Volume 230, Issue 3

Lead and copper(I) chloride arsenite was found in the ancient metallurgic slag from the Vrissaki area, Lavrion district, Attikí Peninsula, Greece. Its chemical composition corresponds to the idealized formula Pb 6 Cu + (AsO 3 ) 2 Cl 7 . The IR spectrum shows the presence of AsO33−$AsO_3^{3 - }$ anions and only a trace amount of O–H bonds. The crystal structure was solved by direct methods and refined to R (F) = 0.0304 based on 1778 unique reflections with I > 2 σ ( I ). The compound is trigonal (rhombohedral), R 3̅, a = 9.8691(2), c = 34.2028(13) Å, V = 2885.01(14) Å 3 , Z = 6. Two crystallographically non-equivalent As 3+ cations occupy apexes of the AsO 3 pyramids. Cu + cation occupies an apex of the CuCl 3 pyramid. The group [Cl 3 Cu–AsO 3 ] is arranged along the c axis. Pb cations occupy two sites with seven- and eight-fold coordination. The crystal-chemical formula of the compound is Pb 6 (Cu + Cl 3 )(As 3+ O 3 ) 2 Cl 4 .

The magnesium intermetallics RE 2 RuMg ( RE = Sc, Y, Er, Tm, Lu) were synthesized by melting of the elements in sealed niobium ampoules followed by different annealing sequences in muffle furnaces. The samples were characterized by powder X-ray diffraction. The structure of Sc 2 RuMg (Pt 2 ZnCd type, P 4/ mmm , a = 326.07(6), c = 760.9(2) pm, w R2 = 0.0749, 138 F 2 values, 9 variables) was refined from single crystal diffractometer data. Sc 2 RuMg is an i2 superstructure of the CuAu type with alternating and tetragonally distorted Ru@Sc 8 and Mg@Sc 8 cubes.

The molecular structures of chloride salts of 2- and 5-substituted derivatives of 8-hydroxyquinoline, Me–H 2 Q + ·Cl – ([C 10 H 10 NO]Cl) and Cl–H 2 Q + ·Cl – ([C 9 H 7 ClNO] + ·Cl – ), were determined by single crystal X-ray diffraction methods; the latter is a new polymorph. In the crystal structures of these salts, several intra- and inter-molecular interactions result in a step-shaped centrosymmetric R44(8)$R_4^4(8)$ ring. Unlike most quinolinium salts, there was no solvent present in these structures. Protonation of the quinoline N atom had an effect on the N···O bite distances and C–N–C angle and greater conjugation of the benzene ring with a hydroxyl group was also observed. π–π Interactions between each pair of quinolinium rings were observed in Me–H 2 Q + ·Cl – but not in Cl–H 2 Q + ·Cl – . In addition, the quantum chemical calculations were performed on the new structures as well as similar compounds for comparison. The optimized structures were compared with the experimental observations for the effect of protonation and of hydrogen bonding interactions.

Three crystal structures of N -methylacetamide (NMA) with the xanthenol host 9-(4-methoxyphenyl)-9 H -xanthen-9-ol ( H ) are reported. The crystal structures were obtained by using different solvent compositions. The host compound was dissolved in equimolar mixtures of N -methylacetamide/ N,N -dimethylacetamide, N -methylacetamide/1,4-dioxane and N -methylacetamide/aniline which yielded H·NMA , H·2NMA and 2H·2NMA , respectively; H·NMA and 2H·2NMA are polymorphs. Thus, compounds with 1:1 and 1:2 host:guest ratios were obtained. H·NMA solved in the monoclinic space group P 2 1 / n whereas both H·2NMA and 2H·2NMA were solved in the triclinic space group P1¯.$P\bar 1.$ For all structures each host molecule is hydrogen bonded to one NMA molecule via (Host)-OH···O-(NMA) linkages. The NMA guests occupy channels and are connected via N–H···O hydrogen bonds forming chains. The thermal stabilities of the compounds were determined using thermogravimetry and differential scanning calorimetry which indicated that 2H·2NMA was the least stable with H·2NMA being the most stable.

Imitative of a supramolecular synthon moiety D comprising two 3,5-bis(hydroxymethyl) substituted benzoic acid moieties ( 2 ), the covalently linked surrogate molecule 1 has been designated and synthesized. Crystal structures have been compared including also substituted and molecularly elongated derivatives of 2 . They show largely common structural features in planar geometry of the building units and layer formation in the crystal packing, while the hydrogen bonded patterns within the layers differ according to the structural molecular changes. Moreover, synthon robustness of the dimer carboxylic acid motif has been confirmed.

Reaction of benzene-1,2,4,5-tetracarboxylic acid (H 4 L) with Zn(II) salt in DMF/MeOH leads to the formation of the new (μ 2 -benzene-1,2,4,5-tetracarboxylato-O,O′)-hexaaqua-dizinc(II)-dihydrate complex [Zn 2 L(H 2 O) 6 ]·2H 2 O ( 1 ) (L = benzene-1,2,4,5-tetracarboxylate). Crystal structure analysis reveals that each tetracoordinated zinc(II) center adopts a distorted tetrahedral geometry occupied by one O carboxylate and three O water atoms. A 3D supramolecular associate in the crystal lattice of 1 has been stabilized by a number of non-covalent interactions (O–H···O). Topology of the H-bonded 3D network has been also analyzed.

Cyanide- and fumarate-bridged bimetallic complex, poly[μ-fumaratotetraaminedizinc(II)di-μ-cyanodicyanonickel(II) dihydrate], {[Zn 2 (μ-fum)(NH 3 ) 4 Ni(μ-CN) 2 (CN) 2 ]·2H 2 O} n ( 1 ) (H 2 fum = Fumaric acid) was synthesized and structurally characterized by vibrational (FT-IR and Raman) spectroscopy, single crystal X-ray diffraction and elemental and thermal analyses techniques. The structure of the complex consists of a one-dimensional polymeric chain, in which the Zn(II) and Ni(II) ions are linked by CN groups. The Ni(II) ion is four coordinated with four cyanide-carbon atoms in a square planar arrangement and the Zn(II) ions are four coordinated with one cyanide nitrogen atom, two amine nitrogen atoms and one fumarate oxygen atom, in a distorted tetrahedral arrangement. In the complex, the adjacent chains are connected by strong O–H···O, O–H···N, N–H···O and N–H···N hydrogen bonding interactions to form a three dimensional network.