Lewis base sequestered chalcogen dihalides: synthetic sources of ChX2 (Ch = Se, Te; X = Cl, Br).

The synthesis and comprehensive characterization of a series of base-stabilized ChX(2) (Ch = Se, Te; X = Cl, Br) is reported using aryl-substituted diazabutadiene and 2,2'-bipyridine (bipy) as the ligands. In stark contrast to free ChX(2) the complexes display excellent thermal stability. Their use as viable ChX(2) reagents that may be stored for later use is demonstrated in principle. The syntheses are simple and high-yielding from commercially available or easily synthesized reagents. The bipy complexes are exceedingly rare examples of this ubiquitous ligand being utilized within Group 16 chemistry; the Se examples are the first to be characterized by X-ray crystallography, and the Te species are only the second.