Work

Tricyanomethane or Dicyanoketenimine—Silylation makes the Difference

Year: 2024

Type: article

Abstract: Pseudohalides such as tricyanomethanide, [C(CN)3]−, are well known in chemistry, biochemistry and industrial chemistry. The protonated species HC(CN)3, a classic hydrogen pseudohalide Brønsted acid, is a very strong acid with a pKa value of −5. However, HC(CN)3 is difficult to handle as it tends to decompose rapidly or, more precisely, to oligo‐ and polymerize. Therefore, silylated pseudohalide compounds with the [Me3Si]+ as the “big organometallic proton” have become interesting, exhibiting similar chemical properties but better kinetic protection. Here, the stepwise silylation of the pseudohalide anion [C(CN)3]− is reported, forming the heavier homologue of HC(CN)3, namely [Me3Si][C(CN)3], and in presence of two additional [Me3Si]+ cations even the dicationic species [(Me3Si−NC)3C]2+ as stable [B(C6F5)4]− salt. Surprisingly, in contrast to the protonated species HC(CN)3, in which the proton is bound to the central carbon atom of [C(CN)3]−, silylation of the [C(CN)3]− anion occurs at one of the three terminal nitrogen atoms, thus forming the long‐sought dicyanoketenimine [Me3Si−NC−C(CN)2]. All further silylation steps take place exclusively on the terminal N atoms of the three CN groups and not on the central carbon atom, until the intriguing, highly symmetrical dication, [(Me3Si−NC)3C]2+, is finally generated. The experimental data are supported by quantum chemical calculations in terms of thermodynamics and chemical bonding.

Source: Angewandte Chemie International Edition

DOI: 10.1002/anie.202413565

Authors: Jonas Surkau, Jonas Bresien, Dirk Michalik, Axel Schulz

Institutions: University of Rostock, Leibniz Institute for Catalysis

Language: English

Topic: Organoboron and organosilicon chemistry

Subfield: Organic Chemistry

Field: Chemistry

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $5,510

Funder: Deutsche Forschungsgemeinschaft