CRYSTAL STRUCTURE OF POTASSIUM PERRUTHEN ATE
June 20, 1954
[CONTRIBUTION FROM THE CHEMISTRY
3317
DIVISION, OAK RIDGE NATIONAL LABORATORY, AND THE DEPARTMENT OF CHEMISTRY UNIVERSITY OF TENNESSEE]
Crystal Structure of Potassium Perruthenate, K R U O ~ ~ . ~ BY MEYERD. SILVERMAN AND HENRIA. LEVY RECEIVED JANUARY 18,1954 The crystal structure of potassium perruthenate has been determined t o be of the scheelite type, space group C%-LI/a; the unit cell, containing four molecules of KRuO,, has the dimensions a0 = 5.609 A 0.002 A. and co = 12.991 f 0.002 A. The atomic positions are Ru a t (OOO), K a t (0, 0, l/*), 0 a t ( x y z ) and crystallographically equivalent positions withx = 0.244, y = 0.117, z = 0.073, accurate to about 0.002. The ruthenium coordination is a tetrahedron slightly flattened along the caxis, with a Ru-0 distance of 1.79 A.
Deville and Debrays first described potassium perruthenate as black brilliant orthorhombic octahedra crystals, derived from a prism of 117'. A later preparation4 was examined by D ~ f e t who ,~ reported from goniometric measurements that the crystal is tetragonal with axial ratio c/a 2.31086 and not isomorphous with potassium permanganate. The compound appears as black, tetragonal octahedra, stable in air. Barkers recognized KRu04 to be isomorphous with scheelite, CaW04. Preparation of Samples. Unit Cell and Space
Group Essentially pure potassium perruthenate was first prepared by the method of Debray and Joly.4 Small black crystals of the salt were ground t o pass a 300 mesh screen and copper-radiation Debye-Scherrer photographs of the powder were taken in cameras of 5.73 cm. and 11.4 cm. diameter. The powder pattern of potassium perruthenate was shown t o be closely similar to the pattern of scheelite with the help of nomographs devised by F r e ~ e l . The ~ lattice constants for the perruthenate were obtained with greatest precision from reflections in the back reflecting region on a DebyeScherrer pattern in which sodium chloride was mixed with the perruthenate in order to provide calibrating lines. The values adopted are: a0 = 5.609 0.002 A., co = 12.991 f 0.002 A., based on a0 for sodium chloride equal to 5.638
A.
Single crystals of the salt, required for the assignment of parameters to the oxygen atoms, were obtained in a new preparation by distilling ruthenium tetroxide into an alkaline solution of potassium ruthenate, placing the mixture in a refrigerator for several days, and washing the crop of small black crystals with the mother liquor and ice-cold distilled water. Specimens whose shapes were approximately tetragonal octahedra about 0.03 X 0.02 cm. were chosen for X-ray study. Equatorial Weissenberg photographs, using unfiltered molybdenum radiation were taken about the c- and b-axes. The observed structure factors are listed in Table I, with calculated signs given by the final parameters. The multiple film technique of de Lange, Robertson and Woodwards was employed for the visual estimation of intensities. Absorption corrections were estimated graphically and applied to the observed intensities. (1) From the doctorate thesis of M . D . Silverman, 1950. This document is based on work sponsored by the Atomic Energy Commission, under the resident graduate program of the Oak Ridge National Laboratory, the Oak Ridge Institute of Nuclear Studies, and the University of Tennessee. ( 2 ) Presented before the Division of Physical and Inorganic Chemistry, 115th National Meeting, American Chemical Society, San Francisco, Calif., March, 1949. (3) H. Sainte-Claire Deville and H. Debray, Compf. rend., 8S, 926 (1876). (4) H. Debray and A. Joly, ibid., 106, 1994 (1888). (5) M. Dufet, Bull. SOC. franc. M i n c ~ a l .11, , 216 (1888). (6)-T.V. Barker, J.. C l r m Soc;,101; 2487- (1912): (7) L. IC.Frevel H. W. R h o and H. C. Anderson, Anal. Chcm., 18,
83 (1948). (8) I. J. de Lange, J. M. Robertson and I. Woodward, Proc. Roy. SOC.(London), A l T l , 398 (1939).
TABLE I OBSERVED STRUCTURE FACTORS FOR KRIIO4 hkl
Fobad.
200 220 400 420 240 440 600 620 260 640 460 800 280 820 660 840 480 10.0.0 860 680 10.2.0 2.10.0 10.4.0 4.10.0 103 004 200 202 105 204 301 107 3 03 206 008 305 208 400 109 402 307 404 2.0.10 406 1.0.11 309 501
-37.2 -40.6 +24,8 f27.2 -28,8 +14.9 -14.2 -16.5 -14.7 -10.9 +12.1 4-10.6 - 8.5 7.4 - 8.7 6.4 6.5 - 4.5 4.0 - 3.6 3.8 - 3.6 - 3.6 3.4 +25.4 -45.4 -35.4 8.5 - 3.8 +41.1 - 6.7 - 5.7 - 8.3 3.2 +20.8 +10.6 -37.3 +27.1 8.5 - 4.9 9.4 -22.7 3.9 2.6 6.6 - 7.4 7.2
+ + + + -
+ -
+
+
+ + + + +
hkl
0.0.12 503 408 505 2.0.12 3.0.11 1.0.13 507 4.0.10 600 602 604 509 3.0.13 2.0.14 606 4.0.12 1.0.15 5.0.11 0.0.16 608 70 1 703 3.0.15 2.0.16 4.0.14 705 6.0.10 1.0.17 5.0.13 707 3.0.17 6.0.12 4.0.16 800 709 2-0.18 802 5.0.15 804 1.0.19 806 7.0.11 6.0.14 0.0.20 808
Fobsd.
-23.9 4.3 +20.2 - 7.9 +15.2 - 5.5 - 8.0 - 6.2 3.8 -12.1 < 1.3 +13.5 4.0 3.9 < 1.4 < 1.4 -12.9 - 5.8 5.5 +12.7 -13.5 - 3.9 - 5.4 3.0 -11.6 < 1.5 4.2 < 1.5 3.0 - 3.0 4.6 - 3.1 8.5 8.4 8.7 - 3.2 < 1.6 < 1.6 - 2.3 - 8.6 2.4 < 1.5 - 2.1 < 1.7 - 7.9 6.9
+
+ +
+ + +
+ + + + + +
+
+
hkl
34.18 4.0.18 24.20 5.0.17 7.0.13 901 903 8.0.10 1.0.21 6.0.16 905 907 4.0.20 7.0.15 8.0.12 3.0.21 5.0.19 2.0.22 909 6.0.18 1.0.23 10.0.0 8.0.14 10.0.2 7.0.17 10.0.4 9.0.11 4.0.22 10.0.6 5.0.21 0.0.24 3.0.23 6.0.20 8.0.16 2.0.24 10.0.8 9.0.13 7.0.19 1.0.25 10~0~10 11.0.1 11.0.3 9.0.15 4.0.24 5.0.23 8.0.18
Fobad.
-2.3 -1.7 +8.2 +2.6 +1.8 +2.6 +1.9
