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  1. The title ketenylidene, [Au 3 (C 2 O)(C 26 H 35 O 2 P) 3 ](C 2 F 6 NO 4 S 2 ), was obtained upon exposure of [2-(dicyclohexylphosphino)-2′,6′-dimethoxy-1,1′-biphenyl]gold(I) bis(trifluoromethanesulfonyl)imide to acetic anhydride at elevated temperature. The ketenylidene bridge caps the tri-gold cluster. The title compound has provided crystals that upon analysis represent the first tri-gold ketenylidene with atomic distances indicative of bonding interaction between the gold atoms.
  2. The synthesis of the title compound, C 13 H 21 NO 2 S, is reported here along with its crystal structure. This compound crystallizes with two molecules in the asymmetric unit. The sulfonamide functional group of this structure features S=O bond lengths ranging from 1.433 (3) to 1.439 (3) Å, S—C bond lengths of 1.777 (3) and 1.773 (4) Å, and S—N bond lengths of 1.622 (3) and 1.624 (3) Å. When viewing the molecules down the S—N bond, the isopropyl groups are gauche to the aromatic ring. On each molecule, two methyl hydrogen atoms of one isopropyl group are engaged in intramolecular C—H...O hydrogen bonds with a nearby sulfonamide oxygen atom. Intermolecular C—H...O hydrogen bonds and C—H...π interactions link molecules of the title compound in the solid state.
  3. The syntheses and crystal structures of the two title compounds, C 11 H 10 O 3 ( I ) and C 17 H 14 BrNO 2 ( II ), both containing the bicyclo[2.2.2]octene ring system, are reported here [the structure of I has been reported previously: White & Goh (2014). Private Communication (refcode HOKRIK). CCDC, Cambridge, England]. The bond lengths and angles of the bicyclo[2.2.2]octene ring system are similar for both structures. The imide functional group of II features carbonyl C=O bond lengths of 1.209 (2) and 1.210 (2) Å, with C—N bond lengths of 1.393 (2) and 1.397 (2) Å. The five-membered imide ring is nearly planar, and it is positioned exo relative to the alkene bridgehead carbon atoms of the bicyclo[2.2.2]octene ring system. Non-covalent interactions present in the crystal structure of II include a number of C—H...O interactions. The extended structure of II also features C—H...O hydrogen bonds as well as C—H...π and lone pair–π interactions, which combine together to create supramolecular sheets.
  4. Energetic properties of bistetrazole derivatives are improved by the step-by-step introduction of functionalities which improve heat of formation, density, and oxygen content. The incorporation of unsaturation between bis(1 H -tetrazol-5-yl) and bis(1 H -tetrazol-1-ol) derivatives leads to planarity which enhances the density of the final product. In this manuscript, we have synthesized compounds 1,2-di(1 H -tetrazol-5-yl)ethane (4), ( E )-1,2-di(1 H -tetrazol-5-yl)ethene (5), and ( E )-5,5′-(ethene-1,2-diyl)bis(1 H -tetrazol-1-ol), (6) using readily available starting materials. Their corresponding dihydroxylammonium salts 7, 8 and 9 are obtained by reacting two equivalents of hydroxylamine (50% in water). New compounds are analyzed using IR, EA, DSC and multinuclear NMR spectroscopy ( 1 H, 13 C and 15 N). The solid-state structures of compounds 6, 7, 8 and 9 are confirmed by single-crystal X-ray diffraction. The energetic performances are calculated using the EXPLO5 (v6.06.02) code and the sensitivities towards external stimuli such as friction and impact are determined according to BAM standard. Compound 6 {( E )-5,5′-(ethene-1,2-diyl)bis(1 H -tetrazol-1-ol)} exhibits a surprisingly high density of 1.91 g cm −3 at 100 K (1.86 g cm −3 at 298 K). Its detonation velocity (9017 m s −1 ) is considerably superior to those of RDX (8795more »m s −1 ), which suggests it is a competitive high-energy-density material.« less
    Free, publicly-accessible full text available July 18, 2023
  5. Miller, S. (Ed.)
    Two new complementary Au(I)-catalyzed methods for the preparation of ester-substituted indolizines from easily accessible 2-propargyloxypyridines and either acetoacetates or dimethyl malonate are reported. These reactions tolerate a wide range of functionality, allowing for diversification at three distinct positions of the product (R, R1, R2). For electron-poor substrates, the highest yields are observed upon reaction with acetoacetates, while neutral and electron-rich substrates give higher yields upon treatment with dimethyl malonate.
    Free, publicly-accessible full text available July 18, 2023
  6. Free, publicly-accessible full text available July 13, 2023
  7. Nitrogen-rich heterocycles are essential for designing novel energetic green materials with the combination of high explosive performance and acceptable mechanical sensitivities. In this work, two sets of high nitrogen-azoles, derived from tetrazoles and triazole assemblies with N -trinitromethane, 5,5′-(2-(trinitromethyl)-2 H -1,2,3-triazole-4,5-diyl)bis(1 H -tetrazole) (TBTN) and N -methylene tetrazole, 5,5′-(2-((1 H -tetrazol-5-yl)methyl)-2 H -1,2,3-triazole-4,5-diyl)bis(1 H -tetrazole) (TBTT) are described. Their molecular structures were confirmed using multinuclear ( 1 H, 13 C, and 15 N) NMR spectra and single-crystal X-ray diffraction analysis. These molecules are attention attracting results emanating from methodologies utilized to access a unique class of tri-ionic salts in reaction with nitrogen-rich bases. The thermostabilities, mechanical sensitivities, and detonation properties of all new compounds were determined. Surprisingly, the nitro-based tri-cationic salts, 5b (Dv = 9376 m s −1 ) and 5c (Dv = 9418 m s −1 ), have excellent detonation velocities relative to HMX (Dv = 9144 m s −1 ), while those of the nitro-free tri-cationic salts, 8b·H2O (Dv = 8998 m s −1 ) and 8c·0.5H2O (Dv = 9058 m s −1 ), are superior to that of RDX (Dv = 8795 m s −1 ) and approach HMX values. Additionally, nearly all new compounds are insensitivemore »to mechanical stimuli because of the high percentage of hydrogen bond interactions (HBs) between the anions and cations, which are evaluated using two-dimensional (2D) fingerprint and Hirshfeld surface analyses. It is believed that the work presented here is the first example of high-performing and insensitive tri-cationic energetic salts, which may establish a discovery platform for the “green” synthesis of future energetic materials.« less
    Free, publicly-accessible full text available June 20, 2023
  8. The discovery of singular organic radical ligands is a formidable challenge due to high reactivity arising from the unpaired electron. Matching radical ligands with metal ions to engender magnetic coupling is crucial for eliciting preeminent physical properties such as conductivity and magnetism that are crucial for future technologies. The metal-radical approach is especially important for the lanthanide ions exhibiting deeply buried 4f-orbitals. The radicals must possess a high spin density on the donor atoms to promote strong coupling. Combining diamagnetic 89 Y ( I = 1/2) with organic radicals allows for invaluable insight into the electronic structure and spin-density distribution. This approach is hitherto underutilized, possibly owing to the challenging synthesis and purification of such molecules. Herein, evidence of an unprecedented bisbenzimidazole radical anion (Bbim 3− ˙) along with its metalation in the form of an yttrium complex, [K(crypt-222)][(Cp* 2 Y) 2 (μ-Bbim˙)] is provided. Access of Bbim 3− ˙ was feasible through double-coordination to the Lewis acidic metal ion and subsequent one-electron reduction, which is remarkable as Bbim 2− was explicitly stated to be redox-inactive in closed-shell complexes. Two molecules containing Bbim 2− (1) and Bbim 3− ˙ (2), respectively, were thoroughly investigated by X-ray crystallography, NMR and UV/Vismore »spectroscopy. Electrochemical studies unfolded a quasi-reversible feature and emphasize the role of the metal centre for the Bbim redox-activity as neither the free ligand nor the Bbim 2− complex led to analogous CV results. Excitingly, a strong delocalization of the electron density through the Bbim 3− ˙ ligand was revealed via temperature-dependent EPR spectroscopy and confirmed through DFT calculations and magnetometry, rendering Bbim 3− ˙ an ideal candidate for single-molecule magnet design.« less
    Free, publicly-accessible full text available May 25, 2023
  9. 1-Amino-1-hydrazino-2,2-dinitroethylene (HFOX) is a potential reactive intermediate for a new class of energetic materials. Now we describe its condensation with various carbonyl compounds in the presence of acidic and basic catalysts. Condensation of HFOX with α-diones and β-diones gives products of much interest. α-Diones undergo cyclization in the presence of base to form six-membered ring products, while β-diones cyclize to five-membered ring products in the presence of acid. One of the exciting reactions is the formation of ammonium (5,6-dimethyl-1,2,4-triazin-3-yl)dinitromethanide salt, 5c, which was isolated by using aqueous ammonia as a nucleophilic base. All new compounds were fully characterized by advanced spectroscopic techniques. The structures of 5, 5c, 5e, 9, 11, and 12a are supported by single crystal X-ray diffraction analysis. Most of the new six membered ring compounds have good thermostabilities (>200 °C), while the fluorinated five membered ring compound, 12b, has the highest density of 2.04 g cm −3 at 25 °C. Heats of formation and detonation properties were calculated by using Gaussian 03 and EXPLO5 software programs. Nearly all new compounds have very good detonation properties, especially, triazine salts, 5e ( D v = 7513 m s −1 ; P = 24.45 G P a), and 5f (more »D v = 7948 m s −1 ; P = 26.27 G P a) as well as azide derivative 11 ( D v = 8166 m s −1 ; P = 25.48 G P a), which are superior to TNT ( D v = 6824 m s −1 ; P = 19.40 G P a). These findings provide a new perspective for the synthesis of novel high performing energetic materials.« less
    Free, publicly-accessible full text available May 23, 2023
  10. Free, publicly-accessible full text available May 18, 2023