Syntheses, structures, and reactivities of two chalcogen-stabilized carbones.

Electronic effects on the central carbon atom of carbone, generated by the replacement of the S(IV) ligand of carbodisulfane (CDS) with other chalcogen ligands (Ph2 E, E=S or Se), were investigated. The carbones Ph2 E→C←SPh2 (NMe) [E=S(1) or Se(2)] were synthesized from the corresponding salts, and their molecular structures and electronic properties were characterized. The carbone 2 is the first carbone containing selenium as the coordinated atom. DFT calculations revealed the electronic structures of 1 and 2, which have two lone pairs of electrons at the carbon center. The trend in HOMO energy levels, estimated by cyclic voltammetry measurements, for the carbones and CDS follows the order of 2>1>CDS. Analysis of a doubly protonated dication and trication complex revealed that the central carbon atom of 2 behaves as a four-electron donor.