Prediction of the properties and thermodynamics of formation for energetic nitrogen‐rich salts composed of triaminoguanidinium cation and 5‐nitroiminotetrazolate‐based anions

Density functional theory and volume‐based thermodynamics calculations were performed to study the effects of different substituents and linkages on the densities, heats of formation (HOFs), energetic properties, and thermodynamics of formation for a series of energetic nitrogen‐rich salts composed of triaminoguanidinium cation and 5‐nitroiminotetrazolate anions. The results show that the ? NO₂, ? NF₂, or ? N₃ group is an effective substituent for increasing the densities of the 5‐nitroiminotetrazolate salts, whereas the effects of the bridge groups on the density are coupled with those of the substituents. The substitution of the group ? NH₂, ? NO₂, ? NF₂, ? N₃, or the nitrogen bridge is helpful for increasing the HOFs of the salts. The calculated energetic properties indicate that the ? NO₂, ? NF₂, ? N₃, or ? N?N? group is an effective structural unit for improving the detonation performance for salts. The thermodynamics of formation of the salts show that all the salts may be synthesized easily by the proposed reactions. The structure‐property relationships provide basic information for the molecular design of novel high‐energy salts. © 2012 Wiley Periodicals, Inc.     

Synthesis and Anti‐proliferative Activity of N,N′‐bis‐substituted 1,2,4‐Triazolium Salts against Breast Cancer and Prostate Cancer Cell Lines

A series of 1,4‐N,N′‐bis‐substituted 1,2,4‐triazolium bromide salts were synthesized and tested for anti‐proliferative activity. 1,4‐Bis(naphthalen‐2‐ylmethyl)‐1,2,4‐triazolium bromide ( 2 ) showed activity against MDA‐MB‐468 breast cancer and PC‐3 prostate cancer cell lines.     

Comparative theoretical studies of substituted bridged bipyridines and their N-oxides

In this work, the experimental synthesized bipyridines azo-bis(2-pyridine),4,4′-dimethyl-3,3′-dinitro-2,2′-azobipyridine, and N,N′-bis(3-nitro-2-pyridinyl)-methane-diamine and a set of designed bipyridines that have similar frameworks but different linkages and substituents were studied theoretically at the B3LYP/6-31G* level of density functional theory. The gas-phase heats of formation were predicted based on the isodesmic reactions, and the condensed-phase heats of formation and heats of sublimation were estimated in the framework of the Politzer approach. The crystal densities have been computed from molecular packing and results show that incorporation of –N=N–, –N=N(O)–, –CH=N–, and –NH–NH– into bipyridines is more favorable than –CH=CH– and –NH–CH₂–NH– for increasing the density. The predicted detonation velocities (D) and detonation pressures (P) indicate that –NH₂, –NO₂, and –NF₂ can enhance the detonation performance, and –NO₂ and –NF₂ are more favorable. Introducing –N=N–, –N=N(O)–, and –NH–NH– bridge groups into bipyridines is also favorable for improving their detonation performance. The oxidation of pyridine N always but that of –N=N– bridge does not always improve the detonation properties. E4–O, the derivative with –N=N– bridge and two –NF₂ substituent groups, has the largest D (9.90 km/s) and P (47.47 GPa). An analysis of the bond dissociation energies shows that all derivatives have good thermal stability.     

Theoretic design of 1,2,3,4-tetrazine-1,3-dioxide-based high-energy density compounds with oxygen balance close to zero

Density functional theory method was used to study the heats of formation (HOFs), electronic structure, energetic properties, and thermal stability for a series of 1,2,3,4-tetrazine-1,3-dioxide derivatives with different substituents and bridge groups. It is found that the groups –NO₂, –C(NO₂)₃, and –N=N– play a very important role in increasing the HOFs of the derivatives. The effects of the substituents on the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels and HOMO–LUMO gaps are coupled to those of different substituents and bridges. The calculated detonation velocities and pressures indicate that the group –NO₂, –NF₂, –ONO₂, –C(NO₂)₃, or –NH– is an effective structural unit for enhancing the detonation performance for the derivatives. An analysis of the bond dissociation energies for several relatively weak bonds indicates that incorporating the groups –NO₂, –NF₂, –ONO₂, –C(NO₂)₃, and –N=N– into parent ring decreases their thermal stability. Considering the detonation performance and thermal stability, 18 compounds may be considered as the target compounds holding the greatest potential for synthesis and use as high-energy density compounds. Among them, the oxygen balances of four compounds are equal to zero. These results provide basic information for the molecular design of the novel high-energy compounds.     

First heterobimetallic AgI–CoIII coordination compound with both bridging and terminal –NO2 coordination modes: synthesis,characterization, structural and computational studies of (PPh3)2AgI–(μ‐κ2O,O′:κN‐NO2)–CoIII(DMGH)2(κN‐NO2)

An unusual heterobimetallic bis(triphenylphosphane)(NO₂)Ag^I–Co^III(dimethylglyoximate)(NO₂) coordination compound with both bridging and terminal –NO₂ (nitro) coordination modes has been isolated and characterized from the reaction of [CoCl(DMGH)₂(PPh₃)] (DMGH₂ is dimethylglyoxime or N,N′‐dihydroxybutane‐2,3‐diimine) with excess AgNO₂. In the title compound, namely bis(dimethylglyoximato‐1κ²O,O′)(μ‐nitro‐1κN:2κ²O,O′)(nitro‐1κN)bis(triphenylphosphane‐2κP)cobalt(III)silver(I), [AgCo(C₄H₇N₂O₂)₂(NO₂)₂(C₁₈H₁₅P)₂], one of the ambidentate –NO₂ ligands, in a bridging mode, chelates the Ag^I atom in an isobidentate κ²O,O′‐manner and its N atom is coordinated to the Co^III atom. The other –NO₂ ligand is terminally κN‐coordinated to the Co^III atom. The structure has been fully characterized by X‐ray crystallography and spectroscopic methods. Density functional theory (DFT) and time‐dependent density functional theory (TD‐DFT) have been used to study the ground‐state electronic structure and elucidate the origin of the electronic transitions, respectively.     

Crystallographic report: A coordination polymer containing [Zn(NO3)(H2O)2(btp)2]+ units bridged by btp ligands (btp = 2,6‐bis(N′‐1,2,4‐triazolyl)pyridine)

A zinc(II) coordination polymer has been formed from Zn(NO₃)₂ and 2,6‐bis(N′‐1,2,4‐triazolyl)pyridine (btp) ligands in which each zinc(II) atom is coordinated by three nitrogen donor atoms from btp and three oxygen donor atoms from a nitrate and two water molecules. Copyright © 2003 John Wiley & Sons, Ltd.     

Theoretical studies on the structures, heats of formation, energetic properties and pyrolysis mechanisms of nitrogen-rich difurazano[3,4-b:3′,4′-e]piperazine derivatives and their analogues

The molecular structure, heats of formation, energetic properties, strain energy and thermal stability for a series of substituted difurazano[3,4-b:3′,4′-e]piperazines and their analogues were studied using density functional theory. The results show that it is a useful way to increase the heat of formation values of energetic compounds by incorporating a five- or six-membered aromatic heterocycle to construct a fused ring system. The calculated detonation properties reveal that introducing one heterocycle to construct a fused ring structure greatly enhances their detonation properties. The substitution of the –NF₂, –NO₂ or –NHNO₂ group is very useful for enhancing the detonation performance for the substituted derivatives. According to molecular structure and natural bond orbital analysis, the introduction of the –NO₂, –NF₂ or –NHNO₂ group decreases the stability of the substituted derivative. There is a weak N–NO₂ bond conjugation in the NO₂-substituted derivatives. An analysis of the bond dissociation energies for several relatively weak bonds suggests that all the unsubstituted derivatives have good thermal stability, but the substitution of –NO₂ or –NF₂ remarkably decreases their stability. Considering the detonation performance and thermal stability, eight compounds may be considered as the potential candidates of high-energy density materials with less sensitivity.     

Synthesis and Characterization of 3,5‐Diamino‐1,2,4‐triazolium Dinitramide

3,5‐Diamino‐1,2,4‐triazole ( 1 , guanozol) was protonated with diluted hydrochloric acid, nitric acid, as well as perchloric acid forming 3,5‐diamino‐1,2,4‐triazolium chloride hemihydrate ( 2 ), 3,5‐diamino‐1,2,4‐triazolium nitrate ( 3 ) and 3,5‐diamino‐1,2,4‐triazolium perchlorate ( 4 ), respectively. In a second step 4 reacted with potassium dinitramide forming 3,5‐diamino‐1,2,4‐triazolium dinitramide ( 5 ) and low soluble potassium perchlorate. Compounds 2 – 5 were characterized by low temperature single X‐ray diffraction, IR and Raman as well as multinuclear NMR spectroscopy, mass spectrometry and differential scanning calorimetry. The heats of formation of 1 – 5 were calculated by the CBS‐4M method to be 81.1 ( 1 ), 124.7 ( 2 ), –76.1 ( 3 ), –25.2 ( 4 ) and 138.7 ( 5 ) kJ·mol^–1. With these values as well as the X‐ray densities several detonation parameters were calculated using both computer codes EXPLO5.03 and EXPLO5.04. In addition, the sensitivities of 1 – 5 were determined by the BAM drophammer and friction tester as well as a small scale electrical discharge device.     

Lamotrigine,an antiepileptic drug,and its chloride and nitrate salts

In lamotrigine [systematic name: 6‐(2,3‐dichlorophenyl)‐1,2,4‐triazine‐3,5‐diamine], C₉H₇Cl₂N₅, (I), the asymmetric unit contains one lamotrigine base molecule. In lamotriginium chloride [systematic name: 3,5‐diamino‐6‐(2,3‐dichlorophenyl)‐1,2,4‐triazin‐2‐ium chloride], C₉H₈Cl₂N₅⁺·Cl⁻, (II), the asymmetric unit contains one lamotriginium cation and one chloride anion, while in lamotriginium nitrate, C₉H₈Cl₂N₅⁺·NO₃⁻, (III), the asymmetric unit contains two crystallographically independent lamotriginium cations and two nitrate anions. In all three structures, N—H...N hydrogen bonds form an R₂²(8) dimer. In (I) and (II), hydrophilic layers are sandwiched between hydrophobic layers in the crystal packing. In all three structures, hydrogen bonds lead to the formation of a supramolecular hydrogen‐bonded network. The significance of this study lies in its illustration of the differences between the supramolecular aggregation in the lamotrigine base and in its chloride and nitrate salts.     

Molecular design of all nitrogen pentazole‐based high energy density compounds with oxygen balance equal to zero

We designed a new family of pentazole‐based high energy density compounds with oxygen balance equal to zero by introducing −NH₂, −NO₂, −N₃, −CF₂NF₂, and −C[NO₂]₃, and the properties including density, heats of formation, detonation performances, and impact sensitivity were investigated using density functional theory. The results show that half of these new energetic molecules exhibit higher densities than RDX (1.82 g/cm³), in which H5 gives the highest density of 2.09 g/cm³. Among all the 54 designed molecules, 22 compounds have higher D and P than RDX and eleven compounds have higher D and P than HMX, indicating that designing the pentazole‐based derivatives with oxygen balance equal to zero is a very effective way to obtain potential energetic compounds with outstanding detonation properties. Taking both the detonation performance and stability into consideration, nine compounds may be recognized as potential candidates of high energy density compounds. It is expected that our results will contribute to the theoretical design of new‐generation energetic explosives.     

Coordination of a triazine ligand with CuII and AgI investigated by spectral,structural, theoretical and docking studies

Two complexes of 5‐phenyl‐3‐(pyridin‐2‐yl)‐1,2,4‐triazine (PPTA), namely (ethanol‐κO)bis(nitrato‐κO)[5‐phenyl‐3‐(pyridin‐2‐yl‐κN)‐1,2,4‐triazine‐κN²]copper(II), [Cu(NO₃)₂(C₁₄H₁₀N₄)(C₂H₆O)] or [Cu(NO₃)₂(PPTA)(EtOH)] ( 1 ), and bis[μ‐5‐phenyl‐3‐(pyridin‐2‐yl)‐1,2,4‐triazine]‐κ³N¹:N²,N³;κ³N²,N³:N¹‐bis[(nitrato‐κO)silver(I)], [Ag₂(NO₃)₂(C₁₄H₁₀N₄)₂] or [Ag₂(NO₃)₂(μ‐PPTA)₂] ( 2 ), were prepared and characterized by elemental analysis, FT–IR spectroscopy and single‐crystal X‐ray diffraction. The X‐ray structure analysis of 1 revealed a copper complex with square‐pyramdial geometry containing two O‐donor nitrate ligands along with an N,N′‐donor PPTA ligand and one O‐donor ethanol ligand. In the binuclear structure of 2 , formed by the bridging of two PPTA ligands, each Ag atom has an AgN₃O environment and square‐planar geometry. In addition to the four dative interactions, each Ag atom interacts with two O atoms of two nitrate ligands on adjacent complexes to complete a pseudo‐octahedral geometry. Density functional theory (DFT) calculations revealed that the geometry around the Cu and Ag atoms in 1 ^opt and 2 ^opt (opt is optimized) for an isolated molecule is the same as the experimental results. In 1 , O—H…O hydrogen bonds form R₁²(4) motifs. In the crystal network of the complexes, in addition to the hydrogen bonds, there are π–π stacking interactions between the aromatic rings (phenyl, pyridine and triazine) of the ligands on adjacent complexes. The ability of the ligand and complexes 1 and 2 to interact with ten selected biomacromolecules (BRAF kinase, CatB, DNA gyrase, HDAC7, rHA, RNR, TrxR, TS, Top II and B‐DNA) was investigated by docking studies. The results show that the studied compounds can interact with proteins better than doxorubicin (except for TrxR and Top II).     

N‐Meth­yl‐N‐(2‐nitro­phen­yl)nitramine and N‐meth­yl‐N‐(3‐nitro­phen­yl)­nitramine

The structures of the two title isomeric compounds (systematic names: N‐meth­yl‐N,2‐dinitro­aniline and N‐meth­yl‐N,3‐di­nitro­aniline, both C₇H₇N₃O₄) are slightly different because they exhibit different steric hindrances and hydrogen‐bonding environments. The aromatic rings are planar. The –N(Me)NO₂ and –NO₂ groups are not coplanar with the rings. Comparison of the geometric parameters of the ortho, meta and para isomers together with those of N‐meth­yl‐N‐phenyl­nitramine suggests that the position of the nitro group has a strong influence on the aromatic ring distortion. The crystal packing is stabilized by weak C—H⋯O hydrogen bonds to the nitramine group.     

Syntheses and structures of cobalt(II), nickel(II), and copper(II) complexes with N,N,N′,N′-tetraalkylpyridine-2,6-dicarboxamides (O-daap) containing nitrate as the counter ion

Reactions of M(NO₃)₂?·?xH₂O [M?=?Co(II), Ni(II), and Cu(II)] with N,N,N′,N′-tetraalkylpyridine-2,6-dicarboxamides(O-daap) in CH₃CN yield [Co(O-dmap)(NO₃)₂] (1), [Co(O-deap)(NO₃)₂] (2), [Co(O-dpap)(NO₃)₂] (3), [Ni(O-dmap)(H₂O)₃](NO₃)₂] (4), [Ni(O-deap)(H₂O)₂(NO₃)](NO₃)] (5), [Cu(O-deap)(NO₃)₂] (6), and [Cu(O-dpap)(NO₃)₂] (7). X-ray crystal structures of 1, 2, 4, 5, and 7 reveal that O-daap ligands coordinate tridentate to each metal, O–N–O, with nitrate playing a vital role in molecular and crystal structures of all the complexes. The coordination geometry in the two Co(II) complexes, 1 and 2, is approximately pentagonal bipyramidal with nitrate bonded in a slightly unsymmetrical bidentate chelating mode. [Ni(dmap)(H₂O)₃](NO₃)₂ (4) and [Ni(deap)(H₂O)₂(NO₃)](NO₃) (5) exhibit octahedral geometry, the former containing uncoordinated nitrate while the latter has one nitrate coordinated unidentate and the other nitrate outside the coordination sphere. The Cu(II) in [Cu(dpap)(NO₃)₂] (7) occupies a distorted square pyramidal geometry and is linked to two unidentate nitrates, although one nitrate is also involved in a weak interaction with the metal through its other oxygen. IR spectra and other physical studies are consistent with their crystal structural data. O-dmap?=?N,N,N′,N′-tetramethylpyridine-2,6-dicarboxamides; O-deap?=?N,N,N′,N′-tetraethylpyridine-2,6-dicarboxamides; and O-dpap?=?N,N,N′,N′-tetraisopropylpyridine-2,6-dicarboxamides.     

Acyclic Schiff base salts derived from 1,3‐diaminopropane and 1,3‐diamino‐2‐hydroxypropane

Two salts of acyclic Schiff base cationic ligands, namely N,N′‐bis(2‐nitrobenzyl)propane‐1,3‐diammonium dichloride monohydrate, C₁₇H₂₂N₄O₄²⁺·2Cl⁻·H₂O, (I), and 2‐hydroxy‐N,N′‐bis(2‐nitrobenzyl)propane‐1,3‐diammonium dichloride, C₁₇H₂₂N₄O₅²⁺·2Cl⁻, (II), were synthesized as precursors in order to obtain new acyclic and macrocyclic multidentate ligands and complexes. The cation conformations in compounds (I) and (II) are different in the solid state, although the cations are closely related chemically. Similarly, the hydrogen‐bonding networks involving ammonium cations, hydroxyl groups and chloride anions are also different. In the cation of compound (II), the hydroxyl group is disordered over two sets of sites, with occupancies of 0.785 (8) and 0.215 (8).     

Reaction of Amidrazones with Phthaloyl Chloride—Synthesis of 1,2,4‐Triazolium Salts (Part I)

Phthaloyl chloride reacts with N‐arylbenzamidrazones to give 1,2,4‐triazolium salts in very good yields. The mechanism described the products formation was discussed. The structure of the obtained products was proved by IR, mass, NMR spectra, and elemental analyses.     

Theoretical predictions on pentaerythritol tetranitrate-based high energy density compounds

A novel family of pentaerythritol tetranitrate (PETN) derivatives based parent PETN skeleton were designed by introducing two energetic groups –NF₂ and –NO₂. Their electronic structure, heats of formation, detonation properties, impact sensitivity, and thermal stability were investigated by using density functional theory. The findings reveal that most of the title compounds have good detonation performance. The –NF₂ group played an important role in improving the densities, heats of detonation, and detonation properties of the designed molecules. The values of h₅₀ for almost all the PETN derivatives are higher than that of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine. An analysis of bond dissociation energy suggests that the N-NO₂ bond tends to be a trigger bond in thermal decomposition. Taking both detonation properties and thermal stabilities into consideration, the three compounds may be selected as potential high-energy-density compounds.     

Polymeric adducts of rhodium(II) tetraacetate with aliphatic diamines: natural abundance 13C and 15N CPMAS NMR investigations

Complexation properties of dimeric rhodium(II) tetracarboxylates have been utilised in chemistry, spectroscopy and organic synthesis. Particularly, the combination of these rhodium salts with multifunctional ligands results in the formation of coordination polymers, and these are of interest because of their gas‐occlusion properties. In the present work, the polymeric adducts of rhodium(II) tetraacetate with flexible ligands exhibiting conformational variety, ethane‐1,2‐diamine, propane‐1,3‐diamine and their N,N′‐dimethyl‐ and N,N,N′,N′‐tetramethyl derivatives, have been investigated by means of elemental analysis, ¹³C CPMAS NMR, ¹⁵N CPMAS NMR and density functional theory modelling. Elemental analysis and NMR spectra indicated the axial coordination mode and regular structures of (1 : 1)_n oligomeric chains in the case of adducts of ethane‐1,2‐diamine, N,N′‐dimethylethane‐1,2‐diamine N,N,N′,N′‐tetramethylethane‐1,2‐diamine and N,N,N′,N′‐tetramethylpropane‐1,3‐diamine. Propane‐1,3‐diamine and N,N′‐dimethylpropane‐1,3‐diamine tended to form heterogeneous materials, composed of oligomeric (1 : 1)_n chains and the additive of dirhodium units containing equatorially bonded ligands. Experimental findings have been supported by density functional theory modelling of some hypothetical structures and gauge‐invariant atomic orbital calculations of NMR chemical shifts. Copyright © 2013 John Wiley & Sons, Ltd.     

Nitrogen‐Rich Energetic Monoanionic Salts of 3,4‐Bis(1 H‐5‐tetrazolyl)furoxan

3,4‐Bis(1H‐5‐tetrazolyl)furoxan (H₂BTF, 2 ) and its monoanionic salts that contain nitrogen‐rich cations were readily synthesized and fully characterized by multinuclear NMR (¹H, ¹³C) and IR spectroscopy, differential scanning calorimetry (DSC), and elemental analyses. Hydrazinium ( 3 ) and 4‐amino‐1,2,4‐triazolium ( 7 ) salts crystallized in the monoclinic space group P2(1)/n and have calculated densities of 1.820 and 1.764 g cm^?3, respectively. The densities of the energetic salts range between 1.63 and 1.79 g cm^?3, as measured by a gas pycnometer. Detonation pressures and detonation velocities were calculated to be 23.1–32.5 GPa and 7740–8790 m s^?1, respectively.     

Syntheses and structures of four new mixed‐amide phosphoric triamides

Phosphoric triamides have extensive applications in biochemistry and are also used as O‐donor ligands. Four new mixed‐amide phosphoric triamide structures, namely rac‐N‐tert‐butyl‐N′,N′′‐dicyclohexyl‐N′′‐methylphosphoric triamide, C₁₇H₃₆N₃OP, (I), rac‐N,N′‐dicyclohexyl‐N′‐methyl‐N′′‐(p‐tolyl)phosphoric triamide, C₂₀H₃₄N₃OP, (II), N,N′,N′′‐tricyclohexyl‐N′′‐methylphosphoric triamide, C₁₉H₃₈N₃OP, (III), and 2‐[cyclohexyl(methyl)amino]‐5,5‐dimethyl‐1,3,2λ⁵‐diazaphosphinan‐2‐one, C₁₂H₂₆N₃OP, (IV), have been synthesized and studied by X‐ray diffraction and spectroscopic methods. Structures (I) and (II) are the first diffraction studies of acyclic racemic mixed‐amide phosphoric triamides. The P—N bonds resulting from the different substituent –N(CH₃)(C₆H₁₁), (C₆H₁₁)NH–, 4‐CH₃‐C₆H₄NH–, (tert‐C₄H₉)NH– and –NHCH₂C(CH₃)₂CH₂NH– groups are compared, along with the different molecular volumes and electron‐donor strengths. In all four structures, the molecules form extended chains through N—H…O hydrogen bonds.     

Hydrogen‐bonded supramolecular networks of N,N′‐bis(4‐pyridylmethyl)oxalamide and 4,4′‐{[oxalylbis(azanediyl)]dimethylene}dipyridinium dinitrate

The molecule of N,N′‐bis(4‐pyridylmethyl)oxalamide, C₁₄H₁₄N₄O₂, (I) or 4py‐ox, has an inversion center in the middle of the oxalamide group. Adjacent molecules are then linked through intermolecular N—H...N and C—H...O hydrogen bonds, forming an extended supramolecular network. 4,4′‐{[Oxalylbis(azanediyl)]dimethylene}dipyridinium dinitrate, C₁₄H₁₆N₄O₂²⁺·2NO₃⁻, (II), contains a diprotonated 4py‐ox cation and two nitrate counter‐anions. Each nitrate ion is hydrogen bonded to four 4py‐ox cations via intermolecular N—H...O and C—H...O interactions. Adjacent 4py‐ox cations are linked through weak C—H...O hydrogen bonding between an α‐pyridinium C atom and an oxalamide O atom, forming a two‐dimensional extended supramolecular network.