Reversible Oxidative Se-Se Coupling of Phosphine Selenides by Ph 3 Sb(OTf) 2 .

Salts of diphosphoniumdiselenide dications ([R3 PSeSePR3 ][OTf]2 ) have been isolated from reactions of trialkylphosphine selenides with triphenylantimony bistriflate. The redox process is speculated to proceed via a cationic coordination complex [Ph3 SbL2 ][OTf]2 (L=Me3 PSe, iPr3 PSe), which is also formed in the reaction of [R3 PSeSePR3 ][OTf]2 with Ph3 Sb. The observations indicate that the reductive elimination of [R3 PSeSePR3 ]2+ from [Ph3 Sb(SePR3 )2 ]2+ is reversible through the oxidative addition of [R3 PSeSePR3 ]2+ to Ph3 Sb.