Crystalline Neutral Aluminum Selenide/Telluride: Isoelectronic Aluminum Analogues of Carbonyls.

ABSTRACT

Neutral aluminum chalcogenides (R-Al(L)═Ch; L = ligand, Ch = chalcogen), stabilized by a Lewis base ligand, represent isoelectronic counterparts to carbonyl compounds and have long been pursued for isolation. Herein, we present the synthesis of an aluminum selenide, [N]-Al(iPr2-bimy)═Se, and an aluminum telluride, [N]-Al(iPr2-bimy)═Te, under ambient conditions ([N] = 1,8-bis(3,5-di-tert-butylphenyl)-3,6-di-tert-butylcarbazolyl; iPr2-bimy = 1,3-diisoproplylbenzimidazole-2-ylidene). These compounds arise from the oxidation reaction of [N]-Al(iPr2-bimy) with Se and (nBu)3P═Te, respectively. One notable characteristic of the Al and Ch interaction is the presence of an Al-Ch σ bond, strengthened by the electrostatic attraction between the Al+ and Ch- centers as well as the donation of lone pairs from Ch into vacant orbitals at Al. This results in an Al-Ch multiple bond with an ambiphilic nature. Preliminary investigations into their reactivity unveil their remarkable propensity for facile (cyclo)addition reactions with diverse substrates, including PhCCH, PhCN, AdN3, MeI, PhSiH3, and C6F6, leading to the formation of unprecedented main group heterocycles and alumachalcogenides.