Organometallics playa key role in organic synthesis. Carbon carbon bond formation without main group and transition metal based reagents as well as catalysts is hardly imaginable, and the tremendous success in recent years in the field of stereoselective synthesis of complex biologically active com pounds would have been impossible without the advances in organometallic chemistry. From the wealth of carbon carbon bond forming reactions in organotransition metal chemistry many new methods have evolved. This was aided considerably by a deepening of our understanding of the relevant reaction mechanisms. Organometallic chemistry is the bridge par excellence between the traditional fields of inorganic and organiC chemistry. It was the intention of the "Volkswagen-Stiftung" to broaden this bridge by starting in 1986 the new interdisciplinary program "Organic Synthesis via Organo metallics." From its very beginning this program grew up after 6 years to now more than 60 projects and its encompasses besides its main topic "Organic Synthesis" mechanistic and structural aspects of organometallic chemistry as well. In a series of symposia sponsored by the "Volkswagen-Stiftung," the former of which were held in Hamburg (February 1986), Wiirzburg (October 1988) and Marburg (July 1990), a forum for intensive discussions and SCientific exchange was established. There, scientists participating in the program met with other experts form academia and from industry. The forth symposium was held in Aachen from July 15 to 18, 1992.