1Moscow Lomonosov State University, Department of Geology, Vorob'evy Gory, 119899 Moscow, Russia
2 Philipp-University, Department of Chemistry, Hans-Meerwein-Strasse, Marburg, Germany.
3Institute of Crystallography,
Leninskii pr. 59, 117333, Moscow, Russia
Keywords: crystal chemistry, copper and zinc phosphates,
X-ray analysis, hydrothermal synthesis, framework structures
In inorganic compounds amphotheric ZnII
and CuII complexes can form the cationic part
of the structure or play the anion role. Amphotheric metal phosphates
are of interest for a number of reasons, one of wich consists
in their formation of zeolite-like framework structures. Two new
microporous Zn,Cu fluoride phosphates have been synthesized under
hydrothermal conditions in the systhem: ZnO - CuO - NH4H2PO4
- KHF2 - LiF - H2O (T = 450oC,
P = 1000 bar). The presence of K, Cu, Zn, P and F in the
samples was confirmed with qualitative X-ray spectral analysis.
The structure formula were detarmined as a result of the crystal
structure investigation.
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a 4.8890(2) b 14.3857(5) c 7.9017(3) 90.134(4)o |
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a 37.834(8) b 9.813(2) c 16.679(3) 92.70(3)o |
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P and Zn tetrahedra together with Cu polyhedra form the mixed anionic framework. K+ cations are located in the cavities of open framework structures. The Jahn-Teller effect, wich is typical for Cu2+ ions, is expressed in specific distortions of copper centered coordination polyhedra: an elongated square pyramide [CuFO4], distorted [CuO4] tetrahedron and square planar [CuO4] coordination.
In view of our previous researches of copper and zinc compounds, namely libethenite Cu2[PO4](OH) [1], Mn2Cu5[PO4]4(OH)2 [2] , Zn2[P2O7] [3], (Na,K){Zn[PO4]}[4], CsNa3Zn7[PO4]6 [5], Zn,P-cancrinite (Cs,K)0.33[Na0.18Fe0.16(H2O)1.05]{Zn[PO4]} [6] and taking into cosideration the last results for two K,Cu,Zn phosphates K2{Cu3FZn[PO4]3} [7] and K3{Cu3FZn2[PO4 ]4 as well as the litterature data, we suggest to divide Cu and Zn phosphates into three group, according to the crystal chemical function of divalent metals. The first group comprises the compounds with Zn or Cu oxocomplexes, forming the cationic part of the structures (libethenite Cu2[PO4](OH), Mn2Cu5[PO4]4(OH)2 , Zn2[P2O7], CsNa3Zn7[PO4]6 ). Phosphates with anionic function of ZnO4 tetrahedra or(and) Cu polyhedra ((Na,K){Zn[PO4]}, Zn,P-cancrinite, K2{Cu3FZn[PO4]3}, K3{Cu3FZn2[PO4 ]4 ) form the second group . And phosphates with Zn and(or) Cu polyhedra playing both anionic and cationic role in the same compound are united in the third group (the minerals of veszelyite group (Cu,Zn)2[(As,P)O4](OH)3.H2O [8]).
The same approach can be applied for the crystal chemical interpretation
not only of phosphates, but
also of the other Zn and Cu
containing oxosalts.
References
1.Yakubovich O.V., Mel'nikov O.K., Kristallografija, 1993, 38, N1, P.63
2. Yakubovich O.V., Mel'nikov O.K., Kristallografija, 1993,.38, N1, P.58
3. Karimova O.V., Yakubovich O.V., Urusov V.S., Vestnik MGU, ser.4 Geology, 1997, N6. P.32
4. Yakubovich O.V., Mel'nikov O.K., Kristallografija, 1989, 34, N1, P.62
5. Yakubovich O.V., Mel'nikov O.K., Urusov V.S., Massa W., Vochadlo S., Doklady Akademii Nauk of Russia, 1996, 348, N6, P.755
6. Yakubovich O.V., Karimova O.V., Mel'nikov O.K., Kristallografija, 1994, 39, P. 630.
7. Massa W., Yakubovich O.V., Karimova O.V., Dem'yanetz L.N., Eur. J. Inorg. & Solid State Chem. (to be published)
8. Piret P., Deliens M., Piret-Meunier J., Canadian
Mineralogist, 1985, 23, 35.