2667
Inorg. Chem. 1982, 21, 2667-2675
Contribution from the Department of Chemistry, Texas A&M University, College Station, Texas 77843
Structures of Two Dirhodium(11) Compounds Containing Hydrogen-Bonded Nitroxyl Groups: 1-0xy)dirhodiumTetrakis(trifluoroacetato)bis( 2,2,6,6- tetramethyl-4-hydroxypiperidinyl(11) and Tetrakis(trifluoroacetato)diaquadirhodium(II) Di-ferf -butyl Nitroxide Solvate F. ALBERT COTTON* and TIMOTHY R. FELTHOUSE Received November 19, 1981 The crystal and molecular structures have been determined by single-crystal X-ray diffraction techniques for the following (2) (Tempol = 2,2,6,6-tetramethyltwo compounds: Rhz(OzCCF3)4(Tempol)2(1) and Rh2(02CCF3)4(H20)2.2DTBN 4-hydroxypiperidinyl-1-oxy and DTBN = di-tert-butyl nitroxide). Compound 1 crystallizes as dark blue prisms in the space group P2, n with two dinuclear molecules residing on crystallographic centers of inversion in a cell of dimensions a = 8.4087 (6) , b = 19.5393 (19) A, c = 12.1912 (10) A, j3 = 107.785 (7)O, and V = 1907.3 (7) A3. The structure was solved by the heavy-atom Patterson method and refined with use of 31 12 data with I > 3 4 0 to final discrepancy indices of R , = 0.035 and R2 = 0.046 with the inclusion of all hydrogen atoms. Four trifluoroacetate groups span the Rh-Rh bond of length 2.405 (1) A; the axial positions are occupied by Tempol ligands, each coordinated at 2.240 (3) A through the 4-hydroxyl oxygen atom, O(5). The Rh'-Rh-O(5) angle is slightly distorted from linearity with a value of 176.39 ( 8 ) O . The piperidine rings of the Tempol ligands in 1 adopt a chair conformation with the N-O bond making an angle of 18.6O with the C2N plane. The nitroxyl oxygen atoms participate in intermolecular hydrogen bonding with the hydroxyl groups from adjacent dinuclear molecules linking the Rh2(0zCCF3)4(Tempol)2 molecules into zigzag chains through the crystal. Compound 2 crystallizes as dichroic irregularly shaped prisms in the space group Pi with one formula unit located on a crystallographic center of inversion in a unit cell of dimensions (I = 10.3765 (20) A, b = 12.1955 (10) A, c = 8.4080 (9) A, CY = 101.442 (S)", j3 = 109.167 (14)', y = 99.439 (11)O, and V = 954.4 (6) A3.The structure was solved by conventional Patterson, Fourier, and least-squares refinement techniques using 3181 data with I > 3 4 to R l and R z values of 0.032 and 0.046, respectively. All hydrogen atoms were included in the refinement. The structure is comprised of Rh2(0zCCF3)4(H20)2 and DTBN molecules with the four trifluoroacetate groups bridging in conventional fashion the Rh-Rh bond of length 2.409 (1) A. Water molecules occupy the axial positions at 2.243 (2) A from the Rh atoms. The water hydrogen atoms participate in hydrogen-bondinginteractions with the nitroxyl oxygen atoms of the DTBN molecules. Two DTBN molecules are found for each dirhodium unit, and these are situated between neighboring Rh2(02CCF,)4(H20)zmolecules. Only one genuine hydrogen bond is formed for each hydrogen atom of the water molecule, although a number of other close contacts exist. The C 2 N 0 group of the nitroxide molecule is nearly planar with the N-O bond making an angle of only 0.7O with the C2N plane. A detailed examination of the structural parameters in eight Rhz(0,CCF3),L2 complexes reveals that the trifluoroacetate bridging groups are essentially unchanged in dimensions upon substitution of a variety of axial donor ligands with the only significant structural changes occurring as a consequence of variations in the L-Rh-Rh-L bonding. The intermolecular hydrogen bonding in 1 and 2 closely resembles that observed in structures of organic nitroxide compounds.
6.
Introduction During the past decade, a vast number of studies have been undertaken on tetrakis(carboxy1ato) complexes of the transition elements containing metal-to-metal bonds.'V2 Naturally, a change in t h e metal atoms or their valence state alters the chemical and electronic properties of M2(02CR),L2 type compounds. These properties may also be very effectively altered by changes in the identity of the R group or the axial donor ligand, L. Substitution of R = CF3for CH, in the group 6B tetracarboxylates causes pronounced variations in the chemical and structural characteristics of these compounds. The Cr-Cr distance of 2.541 (1) A in C r 2 ( 0 2 C C F 3 ) 4 ( E t 2 0 ) 2 3 represents an upper limit4 among known quadruply bonded dichromium(I1) compounds, while in C r 2 ( 0 2 C C H 3 ) 4 ( H 2 0 ) 2 5 (1) (a) For recent reviews see: Cotton, F. A.; Walton, R. A. "Multiple Bonds Between Metal Atoms"; Wiley: New York, 1982. (b) PoraiKoshits, M. A. Zh. Strukt. Khim. 1980, 21, 146; J . S t r u t . Chem. (Engl. Transl.) 1980.21, 369. (c) Templeton, J. L. Prog. Inorg. Chem. 1979, 26, 211. (d) Cotton, F. A. Acc. Chem. Res. 1978, 11, 225. (e) Baranovskii, I. B.; Shchelokov, R. N. Zh. Neorg. Khim. 1978, 23, 3; Russ. J . Inorg. Chem. (Engl. Transl.) 1978, 23, 1. (2) For reviews on specific elements see: (a) Bino, A.; Cotton, F. A. Chem. Uses Molybdenum, Proc. Int. Con$, 3rd 1979, 1 (molybdenum). (b) Dori, 2.Prog. Inorg. Chem. 1981, 28, 239 (tungsten). (c) Felthouse, T. R. Prog. Inorg. Chem. 1982, 29, 73 (rhodium). (3) Cotton, F. A,; Extine, M. W.; Rice, G. W. Inorg. Chem. 1978, 17, 176. (4) Cotton, F. A.; Ilsley, W. H.; Kaim, W. J. Am. Chem. SOC.1980, 102,
3464. (5) Cotton, F. A.; DeBoer, B. G.; LaPrade, M. D.; Pipal, J. R.; Ucko, D. A. Acta Crystallogr., Sect. B 1971, 827, 1664.
0020-1669/82/ 1321-2667$01.25/0
a
the Cr-Cr bond length is nearly 0.2 shorter with a value A. In M ~ ~ ( O ~ C R ) ~ - c o m p lthe e x eMc-Mo s bond length varies less as a function of R, but in contrast to the acetate analogue, Mo2(OzCCF3)? exhibits greater solubility in organic solvents, higher volatility,' enhanced affinity for axial donor ligands,* and, with certain tertiary phosphine ligands, the ability to form equatorial phosphine complexes containing both bidentate and monodentate trifluoroacetate group^.^-'^ The marked thermal stability displayed by M o ~ ( O ~ C C F ,was ) ~ recently found to extend to t h e W:+ analogue in the form of W2(02CCF3)4-2/3(diglyme).11 This compound is sufficiently stable to allow both purification and crystallization by means of sublimation. Furthermore, the compound provides the first example of a tetrakis(carboxylat0) complex of ditungsten(I1) despite more t h a n 2 0 years of efforts.12 Although the first trifluoroacetate complex of Rh24+ was reported in 1963,13 structural d a t a on Rh2(O2CCF,),L2 com-
of 2.362 (1)
(6) Cotton, F. A,; Norman, J. G., Jr. J. Coord. Chem. 1971, 1 , 161.
(7) A consequence of this high volatility has been the determination of the gas-phase structure by electron diffraction: Garner, C. D.; Hillier, I. H.; Walton, I. B.; Beagley, B. J. Chem. Soc., Dalton Trans. 1979, 1279. (8) Cotton, F. A,; Norman, J. G., Jr. J. Am. Chem. SOC.1972, 94, 5697. (9) Girolami, G. S.; Mainz, V. V.; Andersen, R. A. Inorg. Chem. 1980, 19, 805.
(10) Cotton, F. A,; Lay, D. G. Inorg. Chem. 1981, 20, 935. (1 1) Sattelberger, A. P.; McLaughlin, K. W.;Huffman, J. C. J. Am. Chem. SOC.1981, 103, 2880. (12) Abel, E. W.; Singh, A,; Wilkinson, G. J. Chem. SOC.1959, 3097. 0 1982 American Chemical Society
Cotton and Felthouse
2668 Inorganic Chemistry, Vol. 21, No. 7, 1982
plexes were not available until very re~ent1y.l~However, work by Kitchens and in 1970 established that Rh2(02CCF3)4, like its group 6B analogues, showed a tendency to remain intact in the gas phase as evidenced by the ~bservation'~ of a parent ion for Rh2(02CCF3)4in the mass spectrum. The corresponding acetate,I6 p r ~ p i o n a t e , 'and ~ benzoate15 complexes of Rh24+decompose at elevated temperatures to give metallic rhodium (R = CH,, C2H5) or oxide compounds (R = Ph). Further studies of Rh2(02CCF3)4have revealed that electrochemical oxidation to the Rh2(02CCF3)4tcation radical does not occur in CH2C12 solution^'^ although these radicals can be generated for the phosphorus-donor adducts in Freon glasses by y irradiation.'" This behavior toward oxidation is in accord with the general ability of the trifluoroacetate group to stabilize the lower oxidation states of elements of the transition series as well as those of the main group^.'^ In addition to the effect on the thermal and redox properties of Rh2(02CCF,)4 compared to those of other alkyl or aryl carboxylate complexes of R h t + , the trifluoroacetate group also exerts a strong influence on the type and strength of interaction with axial donor atoms in Rh2(02CCF3),L2 compounds. Dimethyl sulfoxide (Me2SO) coordinates to the Rh atoms in Rh2(02CR)4(Me2SO),complexes (R = CH3,20 C2HS2l) through the sulfur atoms, but in the case of Rh2(O2CCF,),(Me2S0)2,21,22 axial ligation occurs through the oxygen atoms. The highly electronegative CF, substituents enhance the Lewis acidity of the Rh atoms so as to allow axial interactions with relatively weak donor molecules. Dimethyl sulfone (Me2S02) normally does not coordinate to transition-metal ions2, but forms a 2:l adduct with Rh2(02CCF3)4.24 Nitroxyl radicals constitute another class of donor ligands that have been used to assess directly the metal-ligand bonding via EPR ~pectroscopy.~~ Although in most cases the nitroxyl radical is not directly coordinated to the metal ion, sufficiently strong Lewis acid sites form complexes with the oxygen atom of the nitroxide Structural data are available for the 2,2,6,6-tetramethyl-4-hydroxypiperidinyl1-oxyB (Tempol) and 2,2,6,6-tetramethylpiperidinyl-1 (Tempo) complexes with Cu(hfac),. Several years ago, Drago et al.27reported that Rh2(O2CCF,),, and not the corresponding butyrate complex, forms a 1:l adduct in solution with 2,2,6,6-tetramethylpiperidinyl-1-oxy (Tempo). Somewhat surprisingly, hyperfine coupling to only one of the rhodium atoms was observed, suggesting a rather limited amount of spin delocalization onto the Rhz4+moiety. As an alternative means of assessing the degree of spin delocalization across the dirhodium(I1) unit, we sought to prepare a 2:l adduct of Rh2(02CCF3)4with Johnson, S. A,; Hunt, H. R.; Neumann, H. M. Inorg. Chem. 1963,2, 960. Porai-Koshits, M. A,; Dikareva, L. M.; Sadikov, G. G.; Baranovskii, I. B. Zh. Neorg. Khim. 1979, 24, 1286; Russ. J . Inorg. Chem. (Engl. Transl.) 1979, 24, 716. Kitchens, J.; Bear, J. L. Thermochim. Acfa 1970, I , 537. Kitchens, J.; Bear, J. L. J . Inorg. Nucl. Chem. 1970, 32, 49. Das, K.; Kadish, K. M.; Bear, J. L. Inorg. Chem. 1978, 17, 930. Kawamura, T.; Fukamachi, K.; Sowa, T.; Hayashida, S.; Yonezawa, T. J . Am. Chem. SOC.1981, 103, 364. Garner, C. D.; Hughes, B. Adu. Inorg. Chem. Radiochem. 1975.17. 1. Cotton, F. A.; Felthouse, T. R. Inorg. Chem. 1980, 19, 323. Cotton, F. A,; Felthouse, T. R. Inorg. Chem. 1980, 19, 2347. Cotton, F. A,; Felthouse, T. R. Inorg. Chem. 1982, 21, 431. The strategy of using CF3groups to enhance the Lewis acidity of the metal center has been used in several mononuclear complexes of hexafluoroacetylacetonate (hfac). A variety of oxygen bases in chloroform form adducts with U02(hfac),, including sulfones, but no solid adducts with these sulfone ligands were reported: Kramer, G. M.; Maas, E. T., Jr.; Dines, M. B. Inorg. Chem. 1981, 20, 1415. Cotton, F. A.; Felthouse, T. R. Inorg. Chem. 1981, 20, 2703. Eaton, S.S.; Eaton, G. R. Coord. Chem. Rev. 1978, 26, 207. Hoffman, B. M.; Eames, T. B. J . Am. Chem. Soc. 1969, 91, 5168. Richman, R. M.; Kuechler, T. C.; Tanner, S. P.; Drago, R. S . J . Am. Chem. SOC.1917, 99, 1055.
Anderson, 0. P.; Kuechler, T. C. Inorg. Chem. 1980, 19, 1417. Dickman, M. H.; Doedens, R. J. Inorg. Chem. 1981, 20, 2677.
Table I. Summary of Crystallographic Data and Data Collection Procedures for the Two Compounds parameter
1
formula space group a, A b, A
RhZ
Fl
2
2OI 2 N 2 C 2 6 H , 6
P2, In 8.4087 (6) 19.5393 (19) 12.1912 (10) 90.0 107.785 (7) 90.0 1907.3 (7)
c, A a, deg
P , deg 7,deg
v.A 3
fw cryst size, mm ~ ( M oKa), cm-' radiation
10.3765 (20) 12.1955 (10) 8.4080 (9) 101.442 (8) 109.167 (14) 99.439 ( 1 1) 954.4 (6)
1002.37 0.25 X 0.27 X 0.52 9.659
982.38 0.10 X 0.15 X 0.30 9.628 graphite-monochromated Mo KZ (A, = 0.710 73 A) W-28 W-2e 0.70 + 0.35 tan 0 0.60 0.35 tan 0
scan type scan width (Aw), deg aperture width, m m max scan speed, deg min-' max counting time, s data collection range
+ 1.5 + tan0
+
1.5 tan e 20.12
20.12
30 +h,+k,tl; 3" G 28 Q 55" 4354 3112
30 +h,tk,tl; 4" < 28 G 52" 3726 3181
no. of unique data no. of data, Fo2 > 3u(FO2) P 0.05 X-ray exposure time, 35.5
0.05 30.1
h
no. of intensity stds time between measmts, s cryst dec no. of variables R, R2 esd largest peak: e A - 3 A:ub a
3 3600
3 3600
negligible
negligible
3 16 0.035 0.046 1.318 0.42 0.07
295 0.032 0.046 1.439 0.46 0.53
Largest peak in the final difference Fourier map. Largest ( 0 ) ratio in the final least-squares cycle.
shift ( A ) to error
suitable nitroxide ligands. These adducts, however, do not rule out some degrees of superexchange through the bridging trifluoroacetate groups. We began our study by investigating the structures of Rh2(02CCF3)4adducts of di-tert-butyl nitroxide (DTBN) and Tempol. With both nitroxides crystalline OH
I
A 0
0
DTBN
Tempol
products were obtained containing the nitroxide ligand and the Rh2(02CCF3)4unit in a 2:l ratio. In each compound the nitroxide avoids direct coordination to the Rh atoms and instead participates in hydrogen-bonding interactions throughout the crystal lattice. Experimental Section Compound Preparation. Rhodium(I1) trifluoroacetate was prepared by a method given by Kitchens and BearIs and was converted to the anhydrous form before use by heating at 150 "C for 30 min. Rh2(02CCF,)4(Tempol)2(1) was prepared by mixing benzene solutions of Rh2(02CCF3)4(0.05 g, 7.6 X lo-' mol) and Tempol (Sigma, 0.05 g, 2.9 X IO4 mol, a 2-fold excess) to give a blue-green powder, which was collected by filtration and washed with benzene.
R h 2 ( 0 2 C C F 3 ) 4 ( T e m p o l ) 2and
Table 111. Atomic Positional Parameters for Rhl(02CCF3)4(H,0)2~2DTBN (2)
Table 11. Atomic Positional Parameters for Rh ,(O,CC F3)4(Tempol) (1)' atom
Inorganic Chemistry, Vol. 21, No. 7, 1982 2669
Rh2(02CCF3)4(H20)2-2DTBN
X
Y
z
0.05518 (3) 0.0784 (6) -0.1387 (6) 0.0677 (7) -0.5103 (4) -0.5880 (4) -0.4816 (4) -0.0365 (3) 0.0650 (3) -0.2859 (3) -0.1828 (3) 0.171 8 (4) 0.6314 ( 5 ) 0.5238 (4) 0.0132 (4) 0.0073 (6) -0.2953 (5) -0.4705 (6) 0.2987 ( 5 ) 0.4466 (6) 0.5901 ( 5 ) 0.7116 (7) 0.6833 (7) 0.3591 (6) 0.3818 (8) 0.3036 (8) 0.2318 (6)
0.05524 (1) 0.1058 (2) 0.0554 (3) 0.0074 (3) 0.1174 (2) 0.0340 (2) 0.1183 (2) -0.0276 (1) 0.0768 (1) -0.0123 (1) 0.0917 (1) 0.1548 (2) 0.2163 (2) 0.2031 (2) 0.0316 (2) 0.0519 (3) 0.05 02 (2) 0.0827 (3) 0.1556 (2) 0.1986 (2) 0.1944 (2) 0.2537 (3) 0.1261 (3) 0.1764 (2) 0.1026 (3) 0.2201 (4) 0.1810 ( 2 )
0.03561 (2) -0.3315 (3) -0.3864 (3) -0.3725 (3) -0.0356 (3) -0.1414 (4) -0.2001 (3) -0.1920 (2) -0.1258 (2) -0.0835 (2) -0.0147 (2) 0.1096 (2) 0.5255 (2) 0.4278 (3) -0.2008 (3) -0.3232 (3) -0.0646 (3) -0.1 114 (4) 0.2192 (3) 0.2168 (3) 0.3290 (4) 0.3352 (5) 0.3391 ( 5 ) 0.4330 (4) 0.4774 (4) 0.5177 ( 5 ) 0.3122 (4)
a Estimated standard deviations for the least significant figures are given in parentheses and are given in this fashion in succeeding
tables.
The powder was then suspended in a benzene solution, and acetone was added dropwise until the powder dissolved. Slow evaporation of the solution readily gave dark blue, blocky crystals. The DTBN complex was first prepared by the addition of Rh2mol) to a 20-mL solution of 1:l (02CCF3)4(0.05 g, 7.6 X benzene-chloroform containing DTBN (Eastman, 0.2 g, 1.4 X mol, a 9-fold excess). The solution was covered with Parafilm containing several pinholes and allowed to evaporate slowly over a 1-week period. The resulting dark green crystals were extremely soluble in the solvent mixture and only formed after nearly all the solvent had evaporated. Unfortunately, all these crystals were found to be badly twinned even though numerous attempts were made to cleave a single crystal from the crystalline mass which had formed. The crystalline dark green solid was redissolved in benzene-chloroform containing a few drops of DTBN and evaporated with exposure to moist air. This time the crystals that formed upon evaporation of the solvent were irregularly shaped dichroic blue-red prisms. Subsequent analysis by X-ray diffraction (vide infra) showed these crystals to be Rh2(02CCF3)4(H20)2*2DTBN (2). X-ray Crystallography. Data Collection, Structure Solution, and Refmement.'O Suitable crystals of 1 and 2 were secured with epoxy cement on glass fibers and mounted on an Enraf-Nonius CAD-4F autodiffractometer. Crystallographic data and data collection parameters are summarized in Table I for both compounds. Details of the data collection techniques and derivation of the intensity and its standard deviation have appeared before" for this diffractometer. For 2 an empirical absorption correction was made using $ scans ($ = 0-360' every 10' for x values near 90'). Nine sets of reflections (632, 621, 532,431, 410, 321, 843, g31,642) were averaged to give an absorption profile for the crystal with maximum, minimum, and average transmission factors of 1.OO, 0.91, and 0.97, respectively. The structures of 1 and 2 were solved straightforwardly with heavy-atom methods from three-dimensional Patterson maps, which revealed the positions of the Rh atoms, followed by successive least-squares refinement and difference Fourier maps. In both structures a difference Fourier map following least-squares refinement (30) All crystallographic computing was done on a linked PDP 11/45-11/60 computer at the Molecular Structure Corp., College Station, TX, with the Enraf-Nonius structure determination package with local modifi-
cations. (31) Bino, A.; Cotton, F. A.; Fanwick, P. E. Inorg. Chem. 1979, 18, 3558.
atom
X
Y
z
0.11699 (2) 0.0271 (2) 0.2337 (3) 0.1630 (3) 0.2133 (4) 0.0384 (4) 0.2045 ( 5 ) 0.1685 (2) -0.0500 (2) 0.1710 (2) -0.0481 (2) 0.3363 (2) 0.5703 (3) 0.6229 (3) 0.0754 (3) 0.1249 (4) 0.0787 (3) 0.1306 (4) 0.6295 ( 5 ) 0.4977 (7) 0.7631 (7) 0.6461 (10) 0.6706 (4) 0.6307 (6) 0.8260 (6) 0.5937 (10)
0.48813 (2) 0.6354 (2) 0.6235 (3) 0.7632 (2) 0.8563 (2) 0.8885 ( 2 ) 0.8899 (2) 0.5536 (2) 0.5777 (2) 0.6535 (2) 0.6761 (2) 0.4679 (2) 0.6541 (2) 0.7499 (2) 0.5870 (3) 0.6530 (3) 0.7089 (3) 0.8373 (3) 0.7458 (4) 0.7739 (10) 0.8231 (6) 0.6246 (6) 0.8497 (3) 0.9570 (4) 0.8707 (6) 0.8206 ( 5 )
0.02147 (3) 0.5881 (2) 0.6224 (3) 0.5388 (3) -0.0670 (4) -0.0348 ( 6 ) 0.1702 ( 5 ) 0.2826 (3) 0.2425 (3) 0.0103 (3) -0.0320 (3) 0.0677 (3) 0.1698 (3) 0.2843 (4) 0.3298 (4) 0.5228 (4) -0.0070 (4) 0.0128 ( 5 ) 0.4631 ( 5 ) 0.4774 (8) 0.6086 (7) 0.4759 (9) 0.2226 ( 5 ) 0.2967 (9) 0.2650 (9) 0.0296 (8)
of the nonhydrogen atoms with anisotropic thermal parameters assigned to these atoms revealed the positions of all hydrogen atoms. The 18 hydrogen atoms in 1 were refined with isotropic thermal parameters, while in 2 only the positional parameters were refined for the 20 hydrogen atoms. An extinction correction was made in 2 according to the equation lFol = IF&l g I J l , where the value of g determined by least-squares refinement is 8.61 X lo-'. This parameter was not varied in the final cycle. Tables of observed and calculated structure factor amplitudes for those reflections with I > 3 4 0 are available for the two structure^.^^
+
Results T h e final values for the atomic positional parameters a r e presented in Tables I1 a n d I11 for compounds 1 and 2, respectively. Tables IIA and IIIA32give anisotropic thermal parameters and refined hydrogen atom positions with isotropic thermal parameters for the two compounds. Bond distances and angles for the nonhydrogen atoms in 1 and 2 appear in Tables IV a n d V, respectively, a n d some hydrogen-bonding contacts for these atoms a r e included a s well. Intra- and interatomic hydrogen distances a n d angles for 1 and 2 a r e compiled in Tables IVA a n d VA,32respectively. Selected least-squares planes and dihedral angles for the two compounds are tabulated in Table VI.32 Both structures contain dinuclear Rh,(02CCF3), molecules with symmetrically bridging trifluoroacetate groups and nitroxide radicals in a 1:2 ratio. A detailed description of each structure will now be given. Rt1,(0~CCF,)~(Tempol)~ (1). Two formula units of 1 comprise the unit cell with crystallographic centers of inversion located a t the midpoints of the Rh-Rh bonds. Figure 1 shows the atom-labeling scheme for one of the dinuclear molecules. Four trifluoroacetate groups symmetrically bridge the Rh-Rh bond of length 2.405 (1) A. T h e central R h 2 ( 0 2 C C ) 4 core of 1 displays essentially Dlh symmetry. Each R h a t o m is in a tetragonally elongated octahedral environment and is displaced 0.070 A out of the equatorial plane of four carboxylate oxygen atoms toward the axial hydroxyl oxygen atom. Some chemically equivalent bond distances and angles within t h e R h 2 ( 0 2 C C F 3 ) , unit include the following: R h - 0 , 2.034 (3) A;C - 0 , 1.250 (5) A; C-CF3, 1.537 (6) A;C-F, 1.266 (6) A; LRh'-Rh-O(trifluoroacetate), 88.02 (8)O ; LRh-0-C(tri(32) Supplementary material.
Cotton and Felthouse
2670 Inorganic Chemistry, Vol. 21, No. 7 , 1982 Table IV. Bond Distances (A) and Angles (Deg) for Rh,(O,CCF,),(Tempol), (1) Excluding the Hydrogen Atom@ 2.405 (1) 2.033 (2) 2.039 (2) 2.029 (2) 2.034 (3) 2.240 (3) 1.231 (5) 1.236 (6) 1.250 (6) 1.271 (6) 1.340 (6) 1.265 (6) 1.245 (4) 1.250 (4) 1.250 (5) 1.254 (5) 88.16 (7) 87.82 (7) 87.82 (7) 88.29 (8) 176.39 (8) 175.94 (9) 87.8 (1) 91.4 (1) 90.2 (1) 92.6 (1) 87.9 (1) 93.9 (1) 176.1 (1) 88.9 (1) 94.9 (1) 116.9 (2) 116.9 (2) 117.4 (2) 116.5 (2) 119.6 (2) O(6"). . .0(5)-C(5) 108.4 (2) O(5"). . .0(6)-N 120.8 (2) 0(6)-N-C( 7) 116.3 (3) -c( 10) 115.5 (3) C(7)-N-C( 10) 125.2 (3) O( l)-C( 1)-0( 2) 130.0 ( 3) -C(2) 114.4 (3) 0(2)-C(l)-C(2) 115.5 (3) F(l)C(2)-F(2) 108.4 (5) -1'(3) 106.1 (5)
0(5)-C(5) O(5). . .0(6") 0(6)-N N-C(7) N-C(l0) C(l)C(2) C(3)-C(4) C(5)-C(6) C(5)-C(13) C(6)-C(7) C(7)-C(8) C(7)C(9) C(lO)-C(ll) C(lO)-C(12) C(lO)-C(13)
1.433 (4) 2.702 (4) 1.282 (4) 1.483 (5) 1.499 (6) 1.530 (5) 1.544 (6) 1.508 (6) 1.497 (6) 1.525 (5) 1.531 (7) 1.533 (7) 1.532 (7) 1.518 (7) 1.536 (6)
F(l)C(2)4(1) F(2)-C(2)-F(3) F(2)-C(2)-C(1) F(3)-C(2)
