Chemistry and ligating properties of the 1,2,4-thiadiphosphole P 2SC 2Bu t2

Abstract

New synthetic routes to the 1,2,4- and 1,3,4-thiadiphospholes, P 2SC 2Bu t 2, are presented. Both η 1-W(CO) 5 and η 5-M(CO) 3 complexes (M=Mo, W) of the 1,2,4-thiadiphosphole ring are described and the molecular structure of the former determined by a single crystal X-ray study is in good agreement with theoretical calculations. The thermal conversion of the η 1-M(CO) 5 complex to the η 5-M(CO) 3 complex is attributable to the entropy change in the reaction. A sequence of [4+2] and [2+2+2] cyclo-addition reactions of the 1,2,4-thiadiphosphole, P 2SC 2Bu t 2, with the phosphaalkyne, PCBu t , affords the tetracyclic cage compound P 4SC 4Bu t 4 which has also been structurally characterised.