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In the crystal of the title compound, C7H5FN4S, the molecules are non-planar, with dihedral angle formed by least-squares planes of tetrazole and benzene rings of 59.94 (8) °. The crystal packing is formed by N—H...S hydrogen bonds, which link the molecules into centrosymmetric dimers with an R 2 2(8) ring motif, and by the offset face-to-face π–π stacking interactions between the benzene rings, which join the dimers into layers parallel to (100). The Hirshfeld surface analysis shows that the most important contributions to the surface contacts are from N...H/H...N (21.9%), S...H/H...S (21.1%), H...H (14.6%), F...H/H...F (11.8%) and C...H/H...C (9.5%) interactions.

1H-Pyridine-2-selenenyl dibromide, C5H5NSeBr2, 1, is a product of the bromination of bis(pyridin-2-yl) diselenide in methylene chloride recrystallization from methanol. Compound 1 is essentially zwitterionic: the negative charge resides on the SeBr2 moiety and the positive charge is delocalized over the pyridinium fragment. The C—Se distance of 1.927 (3) Å is typical of a single bond. The virtually linear Br—Se—Br moiety of 178.428 (15)° has symmetrical geometry, with Se—Br bonds of 2.5761 (4) and 2.5920 (4) Å, and is twisted by 63.79 (8)° relative to the pyridinium plane. The Se atom forms an intermolecular Se...Br contact of 3.4326 (4) Å, adopting a distorted square-planar coordination. In the crystal, molecules of 1 are linked by intermolecular N—H...Br and C—H...Br hydrogen bonds, as well as by non-covalent Se...Br interactions, into a three-dimensional framework. (3aSR,(9aRS)-2,3,3a,9a-Tetrahydro-1H-cyclopenta[4,5][1,3]selenazolo[3,2-a]pyridinium-9 bromide, C10H12NSe+·Br−, 2, is a product of the cycloaddition reaction of 1 with cyclopentene. Compound 2 is a salt containing a selenazolopyridinium cation and a bromide anion. Both five-membered rings of the cation adopt envelope conformations. The dihedral angle between the basal planes of these rings is 62.45 (11)°. The Se atom of the cation forms two additional non-covalent interactions with the bromide anions at distances of 3.2715 (4) and 3.5683 (3) Å, attaining a distorted square-planar coordination. In the crystal, the cations and anions of 2 form centrosymmetric dimers by non-covalent Se...Br interactions. The dimers are linked by weak C—H...Br hydrogen bonds into double layers parallel to (001).

Correction for ‘Novel cationic 1,2,4-selenadiazoles: synthesis via addition of 2-pyridylselenyl halides to unactivated nitriles, structures and four-center Se⋯N contacts’ by Victor N. Khrustalev et al., Dalton Trans., 2021, 50, 10689–10691, DOI: 10.1039/D1DT01322J.

The title compound, [SnCl2(C5H4NSe)2], is the product of a reaction of 2,2'-dipyridyl diselenide with tin tetra-chloride. The mol-ecule is located about a twofold rotation axis. The coordination environment of the Sn(IV) atom is a distorted octa-hedron, with two bidentate 2-pyridine-seleno-late ligands inclined to each other at an angle of 83.96 (7)°. The two Sn-Cl and two Sn-N bonds are in cis configurations, while the two Sn-Se bonds of 2.5917 (3) Å are in a trans configuration, with an Se-Sn-Se angle of 157.988 (15)°. In the crystal, π-π inter-actions between the pyridine rings [centroid-to-centroid distance of 3.758 (3) Å] and weak inter-molecular C-H⋯Cl hydrogen bonds link the mol-ecules into chains along the c axis.

The title compound C8H8N2Se, is the product of the reaction of 2-chloro-1-methylbenzimidazole with sodium hydroselenide. The molecule is almost planar (r.m.s. deviation = 0.041 Å) owing to the presence of the long chain of conjugated bonds (Se=C—NMe—C=C—C=C—C=C—NH). The C=Se bond length [1.838 (2) Å] corresponds well to those found in the close analogs and indicates its pronounced double-bond character. In the crystal, molecules form helicoidal chains along the b axis by means of N—H...Se hydrogen bonds.

The title compound, [SnCl(4)(C(10)H(8)N(2)Se)], was obtained by the reaction of 2,2'-dipyridyl diselenide with tin tetra-chloride. The Sn(IV) ion is coordinated by two N atoms [Sn-N = 2.266 (2) and 2.274 (2) Å] from the bis-(2-pyrid-yl)selenide ligand and four chloride anions [Sn-Cl = 2.3717 (6)-2.3939 (6) Å] in a distorted octa-hedral geometry. The central six-membered chelate ring has a boat conformation with the Se and Sn atoms deviating by 0.692 (3) and 0.855 (3) Å, respectively, from the mean plane through the remaining four ring atoms. The pyridine rings are inclined to each other by a dihedral angle of 49.62 (8)°. The crystal packing exhibits short inter-molecular Se⋯Cl contacts [3.5417 (7) and 3.5648 (7) Å], weak C-H⋯Cl hydrogen bonds and π-π stacking inter-actions between the pyridine rings with a centroid-centroid distance of 3.683 (3) Å.

The title compound, C7H5NSSe, is the product of the reaction of 2-chlorobenzothiazole with sodium hydroselenide. The molecule is almost planar (r.m.s. deviation = 0.018 Å) owing to the presence of the long chain of conjugated bonds (Se=C—N—C=C—C=C—C=C). The geometrical parameters correspond well to those of the analog N-methylbenzothiazole-2(3H)-selone, demonstrating that the S atom does not take a significant role in the electron delocalization within the molecule. In the crystal, molecules form centrosymmetric dimers by means of intermolecular N—H...Se hydrogen bonds. The dimers have a nonplanar ladder-like structure. Furthermore, the dimers are linked into ribbons propagating in [010] by weak attractive Se...S [3.7593 (4) Å] interactions.