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1,2-rearrangement in. beta. -substituted ethyl radicals. A molecular orbital study

Journal Article · · J. Phys. Chem.; (United States)
DOI:https://doi.org/10.1021/j100255a023· OSTI ID:5186607
Ab initio self-consistent field (SCF) calculations in a Gaussian orbital basis set have been carried out on both the equilibrium (open) and bridging (ring) structure of various ..beta..-substituted ethyl radicals (C/sub 2/H/sub 4/X, X = Cl, SH, and PH/sub 2/) in order to study substituent 1,2-migration. For X = Cl the C/sub 2nu/ symmetrically bridged (SB) structure is found at all geometric points to be above the C/sub 2/H/sub 4/ + Cl dissociation energy limit in a multiconfiguration (MC) SCF framework, although single-configuration unrestricted SCF calculations show very shallow minima (for /sup 2/A/sub 1/ and /sup 2/B/sub 1/ states) at long C/sub 2/H/sub 4/-Cl distances. In the MC calculations on the steeply repulsive /sup 2/A/sub 1/ state charge transfer (C/sub 2/H/sub 4/ ..-->.. Cl) is found to be an important stabilizing feature, suggesting a method for stabilizing the ring structure. Bridging structures (both symmetric and slightly unsymmetric) involving relative twisting of the methylene groups are found to be more stable than the SB structures. For both X = SH and PH/sub 2/ the unrestricted SCF results for the ring structures are similar to that for C/sub 2/H/sub 4/Cl. 31 references, 6 figures, 8 tables.
Research Organization:
Bar-Ilan Univ., Ramat-Gan, Israel
OSTI ID:
5186607
Journal Information:
J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 89:9; ISSN JPCHA
Country of Publication:
United States
Language:
English