1. Department of Chemistry, University of Sussex, Falmer, Brighton BN1 9QJ, U.K., Department of Chemistry, University of Bath, Bath BA2 7AY, U.K., Quantum Organic Chemistry Group, Division of Organic Chemistry and Biochemistry, Rudjer Bošković Institute, P.O. Box 180, HR-10 002 Zagreb, Croatia, Institute of Chemistry, University of Tartu, Ravila 14a, 50411 Tartu, Estonia, and Department of Chemistry, University Science Laboratories, University of Durham, South Road, Durham DH1 3LE, U.K.