Organotransition metal compounds have been known for over a century, but it has been only during the past 15 years that most of the major advances in this area have been made. Organotransition metal compounds consist of organic molecules or ligands coordinated to transition metals by one or more carbon atoms. In the present sur vey, the formation, properties, structure, and reactions of various classes of these substances are discussed. Empha sis has been placed on important discoveries and theories that have stimulated the rapid progress of organotransition metal chemistry. Pertinent reviews on various aspects of this subject have also been cited./^\rganometallic compounds containing neutral, unsaturated organic molecules coordinated to certain transition metals were known long before the advent of Werner's theories on coordination compounds. Until about 1950, however, this aspect of coordination chemistry remained fal low, and the structure and bonding of the compounds known at that time were quite perplexing. The discovery of ferrocene and the development of a rational theory of bonding in olefin-transition metal complexes in the early 1950's prompted a vigorous research effort around the world that has attracted the attention of organic chemists, inorganic chemists, crystallographers, and scientists of many allied disciplines. Research in organo transition metal chemistry presently is proceeding at a very rapid rate, and the synthesis and properties of seemingly unlimited new types of "organometallic, T complexes" represent an important frontier in coordina tion chemistry.The purpose of the present survey is twofold. Firstly, because the Werner Symposium is partly historical, some of the more important dis coveries and theories that have led to the present high level of interest in 486 Downloaded by UNIV OF NORTH CAROLINA on February 18, 2015 |