The coordination chemistry of dithiophosphonates: An emerging and versatile ligand class

The phosphor-1,1,-dithiolate class of compounds is the heavier and "softer" congener of the more popular phosphonate derivatives. It contains the S2P functionality as a common feature and several sub-categories are known which include the dithiophosphato [S2P(OR')(2)](-) (R'=typically alkyl), dithiophosphinato [S2PR2](-) (R=alkyl or aryl), and dithiophosphonato [S2PR(OR'](-) (R=typically aryl or ferrocenyl, R'=alkyl) monoanionic ligands. The amidodithiophosphonato derivative of the type [S2PR(NR')](-), is rare. Potential dianionic monoester variants such as [H2S2P(=Q)(OR)] and H2S2P(=Q)R] (Q=O, S) have also been investigated. This review focuses on the dithiophosphonato [S2PR(OR')](-) ligand derivatives which have emerged as an interesting ligand choice to investigate coordination complexes. This review summarizes all reported coordination compounds utilizing dithiophosphonates with an emphasis on structure and coordination modes. It is apparent that the vast majority of compounds reported to date center around only certain metals and a large section thus remain unexplored, leaving tremendous scope and opportunity for further investigation. (C) 2012 Elsevier B.V. All rights reserved.