Vol. 5, No. 2, February 1966
NOTES 317
CONTRIBUTION FROM THE DEPARTMENT OF CHEMISTRY, scattering curve were made according to the tables of Dauben and MASSACHUSETTS Templeton .17 INSTITUTE OR TECHNOLOGY, CAMBRIDGE, MASSACHUSETTS The interesting feature of the photographs obtained in this study was the sharp division of the diffraction spots into two sets, one set having very high intensity and one set having very low The Crystal and Molecular Structure intensity. The former group obeyed the condition that h k 1 = 2n, indicating that the ruthenium atoms formed a bodyof Tetragonal Ruthenium Dioxide1 centered array and, therefore, contributed nothing to the refleck 1 # 212. The latter condition was obeyed tions with h BY F. A . COTTON AND J. T. M A G U E ~ by the spots of very low intensity. It thus seemed likely that the original assignment of the rutile structure to RuOz was, in this Received July 16,1965 case, correct, and refinement was carried out in the space group P4~/mnm. Least-square refinement of four scale factors, the The marked tendency of Re(II1) to form metal-atom oxygen x parameter, and isotropic temperature factors for each clusters3-11 leading to essentially diamagnetic comatom by the usual methods led to a conventional residual of 0.141. pounds suggested that compounds of other d4 heavy Similar refinement in the other possible space groups met with less success indicating that P42/mnm is probably correct. No transition metals having similar magnetic properties significant anomalies were found on the final Fourier difference might also show evidence of metal-atom cluster formap. mation. Like the trimeric Re(II1) compounds! RuO2 The final value of the oxygen x parameter was 0.302 rt 0.002, is highly colored and exhibits a very low magnetic which gives Ru-0 distances of 1.917 ayd 1.999 8. (both f0.008 susceptibility (203 X c.g.s. unit/mole a t 298’K.).12 8.). The closest 0-0 contact is 2.52 A. The previous studiesl3 gave only a mean Ru-0 distance of 1.97 8. with unspecified unThis suggested the presence of some form of strong certainty. The final observed (FOBS) and calculated (FCAL) metal-metal interaction. Although early reports13 structure factors are listed in Table I.
+
+
+ +
based only on powder diffraction data have stated that most transition metal dioxides, including RuO2, MoOz, and WOs, have the rutile structure, this assignment has later been found to be erroneous in the case of Moo2 and WOz. These compounds adopt a distorted form of the basic rutile structure14 in which the metal atoms occur in pairs with the shorter metal-metal distances being -2.5 fi. Thus i t was thought that a similar error might have been made in the case of RuO2, and i t seemed desirable to reexamine this compound by single crystal methods.
Experimental Section Crystals of RuO; grown by high-temperature sublimation in a stream of oxygen were kindly supplied by Professor H. Schafer of the University of Miinster. Anal. Calcd. for RuOz: Ru, 75.95. Found: Ru, 76.00, 76.05, 76.08. Precession photographs of the h01 and Okl zones estatlished that the unit cell ws! tetragonal with a = 4.491 =!= 0.007 A. and c = 3.107 =I=0.005 A. The only observed systematic absence was Okl for k 1 # 2n, which is consistent with the space groups P4~/mnm(No. 136), PJn2 (No. 118), and P 4 m n (No. lO2).’5 There are two formula units per unit cell. The intensity data were collected and corrected in the customary manner .le The equi-inclination Weissenberg method and Zr-filtered Mo Ka radiation were used. Anomalous dispersion corrections to the real part of the ruthenium
+
(1) Supported by the United States Atomic Energy Commission. (2) National Science Foundation Predoctoral Fellow. (3) J. A. Bertrand, F. A . Cotton, and W. A. Dollase, J . A m . Chem. Soc., 85, 1349 (1963); Inovg. Chem., 2, 1166 (1963). (4) W. T. Robinson, J. E. Fergusson, and B. R . Penfold, Proc. Chem. Soc., 116 (1963). ( 5 ) F. A. Cotton and J. T. Mague, ibid., 223 (1964); Inovg.Chem., 3, 1402 (1964). (6) F. A. Cotton and J. T. Mague, ibid., 3, 1094 (1963). (7) J. E. Fergusson, B. R. Penfold, and W. T. Robinson, Natuve, 201, 181 (1964). ( 8 ) J. E. Fergusson and W. T. Robinson, Proc. Chem. Soc., 189 (1964). (9) F. A. Cotton and S. J. Lippard, J . Am. Chem. Soc., 86, 4497 (1964). (10) F. A. Cotton, S. J. Lippard, and J. T. Mague, Inorg. Chem., 4, 508 (1965). (11) B. H. Robinson and J. E. Fergusson, J . Chem. Soc., 5683 (1964). (12) A. N. Guthrie and L. T. Bourland, Phys. Rei’., 37,303 (1931). (13) P. P. Ewald and C. Hermann, “Strukturberichte, 1913-28,” Akademische Verlagsgesellschaft M B H Leipzig, 1931. (14) A. Magneli and G. Andersson, Acta Chem. Scand., 9, 1378 (1955). (15) “International Tables for X-Ray Crystallography,” Kynoch Press, Birmingham, England, 1952, Vol. I. (16) See ref. 6, for example.
TABLE I OBSERVED AND CALCULATED STRUCTURE FACTORS #
1.
L
0 0
0 00
01
0
I
0 0
loBS
FCLL
, 6
3 31
I 5 a 0 1 1
I1
5
0 0 0 0 0 0 0 0 0 0 1 1
1 I 1
I
,
.n. 49.
.,.
37. I>.
2 2
L9.
23
b9.
11.
6 1. .
2 2 I 2
Y
‘I. 40. 36. 11.
b2. 0. .2. 96.
-9. .>a
-*.
6.
.L -0. 51. 11.
29.
-3. 11. 0.
IO05
FCAL
32. -5. 10. 5.
*2
. 3 I3
5
36. 7. 37, 0.
L
0
I. L 0. I.
1
I
43. 0.
2 2I
1
2
1
IO8S
0.
l3 bi 1*
3
-0. -36, ..
0 0
0.
41.
LO.
27. 33.
.19. o.
-3,
0. 60.
.I. 21. 9. 1 95 ..
25s
-8 * L3.
-0.
60.
35.
I‘.0 .
0.
28.
-3. 31.
5..
0.
.2 * I‘.
5.
60
r2.
.I. -I.
LO.
31.
.I.6.
53. 5.
39.
-36. 3.
12.
.I. 3.
37.
30. 3. 1
2
-0. 28,
35. I.
0.
10.
?
