Structure studies of thortveitite-like dimanganese diphosphate, Mn2P2O7

Abstract

temperature factors. It remains to be seen whether or not a sample with composition R6T6M 5 forms an identical structure but without T-T waist contacts. (1)% V= 252.6 (1) A 3, Z= 2, Dx= 3.732 (1) Mg m -3, F(000) = 272, T= 295 K. X-ray powder diffraction data (Cr Ka l, 2 = 2.28975 A, R = 0.083 for 35 reflections), X-ray single-crystal data (MoKa, 2=0.7107A, /z=5.86mm -l, R=0.040 for 672 reflections), and neutron powder diffraction (2= 1.8820/k, R t = 0.051 for 50 reflections). Isomorphism with thortveitite, 8c2Si207, is confirmed, but the refinements, using both a linear and a split-atom model, indicate a disordered bridging oxygen in the diphosphate anion with a non-linear P-O-P bond of 165.9 (1) °. The metal-oxygen distances conform with those of similar compounds. The JCPDS Diffraction File No. is 35-1497 for Mn2P207.Introduetlon. Among the condensed diphosphates there are often groups of isomorphous compounds, e.g. many divalent-metal M2P20 7 diphosphates crystallize with the thortveitite-type structure. The crystal structure of thortveitite, (Sc,Y)2Si207, was originally determined by 0108-2701/84/121995-05501.50 Zachariasen (1930). The space-group symmetry was reported as C2/m, which implies a linear Si-O-Si bond in the disilicate anion. The metal ions are octahedrally coordinated. Since then many studies of thortveitite-type M2X207 compounds (X = Si, P, V or As) have been published, which have in common the peculiarities that the bridging oxygen has a very large thermal motion, and the XO4 tetrahedra are more regular than they should be, considering that they share corners with each other (cf Cruickshank, 1961).

Oxygen‐Atom Transfer Chemistry and Thermolytic Properties of a Di‐tert‐Butylphosphate‐Ligated Mn4O4 Cubane

“…Samples heated to 800 °C, by contrast, display XRD peaks consistent with a manganese metaphosphate/pyrophosphate mixture (Figure 5), 2 Mn(PO 3 ) 2 –Mn 2 P 2 O 7 (Mn 4 P 6 O 19 ) 63. 64 This ratio of phosphates is in agreement with the stoichiometry of Mn and P in complex 1 and with the final ceramic yield at 800 °C (expected: 46.1 %; observed: 47.0 %).…”

Nanocrystalline manganese dihydrogen phosphate dihydrate Mn(H2PO4)2·2H2O and its decomposition product (Mn2P4O12) obtained by simple precipitation route

“…Several manganese (III) phosphates such as MnP 3 O 9 [9], MnPO 4 ·H 2 O [10], MnPO 4 [11], MnHP 2 O 7 [12] and Mn 3 (PO 4 ) 3 [13] are known. Manganese in the oxidation states +2 is observed in MnP 4 O 11 [14], Mn 2 P 4 O 12 [15], Mn 2 P 2 O 7 [15], ␤-Mn 3 (PO 4 ) 2 [16] and Mn 2 P 2 O 7 ·2H 2 O [17], Mn(H 2 PO 4 ) 2 ·2H 2 O [18], etc.…”

“…The Mn(H 2 PO 4 ) 2 ·2H 2 O was synthesized from manganese(II) carbonate and phosphoric acid at low temperature (60-80 • C) with a long time period (>8 h) [15,16], while Mn 2 P 4 O 12 was prepared from manganese chloride and 85%w/w phosphoric acid by hydrothermal or high temperature (300-500 • C) method with along time period (∼20 h) [21]. The other preparation methods have been developed using Mn 2 P 4 O 12 to synthesize Mn 2−x A x P 4 O 12 (A = Ca, Cu, Ba, 0 < x < 2) for using as inorganic pigment in ceramics [22,23].…”

Phosphates: Solid‐State Chemistry

“…7 In general, apparently linear P-O-P linkages in condensed phosphates arise from such disorder and do not reflect a stable geometry.…”