A structural and theoretical study of the thiophosphinite and dithiophosphinate anions

Two novel lithium compounds containing either the phosphorus-chalcogenide anions [Ph2PS] or [Cy2PS2] 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(Ph2PS)(TMEDA)]2 (1), in which a rare example of the 1-S bonding mode was observed for the anion. The dicyclohexyldithiophosphinate anion was incorporated into an aggregated structure with molecular formula [Li5(Cy2PS2)4(OH)]2 (2). DFT calculations were performed on the isolated [R2PS]- and [R2PS2]- 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