A Structural and Theoretical Study of the Thiophosphinite and Dithiophosphinate Anions

Abstract

Two novel lithium compounds containing either the phosphorus-chalcogenide anions [Ph ₂ PS]⁻ or [Cy ₂ PS ₂ ]⁻ were isolated as decomposition products in the attempted formation of phospha(V)guanidinate anions. Lithium diphenylthiophosphinite was structurally characterized as the dimeric TMEDA adduct [Li(Ph ₂ PS)(TMEDA)] ₂ (1), in which a rare example of the κ ¹ -S bonding mode was observed for the anion. The dicyclohexyldithiophosphinate anion was incorporated into an aggregated structure with molecular formula [Li ₅ (Cy ₂ PS ₂ ) ₄ (OH)] ₂ (2). DFT calculations were performed on the isolated [R ₂ PS]⁻ and [R ₂ PS ₂ ]⁻ anions (R = Ph, Cy), indicating delocalization of electron density into the P-S bonds for each model, in agreement with bond-lengths taken from crystallographic data.

Keywords:

• Coordination compound
• crystal structure
• dithiophosphinate
• DFT
• lithium
• thiophosphinite

Acknowledgments

The University of Sussex and the EPSRC are thanked for financial support.

Notes

^aValues taken from compound 1

^bvalues taken from Cp₂Ti(Cy₂PS)₂, see Reference 9.

^aValues taken from [Ph₃Te][Ph₂PS₂], in which only weak secondary cation· anions interactions are present, see Reference 29

^brange of values taken from compound 2.