Representation of Chemical Systems and Interconversions by be Matrices and Their Transformation Properties

✍ Scribed by Prof. Dr. Ivar Ugi; Dr. Paul Gillespie

• Publisher: John Wiley and Sons
• Year: 1971
• Tongue: English
• Weight: 235 KB
• Volume: 10
• Category: Article
• ISSN: 0044-8249
• DOI: 10.1002/anie.197109141

✦ Synopsis

Both CND0/2 and MIND0/2 indicate a definite preference among the possible modes of ring opening : Contrary to earlier qualitative predictions['2J, our results show that disrotation 1 should require the lowest activation energy" Why is this reaction path more favorable than the others? The calculated total energies can be resolved into interpretable energy Analysis of these CNDO partial energies shows that the differences in the activation energies lie almost exclusively in the term that is decisive for covalent bonding (2% ELB, for notation see ref.

1141).

Further dissection of the summation term indicates that the activation energy difference is due mainly to the contributions of the three C-C bonds. In the case of disrotation 1 the carbon centers in the transition state exhibit more pronounced mutual covalent bonding than in conrotation or disrotation 2.