Franz Pertlik

Tetrahedrally coordinated boron in tourmalines from the liddicoatite-elbaite series from Madagascar: Structure, chemistry, and infrared spectroscopic studies

Abstract Four colorless tourmalines of the liddicoatite-elbaite series from pegmatites from Anjanabonoina, Madagascar, have been characterized by crystal-structure determination and by chemical analyses. Optimized formulae range from X(Ca0.57Na0.29□0.14) Y(Al1.41Li1.33Mn2+0.07□0.19) ZAl6T(Si5.86B0.14)O18 (BO3)3V(OH)3.00W[F0.76(OH)0.24] [a = 15.8322(3), c = 7.1034(3) Å] to X(Na0.46Ca0.30□0.24) Y(Al1.82Li0.89Fe2+0.01 Mn2+0.01□0.27) ZAl6T(Si5.56B0.44)O18 (BO3)3V(OH)3.00W[(OH)0.50F0.50] [a = 15.8095(9), c = 7.0941(8) Å] (R = 1.3.1.7%). There is a high negative correlation (r2 = 0.984) between the bond-lengths (~1.618.1.614 Å) and the amount of IVB (from the optimized formulae). Similar to the olenites (from Koralpe, Austria) the liddicoatite-elbaite samples show a positive correlation between the Al occupancy at the Y site and IVB (r2 = 0.988). Short-range order configurations show that the presence of IVB is coupled with the occupancy of (Al2Li) and (Al2□) at the Y site. The structural formulae of the Al-rich tourmalines from Anjanabonoina, Madagascar, show ~ ⃞0.2 (vacancies) on the Y site. We believe that short-range order configurations with Y(Al2□) are responsible for these vacancies. Hence, an oft-used calculation of the Li content by difference on the Y site may be problematic for Al-rich tourmalines (olenite, elbaite, rossmanite). Fourier transform infrared (FTIR) spectra were recorded from the most IVB-rich tourmaline sample. The bands around 5195 and 5380 cm-1 can be assigned to H2O. Because these bands still could be observed in FTIR spectra at temperatures from -150 to +600 °C, it seems unlikely that they result from H2O in fluid inclusions. Interestingly, another FTIR spectrum from a dravite in which the X site is filled completely with Na, does not show bands at ~5200 and ~5400 cm-1. Although not definitive, the resulting spectra are consistent with small amounts of H2O at the X site of the elbaite. The rare-earth element (REE) pattern of the B-rich elbaite (ΣREE: ~150 ppm) demonstrates that this sample is strongly enriched in LREEs compared to HREEs and exhibits a negative Eu anomaly. This sample shows the strongest enrichment of LREEs and a high LaN/YbN ratio of ~351, which seems to confirm an important role of the fractional crystallization process.

Crystal Structures and Hydrogen Bonding Schemes in Four Benzamide Derivatives (2-Hydroxy-benzamide, 2-Hydroxy-thiobenzamide, 2-Hydroxy-N,N-dimethyl-benzamide, and 2-Hydroxy-N,N-dimethyl-thiobenzamide)

Summary2-Hydroxy-benzamide, C7H7NO2; monoclinic; I2/a-C2h6;a=12.901 (2),b=4.982 (1),c=20.987 (3) Å; β=91.50 (2)°;Z=8. 2-Hydroxy-thiobenzamide, C7H7NOS; monoclinic; P21/n-C2h5;a=13.508 (5),b=6.780 (2),c=15.878 (6) Å; β=93.74 (5)°;Z=8. 2-Hydroxy-N,N-dimethyl-benzamide, C9H11NO2; orthorhombic; Pbca-D2h15;a=11.752 (2),b=16.680 (3),c=9.079 (2) Å;Z=8. 2-Hydroxy-N,N-dimethyl-thiobenzamide, C9H11NOS; monoclinic; P21/c-C2h5;a=6.983 (1),b=11.652 (3),c=11.704 (3) Å; β=100.02 (2)°;Z=4. The crystal structures of these four compounds were determined (respectively refined: 2-hydroxy-benzamide) by single crystal X-ray data. The refinements of the structure parameters by least squares methods yielded in all casesR<0.056. The hydrogen atoms were located by means of difference Fourier summations. The O-H ... O distances are 2.513 (1) Å in 2-hydroxy-benzamide (intramolecular) and 2.625 (1) Å in 2-hydroxy-N,N-dimethyl-benzamide (intermolecular). The two O-H ... S distances in 2-hydroxy-thiobenzamide are 2.904 (2) Å and 2.918 (2) Å (intramolecular, two molecules in the asymmetric unit) and 3.228 (2) Å in 2-hydroxy-N,N-dimethyl-thiobenzamide (intermolecular). Clear N-H ... O hydrogen bonds with 2.926 (1) Å and 3.006 (1) Å occur only in the structure of 2-hydroxy-benzamide (intermolecular).Zusammenfassung2-Hydroxy-benzamid, C7H7NO2; monoklin; I2/a-C2h6;a=12.901 (2),b=4.982 (1),c=20.987 (3) Å; β=91.50 (2)°;Z=8. 2-Hydroxy-thiobenzamid, C7H7NOS; monoklin; P21/n-C2h5;a=13.508 (5),b=6.780 (2),c=15.878 (6) Å; β=93.74 (5)°;Z=8. 2-Hydroxy-N,N-dimethyl-benzamid, C9H11NO2; orthorhombisch; Pbca-D2h15;a=11.752 (2),b=16.680 (3),c=9.079 (2) Å;Z=8. 2-Hydroxy-N,N-dimethyl-thiobenzamid, C9H11NOS; monoklin; P21/c-C2h5;a=6.983 (1),b=11.652 (3),c=11.704 (3) Å; β=100.02 (2)°;Z=4. Die Kristallstrukturen dieser vier Verbindungen wurden mittels Röntgen-Einkristalldaten bestimmt (bzw. verfeinert: 2-Hydroxy-benzamid). Die Verfeinerungen der Strukturparameter nach der Methode der kleinsten Quadrate ergab in allen FällenR<0.056. Die Wasserstoffatome konnten anhand von Differenz-Fourier-Summationen belegt werden. Die O-H ... O-Abstände haben folgende Werte: 2.513(1)Å in 2-Hydroxy-benzamid (intramolekular) und 2.625(1) Å in 2-Hydroxy-N,N-dimethyl-benzamid (intermolekular). Die zwei O-H ... S-Abstände sind in 2-Hydroxy-thiobenzamid 2.904(2)Å und 2.918(2)Å (intramolekular, zwei moleküle in der asymmetrischen Einheit) und 3.228(2)Å in 2-Hydroxy-N,N-dimethyl-thiobenzamid(intermollekular). Klar zuzuordnende N-H ... O-Wasserstoffbrücken mit 2.926(1)Å und 3.006(1)Å treten lediglich in der Struktur des 2-Hydroxy-benzamid auf (intermolekular).

Die Kristallstrukturen der Kupfer(II)-oxo-selenite Cu2O(SeO3) (kubisch und monoklin) und Cu4O(SeO3)3 (monoklin und triklin)

AbstractSyntheses within the system CuO-SeO2-H2O revealed four copper(II)-oxo-selenites. The crystal structures of these compounds were determined by single crystal X-ray techniques. Chemical formulae, lattice parameters and space groups are: Cu2O(SeO3)-I [a=8.925 (1) Å, P213], Cu2O(SeO3)-II [a=6.987 (5) Å,b=5.953 (4) Å,c=8.429 (6) Å, β=92.17 (3)°, P21/n], Cu4O(SeO3)3-I [a=15.990 (8) Å,b=13.518 (8) Å,c=17.745 (12) Å, β=90.49 (5)°, P21/a], and Cu4O(SeO3)3-II [a=7.992 (6) Å,b=8.141 (6) Å,c=8.391 (6) Å, α=77.34 (3)°, β=65.56 (3)°, γ=81.36 (3)°,

The structure of freedite, Pb8Cu(AsO3)2O3Cl5

P\bar 1

Die Kristallstruktur der monoklinen Form von As2O3 (Claudetit II)

].All the Cu atoms are-with one exception-[4], [4+1], and [4+2] coordinated by O atoms. The four nearest O atoms are more or less distorted “square planar” arranged. Within the CuO4 squares the Cu-O bond lengths are significantly shorter for the [4] coordinated O atoms as compared with those of the [4+1] and [4+2] coordinated Cu atoms. The exception in the coordination of the Cu atoms is the Cu(1) atom in Cu2O(SeO3)-I with the site symmetry 3, which is trigonal dipyramidal [5] coordinated. A common feature of these four crystal structures is, that O atoms outside the SeO3 groups are tetrahedrally coordinated by four Cu(II) atoms. The Se atoms are as usual [3] coordinated, building up SeO3 pyramids. In all these four compounds the copper-oxygen polyhedra are combined to a three-dimensional network.

The crystal structure of nabokoite, Cu7TeO4(SO4)5 · KCl: The first example of a Te(IV)O4 pyramid with exactly tetragonal symmetry

The mineral claudetite crystallizes monoclinic (a0=5.25,b0=12.99,c0=4.53 Å, β=93.880;Z=4) with space group P 21/n-C2h5. For 680 independent x-ray intensities, collected on aWeissenberg-type diffractometer, an R-factor of 4.9% was obtained. The AsO3-groups of the structure are connected by common oxygen corners in two dimensions forming puckered layers∞2As2O3.

The Distortion of the Hexagonal Close Packing of Oxygen Atoms in Co(OH)2 Compared to Isotypic Brucite-Type Structures

SummaryThe structure of freedite, Pb8Cu(AsO3)2O3Cl5, [a = 13.578(2),b = 20.099(3),c = 7.465(1)Å; β = 105.73(1)°; space group C2/m; Z = 4] was determined by direct methods and Fourier summations. The refinement of the atomic coordinates and thermal parameters-the metal atoms anisotropic, the remaining atoms isotropic-yielded anR value of 0.086 (Rw = 0.061). The five crystallographically independent Pb atoms are each surrounded by three resp. four O atoms and four Cl atoms. The novel feature of this structure are formal [(AsO3)2(CuCl)2(AsO3)2] groups, in which the Cu atoms are tetrahedrally coordinated to two Cl and two As atoms [Cu-Cl = 2.43(8)Å2 × , Cu-As = 2.32(1)Å2 ×]. The mineral is considered to contain Cu(I) and As(III) atoms linked together by covalent Cu-As bonds. The formal groups mentioned are bound to the Pb atoms via Cl and O atoms.ZusammenfassungDie Struktur des Freedits, Pb8Cu(AsO3)2O3Cl5, [a = 13,578(2),b = 20,099(3),c = 7,465(1)Å; β = 105,73(1); Raumgruppe C2/m;Z = 4] wurde anhand direkter Methoden und Fouriersummationen bestimmt. Die Verfeinerung der Ortskoordinaten und der Temperaturparameter - Metallatome anisotrop, übrige Atome isotrop -ergab einenR-Wert von 0,086 (Rw = 0,061). Die fünf kristallographisch verschiedenen Pb-Atome werden von drei bzw. vier O-Atomen sowie jeweils vier Cl-Atomen umgeben. Ein neues Bauprinzip dieser Struktur sind formale [(AsO3)2(CuCl)2(AsO3)2]-Gruppen, in denen die Cu-Atome durch zwei Cl- und zwei As-Atome tetraedrisch umgeben sind [Cu-Cl= 2,43(8)Å2 ×, Cu-As = 2,32(1)Å2 x]. Es wird angenommen, daß in diesem Mineral Cu(I)- und As(III)-Atome vorliegen, die über kovalente Bindungen verknüpft sind. Diese formalen Gruppen sind über die Cl- und O-Atome an die Pb Atome gebunden.

Synthesis and crystal structure of iron(III) selenate(IV) trihydrate, Fe2(SeO3)3 • 3H2O

Die Verfeinerung der Kristallstruktur von Schafarzikit, FeSb2O4,a0=8,59;c0=5,91 A, RaumgruppeP 4mbc-D 4h 13 ,Z=4, bestatigte im wesentlichen die vonZemann gefundene Atomanordnung. Die Struktur konnte bei Verwendung von Weissenberg-Diffraktometerdaten aufR=0,056 verfeinert werden. Die Fe-Atome werden von sechs Sauerstoffen in Form eines Oktaeders umgeben, die Sb-Atome bilden mit drei Sauerstoffen eine flache trigonale Pyramide.