3702 Inorganic Chemistry, Vol. 17, No. 12, I978 Table I. Positional and Thermal Parametersa with Estimated Standard Deviationsb for a-2UO,SO,~7H2O atom X Y Z B, A2 0.07967 (3) U(2) 0.38767 (7) 0.70137 (9) 0.20043 (3) 0.1033 (2) 1.23 (6) S(1) 0.1164 (3) 0.6890 (7) 0.1933 (8) 0.1512 (2) 1.49 (6) S(2) 0.2961 (4) 0.184 (2) O(1) -0.095 (1) 0.1451 (6) 3.6 (2) 0.189 (2) 0.0113 (7) 3.6 (2) O(2) 0.089 (1) 0.703 (2) 0.1239 (7) 3.6 (2) O(3) 0.451 (1) 0.705 (2) 0.2758 (7) 3.3 (2) O(4) 0.326 (1) 0.1194 (7) 3.0 (2) 0.514 (2) O(5) 0.043 (1) 0.734 (2) 0.1604 (6) 3.0 (2) O(6) 0.188 (1) 0.647 (3) 0.0492 (9) 4.6 ( 3 ) 0(7? 0.189 (1) 0.0940 (7) 3.8 (3) 0.850 (2) O(8) 0.030 (1) 0.1826 (8) 4.0 (3) 0.382 (2) O(9) 0.318 (1) 0.1947 ( 7 ) 3.3 (2) 0.039 (2) O(10) 0.341 (1) 0.190 (3) 0.0904 (8) 4.5 (3) O(11) 0.352 (1) 0.1467 (6) 3.2 (2) 0.167 (2) O(12) 0.164 (1) 0.2460 (7) 3.3 (2) 0.483 (2) O(13) 0.534 (1) 0.0274 (7) 4.i (3) O(14) -0.126 (1) 0.439 (2) O(15) 0.656 (2) 0.1869 (9) 4.8 (3) 0.204 (3) O(16) -0.155 (1) 0.020 (2) 0.0223 (7) 3.4 (2) 0.2368 (7) 3.4 (2) 0.892 (2) O(17) 0.556 (1) 0.290 (4) 0.073 (1) 8.3 (6) O(18) 0.595 (2) 0.4069 (9) 4.6 (3) 0.725 (3) O(19) 0.248 (2) 0.4933 C 0.291 H(1) 0.5376 0.2263 0.3904 H(2) 0.5749 0.0021 0.4109 H(3) -0.1889 0.0496 0.5349 H(4) -0.1691 0.1726 0.1982 H(5) 0.7386 0.1481 0.2337 H(6) 0.636 -0.0499 -0.0155 H(7) -0.1522 -0.0787 0.0458 H(8) -0.1857 0.271 0.8398 H(9) 0.6006 0.9967 0.2199 H(10) 0.5901 0.3111 0.0313 H(11) 0.6272 0.2564 0.0777 H(12) 0.5154 0.7538 0.4414 H(13) 0.1952 0.3629 H(14) 0.2741 0.7182 atom Bl, 4, B33 Bl, 51, 5 23 U(1) 1.05 (2) 0.98 (2) 1.54 (2) 0.01 (4) -0.27 (2) -0.01 (2) U(2) 0.95 (2) 0.95 (2) 1.51 (2) 0.03 (4) -0.18 (2) -0.02 (2) The anisotropic temperature factor has the form exp(- 0.25. (Bllh2u*Z+ 2B,,hku*b* + ...)). Here and in the following tables the numbers in parentheses are the estimated standard deviations in the least significant digit. Hydrogen positions were estimated and not refined. An arbitrary isotropic thermal parameter of 6.0 A* was assigned to each of the hydrogen atoms. Table 11. Selected Interatomic Distances (A) 1.75 ( 2 ) 1.76 (2) 2.40 (2) 2.36 (2) 2.33 (2) 2.47 (2) 2.42 (2) 1.49 (2) 1.48 (2) 1.44 (2) 1.47 ( 2 )
1.77 (2) 1.74 (2) 2.41 (2) 2.34 (2) 2.36 (2) 2.41 (2) 2.41 (2) 1.46 (2) 1.48 (2) 1.44 (2) 1.50 (2)
u p of very similar units of two bipyramids and two tetrahedra, a s shown also in Figure 1 for comparison. T h e overall structures of these chains are different; in the chain in the a form the units are repeated according to the b-axis translation, while in the 6 form the replication is by a glide plane. As a result, alternate units in the latter case have reversed orientations. T h e interatomic distances and angles are comparable in the two forms.2 The molecular volume is 2% smaller in the CY form indicating a very slightly more efficient packing. All the water molecules are hydrogen bonded, arid distances 0020-1669/78/1317-3702$01.00/0
Notes Table 111. Hydrogen Bond Distances and Angles distances, A atoms
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O(5)-0(13)-0(15) 0(7)-0( 14)-0( 19) 0(1)-0(15)-0(t 8) O(11)-0(16)-0(19) O( 6)-O( 17)-O( 15) 0(7)-0(18)-0(11) 0(2)-0(19)-0(4)
2.86 (2) 2.70 (3) 2.94 (3) 2.78 (3) 2.84 (2) 2.83 (4) 2.90 (3)
2.65 (3) 2.71 (2) 2.58 (3) 2.73 (3) 2.62 (3) 2.83 (4) 2.92 (3)
angle, deg 120 (1) 94 (1) 89 (1) 96 (1) 113 (1) 121 (1) 157 (1)
and angles for these bonds are listed in Table 111. Acknowledgment. W e thank Dr. L. K. Templeton for assistance with the refinement o f f ” . Registry No. a-2U02S04.71320,39448-26-5. Supplementary Material Available: Data processing formulas, table of angles, and the listing of structure factor amplitudes (24 pages). Ordering information is given on any current masthead page.
References and Notes This work was supported by the Division of Chemical Sciences,Office of Basic Energy Sciences, U S . Department of Energy. K,P. Brandenburg and B. 0. Loopstra, Cryst. Strurt. Commun., 2, 243 (1973). E. H. P. Cordfunke, J . Znorg. Nuci. Chem., 34, 1551 (1972). P2,ca is a nonstandard description of Pca2,. Equivalent positions for P 2 , C U : X, JJ, 2; ’ 1 2 X, -y, --2; X, -y, ‘ 1 2 -k Z ; ‘ 1 2 f X, y , ‘ 1 2 -- Z . L . K. Templeton and D. €3. Templeton, Abstracts, American Crystallographic Association Proceedings, Storrs,Conn., Series 2, Vol. 1, 1973, p 143. P. A. Doyle and P. S. Turner, Acta Crystaiiogr., Sect. A, 24. 390 (1968). D. T. Cromer and D. Liberman, J . Chem. I’hys., 53, 1891 (1970). L. K. Templeton and D. H. Templeton,Acta CrjJstaiiogr.,Sect. A. 34, 368 (1978).
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Contribution from the Chemistry Departments, Nuclear Research Institute, Baghdad, Iraq, and University of Massachusetts, Amherst, Massachusetts 01 003
Crystal Structure of Tetrakis(2,2’-bipyridine dioxide)lanthanum Perchlorate: An Example of Cubic Eight-Coordination A . R . Al-Karaghouli, R. 0 . Day, and J. S. Wood* Receiced August 4 , 1978
On the basis of ligand-ligand repulsions the cube is expected to be a much less favorable coordination geometry for discrete eight-coordinate complexes than the dodecahedron (D2d)or the square antiprism (D4J, for both of which structurally characterized examples abound in the literature.’ However, of the comparatively few examples of MLx stoichiometry (L = unidentate ligand) whose structures have been determined, two of these in fact have cubic geometry, namely, PaFx3-’2and U(NCS)2-3 in the form of its tetraethylammonium salt. The latter complex ion is of interest, for in the cesium salt it adopts the square-antiprismatic geometry4 suggesting that the counterion and crystal-packing arrangement may dictate the geometry and that cubic eight-coordination may not be that unfavorable, a t least for the heavier elements. Approximately cubic geometry is also apparently found in another complex of uranium, namely, tetrakis(bipyridyl)urani~m,~ and we have found for the octakis(pyridine N-oxide) complexes of the lighter lanthanides L n ( ~ y 0 ) ~ that ~ ’ while in one of the crystalline forms the complex ions have a square-antiprismatic geometry, in a second form the coordination polyhedron is distorted from the D4d geometry toward that of a cube, rather *To whom correspondence should be addressed at the University of Massachusetts.
0 1978 American Chemical Society
Inorganic Chemistry, Vol. 17, No. 12, 1978 3703
Notes than toward the dodecahedron or other eight-coordinate geometrye6 As part of a continuing interest in the stereochemistries and electronic structures of complexes having N-oxide ligands we have determined the structure of the tetrakis complex of lanthanum perchlorate with the bidentate ligand 2,2'-bipyridine dioxide [ L a ( b ~ y O ~ ) ~and ~ + find ] this to have nearly cubic coordination geometry. So far as we are aware this represents the first structurally characterized example of a complex containing this ligand, although many complexes containing it are known,7 and the first example of cubic eight-coordination for a lanthanide.
Experimental Section The complex La(bpy02)4(C104)3was prepared according to literature methods: and crystals suitable for X-ray analysis were obtained from ethanolic solution. Anal. Calcd for LaC40H32N8020C13: C, 40.40; N, 9.42; H, 2.70; CI, 8.95. Found: C, 40.48; N, 9.25; H, 2.51; CI, 8.91. Preliminary Weissenberg and precession photography indicated m m m (D2*)Laue symmetry, and the systematic absences, hkO for h k # 2n, h01 for 1 # 2n, and Okl for k # 2n, are in accord with the unambiguous choice of space group Pbcn (D2h14, No. 60).' Data Collection. A wedge-shaped crystal having a maximum dimension of 0.30 mm was cut from a larger crystalline mass and mounted on the tip of a glass fiber. Intensity data were collected using an Enraf-Nonius CAD 4 automated diffractometer and graphitemonochromated molybdenum radiation (fine-focus tube, 45 kV, 20 mA, takeoff angle 3.1°, h(Ka,) 0.70926 A, X(Ka,) 0.71354 A). The lattice constants as determined by the least-squares refinement of the diffraction geometry for 25 reflections having 11.0' I B(Mo Ka) I 16.0' and measured at an ambient laboratory temperature of 22 & 2 'C are a = 12.990 (4), b = 25.884 (7), and c = 14.032 (5) A. A unit cell content of 4 formula units gives a calculated density of 1.695 g/cm3, in good agreement with the observed value of 1.705 g/cm3. This implies crystallographic C2or C, symmetry for the complex ion and probable C, symmetry for one of the perchlorate ions, the others being in general positions. Data were collected using the 8-28 scan mode, with a 8 scan range of (0.55 0.35 tan 8)' centered about the calculated Mo Ka peak position. The scan range was actually extended an extra 25% on both sides of the aforementioned limits for the measurements of background radiation. The scan rates varied from 0.6 to 4.0" 6/min, the rate to be used for each reflection having been determined by a prescan. The intensity, I, for each reflection is then given by I = ((FF)/S)(P- 2(B1 B2)),where P is the counts accumulated during the peak scan, B1 and B2 are the left and right background counts, S is an integer which is inversely proportional to the scan rate, and FF is either unity or a multiplier to account for the occasional attenuation of the diffracted beam. The standard deviations in the intensities were computed as u; = ((FF)2/S2)(P + 4(B1 B 2 ) ) + 0.00212. A total of 2719 independent reflections having 2' I 28(Mo/Ka) 5 43" were measured in the region +h, +k, +I, and, of these, five standard reflections, monitored after every 12000 s of X-ray exposure time, gave no indication of crystal deterioration or loss of alignment. No corrections were made for absorption ( ~ ( M Ka) o = 1.15 mm-I), and the intensities were reduced to relative amplitudes by means of standard Lorentz and polarization factors including the corrections for the monochromator. The 352 reflections having I I 0 . 2 were ~ ~ treated as unobserved and were assigned F, = [c~,/Lp]l/~ and uFo= 0.5F0/c, where c = 0.2 and Lp is the Lorentz-polarization factor. Solution and Refmement of Structure. All computations were carried out on a CDC Cyber 74 computer using local modifications of Zalkin's FORDAP Fourier program, Germain, Main, and Woolfon's directmethods program MULTAN, Prewitt's SFLS and SFLSR full-matrix least-squares routines, and various locally written programs. Neutral-atom scattering factors were taken from the tabulation by Cromer and Waber,lo and an anomalous dispersion correction was included for the lanthanum atom." The agreement factors are defined in the usual manner,12and in all least-squares refinements the quantity minimized was Cw(lFol the weights being evaluated as w1/2 = 2LpFo/u,. The solution of the structure was relatively straightforward, although extensive pseudosymmetry was evident in an initial Fourier map based on the lanthanum atom coordinates derived from a Patterson synthesis. Initial coordinates for 18 independent atoms, including the lanthanum, were in fact obtainable by direct methods despite the pseudosymmetry. Coordinates for the remaining non-
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Table 1. Positional Parameters for La(bpyO,),(C1O,),a~b atom X Y 2 La 0.0 0.23372 (2) 0.25 01 0.0086 (4) 0.2354 (2) 0.0713 (4) N1 0.0666 (5) 0.2681 (2) 0.0238 (4) c11 0.0243 (7) 0.3137 (3) -0.0049 (6) c12 0.0871 (8) 0.3489 (3) -0.0577 (6) C13 0.1893 (7) 0.3372 (3) -0.0783 (6) 0.2295 (6) C14 0.2895 (3) -0.0484 (6) 0.1671 (7) C15 0.2558 (3) 0.0020 (5) 0.1810 (4) 02 0.2292 (2) 0.1910 (4) 0.2154 (4) N2 0.1943 (2) 0.1271 (4) 0.2572 (6) c 21 0.1497 (4) 0.1582 (7) 0.2950 (7) c22 0.1133 (3) 0.0945 (7) 0.2860 (7) C2 3 0.1216 (3) -0.0002 (8) 0.2404 (6) C24 0.1690 (3) -0.0319 (6) 0.2061 (6) C25 0.2042 (3) 0.0332 (6) 03 0.0827 (4) 0.15 36 (2) 0.3142 (3) N3 0.0282 (5) 0.1160 (2) 0.3551 (5) 0.0135 (6) C31 0.1182 (3) 0.4540 (6) C32 -0.0411 (7) 0.0795 (4) 0.5003 (7) c33 -0.0806 (7) 0.0386 (4) 0.4468 (8) -0.0655 (6) c34 0.0360 (3) 0.3461 (8) -0.0121 (6) c35 0.0770 (3) 0.3013 (6) 04 0.0903 (4) 0.3144 (2) 0.3042 (3) N4 0.1177 (5) 0.3152 (2) 0.2428 (4) C41 0.2123 (6) 0.3507 (3) 0.2035 (6) C42 0.2417 (7) 0.3900 (4) 0.1447 (6) c43 0.1761 (8) 0.4311 (4) 0.1238 (6) c44 0.4317 (3) 0.0776 (7) 0.1641 (6) c45 0.0507 (6) 0.3909 (3) 0.2251 (5) c11 0.2766 (2) 0.0141 (1) 0.3575 (2) 011 0.2118 (5) 0.0465 (2) 0.4143 (5) 012 0.3119 (10) 0.0421 (4) 0.2828 (7) 013 0.3575 (6) 0.4141 (7) -0.0015 (3) 014 0.2202 (8) -0.0305 (3) 0.3272 (5) c12 0.5 0 0.25 0.2997 (2) a Esd's in parentheses. The oxygen atoms of perchlorate ion 2 (021. . .024) were refined as a rigid group constrained to the twofold axis. The group parameters are as follows (anales in radians): x,, 0.50; y,, 0.3003 (5);z,, 0.25; @,-2.832
