A method was developed to prepare previously inaccessible 2H-1,4-benzotelluazin-3(4H)-ones carrying electron donating substituents in homocyclic position, based on the regiospecific ortho tellurination of 2-chloro-N(phenyl)acetamides with tellurium tetrachloride to 2-(2-chloroacetylamino)phenyltellurium trichlorides, followed by stepwise reductive cyclization. This method relies on readily accessible precursors and is easily implemented as a three step procedure. Selected intermediates and products were characterized by X-ray crystallography, indicating that strong intramolecular Te-Ocarbonyl coordination in 2-(2-chloroacetylamino)phenyltellurium trichlorides is responsible for the observed regiospecific ortho tellurination. The electronic environment established by this coordination was further modeled using density functional theory. Intermolecular secondary Te...Ocarbonyl bonding interactions were observed for 6-methoxy-2H-1,4-benzotelluazin-3(4H)-one while Te...Br secondary bonding was present in 1,1-dibromo-6-methoxy-2H-1,4-benzotelluazin-3(4H)-one. Electronic structure calculations based on Density Functional Theory were undertaken in order to determine the free energy profiles associated with the cyclizations forming the target products.

A method was developed to prepare 2-acylaminobenzo[1,3]tellurazoles from bis(2-aminophenyl) ditellurides and acylisothiocyanates in good yield following a simple two-step, one pot procedure. It consists of the formation of acylthioureas, followed by reductive cyclization. This method relies on readily accessible precursors and avoids the use of reagents that are highly toxic or sensitive to air or moisture. Three representative products were characterized by X-ray crystallography to probe their tendency to undergo intermolecular chalcogen bonding. 4,6-Dimethyl-2-acetylaminobenzo[1,3]tellurazole lacked such bonding while 5-methyl-2-acetylaminobenzo[1,3] tellurazole showed Te center dot center dot center dot N secondary bonding and 2-acetamidobenzo[1,3]tellurazole formed a supramolecular tetramer as a result of Te center dot center dot center dot O-carbonyl bonding interactions. A computational non-covalent interaction analysis of this tetramer was performed, which indicates that it is more stable by similar to 58 kcal mol(-1) than the monomer would be.

The reaction of substituted phenyl propargyl ethers with tellurium tetrachloride resulted in the formation of (E)- 3-(chloromethylene)-2,3-dihydrobenzo[b][1,4]oxatelluranes, which were isolated as crystalline 4,4-dibromo derivatives. The products represent the first reported bicyclic [1,4]benzoxatelluranes. Their formation indicates preferential anti addition of tellurium tetrachloride across the C-C triple bonds of the chosen propargyl ethers with anti-Markovnikov regioselectivity, contrasting earlier reports of preferential syn addition of tellurium tetrachloride to alkynes. This likely results from the intermediacy of tellurenium cations stabilized by intramolecular Te-O coordination. The resulting adducts underwent electrophilic cyclization under the conditions of their formation. X-ray analyses obtained for two product molecules showed substantial deviations from planarity for the heterocyclic part of these molecules. No Te-O secondary bonding interactions were observed, but Te-Br secondary bonding was present. (E)-3-(Chloromethylene)-6,7-dimethyl-2,3-dihydrobenzo[b][1,4]oxatellurane, prepared by reduction of its 4,4-dibromo derivative, presented as a thick oxidation prone oil. 125Te NMR chemical shifts are compared to those of structurally similar compounds.

A method has been developed to prepare previously inaccessible substituted 1,3-benzotellurazoles following an efficient two-step process, consisting of the tellurination of electron rich phenyl ureas with tellurium tetrachloride and subsequent ring closure of the resulting aryl tellurium trichlorides. Tellurination occurs regiospecifically ortho to the urea moiety due to intramolecular Te-O coordination, producing highly crystalline solids that are readily isolated in yields up to 83 %. Subsequent ring closure, accomplished by heating with phosphorus trichloride and subsequent reduction with hydrazine hydrate, provides access to 1,3-benzotellurazole derivatives. Selected products were characterized by X-ray crystallography.

A method has been developed to prepare 2-arylbenzo-1,3-tellurazoles from bis(2-aminophenyl) ditelluride and aromatic aldehydes by oxidative cyclization following an easily implemented one pot procedure. Imines obtained by combining aldehyde and ditelluride were cyclized with phosphorous oxychloride without prior purification, resulting in the formation of benzo-1,3-tellurazoles carrying aryl or heteroaryl substituents in position 2 in yields up to 58%. Evidence is presented for a radical reaction pathway. This method is set apart from other options by avoiding strongly reducing conditions and minimizing the synthetic effort required to prepare aryl substituted benzo-1,3-tellurazoles. An X-ray crystallographic characterization of 2-(2-quinolinyl)benzo-1,3-tellurazole indicated only weak TeˑˑˑN secondary bonding interactions.

The structure of the title compound, C9H10OTe, at 100 K has orthorhombic (P21212) symmetry with two independent molecules in the asymmetric unit (Z′ = 2). The molecules are folded along their Te...O axes, with their Te–C–O planes angled at an average of 25.1° with respect to the remaining non-H atoms, which are almost coplanar (average deviation from planarity = 0.04 Å). A Hirshfeld plot shows weak intermolecular interactions between the two Te atoms located in each asymmetric molecule, with a Te...Te distance of 3.7191 (4) Å. The structure is strongly pseudosymmetric to the space group Pccn with Z′ = 1. The crystal chosen for data collection was found to be was an inversion twin.

One step, up to 78% isolated yield, six examples. Facile access to 2-N,N-dialkylbenzo[1,3]tellurazoles.

[1,4]Ditellurino[2,3-b:5,6-b′]dipyrazine represents the first reported [1,4]chalcogena[2,3-b:5,6-b′]dipyrazine containing a heavy chalcogens The asymmetric unit consists of three molecules. In contrast to its sulfur analog, which is planar [Lynch et al. (1994) Cryst. Struct. Commun. 50,1470–1472], C8H4N4Te2 is folded along the Te...Te axis to accommodate the larger chalcogenide atoms. The dihedral angle between the two Te2C2 rings of the central ring is 57.9° (mean of three). C—Te bond lengths range from 2.1105 (16) Å to 2.1381 (17) Å, in good agreement with those predicted by their covalent radii. All Te atoms are involved in intermolecular Te...N contacts, with distances in the range 2.894 (2) to 2.963 (2) Å. These result in a spiral supramolecular assembly, forming helical columns.

The reductive cyclization of arenetellurols carrying α,β-unsaturated amide functionalities in the ortho position was investigated. Conceptually, such compounds can form 1,3-tellurazoles without the involvement of the unsaturation in the ring closure, they can form 1,4-tellurazinone derivatives, or they can undergo ring closure to 1,5-tellurazepinones. Amides derived from acrylic and methacrylic acid generated 1,5-tellurazepinones while 2-cinnamylamidobenzenetellurol cyclized to a 1,3-tellurazole derivative. In contrast, the reaction of acetylenedicarboxylic acid and its derivatives with 2-aminoarenetellurols generated 1,4-tellurazepinones, including a derivative of novel tricyclic naphtho [1, 4]tellurazinone. A comparison with analogous reactions of sulfur congeners indicates that their chemistry is a good predictor for the products obtained from 2-aminoarenetellurols. Selected compounds were characterized by X-ray crystallography. The present work offers access to previously unexplored organotellurium heterocycles.

Condensation of 2,3-dichloropyrazine with 2-aminobenzenetellurole and 2-amino-5-methylbenzenetellurole, generated in situ by reduction of the corresponding ditellurides, resulted in the formation of novel 10H-pyrazino[2,3-b][1,4]benzotellurazine and its 7-methyl derivative. The products were purified via their well-crystallized 5,5-dibromo derivatives. X-ray crystallographic analysis of the title compound indicates that it has a pronounced V-shape and forms hydrogen-bonded dimers. Te, N-containing heterocycles have the potential of offering access to supramolecular assemblies.

Treatment of homo- and heterocyclic aromatic substrates with basic deuterium oxide under near- or supercritical conditions results in rapid base-catalyzed hydrogen-deuterium exchange (HDE) in aromatic and benzylic positions. It has been postulated that HDE follows a simple deprotonation-reprotonation mechanism, but little evidence has been provided to date. This study correlates experimentally observed proton exchanges in n-butylbenzene with ab initio calculations of the acidities and potential energy (PE) profiles. In addition to providing further support for carbanion intermediacy in HDE, these results offer new insights into substrate acidities in near- and supercritical aqueous media and the optimal conditions required for their isotope exchange.

Synthetic methods have been developed to prepare novel 1,3-benzotellurazoles carrying acylamino and arylamino moieties in position 2, in order to investigate their propensity to self-assemble to supramolecular structures. The targeted compounds were obtained in yields ranging from 44% to 67%, by reacting bis(2-aminophenyl) ditelluride with acyl- and aryl isothiocyanates, respectively, and subsequent reductive cyclization of the resulting thiourea derivatives. Seven novel 1,3-benzotellurazole derivatives were prepared: 2-benzoylamino-1,3-benzotellurazole, 2-(4-chlorobenzoylamino)-1,3-benzotellurazole, 2-(2-bromobenzoylamino)-1,3-benzotellurazole, 2-(4-bromobenzoylamino)-1,3-benzotellurazole, 2-(4-methoxybenzoylamino)-1,3-benzotellurazole, 2-phenylamino-1,3-benzotellurazole, and 2-(4-chlorophenylamino-1,3-benzotellurazole. A simplified protocol was employed to synthesize all acyl isothiocyanates needed for their preparation from benzoyl halide derivatives and potassium thiocyanate. The reductive cyclization of the intermediate thioureas was challenging, only the use of hydroxymethanesulfinate in the presence of elemental mercury provided synthetically useful product yields. A mechanism was proposed, consisting of the insertion of mercury into the Te-Te bond, followed by intramolecular nucleophilic attack of the thiocarbonyl moiety by the resulting insertion product. All 2-acylamino-1,3-benzotellurazoles are crystalline solids, which are stable to ambient light, air and moderate heat. A characterization of selected samples by X-ray crystallography indicated that they form dimers in solid state, resulting from hydrogen bonding between the exocyclic and endocyclic nitrogen atoms of two adjacent molecules. This sets them apart from 2-alkyl- and 2-aryl-1,3-benzotellurazoles, which are known to self-assemble into supramolecular wires.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

A combined experimental-computational study was conducted on the Raman spectrum of TNT-d5 in the present study. It was found that among the 24 hybrid density functional theory (DFT) methods, O3LYP, tHCTHhyb, and B3LYP simulations yielded the strongest Raman bands which were closest to those measured from experiments. Simulations of hybrid DFT methods did not show that deuterium replacements alter orientations of 2- and 6-nitro with respect to phenyl ring, considering a larger size of the methyl group. However, the deuterium replacements apparently changed the reduced masses for all deuterium related vibrations. Although no difference of structural parameters was shown between TNT and its deuterated analogue, discrepancy was indicated in vibrational zero energy from our simulations. O3LYP simulation exhibited 24 deuterium involved vibrations, which were coupled into seven Raman bands of TNT-d5. This phenomenon can account for the experimental Raman band shifts or split of TNT-d5 when compared with the corresponding bands of TNT. The present study and its outcomes provide in-depth microchemical insights of Raman characteristics of TNT and may facilitate the design of nano-structures of SERS substrates for detection of TNT and its degradation products. All intensities displayed in this study were calculated from numerical simulations.