Anhydrous Single Crystals Research Articles

Synthesis, X-ray structure analysis and density functional study of an unusual anhydrous 5,6-dimethylbenzo-1,3-imidazolium(H3) chloride

The heteroaromatic base 5,6-dimethylbenzo-1,3-imidazole (DMBI) proved to be a Brönsted base in an anhydrous ethanol solution, which contained fac,trans-[Ru(CO)3Cl2]2 at 55°C in air when the DMBI:Ru molar ratio was 2:1. The reaction produced colorless anhydrous single crystals of {(HDMBI)+Cl−}, C9H11ClN2, which were collected and analyzed using X-ray diffraction (XRD) techniques. A network of N–H⋯Cl hydrogen bond type interactions linking the protonated hetero-aromatic base to the chloride anions (bridging bases) stabilizes the crystal and mimics the N–H⋯Cl− interactions that play important roles in CCl channel biological systems. The shortest N⋯Cl contact distance and corresponding N–H⋯Cl angle are 3.073(3)Å and 173(3)°, respectively. The packing is also assisted by weaker C–H⋯Cl− hydrogen bond-type interactions and an extensive network of π⋯π stacking interactions involving HDMBI+ cations. Density functional calculations at the B3LYP/6-31G∗∗ and /6-311++G∗∗ levels for models of fragments of the crystal structure allowed for the evaluation of geometric parameters, hydrogen bond-type interaction formation energies, and infrared parameters for {(HDMBI)+Cl−} and {(HDMBI)+⋯Cl−⋯(HDMBI)+}.

Crystals from Concentrated Glyme Mixtures. The Single‐Crystal Structure of LiClO4.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Crystals from concentrated glyme mixtures. The single-crystal structure of LiClO4.

A procedure for the preparation of high-quality single crystals from concentrated glyme mixtures is presented. Anhydrous single crystals of LiNO(3) and LiClO(4) were prepared in this manner, and the single-crystal structure of LiClO(4) (orthorhombic, Pnma, a = 8.6447(12) A, b = 6.8512(10) A, c = 4.8254(7) A, Z = 4) was determined as an example. This procedure is expected to be widely applicable for not only salts but also a wide range of other materials solvated by glymes.

Electron Paramagnetic Resonance and Electron Nuclear Double Resonance Studies of X-Irradiated Crystals of Cytosine Hydrochloride. Part I: Free Radical Formation at 10 K after High Radiation Doses

Anhydrous single crystals of cytosine hydrochloride (protonated at N3) have been X-irradiated at 10 K and studied using K-band EPR, ENDOR and FSE spectroscopy. At least seven radicals were present at 10 K after X irradiation with a dose of about 150 kGy. Two different protonation states of the one-electron reduced cytosine cation were observed: an amino-protonated species (R1) and the pristine one-electron reduced species (R2) with zero net charge. Apparently three deprotonated versions of the one-electron oxidized cytosine cation were formed: the amino-deprotonated cation (R3), an N3-deprotonated cation (R4) and an N1-deprotonated cation (R5). Finally, two products formed by net hydrogen addition to the cytosine base were observed: a C5 hydrogen-addition radical (R6) and a C6 hydrogen-addition radical (R7). The crystalline lattice of cytosine hydrochloride is characterized in part by a cytosine base initially protonated at the N3-position, thus forming a cytosine base cation, and in part by an extended network of hydrogen bonding involving the chlorine anions. Proton transfer properties of pristine one-electron oxidation and reduction base products in this lattice are discussed and are suggested as explanations of the unusual multitude of positions for deprotonation of the one-electron oxidized species as well as for the two protonation states of the reduction product observed. The magnetic parameters for the amino-protonated species R1 agree well with those extracted from previous studies of cytosine derivatives in frozen solutions and in various glasses.

Preparation of anhydrous single crystals of rare-earth halides

Anhydrous rare-earth halides are prepared by the conversion of the rare-earth oxide to the halide by means of its reaction with the appropriate ammonium halide. Without transfer from the reaction vessel, the halide is melted, then crystallized by slow cooling. The resulting solid usually contains single crystals large enough to permit spectroscopic studies of the compounds.