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

Abstract

The conjugate acids of benzo-2,1,3-selena-and benzo-2,1,3-telluradiazole are the simplest members of the family of N-substituted chalcogenadiazolium cations. Four crystalline phases that in principle contain such molecular ions were isolated and structurally characterized:The stepwise protonation of benzo-2,1,3-teluradiazole in DMSO solution was monitored by 1 H NMR, providing an estimate of the basicity of this molecule relative to pyridine. While most of the structures are consistent with the chalcogen in oxidation state II, the molecular geometry of C6H4(NH)2TeCl4 is suggestive of oxidation state IV. The relationship between the two structural types was examined with DFT calculations.

Crystal structure ofrac-(3aR*,9aS*)-4,4,4-trichloro-1,2,3,3a,4,9a-hexahydro-4λ5,9λ4-cyclopenta[4,5][1,3]tellurazolo[3,2-a]pyridine

“…The bond lengths from the tellurium atom to the two chlorine atoms arranged trans to each other [2.5009 (7)/2.5145 7and 2.5184 (7)/2.5220 (8) Å for the two crystallographically independent molecules, respectively] are close to those in related complexes (Singh et al, 1990;Sundberg et al, 1994;Zukerman-Schpector et al, 2000;Kandasamy et al, 2003;Raghavendra et al, 2006;Dutton et al, 2009;Lee et al, 2010;Rakesh et al, 2012). The third Te-Cl distance (2.8786 (7) and 2.8763 (7) Å for the two crystallographically independent molecules, respectively) is substantially longer than the other two Te-Cl distances.…”

“…For general background and synthesis, see: Petragnani & Stefani (2007); Borisov et al (2013). For related compounds, see: Singh et al (1990); Sundberg et al (1994); Zukerman-Schpector et al (2000); Kandasamy et al (2003); Raghavendra et al (2006);Dutton et al (2009); Lee et al (2010); Rakesh et al (2012). Symmetry codes: (i) Àx; Ày þ 2; Àz þ 1; (ii) x; Ày þ 3 2 ; z À 1 2 ; (iii) x; Ày þ 1 2 ; z À 1 2 ; (iv) Àx þ 1; y À 1 2 ; Àz þ 1 2 .…”

Chalcogen-bond driven molecular recognition at work

“…enhance the extend of the -hole, Vargas-Baca and co-workers prepared various organic crystals of 2Se in the presence of a Bronsted acid. [89] In particular, crystals of salt 2Se•HCl could be formed when 2Se was exposed to HCl (Figure 19a).…”

Synthetic, structural, and computational investigations of N-alkyl benzo-2,1,3-selenadiazolium iodides and their supramolecular aggregates

“…Although benzo-2,1,3-selenadiazole is a weak base, it is readily protonated by strong acids. 45 While the reaction of tert-butyl iodide is likely to proceed by a SN 1 mechanism, it is likely that the primary and secondary iodides prefer a SN 2 mechanism but steric hindrance prevents the reaction of the iso-propyl halide.…”

“…of anions to Se has been observed in related species. For example, a virtual four-membered ring consisting of Se and Cl atoms is formed in the crystal structure of [C 2 H 2 NN(H)Se][Cl] (2.900(1) Å and (3.075 (1) Å) 45. The structure of [C 2 H 2 N(NC (CH 3 ) 3 )Se][Cl] also features a planar selenadiazole ring with one Se-Cl bond distance of 2.605 (1) Å 23.…”