# Unpaired and \sigma Bond Electrons as H, Cl, and Li Bond Acceptors: An Anomalous One-Electron Blue-Shifting Chlorine Bond

Raghavendra, B and Arunan, E (2007) Unpaired and \sigma Bond Electrons as H, Cl, and Li Bond Acceptors: An Anomalous One-Electron Blue-Shifting Chlorine Bond. In: Journal of Physical Chemistry A, 111 (39). pp. 9699-9706.

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## Abstract

Ab initio, DFT, and AIM theoretical studies on H-, Cl-, and Li-bonded complexes have been carried out with typical lone pair $(H_2O)$, \pi $(C_2H_4)$ and \sigma $(H_2)$ bonded pairs, and unpaired $(CH_3)$ electrons as acceptors and HF, ClF, and LiF as donors. Optimization and frequency calculations have been carried out at reasonably high levels (MP2, DFT(B3LYP), and QCISD) with large basis sets up to aug-cc-pVTZ. Not surprisingly, all HF complexes show red shift in stretching frequency and the shift is correlated to the binding energy. However, the $FCl\bullet \bullet \bullet CH_3$ complex shows a large blue shift (about 200 $cm^{-1}$), which appears to be the largest blue shift predicted for any weakly bound complex yet. Analysis of the normal modes of the complex indicates that the shift is due to the mixing of modes between donor and acceptor and it is qualitatively different from the blue shifts reported thus far in hydrogen-bonded complexes. For Cl- and Li-bonded complexes, a correlation between frequency shift and binding energy is not found. However, AIM theoretical analysis shows the similarity in all these interactions. The electron density at the bond critical point shows a strong correlation with the binding energy for H-, Cl-, and Li-bonded complexes. This appears to be the first report on a one-electron chlorine bond.

Item Type: Journal Article Copyright of this article belongs to American Chemical Society. Division of Chemical Sciences > Inorganic & Physical Chemistry 18 Jul 2008 19 Sep 2010 04:47 http://eprints.iisc.ernet.in/id/eprint/15054