The direct reaction of the tBu-DAB ligand with SeCl₄: a redox route to selenium–nitrogen heterocycles

Abstract

The reaction of SeCl4 with the ubiquitous tert-butyl-substituted diazabutadiene ligand results in the isolation of a rare example of a 1,2,5-selenadiazolium cation, representing a novel route to Se-N ring formation; these heterocycles can be derivatised at selenium, which has led to the identification of a short Se...N secondary bonding interaction.

An experimental and computational investigation of the formation and structures of N-hydro and N,N'-dihydro-benzo-2,1,3-chalcogenadiazolium chlorides

“…Raman, 785nm, (cm −1 ): 3065vw, 1527vw, 1495vw, 1392s, 1361vw, 1316vw, 1266vw, 1251vw, 1195w, 1156vw, 1134w, 985w, 975w, 945vw, 897vw, 853vw, 830vw, 801w, 732m, 692w, 585vw, 550s, 484w, 361s, 243vw, 155vs, 113vw. 1 (14) A dilute solution (0.05 M) of benzo-2,1,3-selenadiazole in hot concentrated hydrochloric acid yielded a second crystalline phase upon cooling. This consisted of yellow plate-like crystals which effloresced after removing the mother liquor, precluding characterization by any means other than X-ray diffraction crystallography.…”

“…In this regard, the electrochemical behavior of the family of N-methyl benzo-2,1,3-chalcogenadiazolylium cations (7, R = Me) displays an unusual trend in reduction potentials that was tentatively explained by invoking the dimerization of the tellurium cations in solution. Indeed, not only do the N-monoalkylated cationic rings (2,7) display the same tendency towards supramolecular association as the unsubstituted neutral heterocycles (1, 6) [6] but, contrary to what simple electrostatic arguments would predict, the crystal structures of the selenium [1,2,7] and tellurium [2] examples display very short chalcogen-nitrogen secondary-bonding distances. Neutral isoelectronic analogues of 7 and 9 were obtained by attachment of a borane to one of the nitrogen atoms of benzo-2,1,3-telluradiazole.…”

“…Several groups have recently turned their attention to N-substituted cationic derivatives of the 1,2,5chalcogenadiazole ring (1). These can be obtained from the reaction of a chalcogen halide with alkyl and aryl diimines, as in the case of the derivatives 2 and 4 of the parent heterocycle [1].…”

“…These can be obtained from the reaction of a chalcogen halide with alkyl and aryl diimines, as in the case of the derivatives 2 and 4 of the parent heterocycle [1]. On the other hand, treatment of benzo-2,1,3-telluradiazole (6) with an alkyl triflate yields the monosubstituted species (7) [2].…”

Dicationic Tellurium Analogues of the Classic N‐Heterocyclic Carbene

“…[38,39] Hexahalochalcogenide anions are generally undesirable, as they are readily available sources of halides. [41] Unfortunately, all attempts at metathesis of [TeBr 6 ] 2À were unsuccessful, so a synthetic route was sought avoiding its incorporation (Scheme 6).…”