Semiempirical molecular orbital theory and molecular geometry. I. Analytic procedures for extended Hueckel methods

1969 ◽  
Vol 91 (14) ◽  
pp. 3693-3702 ◽  
Author(s):  
Stanton Ehrenson
Keyword(s):  
Molecular Orbital ◽  
Molecular Geometry ◽  
Molecular Orbital Theory ◽  
Orbital Theory ◽  
Semiempirical Molecular Orbital

Activation Parameters for Ring Opening of (Bicyclo[n.1.1]alk-1-yl)methyl Radicals

1991 ◽  
Vol 44 (10) ◽  
pp. 1417 ◽  
Author(s):  
PE Pigou ◽  
DK Taylor
Keyword(s):  
Molecular Orbital ◽  
Energy Barrier ◽  
Ring Opening ◽  
Activation Parameters ◽  
Molecular Orbital Theory ◽  
Methyl Radicals ◽  
Orbital Theory ◽  
Semiempirical Molecular Orbital

Ring opening of the (bicyclo[1.1.1]pent-1-yl)methyl (4), (bicyclo[2.1.1]hex-1-yl)methyl (5) and (bicyclo[3.1.1]hept-1-yl)methyl (6) radicals has been investigated by semiempirical molecular orbital theory MINDO/3 and AM1) and by experiment. Our results indicate that (4) ring-opens extremely rapidly, with an estimated energy barrier of less than 22 kJ mol-1. The higher homologues (5) and (6) rearrange more slowly with barriers of about 42.2 and 46.0 kJ mol-1 respectively. This trend is also observed in the MINDO/3 and AM1 results, with the latter giving the better agreement with experiment.

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