Volume 63, Issue 12

The crystal structure of di-magnesium hexahydrate trihydrogencarbonate chloride, [Mg 2 (H 2 O) 6 - (HCO 3 ) 3 ]+Cl − , has been determined from high-resolution laboratory powder diffraction data (lattice parameters at r. t.: a = 8.22215(2), c = 39.5044(2) Å, V = 2312.85(2) Å 3 , space group R3̄̄c, Z = 6). The crystal structure of [Mg 2 (H2O) 6 (HCO 3 ) 3 ]+Cl − is built up of alternating sheets of C l − anions and complex [Mg 2 (H 2 O) 6 (HCO 3 ) 3 ]+ cations consisting of two Mg(OH 2 ) 3 O 3 octahedra interconnected by three disordered hydrogen carbonate groups. The packing can be described as a cubic close packing of [Mg 2 (H 2 O) 6 (HCO 3 ) 3 ]+ cations with the Cl − anions filling all octahedral voids. In the temperature range from r. t. up to decomposition, which takes place in the range 398 K < T < 413 K, no structural phase transition occurs.

A new bimetallic complex, [Fe(phen) 3 ] 2 [phen][V 4 O 12 ]·19H 2 O (1) has been obtained under nonhydrothermal conditions and characterized by single-crystal X-ray diffraction, IR and TG analysis. Crystal data: Fe 2 V 4 O 31 N 14 C 84 H 94 , triclinic, P1̄̄, a = 12.920(5), b = 17.833(5), c = 23.420(5) Å , α = 107.119(5)°, β = 90.643(5)°, γ = 107.643(5)°, Z = 2. In compound 1, water molecules build up 1D chains and decameric rings by hydrogen bonds. The hydrogen bond interactions between decameric rings and 1D chains form a 2D supramolecular sheet with large holes. The [V 4 O 12 ] 4− anions fill these holes. The [Fe(phen) 3 ] 2+ cations play a role as charge-compensating and space-filling units. Hydrogen bonding and electrostatic interactions lead to a new 3D supramolecular framework.

Hydrothermal reaction of Zn(NO 3 ) 2 · 6 H 2 O and 2-hydroxypyridine-3-carboxylic acid afforded a novel supramolecular complex, [Zn(C 6 H 4 NO 3 ) 2 (H 2 O) 2 ] (1). The complex has been characterized by macroanalysis, IR spectra, and thermogravimetric and differential thermal analysis (TG/DTA). Single crystal X-ray analysis shows that complex 1 crystallizes in the monoclinic space group P2 1 /c with the cell dimensions a = 7.534(6), b = 12.289(1), c = 7.534(6) Å, β = 100.51°, V = 685.85(1) Å 3 , and Z = 2. The six-coordinated Zn atom is in a severely distorted octahedral geometry. The complex molecules are assembled via strong O-H· · ·O and N-H· · ·O hydrogen bonding interactions into a three-dimensional supramolecular framework. Compared with the free ligand, complex 1 exhibits strong fluorescence in the solid state at room temperature.

Ethylenediaminetetraacetic acid (H 4 EDTA) is widely used in the pharmaceutical and bromatological industries and as a drug in chelation therapies. Besides, coordinated with metal ions it is used for the supplementation of essential trace elements. In this work the synthesis, crystallographic, and spectroscopic studies (EPR, IR, UV/Vis) of [Zn(H 2 O) 4 CuEDTA] · 2H 2 O are reported. The release of the metal cations at gastric pH was also investigated.

By crystallization from strongly acidic aqueous solutions, nickel and zinc tetrahydrogen-decaoxodiperiodate hexahydrate, NiH 4 I 2 O 10 ·6H 2 O and ZnH 4 I 2 O 10 ·6H 2 O, have been obtained and found to be isotypic to CuH 4 I 2 O 10 ·6H 2 O (P2 1 /c, no. 14) with the lattice parameters a = 1070.3, b = 544.0, c = 1187.2 pm, β = 112.6° for the Ni compound and a = 1073.3, b = 545.3, c = 1189.5 pm and β = 112.5° for the Zn compound. The crystal structure of MgH 4 I 2 O 10 ·6H 2 O has been reinvestigated and contrary to former results found to be isotypic to the Cu compound as well. IR and Raman spectra are given and analyzed with respect to the internal vibrations of the H 4 I 2 O 10 2− ion and the hydrogen bonding system. According to high-temperature Raman spectra and DTA and TG measurements, the compounds decompose in the temperature range up to 300 °C via unknown salts with the anions H 4 IO 6 2− and IO 4 − to the corresponding iodates. In the case of the Ni compound the exothermic decomposition to the iodate occurs in two steps.

The unsymmetrical complexes Pd(dpedt)(dddt), Pt(dpedt)(dddt), Pd(dpedt)(dmit), and Au(dpedt)- (dddt) (where dpedt is diphenyl-ethylenedithiolate, dddt is 5,6-dihydro-1,4-dithin-2,3-dithiolate and dmit is 1,3-dithiol-2-thione-4,5-dithiolate) were prepared and characterized. The study of their chemical and electrochemical behavior showed that they are stable in air and could be candidate materials for fabrication of field-effect transistors and other devices.

Ternary mixed Ca/Sr-Ba triplumbides of overall composition A II Pb 3 were synthesized from stoichiometric mixtures of the elements. The structures of the compounds have been determined by means of single crystal X-ray data. All structures exhibit close-packed ordered APb 3 layers containing Pb Kagomé nets, which are stacked in different orientations. Depending on the stacking sequences, the resulting lead polyanion resembles the oxygen nets of the hexagonal (face sharing octahedra, h stacking, Ni 3 Sn-type structure) or the cubic perovskites (corner sharing octahedra, c stacking, Cu 3 Au-type structure). The known binary compound BaPb 3 , the structure of which has been redetermined from single crystal data (trigonal, space group R3̄̄m, a = 729.06(2), c = 2564.43(10) pm, Z = 9, R1 = 0.0353), shows a (hhc) 3 stacking (TaCo3-type structure). A small partial substitution of barium against calcium (Ca 0.03 Ba 0.97 Pb 3 : trigonal, space group R3̄̄m, a = 726.0(2), c = 3443(2) pm, Z = 12, R1 = 0.0542) or strontium (Sr 0.11 Ba 0.89 Pb 3 : a = 727.3(2), c = 3421(2) pm, Z = 12, R1 = 0.0424) causes a structural change to the HT-PuGa 3 structure type with a (hhcc) 3 stacking sequence. At an approximate 1 : 1 ratio (35 to 53 % Sr) of strontium and barium (Sr 0.56 Ba 0.44 Pb 3 : trigonal, space group P6 3 /mmc, a = 715.82(2), c = 1717.91(7) pm, Z = 6, R1 = 0.0309) the PuAl 3 structure type [(hcc) 2 -stacking] has a distinct homogenity range. The series is terminated with the pure c stacking of SrPb 3 and CaPb 3 . As already noted from the above series, the stacking of the close-packed layers is influenced by the ratio of the atomic radii of the contributing elements. The electronic stability ranges, which are discussed on the basis of the results of FP-LAPW band structure calculations and in comparison to further compounds known from the literature, can be explained using Zintl/Wade rules. Still, due to the presence of only partially occupied steep Pb-p bands of σ bonding characteristic, the compounds are metals exhibiting pseudo band gaps at or near the Fermi level. Thus this structure family represents an instructive case of transition from polar ionic/covalent towards (inter)metallic chemistry.

A broad range of azobenzene derivates of the general type I-p-C 6 H 4 -N=N-p-C 6 H 4 -X (1) have been prepared. In the case of X = Ph (b), C≡C-Fc (e, Fc = ferrocenyl), OMe (g), Oi-Pr (i), and NMe 2 (m), these compounds have been characterised by single-crystal X-ray structure analysis. In addition, the closely related 4-dimethylamino-1-(4-iodophenylazo)naphthalene 2 and 8-(4-iodophenylazo) quinoline 3 have also been prepared. Furthermore, the ferrocene derivative Fc-C≡C-p-C 6 H 4 - NH 2 (4), which served as a starting material for the synthesis of I-p-C 6 H 4 -N=N-p-C 6 H 4 -p-C 6 H 4 - C≡C-Fc (1e), was prepared and structurally characterised by X-ray diffraction.

N-Alkyl-o-nitrophenylcarbamates as solids present two carbonyl stretching bands in the region 1700 - 1800 cm −1 but similar N-alkyl-p-nitrophenylcarbamates have only one such band in the IR spectrum. In solution both kinds of carbamate present one carbonyl stretching band, but for the former, the splittings occur when the carbamates crystallize. Four crystal structures were analyzed by X-ray diffraction. The two ortho derivatives have more than one molecule in the asymmetric unit, which is consistent with the IR observations.

Two new flavanes, (2S)-4′ ,7-dihydroxy-6,8-dimethylflavane (1), and (2S)-5,7-dihydroxy-4′-methoxy- 8-methylflavane (2), together with five known flavanes, (2S)-3′ ,7-dihydroxy-4′-methoxy-8- methylflavane (3), (2R)-4′,7-dihydroxy-8-methylflavane (4), (±)-3′,7-dihydroxy-4′-methoxyflavane (5), (±)-4′,7-dihydroxy-3′-methoxyflavane (6), and (2S)-4′,7-dihydroxyflavane (7), were isolated from the stem of Dracaena cambodiana. Their structures were determined by spectroscopic techniques (UV, IR, 1D and 2D NMR). Their antimicrobial activities were preliminarily examined by the filter paper disc agar diffusion method.

A new triterpene, 28-hydroxy-3-oxo-30-lupanoic acid (1), and a triterpene found for the first time as a natural product, 3-oxo-lupane-30-al (2), besides three known triterpenes, 29-nor-21α-H-hopane- 3,22-dione (3), 21α-H-hop-22(29)-ene-3β , 30-diol (4), and betulin (5) have been isolated from the n-hexane extract of Salacia chinensis stems. Their structures were elucidated on the basis of spectral studies.

Phytochemical investigation of the ethyl acetate extract of the stem of Dendrosicyos socotrana Balf. f. resulted in the isolation of a new pentacyclic cucurbitane glycoside Socotroside, in addition to the three known cucurbitacins, dihydrocucurbitacin D, dihydrocucurbitacin F and cucurbitacin G. The structures of the isolated compounds were established on the basis of their spectral data. The isolated cucurbitacin aglycones showed marked cytotoxic activity.

Zr(HSO 4 ) 4 /SiO 2 promotes the regio-, stereo- and chemoselective Claisen-Schmidt condensation of aromatic aldehydes with ketones under solvent-free conditions with improved yields. The work-up of the reaction mixture is simple, and the catalyst is easily removed from the products by simple filtration.

2,5,8-Tri-tert-butyl-1,3,4,6,7,9-hexaazaphenalene (6) was prepared from diethyl 2-[bis(methylsulfanyl) methylene]malonate (1) in four steps. The structure of compound 6 was confirmed by single crystal X-ray diffraction. The phenalene skeleton is nearly planar, and there is no π-π overlap between the hexaazaphenalene rings. A calculation of the homolytic bond dissociation enthalpy (BDE) was performed for compound 6 and its analogs 7 and 8, and the results were used to explain the different reactivity for these three compounds to form the corresponding radicals.

A series of 6,7,8,10-tetrahydropyrimido[5,4-b]quinolin-2,4,9-(1H,3H,5H)-triones 6 were synthesized through one-pot condensation of 5-aminouracil, aldehydes and dimedone in DMF under microwave irradiation without catalyst. The products 6a, d were oxidized to the 7,8-dihydro-pyrimido- [5,4-b]quinolin-2,4,9-(1H,3H,6H)-triones 11a, b. Treatment of 6a, d and/or 11a, b with ethyl iodide in the presence of anhydrous potassium carbonate gave the ethylated derivatives 12a, b and 13a, b, respectively. The structures of the products were confirmed by elemental analyses, IR, MS, 1 H, and 13 C NMR spectra.

1,3-Diisopropyl-4,5-dimethylimidazolium acetylacetonate (2) is obtained from 2,3-dihydro-1,3-diisopropyl-4,5-dimethylimidazol- 2-ylidene (1) and acetylacetone. Its crystal structure reveals the presence of ion pairs linked by C-H ··· O hydrogen bonds. In 2, the acetylacetonate ion adopts the structure of its E/Z-isomer (C).

Lipase-catalyzed resolution of 2-exo-7-syn-7-(1′-propynyl) norbornan-2-ol, a key synthetic intermediate for jasmonoids, was achieved using vinyl chloroacetate as an acyl donor.

C2-symmetric nickel(II) salen complexes [NiL] 1 were deposited on a highly oriented pyrolytic graphite (HOPG) surface from their acetone solutions. They aggregate easily to single, segregated, homochiral polymeric chains of (M)-1D- 1 n [NiL] (2) on the substrate as also found in single crystals. In STM topography, the single helical 1D structures 2 found on the surface were in excellent agreement with the dimension of aligned dimeric aggregates of 1 obtained from X-ray crystallography. Weak intermolecular Ni II ...OMe coordinations (d MeO−Ni = 0.35 nm) were found to be responsible for the formation of the chiral, helical and 1D assemblies on the substrate.

New intermetallic compounds RE 5 T 2 In 4 (RE = Sc, Y, La-Nd, Sm, Gd-Tm, Lu; T = Rh, Ir) were synthesized by arc-melting of the elements or by induction melting of the elements in tantalum crucibles under flowing argon. The samples were characterized by X-ray powder diffraction. They crystallize with the orthorhombic Lu 5 Ni 2 In 4 -type structure, space group Pbam, Z = 2, a 2 : 1 intergrowth variant of CsCl and AlB 2 related slabs of compositions InRE 8 (distorted cubes) and RhRE 6 (distorted trigonal prisms). Susceptibility measurements of Ce 5 Ir 2 In 4 have revealed modified Curie- Weiss behavior above 70 K with an experimental magnetic moment of 2.45(1) μ B / Ce atom. The cerium magnetic moments order ferri- or ferromagnetically at T C = 7.1(2) K.