Reactions of cyclohexene-annulated 3а,6а-diaza-1,4-diphosphapentalene with sulfur, selenium, and CS2: structural features of zwitterionic products

Abstract

The reactions of b- and f-face cyclohexene-annulated 3a,6a-diaza-1,4-diphosphapentalene (CADDP) with elemental sulfur and selenium result in the addition of two chalcogen atoms to one phosphorus atom of CADDP. A specific feature of these structures is that the diazadiphosphapentalene skeleton retains planar geometry, with a significant elongation of the N—P bond. These compounds are zwitterions, as evidenced by their electronic structures, with considerable delocalization of the negative charge in the PS₂ (PSe₂) moieties and of the positive charge in the diazaphosphole ring. The reaction of CADDP with carbon disulfide is a more complicated process accompanied by the decomposition of the CS₂ molecule to form a molecule containing three structurally different CADDP moieties, one of which is a stabilized carbene complex.