New 2,4-dihydro-1H-1,2,4-triazole-3-selones and 3,3'-di(4H-1,2,4-triazolyl)diselenides. Synthesis, biological evaluation, and in silico studies as antibacterial and fungicidal agents.

The reaction of aromatic ring-substituted isoselenocyanates with 2-thiopheacetic and 4-pyridinecarboxylic acid hydrazides yielded selenosemicarbazides which were further converted into previously unknown 1,2,4-triazole-3-selones and 3,3'-di(4H-1, 2,4-triazolyl)diselenides. The structures of the obtained compounds were studied by NMR spectroscopy, IR spectroscopy, and high-resolution mass spectroscopy (HR-MS). The bactericidal and fungicidal activity of some obtained compounds was evaluated in molecular modeling studies such as docking and simulation studies. The compound 3ba was reported as the most promising compound to show robust binding energy with different antibacterial and antifungal compounds. The compounds were observed in strong hydrophilic and hydrophobic interactions and remained in stable binding conformation with the receptor enzymes. Furthermore, the interatomic interaction energies were dominated by Van der Waals and electrostatic energies indicating the formation of stable complexes.

Facile Access to 2-Selenoxo-1,2,3,4-tetrahydro-4-quinazolinone Scaffolds and Corresponding Diselenides via Cyclization between Methyl Anthranilate and Isoselenocyanates: Synthesis and Structural Features.

A practical method for the synthesis of 2-selenoxo-1,2,3,4-tetrahydro-4-quinazolinone was reported. The latter compounds were found to undergo facile oxidation with H2O2 into corresponding diselenides. Novel organoselenium derivatives were characterized by the 1H, 77Se, and 13C NMR spectroscopies, high-resolution electrospray ionization mass spectrometry, IR, elemental analyses (C, H, N), and X-ray diffraction analysis for several of them. Novel heterocycles exhibited multiple remarkable chalcogen bonding (ChB) interactions in the solid state, which were studied theoretically.

Cycloaddition of isoselenocyanates to sodium and magnesium metallacycles.

Heterocumulenes SeCNR (R = C6H4OMe-2, C6H4Me-2) undergo facile cycloaddition to [(H-dpp-bian)Na(Et2O)2] (1) (H-dpp-bian = N-protonated 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) resulting in cycloadducts [(H-dpp-bian)Na(SeCNR)(DME)] (2, 3), which are the first cycloadducts derived from a sodium metallacycle reported so far. A comparative reaction of [(dpp-bian)Mg(THF)3] (10) with SeCNR gives magnesium cycloadducts [(dpp-bian)Mg(SeCNR)(Solv)2] (11, 12), which undergo fast decomposition at room temperature. New compounds are characterized by NMR, EPR, and IR spectroscopy, and elemental and X-ray diffraction analysis. Their electronic structures and reaction pathways were probed using DFT calculations.

Correction: Novel cationic 1,2,4-selenadiazoles: synthesis via addition of 2-pyridylselenyl halides to unactivated nitriles, structures and four-center Se⋯N contacts.

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.

Novel cationic 1,2,4-selenadiazoles: synthesis via addition of 2-pyridylselenyl halides to unactivated nitriles, structures and four-center SeN contacts.

2-Pyridylselenyl halides undergo facile coupling with a triple CN bond of unactivated nitriles. Unprecedented heterocyclization allowed the preparation of a novel class of cationic 1,2,4-selenadiazoles in remarkably high yields. Cationic 1,2,4-selenadiazoles form supramolecular dimers in the crystal via SeN chalcogen bonding, which was studied theoretically.

Bromination of bis-(pyridin-2-yl) diselenide in methyl-ene chloride: the reaction mechanism and crystal structures of 1H-pyridine-2-selenenyl dibromide and its cyclo-adduct with cyclo-pentene (3aSR,9aRS)-2,3,3a,9a-tetra-hydro-1H-cyclo-penta-[4,5][1,3]selenazolo[3,2-a]pyridinium bromide.

1H-Pyridine-2-selenenyl dibromide, C5H5NSeBr2, 1, is a product of the bromination of bis-(pyridin-2-yl) diselenide in methyl-ene 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) Šis 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 inter-molecular Se⋯Br contact of 3.4326 (4) Å, adopting a distorted square-planar coordination. In the crystal, mol-ecules of 1 are linked by inter-molecular N-H⋯Br and C-H⋯Br hydrogen bonds, as well as by non-covalent Se⋯Br inter-actions, into a three-dimensional framework. (3aSR,(9aRS)-2,3,3a,9a-Tetra-hydro-1H-cyclo-penta[4,5][1,3]selenazolo[3,2-a]pyridinium-9 bromide, C10H12NSe+·Br-, 2, is a product of the cyclo-addition reaction of 1 with cyclo-pentene. 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 inter-actions 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 inter-actions. The dimers are linked by weak C-H⋯Br hydrogen bonds into double layers parallel to (001).

Dichloridobis(pyridine-2-seleno-lato-κ(2) N,Se)tin(IV).

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) Šare 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.

[Bis(pyridin-2-yl) selenide-κ(2)N,N']tetra-chloridotin(IV).

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.

1-Methyl-2,3-dihydro-1H-benzimidazole-2-selone.

The title compound C(8)H(8)N(2)Se, is the product of the reaction of 2-chloro-1-methyl-benzimidazole with sodium hydro-selenide. The mol-ecule 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, mol-ecules form helicoidal chains along the b axis by means of N-H⋯Se hydrogen bonds.

1,3-Benzothia-zole-2(3H)-selone.

The title compound, C(7)H(5)NSSe, is the product of the reaction of 2-chloro-benzothia-zole with sodium hydro-selenide. The mol-ecule 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-methyl-benzothia-zole-2(3H)-selone, demonstrating that the S atom does not take a significant role in the electron delocalization within the mol-ecule. In the crystal, mol-ecules form centrosymmetric dimers by means of inter-molecular 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] inter-actions.