Preparation and Characterization of Silicon-Metal Fluoride Reactive Composites

Fuel-rich composite powders combining elemental Si with the metal fluoride oxidizers BiF3 and CoF2 were prepared by arrested reactive milling. Reactivity of the composite powders was assessed using thermoanalytical measurements in both inert (Ar) and oxidizing (Ar/O2) environments. Powders were ignited using an electrically heated filament; particle combustion experiments were performed in room air using a CO2 laser as an ignition source. Both composites showed accelerated oxidation of Si when heated in oxidizing environments and ignited readily using the heated filament. Elemental Si, used as a reference, did not exhibit appreciable oxidation when heated under the same conditions and could not be ignited using either a heated filament or laser. Lower-temperature Si fluoride formation and oxidation were observed for the composites with BiF3; respectively, the ignition temperature for these composite powders was also lower. Particle combustion experiments were successful with the Si/BiF3 composite. The statistical distribution of the measured particle burn times was correlated with the measured particle size distribution to establish the effect of particle sizes on their burn times. The measured burn times were close to those measured for similar composites with Al and B serving as fuels.

Series of Near-IR-Absorbing Transition Metal Complexes with Redox Active Ligands

New soluble and intensely near-IR-absorbing transition metal (Ti, Zr, V, Ni) complexes were synthesized using a redox non-innocent N,N’-bis(3,5-di-tertbutyl-2-hydroxy-phenyl) -1,2-phenylenediamine (H4L) as a ligand precursor. In all the complexes, ([Ti(Lox)2, [Zr(Lox)2], [V(Lsq1)(HLox)] and [Ni(HLox)2], two organic molecules coordinate to the metal center as tri- or tetradentate ligands. The solid-state structures of the complexes were determined using single crystal XRD, and the compounds were further characterized with Electrospray Ionisation Mass Spectrometry (ESI-MS). Thermoanalytical measurements indicated the thermal stabilities of the complexes. All compounds absorb strongly in the near-IR region and show very interesting magnetic and electrochemical properties. Moreover, it was shown that the V and Ni complexes can also convert absorbed near-IR photons to (un)paired electrons, which indicates great promise in photovoltaic applications.

Cu2[Cu(H2O)4][(CH2)4(NH3)2][C6H2(COO)4]2·4H2O — A Three-Dimensional Coordination Polymer with Negativ Excess Charge and Channel-like Voids

Triclinic single crystals of Cu2[Cu(H2O)4][(CH2)4(NH3)2][C6H2(COO)4]2·4H2O have beenprepared in aqueous solution at 55 °C. Space group P-1 (no. 2), a = 799.73(7), b = 977.43(8),c = 1086.27(9) pm, α = 87.194(7), β = 84.679(7), γ = 74.744(6)°, V = 0.81540(12) nm3, Z = 1.There are two unique Cu2+ with CN 4+1 (Cu(1)) and CN 4+2 (Cu(2)), respectively. The Cu-Odistances range from 197.4(2) to 214.9(2) pm (Cu(1)) and 191.6(2) to 240.1(4) pm (Cu(2)).There is a short Cu(1)-Cu(1) contact of 267.02(6) pm. A three-dimensional coordinationpolymer with negative excess charge and channel-like voids extending parallel to [-110] ismade up by Cu2+ and [C6H2(COO)4]4-. These voids accomodate [(CH2)4(NH3)2]2+ and watermolecules, which are not coordinated to Cu2+. Thermoanalytical measurements in airindicated a step-wise loss of water of crystallization commencing at 63 °C, which is finishedat approx. 250 °C followed by an exothermic decomposition yielding CuO. The Cu(1) pairsshow anti-ferromagnetic coupling.

Synthesis, Crystal Structure, Hydrogen Bonding and Thermal Behaviour of a Three-Dimensional Cu(II)-benzene-1,2,4,5-tetracarboxylate Templated by 1,9-Diaminononane

Triclinic single crystals of Cu4(H3N–(CH2)9–NH3)(OH)2[C6H2(COO)4]2·5H2O were preparedin aqueous solution at 80 °C in the presence of 1,9-diaminononane. Space group P-1 (no. 2)with a = 1057.5(2), b = 1166.0(2), c = 1576.7(2) pm, alpha = 106.080(10)°, beta = 90.73(2)° and gamma =94.050(10)°. The four crystallographic independent Cu2+ ions are surrounded by five oxygenatoms each with Cu–O distances between 191.4(3) and 231.7(4) pm. The connection betweenthe Cu2+ coordination polyhedra and the [C6H2(COO)4]4–anions yields three-dimensionalframework with negative excess charge and wide centrosymmetric channel-like voids. Thesevoids extend parallel to [001] with the diagonal of the nearly rectangular cross-section ofapproximately 900 pm. The channels of the framework accommodate [H3N–(CH2)9–NH3]2+cations and water molecules, which are not connected to Cu2+. The nonane-1,9-diammoniumcations adopt a partial gauche conformation. Thermoanalytical measurements in air show aloss of water of crystallization starting at 90 °C and finishing at approx. 170 °C. Thedehydrated compound is