DITHIOPHOSPHONATES AND RELATED P/S-TYPE LIGANDS OF GROUP 11 METALS

Abstract

Within the phosphor-1,1,-dithiolate class of compounds, the dithiophosphonato ligand [S₂PAr(OR′)]⁻ (typically Ar = aryl or ferrocenyl; R′ = alkyl) has emerged as an interesting choice for the preparation of a variety of new metal complexes. This review focuses on the dithiophosphonates and certain related thio species of the group 11 coinage metals, copper, silver and gold, with particular emphasis on structure and coordination modes. Amongst these three metals a rich coordination and structural chemistry had been developed and reported. For copper, a number of new complexes ranging from a single metal center, to di-, tetra-, and Cu₁₄ clusters had been prepared. For silver, the number of reported complexes is not yet abundant but range in nuclearity from Ag₂ to Ag₂₈, which gives an indication of the potential scope. For gold, the majority of complexes are dinuclear gold(I) of the type [AuS₂PR(OR′)]₂ where the variety of R′ can be enormous. A few silver and gold complexes with the title ligand had also been subjected to theoretical studies. New coordination modes have also been observed, particularly in cases where previously isolated complexes have been subjected to further reaction with phosphines. Copper and silver complexes have not yet shown the rich luminescent properties as gold, and developments of the latter are described also.

Keywords:

• copper
• dithiophosphonate
• gold
• group 11 metals
• Lawesson's Reagent
• luminescence
• silver
• trithiophosphonate
• Woollins Reagent

ACKNOWLEDGEMENTS

I gratefully acknowledge financial support from the Robert A. Welch Foundation (Houston, Texas) in the US, which funded my entry into this area of research. In South Africa, where this work is continued, I acknowledge Mintek (Project AuTEK), and the NRF. I thank Rand Refineries for a generous gift of gold salt.