Cu- and Mn-bearing tourmalines from Brazil and Mozambique: crystal structures, chemistry and correlations.

Cu- and Mn-bearing tourmalines from Brazil and Mozambique were characterised chemically (EMPA and LA-ICP-MS) and by X-ray single-crystal structure refinement. All these samples are rich in Al, Li and F (fluor-elbaite) and contain significant amounts of CuO (up to ~1.8 wt%) and MnO (up to ~3.5 wt%). Structurally investigated samples show a pronounced positive correlation between the distances and the (Li + Mn2+ + Cu + Fe2+) content (apfu) at this site with R2 = 0.90. An excellent negative correlation exists between the distances and the Al2O3 content (R2 = 0.94). The samples at each locality generally show a strong negative correlation between the X-site vacancies and the (MnO + FeO) content. The Mn content in these tourmalines depends on the availability of Mn, on the formation temperature, as well as on stereochemical constraints. Because of a very weak correlation between MnO and CuO we believe that the Cu content in tourmaline is essentially dependent on the availability of Cu and on stereochemical constraints.

Ba2Gd2(Si4O13): a silicate with finite Si4O13 chains.

The title compound, dibarium digadolinium(III) tetrasilicate, crystallized from a molybdate-based flux. It represents a new structure type and contains finite zigzag-shaped C(2)-symmetric Si(4)O(13) chains and Gd(2)O(12) dimers built of edge-sharing GdO(7) polyhedra. The [9+1]-coordinated Ba atoms are located in voids in the atomic arrangement. All atoms are in general positions except for one O atom, which lies on a twofold axis. The structure is compared with those of the few other known tetrasilicates.

New crystalline layered zinc phosphate with 10-membered-ring channels perpendicular to layers.

A novel layered zinc phosphate, [N(2)C(6)H(12)](2)[Zn(7)H(3)(HPO(4-x))(5)(PO(4))(3)]H(2)O, with unique 10-membered-ring ellipsoidal channels running perpendicularly to ladder-shaped tetrahedral layers, has been synthesized ionothermally via in situ generation of 1,4-diazabicyclo[2.2.2]octane.

BaY2Si3O10: A new flux-grown trisilicate.

BaY2Si3O10, barium diyttrium trisilicate, is a new silicate grown from a molybdate-based flux. The structure is based on zigzag chains, parallel to [010], of edge-sharing distorted YO6 octahedra, linked by horseshoe-shaped trisilicate groups and Ba atoms in irregular eight-coordination. The layered character of the structure is caused by a succession of zigzag chains and trisilicate groups in planes parallel to (-101). The Ba atoms occupy narrow channels extending parallel to [100]. The mean Y-O, Si-O and Ba-O bond lengths are 2.268, 1.626 and 1.633, and 2.872 A, respectively. The two symmetry-equivalent terminal SiO4 tetrahedra in the Si3O10 unit adopt an eclipsed conformation with respect to the central SiO4 tetrahedron; the Si-O-Si and Si-Si-Si angles are 136.35 (9) and 96.12 (4) degrees, respectively. One Ba, one Si and two O atoms are located on mirror planes; all remaining atoms are in general positions. The geometry of isolated trisilicate groups in inorganic compounds is briefly discussed.

Hydrothermal single-crystal growth in the systems Ag/Hg/X/O (X = VV, AsV): crystal structures of (Ag3Hg)VO4, (Ag2Hg2)3(VO4)4, and (Ag2Hg2)2(HgO2)(AsO4)2 with the unusual tetrahedral cluster cations (Ag3Hg)3+ and (Ag2Hg2)4+ and crystal structure of AgHgVO4.

Single crystals of (Ag3Hg)VO4 (I), (Ag2Hg2)3(VO4)4 (II), AgHgVO4 (III), and (Ag2Hg2)2(HgO2)(AsO4)2 (IV) were grown under hydrothermal conditions (250 degrees C, 5 d) from starting mixtures of elementary mercury, silver nitrate, ammonium vanadate, and disodium hydrogenarsenate, respectively. All crystal structures were determined from X-ray diffraction data, and their chemical compositions were confirmed by electron microprobe analysis. I crystallizes in the tillmannsite structure, whereas II-IV adopt new structure types: (I) I4, Z = 2, a = 7.7095(2) A, c = 4.6714(2) A, 730 structure factors, 24 parameters, R[F2 > 2sigma(F2)] = 0.0365; (II) I42d, Z = 4, a = 12.6295(13) A, c = 12.566(3) A, 1524 structure factors, 55 parameters, R[F2 > 2sigma(F2)] = 0.0508; (III) C2, Z = 4, a = 9.9407(18) A, b = 5.5730(8) A, c = 7.1210(19) A, beta = 94.561(10) degrees , 1129 structure factors, 48 parameters, R[F2 > 2sigma(F2)] = 0.0358; (IV) P31c, Z = 2, a = 6.0261(9) A, c = 21.577(4) A, 1362 structure factors, 52 parameters, R[F2 > 2sigma(F2)] = 0.0477. The most striking structural features of I, II, and IV are the formation of tetrahedral cluster cations (Ag3Hg)3+ and (Ag2Hg2)4+, respectively, built of statistically distributed Ag and Hg atoms with a metal-metal distance of about 2.72 A. The electronic structure of these clusters can formally be considered as two-electron-four-center bonding. The crystal structure of III differs from the protrusive structure types insofar as silver and mercury are located on distinct crystallographic sites without a notable metal-metal interaction >3.55 A. All crystal structures are completed by tetrahedral oxo anions XO4(3-) (X = VV, AsV) and for IV additionally by a mercurate group, HgO2(2-).

A novel copper(II) complex with 1,10-phenanthroline and ciprofloxacin.

The X-ray structure analysis of the title compound, chloro[1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-(piperazin-4-ium-1-yl)-3-quinolinecarboxylate-kappa(2)O(3),O(4)](1,10-phenanthroline-kappa(2)N,N')copper chloride dihydrate, [CuCl(C(17)H(18)FN(3)O(3))(C(12)H(8)N(2))]Cl x 2H(2)O or [CuCl(cfH)(phen)]Cl x 2H(2)O, where cfH is 1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-(piperazin-4-ium-1-yl)-3-quinolinecarboxylate and phen is 1,10-phenanthroline, shows that the geometry around the Cu ion is a slightly distorted square pyramid. Two O atoms of the carbonyl and carboxyl groups of ciprofloxacin and two N atoms of 1,10-phenanthroline are coordinated to the metal centre in the equatorial plane, and a Cl(-) ion is coordinated at the apical position. Extensive intermolecular hydrogen bonding produces a supramolecular structure that consists of alternating six- and 12-membered rings.

Synthesis, structural and spectroscopic properties of two new ethylenediamine-templated gallophosphate-oxalate layered materials.

Two new layered gallophosphate-oxalate materials have been prepared hydrothermally using ethylenediamine and oxalic acid as structure-directing agents. The compounds (C2N2H10)2[Ga2(C2O4)2(HPO4)3].H2O 1 and (C2N2H10)3- [Ga4(C2O4)4(HPO4)4(H2PO4)2] 2 are closely related, consisting of anionic double chains built of alternating paris of GaO6 and HPO4 polyhedra. These double chains are linked via bridging HPO4 or H2PO4 tetrahedra to form corrugated layers containing eight-membered rings. The oxalate group acts as a bidentate ligand to each of the GaO6 octahedron. The corrugated layers are held together by strong to weak hydrogen-bonding interactions between oxalate groups, water and diprotonated ethylenediamine molecules, and the framework components. The compounds were characterized by single-crystal X-ray diffraction, thermogravimetric analysis, and infrared and Raman spectroscopy. Crystal data for 1: monoclinic, space group P21/C (No. 14), a = 6.355(1) A, b = 39.362(8) A, c = 9.249(2) A, beta = 106.7(1) degrees, Z = 2. Crystal data for 2: triclinic, space group P1 (No. 2), a = 8.730(1) A, b = 11.575(1) A, c = 11.696(1) A, alpha = 115.12(1) degree, beta = 90.07(1) degree, gamma = 111.23(1) degree, Z = 2.