Organophosphorus Chemistry provides a comprehensive and critical review of the recent literature. Coverage includes phosphines and their chalcogenides, phosphonium salts, low coordination number phosphorus compounds, penta- and hexa- coordinated compounds, quiquevalent phosphorus acids, nucleotides and nucleic aicds, ylides and related compounds, phosphazenes and the application of physical methods in the study of organophosphorus compounds. This is the 40th in a series of volumes which first appeared in 1970 under the editorship of Stuart Trippett and which covered the literature of organophosphorus chemistry published in the period from January 1968 to June 1969, citing some 1370 publications. The present volume covers the literature from the last eighteen months, citing more than 2200 publications, continuing our efforts to provide an up to date survey of progress in an area of chemistry that has expanded significantly over the past 40 years.