Homoleptic Pnictogen–Chalcogen Coordination Complexes

The synthesis and structural characterization of dicationic selenium and tellurium analogues of the carbodiphosphorane and triphosphenium families of compounds are reported. These complexes, [Ch­(dppe)]­[OTf]2 [Ch = Se, Te; dppe = 1,2-bis­(diphenylphosphino)­ethane; OTf = trifluoromethanesulfonate], are formed using [Ch]2+ reagents via a ligand-exchange protocol and represent extremely rare examples of homoleptic pnictogen → chalcogen coordination complexes. The corresponding arsenic compounds were also prepared, [Ch­(dpAse)]­[OTf]2 [Ch = Se, Te; dpAse = 1,2-bis­(diphenylarsino)­ethane], exhibiting the first instance of an arsenic → chalcogen dative bond. The electronic structures of these unique compounds were determined and compared to previously reported chalcogen dications.