Synthesis of S-Alkyl Phosphinocarbodithioates with Switch between P(III) and P(V) Derivatives

Simple and effective synthetic pathways are described to prepare compounds R 2 P(X)C(S)SCH(Me)Ph with the P atom either in the oxidation state V [R/X = - Bu/O ( 6 ), Ph/S, ( 7 ), - Bu/S ( 8 ), - Bu/Se ( 9 )] or III [R/X = Ph/BH 3 ( 4 ), - Bu/BH 3 ( 5 ), - Bu/lone pair ( 10 )]. Compound 9 is the first example of carbodithioate ester with a P = Se group, and for the first time, a phosphinocarboditioate with a free phosphine function (compound 10 ) is described. Stabilization of the latter crucially depends on the steric protection by the - Bu groups since an analogous derivative with R = Ph is observable but too unstable for isolation. Compound 10 can be reversibly protonated to yield the [ - Bu 2 PHC(S)SCH(Me)Ph] + cation ( 10-H + ), which was isolated as a BF 4 - salt. A few interconversion processes resulting in the facile addition/removal or exchange of the X group in this family of compounds are also described. The oxidation state of the phosphorus atom and the nature of an electron-withdrawing group have a significant impact on the spectral properties.