The hydrothermal synthesis of the new manganese and vanadium oxides, NiMnO3H, MAV3O7 and MA0.75V4O10·0.67H2O (MA=CH3NH3)
Abstract
The hydrothermal reaction of manganese or vanadium oxides in the presence of organic cations leads to the formation of new layered structures. When nickel salts are hydrothermally reacted with tetramethylammonium permanganate a new orthorhombic form of nickel manganese oxide, NiMnO
3
H
x
(where x≤1) is formed. It readily chemically intercalates lithium; it has space group Cmc2
1
, a=2.861(1) Å, b=14.650(1) Å, and c=5.270(1) Å. The magnetic properties of this compound are quite different from the ilmenite NiMnO
3
phase, showing paramagnetism above 390 K and more complex behavior below that temperature. The hydrothermal reaction of vanadium pentoxide with methylamine leads to a series of new layered vanadium oxides, which differ in structure from the corresponding ones prepared in the presence of the tetramethylammonium ion because of the existence of hydrogen bonding. Methylamine is the first organic to form a double sheet vanadium oxide, (CH
3
NH
3
)
0.75
V
4
O
10
·0.67H
2
O, with the δ-Ag
x
V
2
O
5
structure. (CH
3
NH
3
)
0.75
V
4
O
10
·0.67H
2
O is monoclinic, space group C2/m with a=11.673(1) Å, b=3.668(1) Å, c=11.095(1) Å and β=99.865(5)°. (CH
3
NH
3
)V
3
O
7
shows significant buckling of the layers compared with N(CH
3
)
4
V
3
O
7
, and has a monoclinic unit cell, space group P2
1
/c with a=11.834(8) Å, b=6.663(4) Å, c=15.193(9) Å and β=138.104(1)°.
- This article is part of the themed collection: Solid state chemistry: Novel Syntheses and New Materials: Materials Discussion 1
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