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Here we report on the preparation of two hydrogen atom free 3,3'-bi(1,2,4-oxadiazole) derivatives. 5,5'-Bis(fluorodinitromethyl)-3,3'-bi(1,2,4-oxadiazole) was synthesised by fluorination of diammonium 5,5'-bis(dinitromethanide)-3,3'-bi(1,2,4-oxadiazole). For our previously reported analogue 5,5'-bis(trinitromethyl)-3,3'-bi(1,2,4-oxadiazole), a new synthetic route starting from new 3,3'-bi(1,2,4-oxadiazolyl)-5,5'-diacetic acid was developed. In this course also hitherto unknown 5,5'-dimethyl-3,3'-bi(1,2,4-oxadiazole) was isolated. The compounds were characterised by multinuclear NMR spectroscopy, IR and Raman spectroscopy, elemental analysis as well as mass spectrometry. X-ray diffraction studies were performed and the crystal structures for the 5,5'-dimethyl and 5,5'-(fluorodinitromethyl) derivatives are reported. The energetic 5,5'-(fluorodinitromethyl) and 5,5'-(trinitromethyl) compounds do not contain any hydrogen atoms and show remarkable high densities. Furthermore, the thermal stabilities and sensitivities were determined by differential scanning calorimetry (DSC) and standardised impact and friction tests. The heats of formation were calculated by the atomisation method based on CBS-4M enthalpies. With these values and the room-temperature X-ray densities, several detonation and propulsion parameters, such as the detonation velocity and pressure as well as the specific impulse of mixtures with aluminium, were computed using the EXPLO5 code., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Woollins' reagent (WR, (PhPSe2)2) plays an essential role in the selenation of organic compounds. Reaction of WR with pyridine gives the P(V) species PhPSe2 stabilised by pyridine coordination which is the first crystallographically characterised mononuclear RPSe2 system stabilised by an external molecule and has potential as a selenation reagent for reactions under mild conditions.

A practical stereoselective iodide-lithium exchange was used in the first general preparation of functionalized stereodefined acyclic secondary nonstabilized lithium reagents from the corresponding secondary alkyl iodides. These lithium reagents react with various electrophiles including carbon electrophiles with high retention of configuration. Kinetic data on the configurational stability of these acyclic alkyllithium reagents are given. This methodology offers a new entry to chiral synthons for the stereoselective synthesis of open-chain molecules., (Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A new structural arrangement Te3 (RP(III) )3 and the first crystal structures of organophosphorus(III)-tellurium heterocycles are presented. The heterocycles can be stabilized and structurally characterized by the appropriate choice of substituents in Tem (P(III) R)n (m=1: n=2, R=OMes* (Mes*=supermesityl or 2,4,6-tri-tert-butylphenyl); n=3, R=adamantyl (Ad); n=4, R=ferrocene (Fc); m=n=3: R=trityl (Trt), Mesor by the installation of a P(V) 2 N2 anchor in RP(III) [TeP(V) (tBuN)(μ-NtBu)]2 (R=Ad, tBu)., (Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The (1) H NMR chemical shifts of the C(α)H protons of arylmethyl triphenylphosphonium ions in CD2 Cl2 solution strongly depend on the counteranions X(-) . The values for the benzhydryl derivatives Ph2 CHPPh3 (+)  X(-) , for example, range from δH =8.25 (X(-) =Cl(-) ) over 6.23 (X(-) =BF4 (-) ) to 5.72 ppm (X(-) =BPh4 (-) ). Similar, albeit weaker, counterion-induced shifts are observed for the ortho-protons of all aryl groups. Concentration-dependent NMR studies show that the large shifts result from the deshielding of the protons by the anions, which decreases in the order Cl(-) > Br(-) ≫ BF4 (-) > SbF6 (-) . For the less bulky derivatives PhCH2 PPh3 (+)  X(-) , we also find CH⋅⋅⋅Ph interactions between C(α)H and a phenyl group of the BPh4 (-) anion, which result in upfield NMR chemical shifts of the C(α)H protons. These interactions could also be observed in crystals of (p-CF3 -C6 H4 )CH2 PPh3 (+)  BPh4 (-) . However, the dominant effects causing the counterion-induced shifts in the NMR spectra are the CH⋅⋅⋅X(-) hydrogen bonds between the phosphonium ion and anions, in particular Cl(-) or Br(-) . This observation contradicts earlier interpretations which assigned these shifts predominantly to the ring current of the BPh4 (-) anions. The concentration dependence of the (1) H NMR chemical shifts allowed us to determine the dissociation constants of the phosphonium salts in CD2 Cl2 solution. The cation-anion interactions increase with the acidity of the C(α)H protons and the basicity of the anion. The existence of CH⋅⋅⋅X(-) hydrogen bonds between the cations and anions is confirmed by quantum chemical calculations of the ion pair structures, as well as by X-ray analyses of the crystals. The IR spectra of the Cl(-) and Br(-) salts in CD2 Cl2 solution show strong red-shifts of the CH stretch bands. The CH stretch bands of the tetrafluoroborate salt PhCH2 PPh3 (+)  BF4 (-) in CD2 Cl2 , however, show a blue-shift compared to the corresponding BPh4 (-) salt., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A straightforward and efficient alumination of functionalized arenes by using the frustrated Lewis pair Et3 Al and TMPMgCl⋅LiCl (TMP=2,2,6,6-tetramethylpiperidyl) has been developed. In particular, halogenated electron-rich aromatics can be smoothly functionalized by using the frustrated Lewis pair Et3 Al and TMPMgCl⋅LiCl. Compared with previously described alumination methods, this procedure avoids extensive cooling and the need for an excess of base. This in situ procedure has proven to be most practical and allows for regio- and chemoselective metalation of a wide range of aromatics with sensitive functional groups (CONEt2 , CO2 Me, CN, OCONMe2 ) or halogens (F, Cl, Br, I). The resulting aromatic aluminates, which were characterized by using NMR spectroscopy, were subjected to allylations, acylations, and palladium-catalyzed cross-coupling reactions after transmetalation to zinc. It was shown that the nature of the Zn salt used for transmetalation is crucial. Thus, compared with ZnCl2 (2 equiv), the use of Zn(OPiv)2 (2 equiv; OPiv=pivalate) allows the subsequent quenching reactions to be performed with only a slight excess of electrophile (1.2 equiv) and provides interesting functionalized aromatics in good yields., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Filling positions: 7-Azaindoles are important targets in the pharmaceutical industry. All five carbon positions of the azaindole ring system can be functionalized in a predictable manner starting from the appropriately substituted azaindole 1 by directed metalation and halogen/magnesium and sulfoxide/magnesium exchange. The products are fully substituted azaindoles of type 2., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The aza-Morita-Baylis-Hillman (aza-MBH) reaction has been studied in a variety of solvents, a selection of imine substrates and with various combinations of PPh3 and para-nitrophenol as the catalyst system. The measured kinetic data indicates that the effects of solvent and protic co-catalyst are strongly interdependent. These results are most easily reconciled with a mechanistic model involving the reversible protonation of zwitterionic intermediates in the catalytic cycle, which is also supported by (31)P NMR spectroscopy and quantum chemical studies., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We have developed a practical stereoretentive iodine/lithium-exchange process that allows the stereodefined preparation of cis- and trans-cycloalkyllithium compounds from their corresponding stereodefined iodides. Quenching with electrophiles offers stereospecific access to both cis- (up to 96% cis) and trans-cycloalkyl derivatives (up to 99% trans). A detailed study of the thermodynamic stabilities, stereochemical behavior, and reactivities of axially and equatorially substituted cyclohexyllithium reagents is reported. Ab initio calculations demonstrate that the formation of oligomeric cyclohexyllithium structures is pivotal for explaining the observed stereochemical preference., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Treatment of pyridines, quinoline and methylthiopyrazine with the frustrated Lewis pair TMPMgCl·BF(3) (1) leads to organotrifluoro borates which react readily with a variety of aromatic aldehydes in the absence of a transition metal catalyst.

Frustrated Lewis pairs (FLPs), sterically encumbered Lewis acid and base combinations, gained importance due to their ability to activate molecular hydrogen. This property is used in organic synthesis to perform metal-free catalytic hydrogenation of imines, quinolines, or enamines. Moreover, it is possible to perform selective C-H activations using different sterically hindered Lewis acid/base pairs. Thus, the combination of organometallic reagents with different boranes can be used to functionalize selectively a variety of tertiary amines. By combination of sterically hindered metal amides of the type TMP-Met (TMP = 2,2,6,6-tetramethylpiperidyl, Met = Li, MgCl, ZnCl) with the Lewis-acid BF3·OEt2 it is possible to metalate selectively a large number of aromatic N-heterocycles, such as pyridines and quinolines.

The detection, differentiation and visualization of compounds such as gases, liquids or ions are key challenges for the design of selective optical chemosensors. Optical chemical sensors employ a transduction mechanism that converts a specific analyte recognition event into an optical signal. Here we report a novel concept for fluoride ion sensing where a porous crystalline framework serves as a host for a fluorescent reporter molecule. The detection is based on the decomposition of the host scaffold which induces the release of the fluorescent dye molecule. Specifically, the hybrid composite of the metal-organic framework NH2-MIL-101(Al) and fluorescein acting as reporter shows an exceptional turn-on fluorescence in aqueous fluoride-containing solutions. Using this novel strategy, the optical detection of fluoride is extremely sensitive and highly selective in the presence of many other anions.

A Lewis acid-triggered zincation allows the regioselective metalation of various chromones and quinolones. In the absence of MgCl(2), a C(3) zincation is observed, whereas in the presence of MgCl(2) or a related Lewis acid, C(2) zincation occurs. Applications to a natural flavone, isoflavone, and quinolone are shown.

The reaction of commercial Al-powder (3 equiv) and InCl(3) (1-5 mol %) with benzylic chlorides provides various functionalized benzylic aluminum sesquichlorides under mild conditions (THF, 20 °C, 3-24 h) without homocoupling (<5%). These new benzylic organometallics reacted smoothly with various electrophiles (Pd-catalyzed cross-couplings, or Cu-mediated acylations, allylations, or 1,4-addition reactions). Electron-poor benzylic chlorides or substrates prone to Wurtz coupling can be converted to benzylic zinc compounds by the reaction of Al-powder in the presence of ZnCl(2).

5-Formylcytosine (fC or (5-CHO)dC) and 5-carboxylcytosine (caC or (5-COOH)dC) have recently been identified as constituents of mammalian DNA. The nucleosides are formed from 5-methylcytosine (mC or (5-Me)dC) via 5-hydroxymethylcytosine (hmC or (5-HOMe)dC) and are possible intermediates of an active DNA demethylation process. Here we show efficient syntheses of phosphoramidites which enable the synthesis of DNA strands containing these cytosine modifications based on Pd(0)-catalyzed functionalization of 5-iododeoxycytidine. The first crystal structure of fC reveals the existence of an intramolecular H-bond between the exocyclic amine and the formyl group, which controls the conformation of the formyl substituent. Using a newly designed in vitro mutagenicity assay we show that fC and caC are only marginally mutagenic, which is a prerequisite for the bases to function as epigenetic control units., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Sulfoxide-alkene hybrids are introduced as a new class of chiral heterodentate ligands for the Hayashi-Miyaura reaction. The synthesis of these ligands was achieved without the use of protecting groups. A chiral resolution was performed via simple column-chromatographic separation of the diastereomeric ligands. Both diastereomers proved to be excellent ligands in Rh-catalyzed 1,4-addition reactions, furnishing chiral products with high enantioselectivities and, remarkably, opposite stereoconfigurations., (© 2011 American Chemical Society)

Gold(I) and silver(I) complexes of 1-methyl-5-thio-tetrazole (1) have been prepared and the coordination chemistry of this ligand toward metal-phosphine frameworks has been explored. As indicated by IR and Raman data, ligand 1 is deprotonated and the resulted anion acts as a bidentate (S,N)-tetrazole-5-thiolato unit in the new gold(I) complexes, [Au(SCN(4)Me)(PPh(3))] (2), [{Au(SCN(4)Me)}(2)(μ-dppm)] (3), and [{Au(SCN(4)Me)}(2)(μ-dppe)] (4), while it is coordinated only through the sulfur atom as its neutral tetrazole-5-thione form in the silver(I) derivative, [Ag(HSCN(4)Me)(PPh(3))](2)(OTf)(2) (5). Further characterization of the new compounds was performed using multinuclear ((1)H, (13)C, (31)P, (19)F) NMR spectroscopy, mass spectrometry, and DSC measurements. Single-crystal X-ray diffraction studies revealed basically linear P-M-S arrangements in complexes 3-5. The bidentate (S,N) coordination pattern results in a T-shaped (S,N)PAu core in 3 and 4, whereas, in 5, a similar coordination geometry is achieved in the dimer association based on S-bridging ligand 1. Herein, weak (C)H···Au and (C)H···Ag agostic interactions were observed. An intramolecular Au···Au contact occurs in 3, while in 4 intermolecular aurophilic bonds lead to formation of a chain polymer. An intermolecular Ag···Ag contact is also present in the dimer unit of 5. Low-temperature (31)P NMR data for 5 evidenced the presence of monomer and dimer units in solution. Theoretical calculations on model of the complexes 2 and 4 are consistent with the geometries found by X-ray diffraction studies.

Differently substituted hydrazinophosphanes of the type (Me(3)Si)(2)N-N(SiMe(3))-PR(1)R(2) (R(1) = Cl with R(2) = Me, C(6)F(5) and R(1) = Me, R(2) = C(6)H(5)) have been studied in the reaction with Lewis acids such as ECl(3) (E = Al, Ga). For (Me(3)Si)(2)N-N(SiMe(3))-P(Cl)(Me) and (Me(3)Si)(2)N-N(SiMe(3))-P(Me)(C(6)H(5)), only adduct formation was found while a chlorine/methyl exchange reaction was observed for (Me(3)Si)(2)N-N(SiMe(3))-P(Cl)R (R = C(6)H(5) and C(6)F(5)) leading to the formation of (Me(2)ClSi)(Me(3)Si)N-N(SiMe(3))-P(Me)R, which crystallize as ECl(3) adducts. The free hydrazinophosphanes can be obtained by removal of the Lewis acid with the help of a strong base such as 4-(dimethylamino)pyridine (DMAP).

The first anionic tetrazole-2N-oxide has been prepared by mild aqueous oxidation of easily prepared 5-nitrotetrazole with commercially available oxone in high yields. The result of protonating 5-nitrotetrazolate-2N-oxide has been identified as a hydroxytetrazole, and the nitrogen-rich salts including ammonium, hydroxylammonium, guanidinium, aminoguanidinum, diaminoguanidinium, and triaminoguanidinium have been prepared and characterized. When compared to the nitrogen-rich salts of nitrotetrazole, the nitrogen-rich salts of nitrotetrazole-2N-oxide show superior energetic performance as calculated by the EXPLO5 computer code, using heats of formation calculated using the CBS-4M level of quantum mechanical theory. The impact, friction, and electrical spark sensitivities of the nitrogen-rich nitrotetrazolate-2N-oxides were measured and cover the whole range from sensitive to insensitive energetic materials.

The new phosphorus sulfide P(2)S(7), stabilized as the bis(pyridinium) adduct, was obtained from the reaction of P(4)S(10) and sulfur in pyridine, and could be isolated in the form of colourless block-shaped crystals which were characterized using single crystal X-ray diffraction. Coordination of pyridine is weak (d(P-N) = 187 pm) which is supported also by quantum chemical calculations.

The structures of two new salts of the P(2)Se(6)(4-) anion, [(py(2)Li)](4)[P(2)Se(6)].2py and [pyH](4)[P(2)Se(6)].H(2)O, prepared using a new synthetic route in solution starting from easily available educts, are presented. The salts are characterized also in solution by means of multinuclear ((31)P, (77)Se, (7)Li) NMR spectroscopy. The (31)P and (77)Se NMR spectrum of the waterstable P(2)Se(6)(4-) anion are discussed in detail for the first time. The chemical shift of the P(2)Se(6)(4-) anion in the Li(+) salts depends strongly on the solvent used. Remarkably, the newly synthesized salts are stable in water.

The syntheses and characterization of uranyl complexes of nitrogen-containing ligands are reported. For the first time, an actinide complex containing dinitramide ligands coordinated to the actinide center in UO(2)(N(NO(2))(2))(2)(OP(NMe(2))(3))(2) (1) has been isolated and structurally characterized. Using an excess of OP(NMe(2))(3), the dinitramide ligands were replaced by OP(NMe(2))(3) ligands resulting in the formation of the salt [UO(2)(OP(NMe(2))(3))(4)][N(NO(2))(2)](2) (2). Both complexes 1 and 2 were characterized using IR, Raman, as well as (1)H, (13)C, (14)N and (31)P{(1)H} NMR spectroscopy, in addition to C/H/N analysis. The structures of 1 and 2 were determined by single crystal X-ray diffraction. 1: monoclinic, P2(1)/n, a = 12.5389(3), b = 7.9496(2), c = 15.8172(4) A, beta = 110.842(3) degrees , V = 1473.48(6) A(3), Z = 2. 2: orthorhombic, Pbca, a = 14.5640(6), b = 15.3697(6), c = 45.7789(18) A, V = 10247.3(7) A(3), Z = 8. The related complex [UO(2)(N(CN)(2))(2)(OP(NMe(2))(3))(2)] (3) containing the dicyanamide ligand (N(CN)(2)(-)) coordinated to the U(VI) center was synthesized and characterized using IR, Raman, (1)H, (13)C and (31)P{(1)H} NMR spectroscopy. The structure of 3 was determined using single crystal X-ray diffraction and revealed a dinuclear complex containing both terminal and bridging N(CN)(2)(-) ligands. 3: monoclinic, P2(1)/c, a = 15.5873(9), b = 14.2132(6), c = 13.2006(5) A, beta = 100.029(3) degrees, V = 2879.8(2) A(3), Z = 2. Finally, in this investigation of the coordination of relatively nitrogen-rich ligands to uranium centers, the synthesis, characterization, and isolation of the first U(VI) complex showing coordination of the triazolate ligand via a ring nitrogen atom is reported in UO(2)((NC)(2)C(2)N(3))(2)(OPPh(3))(3) (4). Complex 4 was characterized using IR, Raman, (1)H, (13)C and (31)P{(1)H} NMR spectroscopy. The solid state structure of 4 was determined using single crystal X-ray diffraction. 4: monoclinic, P2(1)/n, a = 18.9970(2), b = 31.9500(3), c = 20.1133(2) A, beta = 111.4449(4) degrees, V = 11362.69(19) A(3), Z = 8. To the best of our knowledge, compounds 1 and 2 are the first structurally characterized complexes where a dinitramide ligand is coordinated to an f-block center. Complex 3 is the first structurally characterized actinide dicyanamide complex and a rare example of a dinuclear uranyl complex showing a 12 membered U-N-C ring formed by bridging dicyanamide ligands between two uranyl centers. Finally, complex 4 is the first isolated and structurally characterized uranium complex containing a triazolate ligand coordinated to the U(VI) center. Complexes 3 and 4 are examples of uranyl complexes containing ligands coordinated via nitrogen atoms to the U(VI) center. Whereas the dinitramide ligand can coordinate via N or O atoms, in complex 1, the [N(NO(2))(2)](-) ligand acts as a bidentate chelate ligand, and only coordination via the oxygen atoms to the U(VI) center was observed in the crystalline state.

The solid-state structures of the [U(IV)(NO(3))(6)](2-) anions in the [n-Pr(4)N](2)[U(NO(3))(6)] (1), [n-Bu(4)N](2)[U(NO(3))(6)] (2), and [Ph(4)P](2)[U(NO(3))(6)] x 4 NCCH(3) (3) salts were determined using single-crystal X-ray diffraction. For the first time, a nondisordered structure of the hexanitratouranate(IV) dianion with a coordination number of 12 for the central U(IV) atom was determined. Salts 1-3 were prepared in simple metathesis reactions and characterized using IR spectroscopy, C/H/N analysis, and single-crystal X-ray diffraction. Attempts to prepare a salt containing the [U(IV)(ClO(4))(6)](2-) anion using the analogous route resulted in the isolation of U(ClO(4))(4)(NCCH(3))(5) (4), which was characterized using single-crystal X-ray diffraction. Compound 4 is the first structurally characterized uranium(IV) perchlorate to be reported in the literature.

The solid state structure of the [(CH(3)CN)(2)I](+) cation in [(CH(3)CN)(2)I][AsF(6)] was determined using single crystal X-ray diffraction. The highly reactive cation was prepared by reaction of [I(3)][AsF(6)] with CH(3)CN in liquid SO(2). In the solid state, the CNI backbone consisting of seven atoms is linear and shows a dicoordinate iodine center. The ability of [I(3)][AsF(6)] to act as a source of "[I](+)" to CH(3)CN and N(2)O is compared, and the computed structures of the [CH(3)CNI](+), [(CH(3)CN)(2)I](+), [IN(2)O](+) and [ION(2)](+) cations are discussed.

We present an unusual discrete P-Te anion, P(4)Te(2)(2-), which is readily obtained by the oxidation of white phosphorus with Te(2)(2-) in N-methyl imidazole at ambient temperature. According to the (31)P and (125)Te NMR spectra, the anion P(4)Te(2)(2-) had a bicyclo[1.1.0]tetraphosphane ("butterfly") structure with the tellurium atoms in the exo positions. The anion was remarkably stable at ambient temperature and disproportionated only slowly with the formation of elemental tellurium. P(4)Te(2)(2-) is the first P-Te anion with a bicyclo[1.1.0]tetraphosphane structure. When Se(2)(2-) or S(2)(2-) was reacted with white phosphorus, the analogous seleno- and thiophosphate anions P(4)Se(2)(2-) and P(4)S(2)(2-) were formed, thus completing the series of phosphorus-chalcogen anions P(4)Ch(2)(2-) (Ch = S, Se, Te). The synthesis of P(4)Te(2)(2-) demonstrated that binary P-Te anions do exist as stable species in solution.

In this contribution, the synthesis and structural characterization of the 4,5-dicyano-1,2,3-triazolate anion in its sodium, ammonium, guanidinium, aminoguanidinium, diaminoguanidinium, and triaminoguanidinium salts is reported. The synthesis of 4,5-dicyano-2H-triazole (1) was repeated as described in the literature (Johansson, P. et al. Solid State Ionics 2003, 156, 129) and spectroscopically characterized using (1)H, (13)C, and (15)N NMR, IR, and Raman spectroscopy, as well as differential scanning calorimetry (DSC) and mass spectrometry (DEI+). The molecular structure was determined for the first time using X-ray diffraction (1: monoclinic, P2(1)/c, a = 6.0162(6) A, b = 11.2171(10) A, c = 7.5625(7) A, beta = 94.214(8) degrees, V = 508.97(8) A(3), Z = 4). Compound 1 was deprotonated using Na(2)CO(3) to form the corresponding sodium salt of the 4,5-dicyano-1,2,3-triazolate anion (2) as a monohydrate. This compound was also characterized using (13)C, (14)N, (15)N NMR, IR, and Raman spectroscopy, as well as single crystal X-ray diffraction (2: monoclinic, P2(1)/c, a = 3.6767(6) A, b = 20.469(4) A, c = 9.6223(13) A, beta = 97.355(13) degrees, V = 718.2(2) A(3), Z = 4). Reaction of 2 with AgNO(3) yielded silver 4,5-dicyano-1,2,3-triazolate (3) which was characterized using IR and Raman spectroscopy, as well as DSC, and was used to prepare the ammonium (4), guanidinium (5), aminoguanidinium (6), diaminoguanidinium (7), and triaminoguanidinium (8) salts of the 4,5-dicyano-1,2,3-triazolate anion in a metathetical reaction from the corresponding ammonium and guanidinium halides. All new compounds (4-8) were spectroscopically characterized ((1)H and (13)C NMR, IR, Raman), the stabilities investigated using DSC, the mass spectra obtained using the FAB+ and FAB- methods and the solid state structures determined using single crystal X-ray diffraction: (4): orthorhombic, Pnma, a = 6.5646(13) A, b = 7.5707(16) A, c = 13.303(3) A, V = 661.1(2) A(3), Z = 4; (5): monoclinic, Cc, a = 12.6000(11) A, b = 17.1138(15) A, c = 12.0952(9) A, beta = 106.098(7) degrees, V = 2505.9(4) A(3), Z = 12; (6): monoclinic, Pa, a = 7.0921(9) A, b = 7.2893(9) A, c = 8.8671(11) A, beta = 105.141(11) degrees, V = 442.48(10) A(3), Z = 2; (7): monoclinic, P2(1), a = 3.7727(4) A, b = 15.6832(17) A, c = 8.3416(10) A, beta = 101.797(10) degrees, V = 483.13(9) A(3), Z = 2; (8): monoclinic, C2/c, a = 14.0789(14) A, b = 11.5790(11) A, c = 13.5840(14) A, beta = 115.239(10) degrees, V = 2003.1(3) A(3), Z = 8. The impact and friction sensitivities of compounds 4-8 were investigated using drop hammer and friction apparatus methods, and all compounds were found to be neither impact (> 30 J) nor friction sensitive (> 360 N). The detonation parameters of compounds 5- 8 were computed using the EXPLO5 code.

Methylation of 5-amino-1H-tetrazole (1) gives 1-methyl-5-amino-1H-tetrazole (2) and 2-methyl-5-amino-1H-tetrazole (3). A new family of energetic silver complexes based on ligands 1, 2 and 3 with perchlorate and nitrate anions (10-15) were synthesized and characterized by using IR, Raman, and NMR ((1)H, (13)C, (14)N, and (35)Cl NMR) spectroscopy, elemental analysis, and mass spectrometry. The crystal structures of the compounds were determined where possible and reveal interesting structural details that are discussed herein. Additionally, differential scanning calorimetry was used to assess the thermal stability of the new salts, which showed excellent thermal stabilities at temperatures up to and above 225 degrees C. Standard tests were also used to assess the sensitivity of the materials towards impact and friction. All the silver complexes showed increased sensitivity values in comparison with analogous protonated 5-amino-1H-tetrazolium perchlorate and nitrate salts. Some of these materials have sensitivity values that are comparable to commonly used primary explosives and all of them either deflagrate (12-14) or detonate loudly (10 and 11) on contact with an open flame. Lastly, nitrate salt 11 is easily initiated by thermal shock. It shows reasonably low sensitivity in comparison with other silver salts (e.g., silver azide or silver fulminate), which makes handling it much less hazardous. Compound 11 also has good thermal stability, decomposing at approximately 300 degrees C, and shows interesting properties as a more environmentally benign alternative to lead(II) diazide in initiation devices for civil and military applications.

Four new salts of the P2Se8(2-) anion have been prepared, starting from easily available reagents using different reaction strategies including reaction of the elements, oxidation of P4Se3 with alkalimetal diselenides and elemental selenium, and the use of an ionic liquid as a reaction medium. Multinuclear NMR investigations show the presence of both chair-P2Se8(2-) and twist-P2Se8(2-) in solution, with twist-P2Se8(2-) being the predominant conformer. The interconversion between the two conformers is slow on the NMR time scale. Structural investigations of the new salts by single-crystal X-ray diffraction show that chair-P2Se8(2-) is the conformer mostly found in the solid state. A first structural characterization of twist-P2Se8(2-) is reported. The bonding situation in the P2Se8(2-) anion as well as the relative stability of the chair, twist, and boat conformers was elucidated by quantum chemical calculations.

1-methyl-5-aminotetrazole (4, MAT) can easily be protonated by strong acids, yielding known but largely uninvestigated 1-methyl-5-aminotetrazolium nitrate (4a) and perchlorate (4b). Methylation, rather than protonation, of 4 with iodomethane followed by the exchange of the iodide (5a) for nitrate (5b), perchlorate (5c), azide (5d), and dinitramide (5e) yields a new family of energetic methylated aminotetrazole salts. In all cases, stable salts were obtained and fully characterized by vibrational (IR, Raman) spectroscopy, multinuclear NMR spectroscopy, mass spectrometry, elemental analysis, and X-ray structure determination. Compounds 4a, 4b, and 5c crystallize in the monoclinic space group P2(1)/n, whereas compounds 5b and 5e crystallize in the orthorhombic space group P2(1)2(1)2(1) and 5d in the orthorhombic Fddd. Initial safety testing (impact, friction, and electrostatic sensitivity) and thermal stability measurements (DSC) were also carried out. The MAT salts all exhibit good thermal stabilities (decomposition above 150 degrees C). The constant volume energies of combustion (DeltacU) of 4a, 5b, 5d, and 5e were determined to be -2510(10) cal/g, -3190(30) cal/g, -4500(100) cal/g, and -2570(70) cal/g, respectively, experimentally using oxygen bomb calorimetry. From the experimentally determined density, chemical composition and energies of formation (back calculated from the heats of combustion), the detonation pressures and velocities of 4a (8100 m/s, 25.6 GPa), 5b (7500 m/s, 20.2 GPa), 5d (8200 m/s, 21.7 GPa), and 5e (7500 m/s, 21.2 GPa) were predicted using the EXPLO5 code.

N-Nitroso- (5a,c) and N-nitraminotetrazoles (6a-c) were synthesized from the corresponding aminotetrazoles (3a-c) either by the direct nitration with acetic anhydride/HNO3 or by dehydration of the corresponding nitrates (4a-c) with concentrated sulfuric acid. The conversion of the N-nitrosoaminotetrazoles (5a,c) with peroxytrifluoroacetic acid (CF3CO3H) yielded the corresponding nitramines in high yield (6a (82%), 6c (80%)). The N-nitroso- (5a,c) and N-nitraminotetrazoles (6a-c) have been fully characterized by vibrational (IR, Raman) and multinuclear NMR spectroscopy (14N/15N, 1H, 13C), mass spectrometry, and elemental analysis. A detailed discussion of the 15N chemical shifts and 1H-15N coupling constants is given. The molecular structures in the solid state were determined by single-crystal X-ray diffraction (3a,c; 5a,c; 6a-c) and a detailed discussion of the molecular structures will be presented. Furthermore, the structure and bonding as well as N,N rotational barriers are discussed on the basis of theoretically obtained data (B3LYP/6-31G(d,p), NBO analysis). In the case of two N-nitraminotetrazoles (6a,c) the physicochemical properties (e.g., D, P, delta(f)H degrees) were evaluated. The heat of formation was calculated to be positive for 6a and 6c (+2.8 and +85.2 kcal mol(-1), respectively) and the calculated detonation velocity with 5988 (6a) and 7181 (6c) m s(-1) reaches values of TNT and nitroglycerin.

1,5-Diamino-1H-tetrazole (2, DAT) can easily be protonated by reaction with strong mineral acids, yielding the poorly investigated 1,5-diaminotetrazolium nitrate (2a) and perchlorate (2b). A new synthesis for 2 is introduced that avoids lead azide as a hazardous byproduct. The reaction of 1,5-diamino-1H-tetrazole with iodomethane (7a) followed by the metathesis of the iodide (7a) with silver nitrate (7b), silver dinitramide (7c), or silver azide (7d) leads to a new family of heterocyclic-based salts. In all cases, stable salts were obtained and fully characterized by vibrational (IR, Raman) spectroscopy, multinuclear NMR spectroscopy, mass spectrometry, elemental analysis, X-ray structure determination, and initial safety testing (impact and friction sensitivity). Most of the salts exhibit good thermal stabilities, and both the perchlorate (2b) and the dinitramide (7c) have melting points well below 100 degrees C, yet high decomposition onsets, defining them as new (7c), highly energetic ionic liquids. Preliminary sensitivity testing of the crystalline compounds indicates rather low impact sensitivities for all compounds, the highest being that of the perchlorate (2b) and the dinitramide (7c) with a value of 7 J. In contrast, the friction sensitivities of the perchlorate (2b, 60 N) and the dinitramide (7c, 24 N) are relatively high. The enthalpies of combustion (Delta(c)H degrees ) of 7b-d were determined experimentally using oxygen bomb calorimetry: Delta(c)H degrees (7b) = -2456 cal g(-)(1), Delta(c)H degrees (7c) = -2135 cal g(-)(1), and Delta(c)H degrees (7d) = -3594 cal g(-)(1). The standard enthalpies of formation (Delta(f)H degrees ) of 7b-d were obtained on the basis of quantum chemical computations using the G2 (G3) method: Delta(f)H degrees (7b) = 41.7 (41.2) kcal mol(-)(1), Delta(f)H degrees (7c) = 92.1 (91.1) kcal mol(-)(1), and Delta(f)H degrees (7d) = 161.6 (161.5) kcal mol(-)(1). The detonation velocities (D) and detonation pressures (P) of 2b and 7b-d were calculated using the empirical equations of Kamlet and Jacobs: D(2b) = 8383 m s(-)(1), P(2b) = 32.2 GPa; D(7b) = 7682 m s(-)(1), P(7b) = 23.4 GPa; D(7c) = 8827 m s(-)(1), P(7c) = 33.6 GPa; and D(7d) = 7405 m s(-)(1), P(7d) = 20.8 GPa. For all compounds, a structure determination by single-crystal X-ray diffraction was performed. 2a and 2b crystallize in the monoclinic space groups C2/c and P2(1)/n, respectively. The salts of 7 crystallize in the orthorhombic space groups Pna2(1) (7a, 7d) and Fdd2 (7b). The hydrogen-bonded ring motifs are discussed in the formalism of graph-set analysis of hydrogen-bond patterns and compared in the case of 2a, 2b, and 7b.

A novel linear trinuclear mu-O-bridging 2-phosphinophenolate nickel(II) complex with fac-tris(P(intersection)O- chelates) in the terminal positions and the three oxygen atoms each facing the central nickel(II) cation was synthesized and structurally characterized by X-ray crystallography. To the best of our knowledge, this is the first example of an octahedral Ni(II) tris(P(intersection)O- chelate).

While there is extensive information on 1,8-di(amino)naphthalene (i.e., the parent compound of the "proton sponge" series), the corresponding phosphorus compound has not been described. A high-yield synthesis of 1,8-di(phosphinyl)naphthalene (9) and the 1-naphthylphosphine reference compound (4) is now reported. Thermal decomposition of 9 leads to intramolecular dehydrogenative P-P coupling to afford 1,2-dihydro-1,2-diphosphaacenaphthene (10). Protonation of 9 and 4 with CF(3)SO(3)H gives quantitative yields of the monophosphonium salts 11 and 5, respectively. With excess acid and traces of moisture, the hydronium salt [C(10)H(6)(PH(2))(PH(3))](+)[H(3)O](+)2[CF(3)SO(3)](-) (13) is obtained. The structures of 9, 11, and 13 have been determined. Molecules of 9 have a planar naphthalene skeleton, C(10)H(6)P(2), with the two -PH(2) groups in a transoid conformation. The molecules form loose dimers in the crystal, the individual chiral enantiomers of which are related by a center of inversion. In contrast to the situation for the amino analogue, and despite the proximity of the two -PH(2) functions, there is no intra- or intermolecular hydrogen bonding. Solutions of 9 (in CD(2)Cl(2)) show equivalent P-bound hydrogen atoms due to conformational fluctionality. By analysis of the ABCD(2)XX'D'(2)C'B'A' spin system, it was shown that, in 9, there are strong through-space pericouplings [(n)J(P(X)P(X)(')) = 221.6 Hz, (n)J(P(X)H(D)(')) = 31.7 Hz, (n)J(H(D)H(D)(')) = 3.9 Hz]. In the cations of 11, the C(10)H(6)P(2) skeleton is also planar (by C(s) symmetry), with the -PH(2) and -PH(3)(+) groups in a conformation which rules out any P-H...P hydrogen bonding. The hydronium cation and the two triflate anions in 13 are associated into an anionic network through extensive hydrogen bonding surrounding stacks of the phosphonium cations. In solution, the cations of 11 and 13 show separate (31)P resonances for the two phosphorus atoms with fully resolved (1)J(PH) couplings, which indicate that there is no intra- or intercationic proton exchange. By contrast, the NMR spectra of solutions of [C(10)H(6)(NH(2))(NH(3))](+)X(-) salts show proton scrambling equilibrating all five N-bound hydrogen atoms, and in the crystal, the conformations of the cations feature intramolecular N-H...N hydrogen bonding.

The synthesis and characterization of the dioxouranium(VI) dibromide and iodide hydrates, UO(2)Br(2)x3H(2)O (1), [UO(2)Br(2)(OH(2))(2)](2) (2), and UO(2)I(2)x2H(2)Ox4Et(2)O (3), are reported. Moreover, adducts of UO(2)I(2) and UO(2)Br(2) with large, bulky OP(NMe(2))(3) and OPPh(3) ligands such as UO(2)I(2)(OP(NMe(2))(3))(2) (4), UO(2)Br(2)(OP(NMe(2))(3))(2) (5), and UO(2)I(2)(OPPh(3))(2)(6) are discussed. The structures of the following compounds were determined using single-crystal X-ray diffraction techniques: (1) monoclinic, P2(1)/c, a = 9.7376(8) A, b = 6.5471(5) A, c = 12.817(1) A, beta = 94.104(1) degrees , V = 815.0(1) A(3), Z = 4; (2) monoclinic, P2(1)/c, a = 6.0568(7) A, b = 10.5117(9) A, c = 10.362(1) A, beta = 99.62(1) degrees , V = 650.5(1) A(3), Z = 2; (4) tetragonal, P4(1)2(1)2, a = 10.6519(3) A, b = 10.6519(3) A, c = 24.0758(6) A, V = 2731.7(1) A(3), Z = 4; (5) tetragonal, P4(1)2(1)2, a = 10.4645(1) A, b = 10.4645(1) A, c = 23.7805(3) A, V = 2604.10(5) A(3), Z = 4, and (6) monoclinic, P2(1)/c, a = 9.6543(1) A, b = 18.8968(3) A, c = 10.9042(2) A, beta =115.2134(5) degrees , V = 1783.01(5) A(3), Z = 2. Whereas 1 and 2 are the first UO(2)Br(2) hydrates and the last missing members of the UO(2)X(2) hydrate (X = Cl --> I) series to be structurally characterized, 4 and 6 contain room-temperature stable U(VI)-I bonds with 4 being the first structurally characterized room temperature stable U(VI)-I compound which can be conveniently prepared on a gram scale in quantitative yield. The synthesis and characterization of 5 using an analogous halogen exchange reaction to that used for the preparation of 4 is also reported.

The trichloro-bridged dinuclear Ru(II) complex tri-micro-chloro-bis[[1,1,1-tris(diphenylphosphinomethyl)ethane-kappa(3)P,P',P"]ruthenium(II)] hexafluorophosphate ethanol solvate, [Ru(2)Cl(3)(tripod)(2)]PF(6).C(2)H(6)O, containing the tripod [1,1,1-tris(diphenylphosphinomethyl)ethane, C(41)H(39)P(3)] ligand, was unexpectedly obtained from the reaction of [Ru(III)Cl(3)(tripod)] with 1,4-bis(diphenylphosphino)butane (dppb), followed by precipitation with NH(4)PF(6). The magnetic moment of the compound at room temperature indicates that the dinuclear [Ru(2)(micro-Cl)(3)(tripod)(2)](+) cation is diamagnetic. A single-crystal X-ray structure determination revealed that the two Ru atoms are bridged by the three Cl atoms. The coordination sphere of each Ru atom is completed by the three P atoms of a tripod ligand. The two P(3)Ru units are exactly eclipsed, while the bridging Cl atoms are staggered with respect to the six P atoms. The Ru...Ru distance is 3.3997 (7) A and the mean Cl-Ru-Cl bond angle is 77.7 degrees.

The title compound (systematic name: 4,10-dinitro-2,6,8,12-tetraoxa-4,10-diazatetracyclo[5.5.0.0(3,11).0(5,9)]dodecane), C(6)H(6)N(4)O(8), exhibits the highest density among known N-nitramines, due to its close-packed crystal structure. It may be regarded as consisting of a distorted hexagonal close-packed lattice formed by the isowurtzitane cages, with the nitro groups occupying the free space between the cages.

Cationic, neutral, and anionic arsenic and antimony halides formed binary arsenic and antimony azide species M(N(3))(4)(+), M(N(3))(4)(-), and M(N(3))(6)(-) (M = As, Sb) upon reaction with trimethylsilyl azide or sodium azide. The compounds were obtained as pure substances or salts, and their identity was established by vibrational spectroscopy and multinuclear NMR spectroscopy and partially by elemental analysis. Attempts to synthesize pentaazides, M(N(3))(5) (M = As, Sb), failed due to spontaneous decomposition of the compounds. Density functional theory (B3LYP) was applied to calculate structural and vibrational data. Vibrational assignments of the normal modes for the isolated azide compounds were made on the basis of their vibrational spectra in comparison with computational results. The molecular structures and vibrational spectra of the arsenic and antimony pentaazides have been investigated theoretically. These calculations (B3LYP) show minima structures (NIMAG = 0) for all reported compounds. It is shown that the M(N(3))(4)(+) (M = As, Sb) cations exhibit ideal S(4) symmetry and the M(N(3))(6)(-) anions (M = As, Sb) ideal S(6) symmetry. The structure of the hexaazidoarsenate(V) has been determined by X-ray diffraction as its pyridinium salt. [py-H][As(N(3))(6)] crystallizes in the triclinic space group P with a = 6.8484(7), b = 7.3957(8), and c = 8.0903(8) A, alpha = 91.017(2), beta = 113.235(2), and gamma = 91.732(2) degrees, V = 376.29(7) A(3), and Z = 1. The structure of the As(N(3))(6)(-) anion exhibits only S(2) symmetry but shows approximately S(6) symmetry. The calculated and experimentally observed structure as well as the calculated and observed IR and Raman frequencies for all azide species (except M(N(3))(5)) are in reasonable agreement.