Halogenated methyl radicals

We are studying the electronic structure of small halogen-containing radicals (CH2Cl, CH2F, etc.) that are involved into the ozone depletion process in collaboration with the experimental group of Prof. Hanna Reisler (USC).

Among interesting findings are additional bonding due to the interaction of the unpaired electron with the lone pair of halogens, and unusually large (i. e., ~100%) negative anharmonicities of out-of-plane vibrational modes.

CH2Cl Energy Levels

Ground state: bond order = 3/2 (full σ + 1/2π). CCl bond contraction, frequency increase, and anomalous charge distribution: C-0.4Cl+0.03

Valence 12A1 state: bond order = 3/2 (1/2σ + full π). CCl bond elongation and OPLA frequency increase.

Rydberg states: bond order = 2 (full σ + full π). CCl bond contraction and OPLA frequency increase.

Effective potentials for OPLA motions in CH2Cl and CH2F calculated at the CCSD(T)/6-311(+,+)G(3df,3pd) level of theory. Note that the fundamental 0-1 transition differs by more than factor of two from the harmonic frequency.

Effective potentials for OPLA motions in CH2Cl and CH2F

Related Publications

30. S. V. Levchenko, A. V. Demyanenko, V. L. Dribinski, A. B. Potter, H. Reisler, and A. I. Krylov
Rydberg-valence interactions in CH2Cl→CH2+Cl photodissociation: Dependence of absorption probability on ground state vibrational excitation
J. Chem. Phys. 118, 9233 – 9240 (2003) Abstract  PDF (119 kB) 

25. S. V. Levchenko and A. I. Krylov
Electronic structure of halogen-substituted methyl radicals: Equilibrium geometries and vibrational spectra of CH2Cl and CH2F
J. Phys. Chem. A 106, 5169 – 5176 (2002) Abstract  PDF (86 kB) 

21. S. V. Levchenko and A. I. Krylov
Electronic structure of halogen-substituted methyl radicals: Excited states of CH2Cl and CH2F
J. Chem. Phys. 115, 7485 – 7494 (2001) Abstract  PDF (133 kB)