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Manganese(III) phosphate

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Manganese(III) phosphate
Names
Other names
  • Manganic phosphate
  • Manganese monophosphate
Identifiers
CAS Number
3D model (JSmol)
PubChem CID
CompTox Dashboard (EPA)
InChI
  • InChI=1S/Mn.H3O4P/c;1-5(2,3)4/h;(H3,1,2,3,4)/q+3;/p-3
SMILES
  • P(=O)().
Properties
Chemical formula MnPO4
Molar mass 149.91 g/mol (anhydrous)
167.92 g/mol (monohydrate)
Appearance Purple (anhydrous)
Pale-green (monohydrate)
Density 3.4 g/cm (anhydrous)
3.16 g/cm (monohydrate)
Melting point 400 °C (752 °F; 673 K) (decomposes, anhydrous)
Solubility in water Insoluble
Solubility Insoluble in acetonitrile, ethanol, and acetone
Structure
Crystal structure Orthorhombic
Space group Pmna
Lattice constant a = 9.65 Å, b = 5.91 Å, c = 4.78 Å
Lattice volume (V) 272 Å
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). Infobox references
Chemical compound

Manganese(III) phosphate is an inorganic chemical compound of manganese with the formula MnPO4. It is a hygroscopic purple solid that absorbs moisture to form the pale-green monohydrate, though the anhydrous and monohydrate forms are typically each synthesized by separate methods.

Production and properties

Manganese phosphate monohydrate is produced by the reaction of an Mn(II) salt, such as manganese(II) sulfate, and phosphoric acid, followed by oxidation by nitric acid. Another method of producing the monohydrate is by the comproportionation of permanganate and Mn(II) in phosphoric acid:

MnO4 + 4 Mn + 10 PO4 + 8 H → 5 + 4 H2O

The diphosphomanganate(III) ion slowly converts to the monohydrate. Heating of the monohydrate does not yield the anhydrous form, instead, it decomposes to manganese(II) pyrophosphate (Mn2P2O7) at 420 °C:

4 MnPO4·H2O → 2 Mn2P2O7 + 4 H2O + O2

To produce the anhydrous form, lithium manganese(II) phosphate is oxidized with nitronium tetrafluoroborate under inert conditions.

The anhydrous form is sensitive to moisture. In the absence of moisture, it decomposes at 400 °C, but when moisture is present, it slowly transitions to an amorphous phase and decomposes at 250 °C.

Structure and natural occurrence

Purpurite, natural MnPO4

The anhydrous form has an olivine structure and naturally occurs as the mineral purpurite. The monohydrate has a monoclinic structure, similar to that of magnesium sulfate monohydrate, but has distortions at the octahederal manganese center due to the Jahn-Teller effect. It naturally occurs as the mineral serrabrancaite.

The monohydrate form has cell parameters of a = 6.912 Å, b = 7.470 Å, β = 112.3°, and Z = 4. It consists of interconnected distorted trans- octahederons.

References

  1. ^ Yiqing Huang; Jin Fang; Fredrick Omenya; Martin O'Shea; Natasha A. Chernova; Ruibo Zhang; Qi Wang; Nicholas F. Quackenbush; Louis F. J. Piper; David O. Scanlon; M. Stanley Whittingham (2014). "Understanding the stability of MnPO4". Journal of Materials Chemistry A. 2 (32): 12827–12834. doi:10.1039/C4TA00434E.
  2. Eiichi Narita; Taijiro Okabe (1982). "Inhibition of catalytic decomposition of acid permanganate solutions". Industrial & Engineering Chemistry Product Research and Development. 21 (4): 662–666. doi:10.1021/i300008a030.
  3. ^ Narita Eiichi; Okabe Taijiro (1983). "The Thermal Decomposition of Manganese(III) Phosphate Monohydrate". Bulletin of the Chemical Society of Japan. 56 (9): 2841–2842. doi:10.1246/bcsj.56.2841.
  4. Slobotka Aleksovska; Vladimir M. Petruševski; Bojan Šoptrajanov (1997). "Infrared spectra of the monohydrates of manganese(III) phosphate and manganese(III) arsenate: relation to the compounds of the kieserite family". Journal of Molecular Structure. 408–409: 413–416. Bibcode:1997JMoSt.408..413A. doi:10.1016/S0022-2860(96)09720-7.
  5. ^ Philip Lightfoot; Anthony K. Cheetham; Arthur W. Sleight (1987). "Structure of manganese(3+) phosphate monohydrate by synchrotron x-ray powder diffraction". Inorganic Chemistry. 26 (21): 3544–3547. doi:10.1021/ic00268a025.
  6. "Purpurite". mindat.org. Retrieved 5 September 2023.
  7. "Serrabrancaite". mindat.org. Retrieved 5 September 2023.
Manganese compounds
Manganese(−I)
Manganese(0)
Manganese(I)
Manganese(II)
Manganese(II,III)
Manganese(II,IV)
Manganese(III)
Manganese(IV)
Manganese(V)
Manganese(VI)
Manganese(VII)
Phosphates
H3PO4

He
Li3PO4 Be BPO4
+BO3
C (NH4)3PO4
(NH4)2HPO4
NH4H2PO4
-N
O +F Ne
Na3PO4
Na2HPO4
NaH2PO4
Mg3(PO4)2 AlPO4 Si P +SO4
-S
Cl Ar
K3PO4
K2HPO4
KH2PO4
Ca3(PO4)2 ScPO4 Ti VPO4 CrPO4 Mn3(PO4)2
MnPO4
Fe3(PO4)2
FePO4
Co3(PO4)2 Ni3(PO4)2 Cu3(PO4)2 Zn3(PO4)2 GaPO4 Ge As -Se Br Kr
Rb3PO4 Sr3(PO4)2 YPO4 Zr3(PO4)4 Nb Mo Tc Ru Rh Pd Ag3PO4 Cd3(PO4)2 InPO4 Sn SbPO4
-SbO4
Te I Xe
Cs3PO4 Ba3(PO4)2 * LuPO4 Hf Ta W Re Os Ir Pt AuPO4 Hg Tl3PO4 Pb3(PO4)2 BiPO4 Po At Rn
Fr Ra ** Lr Rf Db Sg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og
 
* LaPO4 CePO4 PrPO4 NdPO4 PmPO4 SmPO4 EuPO4 GdPO4 TbPO4 DyPO4 HoPO4 ErPO4 TmPO4 YbPO4
** AcPO4 Th3(PO4)4 Pa U(PO4)2 Np PuPO4 AmPO4 CmPO4 Bk Cf Es Fm Md No
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