Carbene and Carbyne Complexes of Ruthenium, Osmium, and Iridium

Abstract

Publisher Summary This chapter discusses the carbene and carbyne complexes of ruthenium, osmium, and iridium. The importance of transition-metal carbene complexes and of transition-metal carbyne complexes is now well appreciated. The wealth of empirical information collected for transition-metal carbene and carbyne complexes may be best interpreted within the framework of sound theoretical models for these compounds. Theoretical studies of metal–carbene complexes have been undertaken by several groups. The chemistry of transition metal–carbyne complexes is rather less developed than the chemistry of carbene complexes. The development of the chemistry of carbene complexes of the Group 8A metals, Ru, Os, and Ir, parallels chemistry realized initially with transition metals from Groups 6 and 7. Although transition-metal alkylidene complexes––that is, carbene complexes––containing only hydrogen or carbon-based substituents were first recognized over 15 years ago, it is only relatively recently that Ru, Os, and Ir alkylidene complexes have been characterized. In 1980, a stable dichlorocarbene complex of osmium (II) was described, and since then a large number of dihalocarbene complexes of ruthenium, osmium, and iridium has been prepared. Transition-metal carbyne complexes are still relatively uncommon as only a few synthetic approaches to these compounds have proved generally applicable. M=C and M=C bonds are now well-established features of the chemistry of Ru, Os, and Ir. Many exciting possibilities exist for using these functions in further reactions.