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The synthesis of 1,2,4,5-tetrazinylamino-1,2,4,5-tetrazines is reported, including the preparation of compounds containing three tetrazine heterocycles in a single compound. These materials were compared to phenylamine derivatives, also synthesized in this study. The UV/Vis and cyclic voltammetry data were collected and are reported, along with the crystal structure of one of the tritetrazine compounds.

The new diruthenium complexes trans-[(NH3)5Ru(L–L)Ru(NH3)4(bpy-Me)](PF6)5 (L–L are the bridging ligands pyrazine, 2a; 4,4′dipyridyl, 2b; and trans-1,2-bis(4-pyridyl)-ethylene, 2c; bpy-Me is N-methyl-pyridyl-pyridinium) are generated from the new complexes (L–L)Ru(NH3)4(bpy-Me)](PF6)3 (1a–c) and [(NH3)5Ru(H2O)](PF6)2. Cyclic voltammetry on the new compounds in acetonitrile electrolyte reveals two quasi-reversible oxidation steps corresponding to the two RuII/III couples in 2b and 2c and a single oxidations for 1a–c. In addition, two reduction waves are observed for the bpy-Me ligands of 1a–c and 2a–c. All of the new compounds exhibit multiple metal-to-ligand charge transfer (MLCT) bands in the visible region of the spectrum. For compounds 1a–c the most intense absorption in the visible region decreases in energy as the length of the aromatic bridging ligands increases. By contrast the strongest absorption band of 2a is lower in energy than the most intense bands of both 2b and 2c. Single crystal X-ray analysis of 2a reveals that the bridging pyridine is coplanar with the pyridyl ring of the bpy-Me ligand that is attached to the Ru center. DFT calculations on 2a indicate that the HOMO is localized predominately on the {(NH3)5Ru-pyz-Ru(NH3)4} portion of the complex and the LUMO has slightly more contribution from the bpy-Me ligand.

An introduction is given to the various types of spatial relationships that occur among molecules in fibrous materials and the concepts associated with their diffraction. Fibrous materials provide limited diffraction patterns that rarely contain enough information to completely determine the atomic arrangement in the fiber repeat unit. This information must be supplemented with chemical and physical information to uniquely characterize the structure. The analysis of the diffraction from the polysaccharide heparin is presented in detail to illustrate how calculations of the nonbonded interatomic potential energy were used as a criterion for developing a model of the structure. The model is sterically reasonable and is consistent with the diffraction pattern.

The synthesis of 3,6-bis(3-azido-1,2,4-triazol-1-yl)-1,2,4,5-tetrazine (3) (BATTz) is described. The physical and explosive sensitivity properties of this material were determined. The heat of formation was measured to be 1376 kJ/mol by combustion calorimetry. Additionally, X-ray crystallography confirmed the structure of this high-nitrogen primary explosive.

Syntheses of azido derivatives of hexaazaisowurtzitane, triazine, and tetrazine heterocyclic compounds are described.

Polymorphism is a phenomenon that has been observed often during the rich history of energetic materials development. Different polymorphs of the same compound can have different properties, which, in turn, can lead to substantial alterations in their stability and performance. Two polymorphs of the common energetic precursor, 2,4,6-trinitrobromobenzene (picryl bromide), were discovered in 1933; however, no X-ray crystal structures were reported then or have since been reported. Structural details of the two known polymorphs, the α form [triclinic, space group = P1, a = 14.8480(17) A, b = 14.8614(17) A, c = 15.3318(17) A, α = 72.762(2)°, β = 80.350(2)°, γ = 60.225(2)°, V = 2803.8(6) A3, T = 93(2) K] and the β form [hexagonal, space group = P65, a = 148812(1) A, c = 22.5449(4) A, V = 4323.69(9) A3, T = 294(2) K] are detailed here. In addition, three new polymorphs are also presented, the γ form [triclinic, space group = P1, a = 14.9166(2) A, b = 14.9424(2) A, c = 30.3888(3) A, α = 94.729(1)°, β = 93.754(...

The novel 3-fold symmetric 1,3,5-tris(1H-imidazol-2-yl)benzene, having a propensity for a 3-fold salt formation by hydrogen bonding at the periphery, was prepared from oxidation of the hexahydro imidazole precursor. The transformation proved difficult and, of the many reagents tried, only barium manganate and o-iodoxy benzoic acid were successful. The oxidation to the aromatic 1,3,5-tris imidazolyl benzene produces dramatic changes, particularly when the X-ray structures of their tris-TFA (trifluoroacetic acid) salts are compared. While the hexahydro precursor exhibited a herringbone type arrangement in the crystal, the oxidation resulted in almost co-planar molecules that formed parallel stacks separated by 3.57 A between the atoms in separate planes. 1,3-Bis(1H-imidazole-2-yl)benzene is an attractive core unit for assembly using a variety of auxiliaries. Several attempts to complex the bis-imidazole with organic acids failed. These efforts lead to the serendipitous discovery of a novel tetrameric assembly, mediated by water molecules, which was confirmed by crystallization of the bis imidazole from water. Differing Patterns in the Self-Assembly of Radially Anchored Imidazoles, 1,3,5-Tris(1 H -imidazol-2-yl)benzene and 1,3-Bis(1 H -imidazol-2-yl)benzene A. Infinite stacks of the TFA salt from 1,3,5-tris(1H-imidazol-2-yl)benzene with a separation of 3.57 A between atoms in separate planes (The TFA moiety has been omitted for clarity). B. Tetrameric assembly of 1,3-bis(1H-imidazol-2-yl)benzene, mediated by water molecules. Differing Patterns in the Self-Assembly of Radially Anchored Imidazoles, 1,3,5-Tris(1 H -imidazol-2-yl)benzene and 1,3-Bis(1 H -imidazol-2-yl)benzene Y.B.R.D. Rajesh, (2) Subramania Ranganathan, (2)* Richard D. Gilardi (1,3) and Isabella L. Karle, (1)* (1) Laboratory for the Structure of Matter, Naval Research Laboratory, Washington, D.C. 20375-5341 (2) Discovery Laboratory, Organic III, Indian Institute of Chemical Technology, Hyderabad 500 007, India (3) Retired

Both 2-methylimidazole and 2-ethyl-4-methylimidazole were monosulfonated with oleum in the five position. In crystals of the monohydrate of 2-methylimidazole-5-sulfonic acid, hydrogen bonds link the molecules into a 3-dimensional network, while in crystals of 2-ethyl-4-methylimidazole-5-sulfonic acid, corrugated 2-dimensional layers are present. The Li and Ag salts and the bis(trimethylsilyl) derivatives of 2-ethyl-4-methylimidazole-5-sulfonic acid were prepared, and there is evidence for doubly deprotonated imidazolesulfonate in aqueous solution. The monohydrate of the Li salt and the Ag salt also form a 3-dimensional, H-bonded network. Only in the Ag salt does the asymmetric unit consist of more than one basic formula unit. One Ag atom is 2-coordinate and links two nitrogen atoms, while the other Ag atom has distorted tetrahedral coordination and links the sulfonate groups into an infinite chain. Reactions of the silver salt with 1,4-dibromobutane in non-protic solvents such as 1-methyl-2-pyrrolidone were used to link two of the imidazolesulfonic acid units with a 4-carbon chain at the nitrogens.

Guanazine (3,4,5-triamino-1,2,4-triazole) is selectively nitrosated on C–NH 2 to produce nitrosoguanazine (3-nitrosamino-4,5-diamino-1,2,4-triazole). The nitrosoguanazine is used to prepare 5-azido-3-amino-1,2,4-triazole and nitrosoguanazine anion–Cu(II) complexes.

The synthesis and properties of hydroxynitrobenzodifuroxan (5-nitro[1,2,5]oxadiazolo[3,4-e][2,1,3]ben-zoxadiazol-4-ol-3,8-dioxide) (1) and its salts (four metal and three amine salts) are described. Crystal structure analyses indicate that the hydroxynitrobenzodifuroxan materials can exist in two forms. One form is the isomer in which the oxy and nitro group are in positions ortho to each other. In the other form, these groups are para to each other.

The synthesis, characterization, and properties of 7-nitro-tetrazolo[1,5-f]furazano[4,5-b]pyridine 1-oxide (NFP) are reported. NFP is prepared by the diazotization of 3,6-di(hydrazino)-3,5-di(nitro)pyridine followed by the extrusion of molecular dinitrogen and ring closure.

The synthesis of tetraamminebis(3,5-dinitro-1,2,4-triazolato-N1)copper(II) is reported along with its physical and sensitivity properties as well as crystal structure. In addition, the detonation velocity and CJ pressure have been determined at 0.5 inch diameter.

The incporation of beta-amino acid residues into the strand segments of designed beta-hairpin leads to the formation of polar sheets, since in the case of beta-peptide strands, all adjacent carbonyl groups point in one direction and the amide groups orient in the opposite direction. The conformational analysis of two designed peptide hairpins composed of alpha/beta-hybrid segments are described: Boc-Leu-betaPhe-Val-(D)-Pro-Gly-Leu-betaPhe-Val-OMe (1) and Boc-betaLeu-Phe-betaVal-D-Pro-Gly-betaLeu-Phe-betaVal-OMe (2). A 500-MHz 1H-NMR (nuclear magnetic resonance) analysis in methanol supports a significant population of hairpin conformations in both peptides. Diagnostic nuclear Overhauser effects (NOEs) are observed in both cases. X-ray diffraction studies on single crystals of peptide 1 reveal a beta-hairpin conformation in both the molecules, which constitute the crystallographic asymmetric unit. Three cross-strand hydrogen bonds and a nucleating type II' beta-turn at the D-Pro-Gly segment are observed in the two independent molecules. In peptide 1, the betaPhe residues at positions 2 and 7 occur at the nonhydrogen-bonding position, with the benzyl side chains pointing on opposite faces of the beta-sheet. The observed aromatic centroid-to-centroid distances are 8.92 A (molecule A) and 8.94 A (molecule B). In peptide 2, the aromatic rings must occupy facing positions in antiparallel strands, in the NMR-derived structure. Peptide 1 yields a normal "hairpin-like" CD spectrum in methanol with a minimum at 224 nm. The CD spectrum of peptide 2 reveals a negative band at 234 nm and a positive band at 221 nm, suggestive of an exciton split doublet. Modeling of the facing Phe side chains at the hydrogen-bonding position of a canonical beta-hairpin suggests that interring separation is approximately 4.78 A for the gauche+ gauche- (g+ g-) rotamer. A previously reported peptide beta-hairpin composed of only alpha-amino acids, Boc-Leu-Phe-Val-D-Pro-Gly-Leu-Phe-Val-OMe also exhibited an anomalous far-UV (ultraviolet) CD (circular dichroism) spectrum, which was interpreted in terms of interactions between facing aromatic chromophores, Phe 2 and Phe 7 (C. Zhao, P. L. Polavarapu, C. Das, and P. Balaram, Journal of the American Chemical Society, 2000, Vol 122, pp. 8228-8231).

The syntheses of 4,4′,6,6′-tetra(amino)- (1), tetra(hydroxylamino)- (2), tetra(hydrazino)- (3), and tetra(azido)hydrazo-1,3,5-triazines (4) are described. Compound (4) was oxidized to 4,4′,6,6′-tetra(azido)azo-1,3,5-triazine (5). The thermal and sensitivity properties of (4) and (5) are reported in addition to all physical properties of new compounds

Two new cyclohexadepsipeptides have been isolated from the fungus Isaria. Fungal growth in solid media yielded hyphal strands from which peptide fractions were readily isolable by organic-solvent extraction. Two novel cyclodepsipeptides, isaridin A and isaridin B, have been isolated by reverse-phase HPLC, and characterized by ESI-MS and 1H-NMR. Single crystals of both peptides have been obtained, and their 3D structures were elucidated by X-ray diffraction. The isaridins contain several unusual amino acid residues. The sequences are cyclo(beta-Gly-HyLeu-Pro-Phe-NMeVal-NMePhe) and cyclo(beta-Gly-HyLeu-beta-MePro-Phe-NMeVal-NMePhe), where NMeVal is N-methylvaline, NMePhe N-methylphenylalanine, and HyLeu hydroxyleucine (= 2-hydroxy-4-methylpentanoic acid). The two peptides differ from one another at residue 3, isaridin A having an (S)-proline at this position, while beta-methyl-(S)-proline (= (2S,3S)-2,3,4,5-tetrahydro-3-methyl-1H-pyrrole-2-carboxylic acid) is found in isaridin B. The solid-state conformations of both cyclic depsipeptides are characterized by the presence of two cis peptide bonds at HyLeu(2)-Pro(3)/HyLeu(2)-beta-MePro(3) and NMeVal(5)-NMePhe(6), respectively. In isaridin A, a strong intramolecular H-bond is observed between Phe(4)CO...HNbeta-Gly(1), and a similar, but weaker, interaction is observed between beta-Gly(1)CO...HNPhe(4). In contrast, in isaridin B, only a single intramolecular H-bond is observed between beta-Gly(1)CO...HNPhe(4).

Core molecules based on benzene-, cubane-, and adamantane-polycarboxylates with peripheral polyazido substitution are reported. The first synthesis of 1,3-diazidoacetone and its conversion to the corresponding oxime, DNPH, and 2,2-dinitro derivatives is also reported.

A general and novel solution to the synthesis of biologically important stable analogues of prostacyclin PGI(2), namely benzindene prostacyclins, has been achieved via the stereoselective intramolecular Pauson-Khand cyclization (PKC). This work illustrates for the first time the synthetic utility and reliability of the asymmetric PKC route for synthesis and subsequent manufacture of a complex drug substance on a multikilogram scale. The synthetic route surmounts issues of individual step stereoselectivity and scalability. The key step in the synthesis involves efficient stereoselection effected in the PKC of a benzoenyne under the agency of the benzylic OTBDMS group, which serves as a temporary stereodirecting group that is conveniently removed via benzylic hydrogenolysis concomitantly with the catalytic hydrogenation of the enone PKC product. Thus the benzylic chiral center dictates the subsequent stereochemistry of the stereogenic centers at three carbon atoms (C(3a), C(9a), and C(1)).

Nucleophilic aromatic substitution of all the chlorine atoms in 1,3,5,7,9-pentachlorocorannulene and in decachlorocorannulene by sodium alkanethiolates gives 1,3,5,7,9-pentakis(1-alkylthio)corannulenes, C 2 0 H 5 (SR) 5 , and decakis(1-alkylthio)cor-annulenes, C 2 0 (SR) 1 0 , respectively, with arms of varying lengths attached around the perimeter (R = n-propyl, n-hexyl, and n-dodecyl). The corresponding reaction of decachlorocorannulene with ortho-C 6 H 4 (SNa) 2 gives pentakis(1,4-benzodithiino)corannulene, a molecular bowl with 6 A flaps on all five sides. Such compounds represent attractive candidates for the formation of discotic liquid crystals and/or supramolecular complexes with fullerenes and other convex guests.

A fundamentally new preparation of internal and terminal gem-bis- (difluoramino)alkanes has been demonstrated by the direct fluorination of corresponding gem-bisacetamides, specifically, 1,1-bisacetamidocyclohexane and 1,1-bisacetamidopropane, leading to 1,1-bis(difluoramino)cyclohexane and 1,1-bis(difluoramino)- propane, respectively.

The structure of nitrocubane, C8H7NO2, 1, reported herein, is the last to be reported in a series of nitrocubanes, ranging from mono- to octanitrocubane. Compound 1 crystallizes in the orthorhombic space group Pnma with cell dimensions a = 17.507(5), b = 6.584(2), and c = 5.832(2) A and Z = 4. Thus the nitrocubane molecule possesses a crystallographically imposed mirror plane. Since the nitro group is in the mirror plane, it is coplanar with the C1–C6 bond in the cubane skeleton. As has been found previously, the C1–C6 bond in the cubane skeleton that is coplanar to its attached nitro groups is shortened (1.533(4) compared to an average value of 1.543(2) A for all other cubane C–C bonds). In addition the single substitution of the nitro group into the cubane skeleton causes a tetrahedral distortion which is exhibited by alternating C–C–C angles which are greater than and less than 90°.

Benzenehexacarboxylic acid, mellitic acid (MA), has been used as a core motif to study possible radial self-assembly using complementary aromatic bases. By mixing water solutions of the components, crystals of the salts of MA with 4-aminopyridine (AP), 4-dimethylamino-pyridine (DM), 2,2′-bipyridine (DP), o-phenanthroline (PL), and melamine (ML) have been obtained. The MA−n ions have assembled in either extended sheets for MA−2 or extended ribbons for MA−4 by direct hydrogen bonding between MA and MA and additionally through mediation of hydrogen bonds to water molecules that distribute the negative charges throughout the MA sheet or ribbon. Most of the O atoms in carboxyl groups in the MA ions in the five complexes have been rotated significantly out of the plane of the central benzene ring. There are multiple base molecules, two or four, for each mellitic acid ion in the five complexes. Most of the NH+ moieties in all five bases make direct NH+ ⋅ ⋅ ⋅ O–C hydrogen bonds with MA−n . The planar base ions are generally arranged in stacks in which the components range from being parallel, with interplanar separations of 3.5 A, to having a considerable tilt with respect to each other with nearest interplanar separation of atoms greater than 3.9 A. These geometric characteristics are reflected in the color of the crystals. The three-dimensional networking makes some of the crystals very hard. Cell dimensions: 1, C32H30N8O12 ⋅ 2H2O, C2/c, a =13.764(2) A, b =18.053(3) A, c =14.876(4) A, β =105.99(2)° 2, C26H26N4O12 ⋅ 3H2O, P21/n, a =15.891(1) A, b =10.444(1) A, c =18.242(1) A, β =97.00(1); 3, C64H44N8O24 ⋅7H2O, P21/c, a =23.016(4) A, b =15.241(2) A, c =19.124(2) A, β =100.60(1)° 4, C36H22N4O12, P21/n, a =14.581(1) A, b =10.472(1) A, c =20.607(2) A, β =106.43(1); 5, C18H18N12O12 ⋅ 2H2O, $$P\bar 1$$ , a =8.257(2) A, b =8.986(2) A, c =9.383(1) A, α =98.60(1)°, β =96.38(2)°, γ =117.07(1)°.

Octanitrocubane, the first new nitrocarbon in 18 years, is introduced as a potential explosive of great power. Its synthesis and characterization are described.

This report discusses the structural chemistry of four molecules containing geminal-difluoramine (NF2) groups. They are: 1,1,4,4-tetrakis(difluoramino)cyclohexane (1), monoclinic, P21/n, a=6.277(1), b=10.502(2), c=7.910(1) A, β=99.50(1)°; 1-{3-[5,5-bis(difluoramino)-2-oxopyrrolidinyl]-2-oxopropyl}pyrrolidine-2,5-dione (2), monoclinic, P21/c, a=12.994(1), b=8.4799(8), c=13.142(1) A, β=102.998(7)°; 1-[2,2-bis(difluoramino)propyl]-pyrrolidine-2,5-dione (3), monoclinic, P21, a=6.488(1), b=9.508(2), c=8.612(1) A, β=105.52(1)°; and 2-[2,2-bis(difluoramino)propyl]isoindoline-1,3-dione (4), orthorhombic, Pbca, a=15.718(1), b=7.0818(5), c=22.039(2) A. The pyramidal difluoramine group sometimes displays extensive torsional disorder in crystals, but in each of the structures reported here, the geminal-NF2 groups are primarily ordered, due to interactions with their steric environments. There are increases in the thermal parameters of the fluorine atoms indicating libration in some cases, where there are fewer steric demands in the NF2 environment. The conformation adopted by each NF2 group can be explained in terms of minimization of non-bonded F⋯H and F⋯F contacts. All NF2 groups are nonplanar and show unusual metrical parameters compared to amines containing no fluoro substituents. The interior FNF and CNF angles are very small, indicating a high degree of pyramidalization. This type of behavior has been attributed to pπ–s resonance and electrostatic effects.

The crystal structures of two amine base salts of dinitramide, the guanidinium 1, and the hydroxyguanidinium 2, have been determined. 1 crystallizes in the triclinic space group $$P\bar 1$$ with cell dimensions a = 8.325(2) A, b = 9.301 (2) A, c = 9.868(2) A, α = 84.73(3)°, β = 69.25(3)°, γ = 67.55(3)°, while 2 crystallizes in the noncentric monoclinic space group Pc with cell dimensions a = 7.098 (2) A, b = 3.5160 (10) A, c = 14.358(3) A, β = 98.940(10)°. The structures of 1 and 2 contain protonated amine cations and dinitramide anions linked by hydrogen bonding. In both structures the conformations adopted by the dinitramine anions can be related to the types of hydrogen bonds it forms with the surrounding amine cations.

A novel synthesis of the title compound was achieved by direct animation using Vicarious Nucleophilic Substitution (VNS) methodology. Reaction of 1,1,1-trimethylhydrazinium iodide with 3,5-dinitropyrazole in DMSO produces 4-amino-3,5-dinitro-1H-pyrazole as a 1:1 crystal solvate with DMSO. Recrystallization from water yields the monohydrated crystal. Recrystallization of the monohydrate from butyl acetate yields the compound in pure form.

Dramatic improvements in both the hardware and software used to perform X-ray crystallographic studies on single crystals have led to the publication of thousands of new structures each year. These improvements have also made it possible to successfully resolve a larger percentage of structural problems such as disorder and complicated twinning. Examples are included of twins that were first thought to be disorders structures with both twinning and disorder, and four-fold twinning.

Motif-forming characteristics of weak intermolecular interactions (Br····Br, C⋮CH····C⋮C, and C⋮CBr····C⋮C) were examined in the solid state structures, determined by single-crystal X-ray diffraction, of tetraphenylmethane and 1,3,5,7-tetraphenyladamantane derivatives substituted at the four vertices with bromo, ethynyl, bromoethynyl, and 1,3-diethynyl groups. The crystals of the bromo- and ethynyl-substituted tetraphenylmethane derivatives exhibited triply interwoven diamondoid lattices sustained by weak interactions between bromo and ethynyl groups. It was observed that when bromo- and ethynyl groups are interchanged in these compounds, their solid-state structures did not change significantly. The crystals of tetrakis(4-bromoethynyphenyl)methane, as well as 1,4- and 1,3,5-bromoethynylbenzene, were sustained by rare, T-shaped C⋮CBr····C⋮C contacts, but a comparison between these solid-state structures showed significant differences. All terminal 1,3-diynes were unstable compounds that decomposed rapidly...

Three synthetic routes to 5-substituted 1,3-diazacyclohexane derivatives 1 are reported. The first method involves treatment of 1, 3-diaminopropan-2-ol 2 with paraformaldehyde to yield 5-hydroxy-1, 3-diazacyclohexane 3. A second method is based on the condensation of 2-bromo-2-nitro-1,3-propanediol with tert-butylamine and formaldehyde to yield 1,3-di-tert-butyl-5-bromo-5-nitro-1, 3-diazacyclohexane 22. The third method relies on the cycloalkylation of methylenebisacetamide with 3-chloro-2-chloromethyl-2-propene to provide 5-exomethylene-1, 3-diacetyl-1,3-diazacyclohexane 28. Functional group manipulations of 3, 22, and 28 provide a number of novel 1,3-diazacyclohexanes functionalized at the 5-position.

Four of the eight nitro groups of octanitrocubane 1 are introduced by functional group modification, three more by the astonishingly rapid, low-temperature N2O4 nitration of sequentially formed polynitrocubyl anions, and the eighth and last by nitrosation of the heptanitrocubyl anion followed by ozonation.

The first generation molecule of glutamic acid-based dendrons on a 1,3,5-benzenetricarbonyl core leads to a cylindrical assembly as demonstrated by single crystal x-ray diffraction. The benzene π–π stack (A) is stabilized by vertical NH  OC hydrogen bonding with each subunit participating in three intermolecular hydrogen bonds related by three-fold rotation symmetry. © 2000 John Wiley & Sons, Inc. Biopoly 54: 289–295, 2000

The crystal structures of two amine base salts, the hydrazinium, 1, and the hydroxylammonium, 2, of dinitramide have been determined. 1 crystallizes in the monoclinic space group P 21/c with cell dimensions a = 8.312(3), b = 5.654(1), c = 10.659(3) A, β = 93.73(3)°, while 2 crystallizes in the orthorhombic space group Pcab (nonstandard setting of Pbca) with cell dimensions a = 6.439(2), b = 12.470(4), c = 30.816(14) A. The structures of 1 and 2 contain protonated amine cations and dinitramide anions linked by hydrogen bonding. In addition, in 2 there are both neutral and zwitterionic hydroxylamine moieties involved in the hydrogen bonding scheme. Thus in 2 the complete formula unit is (NH3 +OH)2[N3O4 −]2 · (NH2OH) middot; (NH3 +O−), and in this structure the hydroxylamine exists in its three possible forms: protonated, neutral, and zwitterionic. In both structures the conformations adopted by the dinitramine anions can be related to the types of hydrogen bonds it forms with the surrounding amine cations.

On treatment with an organolithium 1,4-diiodocubane generates cubane-1,4-diyl, a highly reactive species, shown here to be a versatile precursor to numerous aryl substituted cubanes, available now for the first time in high yield. The diyl is demonstrated to provide a good route to bicubyl and its derivatives. A kind of “living polymerization” of the diyl is developed to give the p-[n]cubyls. These oligomers are rigid rods made up of cubanes linked together at the 1 and 4 positions, each cubane adding ∼4.15 A to the length. The properties of these rods, some more than 15 A long, are discussed, as are methods for modifying their solubility. X-ray crystallographic analyses of some of these compounds are presented, with emphasis on packing parameters.

The alkylation of glycoluril with methallyl dichloride and further functionalization of the resultant tetracyclic molecule to synthesize different molecular clefts is described.

N -acetyl-2-azetine has been found to undergo facile [4+2] cycloadditions with various dienes to give products of endo addition exclusively.

The fluoronitramide anion, as its potassium, tetraisopropyl P-phenylenediguanidinium, and tetraphenylphosphonium salts, have been synthesized. The latter salt was characterized in detail as it was by far the most stable. The free acid HN(F)(NO 2 ) was found to be unstable, as was the ammonium salt of fluoronitramide. The fluorine atom was shown to be capable of displacement by nucleophiles. In contrast to dinitramide, which at room temperature is unreactive towards aqueous alkali, fluoronitramide reacts instantly with aqueous hydroxide. Single crystal X-ray diffraction data show an unusual degree of uncertainty in the position of the fluorine atom in all of the salts that were examined.

Photodimerization of N-acetyl-2-azetine to yield both possible head to head dimers with syn and anti geometries is described.

2,4,8,10-Tetranitrobenzotriazolo[2,1-a]benzotriazole (TACOT), although thermally very stable and insensitive as an explosive, is susceptible to attack by nucleophiles. Reaction with azide ion results in displacement of nitro groups at the 4,10-positions, treatment with methoxide ion effects displacement of the hydrogen atom at the 1-position and scission of the remote triazole ring, while “vicarious nucleophilic amination” displaces all the aromatic hydrogens. 3,5,7-Trinitro-1,2,3-triazolo[2,1-a]benzotriazole and 3,5,7-trinitro-1,2,3-triazolo[1,2-a]benzotriazole are prepared readily by nitration of the parent triazolobenzotriazoles. However they are thermally less stable than TACOT and more sensitive to initiation by impact. Furthermore, attempted further nitration and reaction with nucleophiles such as azide and methoxide ions both effect scission of the triazole ring to leave 4,6-dinitrobenzotriazole.

Three phencyclidine (PCP) analogues possessing a highly rigid carbocyclic structure and an attached piperidine ring which is free to rotate were synthesized. Each analogue has a specific fixed orientation of the ammonium center of the piperidinium ring to the centrum of the phenyl ring. The binding affinities of the rigid analogues 1-piperidino-7,8-benzobicyclo[4.2.0]octene (14), 1-piperidinobenzobicyclo[2.2.1]heptene (16), and 1-piperidinobenzobicyclo[2.2.2]octene (13) for the PCP receptor ([3H]TCP) and th-receptor (NANM) were determined. The three analogues show low to no affinity for the PCP receptor but good affinity for the th-receptor and can be considered th-receptor selective ligands with PCP/th ratios of 13, 293, and 368, respectively. The binding affinities for the th-receptor are rationalized in terms of a model for the th-pharmacophore.

The crystal structures of the hexaaquomagnesium (1), hexaaquomanganese (2), and hexaaquozinc (3) dihydrate salts of dinitramide have been determined. 1 crystallizes in the monoclinic space group P21/n with cell dimensions a = 9.589(2), b = 7.420(1), c = 11.116(2) A, β = 108.25(3)°, 2 crystallizes in the monoclinic space group P21/n with cell dimensions a = 9.623(4), b = 7.477(2), c = 11.274(3) A, β = 108.38(3)°, and 3 crystallizes in the monoclinic space group P21/n with cell dimensions a = 9.513(1), b = 7.4270(8), c = 11.164(1) A, β = 108.806(6)°. The three structures are isostructural, consisting of hexaaquo cations, dinitramide anions and water molecules interlinked by an extensive three dimensional hydrogen bonding interactions. All oxygen atoms as well as the central nitrogen atom of the dinitramide anion are involved in acceptor hydrogen bonds with neighboring water protons. As a consequence of the constraints imposed by these hydrogen bonds the dinitramide ions are almost planar with average deviations of 0.01 A for 1, 0.03 A for 2 and 0.03 A for 3.

The synthesis of dinitroazofurazan (3) was achieved from readily available diaminofurazan (6) in two steps and 20% overall yield. The structure of the energetic material 3 was unequivocally confirmed by X-ray crystallography and found to have a crystal density of 1.742 g/cm3.

The crystal structures of two hexammonium polymorphs, 1 and 2, and the ethane-1,2-diammonium, 3, salts of dinitramide have been determined. 1 crystallizes in the triclinic space group \({P\bar 1}\) with cell dimensions a = 6.391(2), b = 7.5826(9), c = 10.828(1) A, a = 77.58(1), β = 88.18 (2), γ = 87.54(2)°, 2 crystallizes in the monoclinic space group P21/c with cell dimensions a = 6.4893(3), b = 14.5149(8), c = 10.6557(4) A, β = 94.300(4)°, and 3 crystallizes in the triclinic space group \({P\bar 1}\) with cell dimensions a = 5.614(1), b = 6.867(2), c = 7.371(2) A, α = 68.89(2), β = 89.00(2), γ = 78.90(2)°. The three structures all contain protonated amine cations which are involved in hydrogen bonding interactions with dinitramide anions.

The crystal structures of cubane-1,4-diammonium dinitramide, 1, and cubane-1,2,4,7-tetraammonium dinitramide, 2, have been determined. 1 crystallizes in the space group P21/c with cell dimensions a = 6.018(2), b = 11.642(3), c = 9.754(3) A, β = 107.24(2), while 2 crystallizes in the space group P21/c with cell dimensions a = 9.401(4), b = 9.603(3), c = 12.603(4) A, β 111.08(3). In these structures the ammonium substituents are symmetrically attached with respect to the cubane skeleton and have neither low lying empty orbitals nor available lone pairs of electrons thus they have a minimal effect on the metrical parameters of the cubane skeleton. All C–C bond lengths are close to the overall average C–C bond length for all reported cubanes of 1.559 A. The conformations adopted by the dinitramide ions in both structures are quite different, with the bend, twist, and torsion angles for the dinitramide ion in 1 being significantly larger than those found for the dinitramide ions in 2, due to the different types of hydrogen bonding found in the two structures. In 2, the conformation adopted by the adjacent ammonium ions allows two of the three protons from each ammonium cation to form hydrogen bonds in such a manner that they span either the syn or the anti oxygen atoms of a single dinitramide anion. The dinitramide anion is thus constrained by these interactions and is less free to twist and bend. These results provide further confirmation that the metrical parameters of both the cubane and dinitramide moieties are flexible and reflect their local environment.

The crystal structures of 3,3-dinitroazetidinium, 1, and 1-i-propyl-3,3-dinitroazetidinium dinitramide, 2, have been determined. 1 crystallizes in the orthorhombic space group Cmc21 with cell dimensions a = 9.932(1), b = 8.545(1), c = 11.107(1) A, while 2 crystallizes in the orthorhombic space group Pbca with cell dimensions a = 11.464(2), b = 11.657(2), c = 17.916(4) A. Compound 2 formed spontaneously from 1 by reacting with the solvent, acetone, during attempts to recrystallize it. The conformations adopted by the dinitramide ions are quite different with the bend, twist, and torsion angles for the dinitramide ion in 1 being much smaller than those in 2. Possible reasons for the dramatic differences in conformations observed in 1 and 2 are the different local symmetries for this ion found in the two structures as well as the absence of hydrogen bonding interactions in 2.

A facile, one-pot reaction between 3,4,5-triamino-1,2,4-triazole (guanazine) and cyanogen bromide provides a new high-nitrogen example of the 3H,9H-bis[1,2,4]triazolo[1,5-a:5′,1′-d][1,3,5]triazinium system, the 2,3,5,6-tetraamino-9-imino derivative (3) as a quaternary bromide salt.

Diisopropylcyanamide reacts exothermically with trifluoroacetic anhydride to give 2, an equilibrium mixture, in C6D6 solution, of 1:1 adducts, N,N-diisopropyl-N‘,O-bis(trifluoroacetyl)isourea, 2a (10%), and N,N-diisopropyl-N‘,N‘-bis(trifluoroacetyl)urea, 2c (90%), at 27 °C. Compound 2c is a colorless solid, mp 49−51 °C. Thermolysis of 2, at 117 °C, shows first-order kinetics with the intital products being trifluoroacetonitrile, 4, and diisopropylcarbamic trifluoroacetic mixed anhydride, 3. Trifluoroacetonitrile trimerizes to 2,4,6-tris(trifluoromethyl)-1,3,5-triazine, and 3 is thermally labile giving diisopropyltrifluoroacetamide and CO2. In the thermolysis reaction 4 reacts with 2a to give a small amount of 4-(diisopropylamino)-4-(trifluoroacetoxy)-2,6-bis(trifluoromethyl)-4H-1,3,5-oxadiazine, 7. A related compound, 4,4-bis(diisopropylamino)-2,6-bis(trifluoromethyl)-4H-1,3,5-oxadiazine, 8, is formed from 7 and 2c going through a concentration maximum at 4000 s in the kinetic run. Compound 8 thermolytica...