1. Instituto
de Quimica-Fisica “Rocasolano”, CSIC, C/Serrano 119, 28006 Madrid, Spain
2. Dow Corning Corporation, 2200 West Salzburg Road, Midland, Michigan 48641, United States
3. Department
of Chemistry, University of Reading, Whiteknights, P.O. Box 224, Reading RG6 6AD, U.K.