1. Department of Chemistry, Birkbeck College, University of London, Gordon House, 29 Gordon Square, London WC1H 0PP, U.K., Department of Analytical Science, SmithKline Beecham Pharmaceuticals, New Frontiers Science Park, 3rd Avenue, Harlow, Essex CM19 5AW, U.K., and Department of Safety Assessment, SmithKline Beecham Pharmaceuticals, The Frythe, Welwyn, Herts AL6 9AR, U.K.