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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Organometallics 13 (1994), S. 1044-1046 
    ISSN: 1520-6041
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 56 (2000), S. 404-406 
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The structure of the title compound, SrCrP2O7, belongs to the series of isotypic crystal structures SrMP2O7 (M = Cr, Mn, Fe, Co, Ni, Cu, Zn or Cd) and is closely related to α-Ca2P2O7. Chromium(II) shows a 4+1 square-pyramidal coordination by oxygen. [CrO5] units and the [P2O7] groups build a three-dimensional framework with channels along the a axis, and Sr occupies these channels. In addition to the work on SrCrP2O7, lattice parameters for SrMnP2O7 have been determined for the first time and unit-cell dimensions for SrZnP2O7 have been redetermined.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 56 (2000), S. 133-135 
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Single crystals of mercury(II) polyphosphate, Hg(PO3)2, were prepared from HgO in an acidic polyphosphate melt. The structure is isotypic with α-Cd(PO3)2 and comprises infinite polyphosphate chains with a period of four phosphate units. Chains of the form 1∞[PO3−] are linked by Hg2+ to form a three-dimensional network. The Hg atom is located at the centre of a distorted octahedron of O atoms with distances 2.173 (5) 〈 (Hg—O)mean 〈 2.503 (6) Å. The [HgO6] polyhedra form zigzag-like chains of the form 1∞[HgO2O4/2] parallel to the c axis.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0044-2313
    Keywords: Chromium(II)-orthophosphate ; crystal growth ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Beiträge zum thermischen Verhalten und zur Kristallchemie von wasserfreien Phosphaten. XIX. Tri-chrom(II)-bis-phosphat Cr3(PO4)2 (≙ Cr6(PO4)4) - Ein Übergangsmetall(II)- Orthophosphat mit neuem StrukturtypIntensiv blau-violette Kristalle des bislang unbekannten Tri-chrom(II)-bis-phosphats, Cr3(PO4)2, entstehen bei der Reduktion von CrPO4 mit Chrom oberhalb von 1050°C (evakuierte Quarzglasampullen, wenige mg NH4I oder I2 als Mineralisator). Die Kristallstruktur von Cr3(PO4)2 enthält sechs kristallographisch unabhängige Cr2+ in der Elementarzelle (P212121, Z = 8, a = 8,4849(10) Å, b = 10,3317(10) Å, c = 14,206(3) Å). Davon sind fünf in der ersten Koordinationssphäre von vier Sauerstoffatomen leicht verzerrt quadratisch-planar umgeben (1,96 Å ≤ d(Cr—O) ≤ 2.15 Å). Deren Koordination wird vervollständigt durch zwei bzw. drei weiter entfernte Sauerstoffatome (2,32 Å ≤ d(Cr—O) ≤ 3,21 Å). Das sechste Cr2+-Ion ist stark verzerrt oktaedrisch koordiniert (d(Cr—O): 1,97, 2,04, 2,15, 2,28, 2,29, 2,53 Å).Die vier kristallographisch unterschiedlichen [PO4]-Gruppen zeigen nur geringe Abweichungen von der Geometric eines idealen Tetraeders (1,51 Å ≤ d(P—O) ≤ 1,57 Å; 104,3° ≤ ∠(O—P—O) ≤ 114,4°).Für die Cr2+ wurde mit μexp = 4,28(2) μB (θP = -54,8(5) K) ein ungewöhnlich niedriges mittleres magnetische Moment gefunden.
    Notes: Deep blue-violet single crystals of hitherto unknown chromous orthophosphate have been obtained reducing CrPO4 by elemental Cr at temperatures above 1050°C in evacuated silica ampoules (NH4I or I2 as mineraliser). The complex structure of Cr3(PO4)2 (P212121, Z = 8, a = 8.4849(10) Å, b = 10.3317(10) Å, c = 14.206(2) Å) contains six crystallographically independent Cr2+ per unit cell. Five of them are coordinated by four oxygen atoms which form a distorted (roof shaped) square plane as first coordination sphere at interatomic distances 1.96 Å ≤ d(Cr—O) ≤ 2.15 Å. Their coordination is completed by additional oxygen atoms (2 or 3) at distances 2.32 Å ≤ d(Cr—O) ≤ 3.21 Å. The sixth Cr2+ shows six-fold octahedral coordination with strong radial distortion (d(Cr—O): 1.97, 2.04, 2.15, 2.28, 2.29, 2.53 Å).The four different [PO4] groups exhibit only minor deviations from ideal tetrahedral geometry (1.51 Å ≤ d(P—O) ≤ 1.57 Å, 104.3° ≤ ∠(O—P—O) ≤ 114.4°).An unusually low magnetic moment μexp = 4.28(2) μB (θP = -54.8(5) K) has been observed for Cr2+.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0044-2313
    Keywords: Chromium(II, III)pyrophosphate ; preparation ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Contributions on the Thermal Behaviour of Anhydrous Phosphates. IX. Synthesis and Crystal Structure of Cr6(P2O7)4. A Pyrophosphate Containing Di- and Trivalent ChromiumCr6(P2O7)4 (Cr22+Cr43+(P2O7)4) can be obtained reducing CrPO4 by phosphorus (950°C, 48 h, 100 mg iodine as mineralizer). By means of chemical transport reactions (transport agent iodine; 1050 → 950°C) the compound has been separated from its neighbour phases (Cr2P2O7, CrP3O9) and crystallized (greenish, transparent crystals; edge length up to 0.3 mm). The crystal structure of Cr6(P2O7)4 (Spcgrp.: P-1; z = 1; a = 4.7128(8) Å, b = 12.667(3) Å, c = 7.843(2) Å, α = 89.65(2)°, β = 92.02(2)°, γ = 90.37(2) has been solved and refined from single crystal data (2713 unique reflections, 194 parameter, R = 0.035). Cr2+ is surrounded by six oxygen atoms which occupy the corners of an elongated octahedron (4 × dCr—O ≍ 2.04 Å; 2 × dCr—O ≍ 2.62 Å). The Cr3+ ions are also coordinated octahedraly (1.930 Å ≤ dCr—O ≤ 2.061 Å). The crystallographically independent pyrophosphate groups show nearly eclipsed conformation. The bridging angles (P—O—P) are 136.5° and 138.9° respectively.
    Notes: Cr6(P2O7)4 (Cr22+Cr43+(P2O7)4) entsteht bei der Reduktion von CrPO4 mit Phosphor (950°C, 48 h, 100 mg Iod als Mineralisator). Mittels chemischer Transportreaktionen (Transportmittel Iod; 1050→ 950°C) kann die Verbindung von Nachbarphasen (Cr2P2O7, CrP3O9) getrennt und kristallisiert werden (grünliche, transparente Kristalle; Kantenlänge bis 0,3 mm). Die Kristallstruktur von Cr6(P2O7), (RG.: P-1; z = 1; a = 4,7128(8) Å, b = 12,667(3) Å, c = 7,843(2) Å, α = 89,65(2)°), β = 92,02(2)°, γ = 90,37(2)°) wurde anhand von Einkristalldaten (2713 symmetrieunabhängige Reflexe, 194 freie Parameter, R-Wert: 3,5%) bestimmt und verfeinert. Cr2+ ist gestreckt oktaedrisch von Sauerstoff koordiniert (4×dCr-O ≍ 2,04 Å; 2×dCr-O ≍ 2,62 Å). Die Koordination der Cr3+-Ionen ist ebenfalls oktaedrisch (1,930 Å ≤ dCr-O, ≤ 2,061 Å). Die beiden symmetrieunabhängigen Pyrophosphatgruppen haben nahezu ekliptische Konformation, während die Winkel (P—O—P) 136,5° bzw. 138,9° betragen.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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