Ethyl 2-(2-Ethoxy-2-oxoethylidene)-1,3-diselenole-4-carboxylate—an Example of Unconventional Bonding in Organic Selenides

Abstract

Reaction of ethyl propiolate with lithium hexamethyldisilazide in tetrahydrofuran followed by the addition of elemental selenium provides ethyl 2-(2-ethoxy-2-oxoethylidene)-1,3-diselenole-4-carboxylate in 75% yield and as a mixture of geometrical isomers 2, 3. X-Ray crystallographic studies, as well as density functional calculations reveal close oxygen–selenium contacts that are the result of unconventional bonding interactions.