Electronic Structure, Isomerism, and Chemical Bonding in B7- and B7
The electronic structure and chemical bonding of B7- and B7 have been investigated using photoelectron spectroscopy and ab initio calculations. Complicated, but well-resolved, photoelectron spectra were obtained for B7- at several photon energies and were shown distinctly to contain contributions from different B7- isomers. The structures of the global minima and low-lying isomers were identified using extensive ab initio calculations. Two almost degenerate pyramidal structures I (C6v, 3A1) and II (C2v, 1A1) were the most stable for B7-. The triplet structure-I is slightly more stable than the singlet structure at our highest level of theory[RCCSD(T)/6-311+G(2df)] by 0.7 kcal/mol only. The next lowest singlet structure V (C2v, 1A1) was perfectly planar and was 7.8 kcal/mol higher in energy at RCCSD(T)/6-311+G(2df) level. The observed photoelectron spectra can only be explained when contributions from all these three low-lying isomers were considered; the observed spectral feature s were in good agreement with the calculated detachment transitions from the three isomers. Analyses of the molecular orbitals and chemical bonding revealed evidence that the triplet pyramidal C6V structure-I has a twofold ( and ) aromaticity, the singlet pyramidal C2V structure-II has -aromaticity and -antiaromaticity, and the singlet planar C2V structure V has a twofold ( and ) antiaromaticity.
- Research Organization:
- Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 15007500
- Report Number(s):
- PNNL-SA-41377; 3225; KP1301030
- Journal Information:
- Journal of Physical Chemistry A, 108(16):3509-3517, Journal Name: Journal of Physical Chemistry A, 108(16):3509-3517
- Country of Publication:
- United States
- Language:
- English
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