Search results for "Crystal system"
showing 10 items of 13557 documents
The preparation, IR spectrum and structure of the Di-μ3-hydroxo-μ-sulphatotetrakis-μ-(isonicotinato-N-oxide)tetraaqua-tetracopper(II)
1982
Abstract A very unusual new copper(II) complex with isonicotinate N-oxide (N-inicO), Cu4(N-inicO)4SO4(OH)2(H2O)4 has been prepared and its crystal and molecular structure determined from three dimensional X-ray diffraction data. The crystals belong to the monoclinic space group C2. The cell parameters are a = 19.089(8), b = 6.884(3), c = 19.533(12) A, β = 140.9(3)°, dobs = 1.99, dcalc = 2.01 and Z = 2. The structure was refined to a final R-value of 0.062. The monomeric tetranuclear complex resembles a space ship with the sulphate group at its top and pyridine rings as wings. Two copper atoms are very close to each other in the molecule; the Cu1Cu1′ distance is 2.885 A. The coordination ar…
Hexachlororhenate(IV) salts of ruthenium(III) cations: X-ray structure and magnetic properties
2012
Abstract Two novel rhenium(IV)–ruthenium(III) compounds of formulae [RuCl(NH3)5]2[ReCl6]Cl2 (1) and [RuCl2(en)2]2[ReCl6]·2CH3CN (2) (en = 1,2-ethylenediamine) have been prepared and characterized. Their crystal structures were determined by single-crystal X-ray diffraction. 1 crystallizes in the monoclinic system with C2/m as space group, whereas 2 crystallizes in the triclinic system with space group P(−1). The crystal structures of 1 and 2 are made up of discrete [ReCl6]2− anions and [RuCl(NH3)5]2+ (1) or [RuCl2(en)2]+ (2) cations held together by N–H···Cl hydrogen bonds, van der Waals and electrostatic forces. The magnetic properties were investigated from susceptibility measurements per…
Synthesis, structure and magnetic properties of Mn(II) and Cu(II) complexes with the dicyano-acetic acid methyl ester anion
2001
The preparation of the sodium salt of dicyano-acetic acid methyl ester (NaCH 3 OC(O)C(CN) 2 ) (NaL) is reported. The structure of this anion is related to the structure of the dicyanamide, whose chelating capability has been used to develop 2D networks. Two new complexes of formula [M(L) 2 (H 2 O) 2 ] (M=Mn 2+ ( 1 ) and Cu 2+ ( 2 )) have been synthesized and their crystal structures determined by single-crystal X-ray diffraction. The coordination geometry of Mn atom in 1 is approximately octahedral, and the Mn atoms are μ 2 -bridged by two pairs of L − resulting in an infinite one-dimensional chain. Two types of hydrogen bonds link the chains within a 3-dimensional infinite lattice. The coo…
Crystal structure of a new polytype in the V–P–O system: is ω-VOPO4 a dynamically stabilised metastable network?
2001
Abstract ω-VOPO 4 has been prepared by thermal decomposition of different oxovanadium hydrogen phosphates, namely VO(HPO 4 ) n H 2 O ( n =2( α ), 2(β) and 4) and β-NH 4 (VO 2 )(HPO 4 ). The ω-VOPO 4 phase only remains well crystallised at relatively high temperatures. Its crystal structure has been determined ab initio from X-ray powder diffraction data collected at 475°C. The cell is tetragonal (space group P4 2 /mmc) with a =4.8552(3) A and c =8.4301(6) A. Starting positional parameters were obtained by direct methods, and the structure was refined using Rietveld profile refinement principles. Disorder of two oxygen sublattices is observed. To rationalise some features of the crystal stru…
CCDC 832999: Experimental Crystal Structure Determination
2012
Related Article: E.Matczk-Jon, B.Kurzak, W.Sawka-Dobrowolska|2012|Polyhedron|31|176|doi:10.1016/j.poly.2011.09.007
Preparation and structure of the 17-electron (η5-C5R5)Mo(OH)2(dppe) (R=Me, Et) organometallic compounds containing two gem-terminal hydroxide ligands
2000
International audience; Oxidation of (η5-C5R5)MoH3(dppe) (R=Me, Et) by Cp2Fe+ in wet THF leads to the formation of the corresponding (η5-C5R5)Mo(OH)2(dppe). These compounds show a low-potential reversible oxidation wave. The structure of the C5Et5 complex has been confirmed by X-ray diffraction methods: triclinic; space group ; a=11.030(1); b=12.533(1); c=16.241 (1) Å; α=68.585(7); β=75.197(5); γ=83.991(7)°; V=2020.6(3) Å3; Z=2; Dcalc=1.324 g cm−3, μ(Mo–Kα)=0.441 mm−1; R1=0.0325; wR2=0.0875 for 415 parameters and 6823 independent reflections [Rint=0.0177] with I=2σ(I). The molecule shows a four-legged piano-stool geometry with two terminal OH ligands in a relative trans configuration. The c…
Effect of bone loss on the fracture resistance of narrow dental implants after implantoplasty. An in vitro study
2021
Background Implantoplasty (IP) involves polishing of the exposed surface of implants affected by peri-implantitis (PI). A study was made to determine whether the degree of bone loss influences the fracture resistance of implants with or without IP. Material and Methods An in vitro study was carried out on 32 narrow (3.5 mm) dental implants with a rough surface and external hexagonal connection. Implantoplasty was performed in half of the implants of the sample. Both the IP and control implants were divided into two subgroups according to the amount of bone loss (3 mm or 7.5 mm). Standardized radiographic assessment of implant width was performed using specific software. The main outcome var…
Water and carbon oxides on monoclinic zirconia: experimental and computational insights
2014
Zirconium oxide (ZrO2, zirconia) is an interesting catalytic material to be used in biomass conversion, e.g., gasification and reforming. In this work, we show that reducing and hydrating pretreatments affect the surface sites on monoclinic zirconia. The multitechnique approach comprises temperature-programmed surface reactions (TPSR) under CO and CO2 at 100-550 °C, in situ DRIFTS investigations of the surface species and density functional theory (DFT) calculations. The key findings of the work are: (1) formates are formed either directly from gas-phase CO on terminal surface hydroxyls or via the linear CO surface species that are found exclusively on the reduced zirconia without water tre…
Metal Phosphonates Based on {[(Benzimidazol‐2‐ylmethyl)imino]bis(methylene)}bis(phosphonic Acid): Syntheses, Structures and Magnetic Properties of th…
2006
Five compounds based on {[(benzimidazol-2-ylmethyl)imino]bis(methylene)}bis(phosphonic acid) [(C7H5N2)CH2N(CH2PO3H2)2], namely [M{(C7H5N2)CH2N(CH2PO3H)2}] [M = Mn (1), Fe (2), Co (3), Cu (4), Cd (5)] have been synthesized under hydrothermal conditions. These compounds are isostructural, crystallizing in the orthorhombic space group Pbca, with a = 15.331(2), b = 10.7150(16), and c = 16.715(2) A for 1; a = 15.320(3), b = 10.477(2), and c = 16.764(3) A for 2; a = 15.207(2), b = 10.4626(16), and c = 16.794(3) A for 3; a = 15.101(3), b = 10.3517(17), and c = 16.997(3) A for 4; and a = 15.4679(19), b = 10.8923(13), and c = 16.6175(19) for 5. Each compound shows a one-dimensional chain structure w…
Complexes of organometallic compounds
1971
Abstract A number of novel compounds of dimethyllead(IV) and diphenyllead(IV) moieties with ligands having a rigid geometry when coordinating, have been prepared and characterized. The goal of the work was the building of model molecules for five-coordinated R 2 Pb IV , with known configuration of the CPbC skeleton. From spectroscopic data it is inferred that the complexes under investigation have a distorted bipyramidal trigonal structure, with the CPbC moiety allocated in the trigonal plane.