1

Treatments...................................................................... 7 1.6 The Barrelene to Semibullvalene Rearrangement ...... 9 1.7 More Modern Computation of the Barrelene to

Semibullvalene Conversion ......................................... 10 1.8 Detailed Reactivity of Intermediate Diradicals in

the Barrelene to Semibullvalene Rearrangement ..... 12 1.9 Single-Photon Counting Metholodogy ........................ 15 1.10 The Meta Effect............................................................ 16 1.11 An Example Where Superficially Identical

Diradicals Give Different Reactivity .......................... 20 1.12 Delta-Density Matrices and Reactivity ...................... 23 1.13 Conclusion..................................................................... 27 Acknowledgment ................................................................... 27 References.............................................................................. 27

1.1 INTRODUCTION

This chapter covers the development of theoretical organic photochemistry in the writer’s research group, from its primitive beginnings to its present state. A series of examples are selected from the author’s research as exemplifying basic principles and computational methodology. The development of increasingly powerful theoretical and mechanistic treatments is shown with examples

.