- The Crystal Structure of MnF3 Revisited
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We correct the crystal structure of MnF3, of which the space group was reported as monoclinic C2/c (no. 15) with a = 8.9202, b = 5.0472, c = 13.4748 ?, β = 92.64°, V = 606.02 ?3, Z = 12, mS48, T not given, likely 298 K. In the structure model proposed here, we use a unit cell of one third of the former volume. The ruby red crystals of MnF3 were synthesized by a high-pressure/high-temperature method, where MnF4 was used as a starting material. As determined on a single crystal, MnF3 crystallizes in the monoclinic space group I2/a (no. 15) with a = 5.4964(11), b = 5.0084(10), c = 7.2411(14) ?, β = 93.00(3)°, V = 199.06(7) ?3, Z = 4, mS16, T = 183(2) K. The crystal structure of MnF3 is related by a direct group-subgroup transition to the VF3 structure-type. We performed quantum chemical calculations on the crystal structure to allow the assignment of bands of the obtained vibrational spectra.
- Bandemehr, Jascha,Stoll, Christiane,Heymann, Gunter,Ivlev, Sergei I.,Karttunen, Antti J.,Conrad, Matthias,Huppertz, Hubert,Kraus, Florian
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- Mass and FTIR spectroscopic investigations of gaseous manganese tetrafluoride
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Knudsen effusion mass spectrometry has been applied to establish the optimum in situ conditions for the MnF4 synthesis. MnF4 has been generated in the gas phase over the MnF3(s)-TbF4(s) system at 650-780 K in the Knudsen cell. Under the same conditions the supplying gas for the matrix isolation IR spectra was formed. The infrared spectrum of argon-isolated MnF4 molecules has been obtained for the first time. A Td symmetry is suggested for the MnF4 molecule.
- Nunziante Cesaro,Rau,Chilingarov,Balducci,Sidorov
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p. 179 - 181
(2008/10/08)
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- Synthesis of Manganese Tetrafluoride at Atmospheric Pressure
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The fluorination rate of powdery MnF3 is measured by the gravimetric method at 450-540°C, fluorine partial pressure 1.0-10.1 kPa, near-atmospheric total pressure, and the linear rate of (F2 + N2) gas mixture 2.0 cm/s. It is shown that the rate law of fluorination α = 10-0.14exp[-84.7 × 103/RT]ρF20.57τ. A new procedure of MnF4 synthesis from particulate MnF2 and MnF3 in a fluorine flow at atmospheric pressure and the design of a fluorination reactor are described. They are shown to afford relatively high reaction rates (up to 35 g/h based on MnF4) and high yields with respect to fluorine (up to 42%).
- Rakov,Khaustov,Ostropikov
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p. 465 - 469
(2008/10/08)
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- Kinetics of Fluorination of Manganese Compounds with Fluorine Gas
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The kinetics of fluorination of MnO2, MnF2, and KMnF3 powders by fluorine in nitrogen carrier gas at atmospheric pressure was studied by gravimetry. The kinetic equations of fluorination were deduced. MnO2 converts to MnF3 markedly more rapidly than MnF2. The volatile product (MnF4) forms above 780 K.
- Rakov,Ostropikov,Khaustov
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p. 149 - 153
(2008/10/08)
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- The Crystal Structure of Manganese Tetrafluoride
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Single crystals of dark blue MnF4 have been obtained by high pressure fluorination (pF2 ca. 3 kbar) of MnF2.There exist two modifications: α-MnF4 crystallizes tetragonally body centered with a = 12.63(1), c = 6.049(5) Angstroem, space group I41/a-C4h6 (No. 88), Z = 16; the structure of β-MnF4, (probably) rhombohedral with a = 19.56(2), c = 13.00(1) Angstroem, Z = 72, is yet unknown in detail.MnF4 is paramagnetic with μeff (301.2 K) =3.87 B.M..The Curie-Weiss law is obeyed down to 22.4 K; the Madelung Part of lattice energy (MAPLE) is calculated to be 2475 kcal/mol. - Key words: Manganese Tetrafluoride, Preparation, Crystal Structure, Magnetism, MAPLE
- Mueller, Bernd G.,Serafin, Michael
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p. 1102 - 1106
(2007/10/02)
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