Dense Iodine‐Rich Compounds with Low Detonation Pressures as Biocidal Agents

Fifteen iodo compounds and six iodyl compounds with an iodine content between 45.3 and 89.0 % were prepared. The mono, di, and triiodyl compounds were obtained from the corresponding iodo compound by employing Oxone. All the compounds were characterized by IR, ¹H and ¹³C NMR, elemental analysis, and differential scanning calorimetry (DSC). The impact sensitivity was measured by using BAM (Bundesamt für Materialforschung) methodology. Based on the calculated heats of formation and experimental densities, the detonation properties and detonation products were predicted by employing Cheetah 6.0. A total percentage of iodine‐containing species in wt % (I₂, HI, and I in gas phase) ranged from 46.7 ( 21 ) to 88.94 % ( 11 ) was found in the detonation products. The high concentration and easy accessibility of iodine and/or iodine‐containing species is very important in developing materials suitable as Agent Defeat Weapons (ADWs).     

Cubic Mesophase in an Unsymmetrical Alkyl Ammonium Salt. Synthesis and Structural Model

N,N,N‐butylethylpentylpropylammonium iodide 4 and related molecules have been selectively synthesised from commercially available aldehydes, amines and alkyl iodides using a reductive alkylation procedure. The crystalline texture of 4 obtained on cooling is optically isotropic between crossed polarisers, indicating a cubic structure. Differential scanning calorimetry (DSC, +10 K min^?1) reveals a glass phase transition at ?59 °C and a melting point at 192 °C. The melting entropy (23.9 J mol^?1 K^?1) indicates a first‐order transition between a highly disordered mesophase and the isotropic liquid. Powder X‐ray diffraction patterns were indexed in the cubic system (a=14.08Å; Pm n space group). In this cell, the molecular packing with Z=6 corresponds to a rather low compactness of 65 %. Iodine and tetraalkylammonium ions occupy positions with a m2 site symmetry. These highly symmetrical states may be generated by stepwise rotation of the ammonium cation. The same structural model for orientationally disordered crystal (ODIC) phases can be applied to a series of tetraalkylammonium bromides and iodides.     

Experimental Charge Density Evidence for Pnicogen Bonding in a Crystal of Ammonium Chloride

Chemical binding in crystalline ammonium chloride, a simple inorganic salt with an unexpectedly complex bonding pattern, was studied by using a topological analysis of electron density function derived from high‐resolution X‐ray diffraction. Supported by periodic quantum chemical calculations, it provided experimental evidence for weak σ‐hole bonds (1.5 kcal mol^?1) that involve ammonium cations in a crystal. Our results show this type of supramolecular interaction to be more numerous than has been found to date by using gas‐phase calculations or statistical analysis of CSD.     

Piezochromism in Nickel Salicylaldoximato Complexes: Tuning Crystal‐Field Splitting with High Pressure

The crystal structures of bis(3‐fluoro‐salicylaldoximato)nickel(II) and bis(3‐methoxy‐salicylaldoximato)nickel(II) have been determined at room temperature between ambient pressure and approximately 6 GPa. The principal effect of pressure is to reduce intermolecular contact distances. In the fluoro system molecules are stacked, and the Ni???Ni distance decreases from 3.19 Å at ambient pressure to 2.82 Å at 5.4 GPa. These data are similar to those observed in bis(dimethylglyoximato)nickel(II) over a similar pressure range, though contrary to that system, and in spite of their structural similarity, the salicyloximato does not become conducting at high pressure. Ni–ligand distances also shorten, on average by 0.017 and 0.011 Å for the fluoro and methoxy complexes, respectively. Bond compression is small if the bond in question is directed towards an interstitial void. A band at 620 nm, which occurs in the visible spectrum of each derivative, can be assigned to a transition to an antibonding molecular orbital based on the metal 3d(x²?y²) orbital. Time‐dependent density functional theory calculations show that the energy of this orbital is sensitive to pressure, increasing in energy as the Ni–ligand distances are compressed, and consequently increasing the energy of the transition. The resulting blueshift of the UV‐visible band leads to piezochromism, and crystals of both complexes, which are green at ambient pressure, become red at 5 GPa.     

High Pressure Behavior of Mercury Cyanamide HgCN2

Using the diamond anvil cell technique, angle‐dispersive X‐ray diffraction and Raman spectroscopy were employed to study the high pressure behavior of mercury cyanamide. Its decomposition under pressure starts at 1.9 GPa and is not completed even up to 10 GPa. The decomposition product α‐Hg transforms to β‐Hg during 7–10 GPa, while the C/N residual is not detectable by X‐ray diffraction. The zero pressure bulk modulus of mercury cyanamide is estimated as 38.5 GPa.     

Creating Reactivity with Unstable Endmembers using Pressure and Temperature: Synthesis of Bulk Cubic Mg0.4Fe0.6N

Alloy and nitride solid solutions are prominent for structural, energy and information processing applications. There are frequently however barriers to making them. We remove barriers to reactivity here using pressure with a new synthetic approach. We target pressures where the reasons for cubic endmember nitride instability can become the driving force for cubic nitride solid solution stability. Using this approach we form a novel rocksalt Mg_0.4Fe_0.6N solid solution at between 15 and 23 GPa and up to 2500 K. This is a system where, neither an alloy nor a nitride solid solution form at ambient conditions and bulk MgN and FeN endmembers do not form, either at ambient or at high pressure. The new nitride is formed, by removing endmember lattice mismatch with pressure, allowing a stabilizing redistribution of valence electrons upon heating. This approach can be employed for a range of normally unreactive systems. Mg, Fe and enhanced nitrogen presence, may also indicate a richer reaction chemistry in our planets interior.     

Li4Ca3Si2N6 and Li4Sr3Si2N6 – Quaternary Lithium Nitridosilicates with Isolated [Si2N6]10– Ions

The isotypic nitridosilicates Li₄Ca₃Si₂N₆ and Li₄Sr₃Si₂N₆ were synthesized by reaction of strontium or calcium with Si(NH)₂ and additional excess of Li₃N in weld shut tantalum ampoules. The crystal structure, which has been solved by single‐crystal X‐ray diffraction (Li₄Sr₃Si₂N₆: C2/m, Z = 2, a = 6.1268(12), b = 9.6866(19), c = 6.2200(12) Å, β = 90.24(3)°, wR₂ = 0.0903) is made up from isolated [Si₂N₆]^10– ions and is isotypic to Li₄Sr₃Ge₂N₆. The bonding angels and distances within the edge‐sharing [Si₂N₆]^10– double‐tetrahedra are strongly dependent on the lewis acidity of the counterions. This finding is discussed in relation to the compounds Ca₅Si₂N₆ and Ba₅Si₂N₆, which also exhibit isolated [Si₂N₆]^10– ions.     

Facile Access to Transition‐Metal–Carbonyl Complexes with an Amidinate‐Stabilized Chlorosilylene Ligand

Three transition‐metal–carbonyl complexes [V( L )(CO)₃(Cp)] ( 1 ), [Co( L )(CO)(Cp)] ( 2 ), and [Co( L₂ )(CO)₃]⁺[CoCO)₄]^? ( 3 ), each containing stable N‐heterocyclic‐chlorosilylene ligands ( L ; L =PhC(NtBu)₂SiCl) were synthesized from [V(CO)₄(Cp)], [Co(CO)₂(Cp)], and Co₂(CO)₈, respectively. Complexes 1 , 2 , 3 were characterized by NMR and IR spectroscopy, EI‐MS spectrometry, and elemental analysis. The molecular structures of compounds 1 , 2 , 3 were determined by single‐crystal X‐ray diffraction.     

Synthesis and Structure of a Macrocyclic Dinickel Complex Incorporating a Hypercoordinated Sulfenium(II) Cation

The synthesis and structure of a macrocyclic dinickel complex incorporating a hypercoordinated sulfenium(II) cation are reported. The novel complex [Ni₂L³(Cl)]²⁺ was obtained from a reaction of the per‐hydroxyethylated N₆S₂ macrocycle H₂L² with NiCl₂(H₂O)₆ in the presence of air, and isolated as its ClO₄ or BPh₄ salt. The structure reveals a three‐coordinate sulfenium cation that is stabilized by two intramolecularly coordinating amino groups. The N–S bonds are 2.087(7) Å and 2.105(6) Å and the N–S–N bond angle is 168.2(2)°. The bonding is best described by a N,N‐chelated sulfur(II) atom (3c–4e bond) bearing two lone pairs and a formal charge of +1.     

Al3Li4(BH4)13: A Complex Double‐Cation Borohydride with a New Structure

The new double‐cation Al–Li–borohydride is an attractive candidate material for hydrogen storage due to a very low hydrogen desorption temperature (～70 °C) combined with a high hydrogen density (17.2 wt %). It was synthesised by high‐energy ball milling of AlCl₃ and LiBH₄. The structure of the compound was determined from image‐plate synchrotron powder diffraction supported by DFT calculations. The material shows a unique 3D framework structure within the borohydrides (space group=P‐43n, a=11.3640(3) Å). The unexpected composition Al₃Li₄(BH₄)₁₃ can be rationalized on the basis of a complex cation [(BH₄)Li₄]³⁺ and a complex anion [Al(BH₄)₄]^?. The refinements from synchrotron powder diffraction of different samples revealed the presence of limited amounts of chloride ions replacing the borohydride on one site. In situ Raman spectroscopy, differential scanning calorimetry (DSC), thermogravimetry (TG) and thermal desorption measurements were used to study the decomposition pathway of the compound. Al–Li–borohydride decomposes at ～70 °C, forming LiBH₄. The high mass loss of about 20 % during the decomposition indicates the release of not only hydrogen but also diborane.     

A New Energetic Complex [Co(2,4,3‐tpt)2(H2O)2]·2NO3: Synthesis,Structure, and Catalytic Thermal Decomposition for Ammonium Perchlorate

The energetic complex, [Co(2,4,3‐tpt)₂(H₂O)₂] · 2NO₃ ( 1 ) [2,4,3‐tpt = 3‐(2‐pyridyl)‐ 4‐(4'‐pyridyl)‐5‐(3′‐pyridyl)‐1H‐1,2,4‐triazole], was synthesized and characterized by single‐crystal X‐ray diffraction, thermogravimetric analyses, elemental analysis, X‐ray powder diffraction, and IR spectroscopy. The title complex is a 0D motif with a unit of [Co(2,4,3‐tpt)₂(H₂O)₂]²⁺, whereas NO₃^– ions not only act as counter anions to balance the charge of the Co^II cations, but also provide hydrogen bond interactions, which make the 0D motif into a 1D chain. Furthermore, the thermal decomposition of ammonium perchlorate (AP) with complex 1 was explored by differential scanning calorimetry (DSC) over the temperature range from 50–500 °C. AP is completely decomposed in a shorter time in the presence of complex 1 , and the decomposition heat of the mixture is 2.143 kJ g^–1, significantly higher than pure AP. By Kissinger's method, the ratio of E_a/ln(A) is 11.87 for the mixture, which indicates that complex 1 shows good catalytic activity toward AP decomposition.     

A New Ammine Dual‐Cation (Li,Mg) Borohydride: Synthesis,Structure, and Dehydrogenation Enhancement

A new ammine dual‐cation borohydride, LiMg(BH₄)₃(NH₃)₂, has been successfully synthesized simply by ball‐milling of Mg(BH₄)₂ and LiBH₄ ? NH₃. Structure analysis of the synthesized LiMg(BH₄)₃(NH₃)₂ revealed that it crystallized in the space group P6₃ (no. 173) with lattice parameters of a=b=8.0002(1) Å, c=8.4276(1) Å, α=β=90°, and γ=120° at 50 °C. A three‐dimensional architecture is built up through corner‐connecting BH₄ units. Strong N? H???H? B dihydrogen bonds exist between the NH₃ and BH₄ units, enabling LiMg(BH₄)₃(NH₃)₂ to undergo dehydrogenation at a much lower temperature. Dehydrogenation studies have revealed that the LiMg(BH₄)₃(NH₃)₂/LiBH₄ composite is able to release over 8 wt % hydrogen below 200 °C, which is comparable to that released by Mg(BH₄)₃(NH₃)₂. More importantly, it was found that release of the byproduct NH₃ in this system can be completely suppressed by adjusting the ratio of Mg(BH₄)₂ and LiBH₄ ? NH₃. This chemical control route highlights a potential method for modifying the dehydrogenation properties of other ammine borohydride systems.     

Lewis‐Base Stabilized N‐Silver(I) Succinimide Complexes: Synthesis,Crystal Structures and Their Use as CVD‐Precursors

Four Lewis‐base stabilized N‐silver(I) succinimide complexes of type [L_n·R_m·AgNC₄H₄O₂] (L = N,N,N′,N′‐tetramethylethylenediamine (TMEDA), n = 1, m = 0, 2a ; L = P(OEt)₃, n = 2, m = 0, 2b ; L = PPh₃, m = 0, n = 2, 2c ; L = P(OMe)₃, R = TMEDA, n = 1, m = 1, 2d ) were prepared by a “one‐pot” synthesis methodology and characterized. The molecular structures of 2a and 2c have been determined by using X‐ray single crystal analysis. Complex 2a exists as ion pair {[Ag(TMEDA)₂]⁺[Ag(NC₄H₄O₂)₂]^–} in the solid state and complex 2c is a monomer with the three‐coordinate silver atom. Complex 2b was used as precursor in the deposition of silver for the first time by using MOCVD technique. The silver films obtained were characterized using scanning electron microscopy (SEM) and energy‐dispersion X‐ray analysis (EDX). SEM and EDX studies show that the dense and homogeneous silver films could be obtained.     

Halometallate Complexes of Germanium(II) and (IV): Probing the Role of Cation,Oxidation State and Halide on the Structural and Electrochemical Properties

The Ge^IV chlorometallate complexes, [EMIM]₂[GeCl₆], [EDMIM]₂[GeCl₆] and [PYRR]₂[GeCl₆] (EMIM=1‐ethyl‐3‐methylimidazolium; EDMIM=2,3‐dimethyl‐1‐ethylimidazolium; PYRR=N‐butyl‐N‐methylpyrrolidinium) have been synthesised and fully characterised; the first two also by single‐crystal X‐ray diffraction. The imidazolium chlorometallates exhibited significant C?H???Cl hydrogen bonds, resulting in extended supramolecular assemblies in the solid state. Solution ¹H NMR data also showed cation–anion association. The synthesis and characterisation of Ge^II halometallate salts [EMIM][GeX₃] (X=Cl, Br, I) and [PYRR][GeCl₃], including single‐crystal X‐ray analyses for the homologous series of imidazolium salts, are reported. In these complexes, the intermolecular interactions are much weaker in the solid state and they appear not to be significantly associated in solution. Cyclic‐voltammetry experiments on the Ge^IV species in CH₂Cl₂ solution showed two distinct, irreversible reduction waves attributed to Ge^IV–Ge^II and Ge^II–Ge⁰, whereas the Ge^II species exhibited one irreversible reduction wave. The potential for the Ge^II–Ge⁰ reduction was unaffected by changing the cation, although altering the oxidation state of the precursor from Ge^IV to Ge^II does have an effect; for a given cation, reduction from the [GeCl₃]^? salts occurred at a less cathodic potential. The nature of the halide co‐ligand also has a marked influence on the reduction potential for the Ge^II–Ge⁰ couple, such that the reduction potentials for the [GeX₃]^? salts become significantly less cathodic when the halide (X) is changed Cl→Br→I.     

Sustainable Chiral Polyamides with High Melting Temperature via Enhanced Anionic Polymerization of a Menthone‐Derived Lactam

Polyamides are very important polymers that find applications from commodities up to the automotive and biomedical sectors, and their impact is continuously growing. The synthesis of structurally significant, chiral, and sustainable polyamides is described via a new, convenient, and solvent‐free anionic polymerization of a biobased ε‐lactam, which is obtained from the renewable terpenoid ketone l ‐menthone in a one‐step synthesis. These polyamides are shown to have outstanding structural and thermal properties, which are thus introduced via the structure and chirality of the natural lactam monomer and which are discussed and compared with those of petroleum‐based, established, and commercial polyamide Nylon‐6. X‐ray data reveal a remarkable degree of crystallinity in these green polymers and emphasize the impact of their structural features on the resulting properties.

     

Synthesis of Di‐ and Trixanthones that Display High Stability and a Visual Fluorescence Response to Strong Acid

Three dixanthones ( 1 – 3 ) and an unprecedented C_3h‐symmetric trixanthone ( 4 ) were synthesized through a three‐step approach in overall yields above 63 %. These compounds possessed a planar π‐conjugated system and formed tight face‐to‐face columnar stacks, as confirmed by single‐crystal structural analysis. In comparison with xanthone, the fluorescence emissions of compounds 1 – 4 showed significant red‐shifts, with improved quantum yields. Moreover, the fluorescence emissions of compounds 1 – 4 could be modulated in a strongly acidic environment without decomposition, which led to a further red‐shift of the emissions, as well as enhancement of the emission intensities. These compounds have potential applications as optoelectronic materials and/or chemosensors.