Recent Advances in Osmium Chemistry

Abstract

Publisher Summary This chapter discusses the recent advances in osmium (Os) chemistry. The chapter explains the synthesis, properties, and chemistry of coordination complexes, focusing on the literature since the end of 1985. Analogous ruthenium (Ru) chemistry is also included to show the similarities and differences in the chemistry of these elements. Appropriate literature dealing with organometallic chemistry is referred relevant to the discussion on the coordination chemistry, because Os chemistry often transcends these traditional boundaries. Osmium complexes exist in every oxidation state from II– to VIII, but generally the coordination chemistry is restricted to oxidation states II through VIII. Most Os(IV) complexes are low spin and octahedral. Although they have two unpaired electrons, they often have anomalous magnetic properties at room temperature. This is because of quenching of the electron spin by the orbital spin, as a consequence of the large spin-orbit coupling constant. A large number of carbonyl complexes of Os have been prepared and characterized, but only CO complexes are discussed in the chapter, those with ligands that are normally associated with classical coordination chemistry. Reactions analogous to the protonation of π -acid ligand bound to Os ammine complexes have been observed with other electrophiles.