Biography: Detlef Schroder, born 1963 in Wilster, Germany, obtained his Ph. D. with Prof. Schwarz at the TU Berlin in 1992, and is currently working as research assistant in the laboratory of Prof. Schwarz. He is the recipient of the 1993 Schering Award. Christoph Heinemann, born 1968 in KSln, Germany, obtained his Ph. D. with Prof. Schwarz in the field of gas-phase chemistry in 1995. In 1995 he received the “Young Scientist Award” of the Leopoldina and in 1996 the Schering Award. Currently he is working in the research management of Hoechst AG, Frankfurt. Wolfram Koch, born 1959 in Darmstadt (Hessen), obtained his doctorate in 1986 under the tutelage of Prof. Schwarz after studying chemistry in Darmstadt and Berlin. Since 1992 he works as Professor for Theoretical Organic Chemistry at TU Berlin. In between, he was an IBM post-doctoral fellow at the IBM Almaden Research Center in San Jose, CA and a research staff member at the Institute for Supercomputing and Applied Mathematics at the IBM Scientific Center in Heidelberg. He is the recipient of the 1987 Schering Award. Helmut Schwarz, born in 1943, spent four years as a chemical technician before reading chemistry at the Technische Universitat Berlin (TUB), where he obtained his Ph. D. under the supervision of F. Bohlmann in 1972 and his habilitation in 1974. Since 1978 he has been associated with the TUB as a Professor of Chemistry and has resisted all temptation to leave Berlin for good. He held visiting appointments in Cambridge, Lausanne, Jerusalem, Haifa, Auckland, and Canberra. Among his several awards are the Otto-Klung, Otto-Bayer, and Leibniz Prizes, and the Max-Planck Research Award, which he received jointly with C. Lifshitz. In 1992 the Hebrew University of Jerusalem conferred an honorary doctorate on him and he received in 1994 the J. J. Thomson Gold Medal. He is a fellow of the Leopoldina (Halle), the Academy of Sciences at Erfurt and at Berlin-Brandenburg, and an Overseas Fellow of Churchill College, Cambridge. His current interests, besides the topic of his review, focus on the generation and characterization of elusive molecules of interstellar and atmospheric importance.