2. D.L. Rogachev, V. Ya. Kuznetsov, A. I. Gusev, and E. B. Chuklanova, Zh. Strukt. Khim., 30, No. 4, 182-184 (1989).

3. L.P. Solov'eva, V. E. Ovchinnikov, E. N. Ipatova, and V. I. Andrianov, Kristallografia, 24, No. 4, 821-823 (1979).

4. C.M. Sheldrick, SHELX-76: Program for Crystal Determination, Cambridge University Press, England (1976).

5. R.L. Davidovich, M. A. Medkov, M. D. Rizaeva, and B. V. Bukvetskii, Izv. Akad. Nauk SSSR, Ser. Khim., No. 7, 1447-1452 (1982).

CRYSTAL STRUCTURE OF KsHf3Flv.H20

A. I. Gusev, E. B. Chuklanova, V. Ya. Kuznetsov, and D. L. Rogachev

UDC 548.736:546.832'32'161

Our research into the system HfO 2-SO 3-KF-H20 identified the compound in [I] as Kz.7sHf55.Ts.0.SH20. We now assign it the formula HsHf3FIT.H20. Parameters of the unit cell are [a = 8.359(3), b = 13.288(3), c = 15.177(3) ~, space group Pnam, V = 1685(1) ~3, Z = 4, Pcalc = 4.222(3) gm/cma]. The intensities of 1350 reflections with I ~ 2a(1) were determined on a CAD-4 automatic diffractometer (IMoK~, ~/20 scan, graphite monochromator, Hma X = 9, Kma x = 15, Lma x = 18). Structural calculations were carried out using the SHELX suite of programs [2]. The structure was solved by the heavy atom method and refined using anisotropic temperature factors to give R = 0.052. For the final refinement we used 1305 reflections. Atomic coordinates and their errors are given in Table i.

One of the two independent hafnium atoms (Hf I) occupies a general position, the other one (Hf 2) is situated on the m plane (Fig. i). This, and the other Hf atom, are each coordi- nated by 7 F atoms (Hf-F distances in the polyhedra are given in Table 2). The polyhedron of both Hf atoms can be regarded as distorted pentagonal bipyramids with F 5 and F 6 occupying the apices in the Hf I polyhedron and F 7 and F 9 those in the Hf 2 polyhedron. Distortion of the bipyramids is manifested in a puckering of the equatorial plane. In the Hf, polyhedron the F l (F 5 -F ! = 3.15 ~) and F 2 (F 6 -F 2 = 3.14 ~) atoms are particularly strongly displaced from this plane. The distances from the peaks of the Hf I to the remaining atoms of the equatorial plane lie within 2.62-3.10 ~ (error for the F-F distances is 0.02 ~). In the Hf 2 polyhedron the most strongly displaced atoms from the equatorial plane are Fl0 (F 9-FI0 = 3.50 A) and F s (F 7-F 9 = 3.18 ~).

The gf Z polyhedra are joined in pairs across the common F I -F~ edge. This grouping is joined to the Hf 2 polyhedra across the F 4 vertex. Thus infinite anion chains [(Hf3FlT)5-]~ are formed along the c axis (Fig. 2). The K + cations and H20 molecules lie between the chains. Eight F and O atoms are situated at distances of less than 3.3 i from the K l atom and nine F atoms from K 2 and K 3 (Table 3).

Molecules of H20 lie in the mirror plane m and are situated opposite the~7-F10 and Fl0-F 9 edges of the Hf 2 polyhedron. The shortest Hf 2-0 distance is 3.82(2) i. Those to

TABLE I. Atomic Coordinates

Ator~ x y z Atom_ x y z

HIt Hr.2 K~ Ke Ks F~ F2 F3

0,4170(i) 0,f485(2) 0,327t (7) 0,095t(7) 0,t360(t0) 0,430(2) 0,444(2) 0,377(2)

0,6052(1) 0,4521(t~ 0,2247(4) 0,4076(4) 0,7526(6) 0,444(1) 0,721(i) 0,725(i)

0,0602 0,25 0,1314(4) 0,5590(4) 0,25 0,042(i) 0,979(I) 0,137(I)

F, Fs F~

i!o 0,282(2) 0.209(2) o,616(2) 0,357(2) 0.062(2) o,oo4(3) 0,068(2) 0,308(4)

o.54S(1) o,59o(.~) ,J,598(1) 0,379(t) 0,433(t) o,57.1(t) o,3o8(i) 0.595(2)

0J6T(1) 0,999(I) 0,128(I) 0,25 0,372(I) 0,25 0,25 0,75

GNIIKHTEOS, Moscow. IKHTREMS KNTS Russian Academy of Sciences, Apatiti. Translated from Zhurnal Strukturnoi Khimii, Vol. 33, No. 6, pp. 195-197, November-December, 1992. Orig- inal article submitted December 16, 1991.

0022-4766/92/3306-0937512.50 �9 1993 Plenum Publishing Corporation 937

f~ ~5

\ / ,\ r/"

$ ' o / " \ ' \ 07 o d o~ o e c.

d'" "\O ,, H"F OK 07 eO

Fig. l Fig. 2

Fig. i . Structure of KsHfaFIT.H20. Projection yz.

Fig. 2. Scheme for the chains in the KsHf3FIT.H20 structure. jection yz.

Pro-

TABLE 2.

Atoms IDistance Atoms

h

1 HfI--F I 2,12 HfI--F 4 Hf~--F~ 2,t6(t) Hf~--F~ Hf,- -F 2 1,98(I) Hft--F6 H~--F~ 2,000)

Hf-F Distances (A) in the Hf Polyhedra

�9 f Distant I: Atom.~

2,11(I) HL--F4(2) '1,99(I) Hf2--F ~ t,96(1) Hf2--F~(2 )

I Distanc~ Atoms

I 2,11(I) Hf2--F~ 2,00(2) i H[~--FIo 2,0i(I) ;i

d

Distance

i ,99(2) 2,03(2)

TABLE 3. K-F and K-O Distances (A)

Atoms Dis tance Atoms Dis tance Atoms Dis tance

K1--F 2 K1--F5 K1--Fi o KI--F~ KI--O

' K,--F~ K~--F~ KI--F,

2,65 2,68 2,74 2,74 2,74 2,82 2,87 3,03

Ko --F 6 K~,--F~ K~--F~ K~--F~ K~--F s Ko--F s

K.--F IG--F~

2,64 2,70 2,71 2,71 2,74 2,75 2,87 3,03 3,23

Ks--F. K3--Fa(2) K3--F~(2) K~--F3(2) K3--F4(2)

2,66 2,67 2,72 2,78 3,24

the F atoms are 0-F 7 (2.82 A) and 0-F10 (3.02 A). It is probable that the H20 molecule forms hydrogen bonds with these atoms thereby joining the chains of Hf polyhedra.

1.

2.

LITERATURE CITED

M. M. Godneva, D. L. Motor, R. F. Okhrimenko, and S. D. Nikitina, Zh. Inorg. Khim., 34, No. 2, 508-512 (1989). C. M. Sheldrick, SHELX-76, Program for Crystal Determination, University of Cambridge ( 1 9 7 6 ) .

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