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 Zn^II and Cu^II 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 = 450^oC, 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.

formula	unit cell parameters, A	space group	c, gr/cm3	Z	radi-ation	refl. number	R1	s
K2Cu3FZn(PO4)3	a 4.8890(2) b 14.3857(5) c 7.9017(3) 90.134(4)o	P21/m	3.81	2	CuK	975	0.0452	1.175
K3Cu3FZn2(PO4)4	a 37.834(8) b 9.813(2) c 16.679(3) 92.70(3)o	C2/c	3.60	16	MoK	4992	0.0247	0.845

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[Na_0.18Fe_0.16(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.