Dialkynyl selenides: Synthesis, 13C NMR spectra, and molecular orbital calculations

Reactions of SeCl4 with lithium bis(trimethylsilyl)amide and terminal acetylenes in the presence of BuLi or AIBN afforded the corresponding dialkynyl selenides in moderate to high yields. The reaction may proceed via a selenium amide 7 and an alkynyl selenium amide 8. The comparison of 13C NMR spectra of dialkynyl selenides and tellurides has disclosed that the differences of the chemical shift of acetylenic carbons between Se and Te derivatives are consistent regardless of their substitution patterns. Ab initio molecular orbital calculations are reported for dialkynyl ether and chalcogenides. The calculated structures, charge distributions, and orbital energies are discussed.