICALS
REACTION INTERMEDIATES
THEORETICAL DATA
VIBRATIONAL STATES