Organometallics 1995, 14, 4222-4227
4222
Preparation of New Bis(arene)ruthenium(II)Complexes. X-ray Crystal Structures of [(qs-biphenyl)2Ru] [BF4]2 and the syn and anti Isomers of [(q6-fluorene)2Rul [BF412 Leigh Christopher Porter,* Swamy Bodige, and Henry Edward Selnau, Jr. Department of Chemistry, The University of Texas at El Paso, El Paso, Texas 79968
Henry Hall Murray I11 and Jonathan M. McConnachie Corporate Research, Exxon Research and Engineering Company, Annandale, New Jersey 08801 Received December 14, 1994@ New sandwich complexes of the type [bis(l16-arene)Rul[BF41~, where the arenes are biphenyl, bibenzyl, fluorene, and trans-stilbene, have been synthesized. These complexes dication with the appropriate arene were prepared by reacting the [(acetone>3(q6-arene)Rulz+ in refluxing trifluoroacetic acid. A crystal structure determination of the [(@biphenyl)zRu][BF4]2 complex establishes that the metal ion lies coordinated between two biphenyl ligands and binds in a n v6 manner to one of the arene rings of each. The X-ray crystal structure of the [(~6-fluorene)~Rul[BF412 complex was also determined and found to be similar with respect to the coordination of the transition metal. However, in the fluorene complex two isomeric forms ( s y n and a n t i ) were found to be present in the same lattice in equal proportion, differing principally with respect to the relative orientation of the methylene bridges.
Introduction Transition-metal sandwich complexes of polycyclic aromatic hydrocarbons (PAH's) constitute a potentially vast source of new systems exhibiting a number of interesting and potentially significant electronic prope r t i e ~ . l -Bis(arene) ~ complexes of iron and ruthenium have recently found use as structural elements in the construction of new molecular solids exhibiting interesting features of structure and conductivity.lZ2 In instances where the ligands consist of large polycyclic aromatic hydrocarbons, band structure calculations have been carried out and predict a wealth of lowdimensional solid-state phenomena, including conductivity . Our interest in the structures and properties of transition-metal complexes containing PAH's as ligands prompted us to explore new synthetic procedure^.^ The synthetic procedures that were developed during the course of these investigations proved to be sufficiently general t o enable a variety of new Ru" sandwich complexes to be synthesized, the preparation of many of which until now has remained elusive. In this paper @Abstractpublished in Advance ACS Abstracts, August 1, 1995. (1)(a) Ward, M. D. Organometallics 1987,6,754. (b) Ward, M. D.; Johnson, D. C. Inorg. Chem. 1987,26,4213. ( c ) Ward, M. D.; Fagan, P. J.; Calabrese, J. C.; Johnson, D. C. J. A m . Chem. SOC.1989,111, 1719.(d) Li, S.; White, H. S.; Ward, M. D. Chem. Mater. 1992,4,1082. (e) Fagan, P. J.; Ward, M. D. Sci. Am. 1992,48. (2) (a) Lehn, J.-M. Angew. Chem., Int. Ed. Engl. 1988,27,89. (b) Carter, R. L., Ed. Molecular Electronic Devices; Marcel Dekker: New York, 1982. ( c ) Miller, J. S. Extended Linear Chain Compounds; Plenum: New York, 1982-1983; Vols. 1-3. (d) Desiraju, G. Crystal Engineering; Elsevier: New York, 1989. (e) Miller, J. S.; Epstien, A. J.; Reiff, W. M. Science 1988,240,40. (3) (a) Burdett, J. K.; Canadell, E. Organometallics 1985,4,805. (b) Lauher, J. W.; Elian, M.; Summerville, R. H.; Hoffmann, R. J . A m . Chem. SOC.1976,98, 3219. (4) Bush, B. F.; Lynch, V. M.; Lagowski, J. J. Organometallics 1987, 6,1267. (b) Bush, B. F.; Lagowski, J. J. J . Organomet. Chem. 1990, 386,37.
we describe the syntheses of ruthenium(I1) sandwich complexes of biphenyl, bibenzyl, fluorene, and transstilbene. In addition we describe the X-ray crystal structures of [(@-biphenyl)zRul[BF4]2and two isomeric the last forms (syn and anti) of [(~6-fluorene)~Rul[BF41~, two found cocrystallized within the same lattice.
Experimental Section All manipulations were carried out using standard Schlenk techniques under oxygen-free nitrogen or a n inert-atmosphere glovebox. Methanol was dried and distilled over finely divided Mg metal, and all halogenated solvents were distilled over P205. Biphenyl, bibenzyl, fluorene, and trans-stilbene were all purchased from Aldrich Chemical Co., Inc., and used as received. Ruthenium(II1) chloride hydrate was obtained from the Engelhard Corporation. Preparation of the [(1,5-COD)RuC121, polymer was carried out using the reported literature procedure.6 The chloro-bridged Ru" dimers of biphenyl, bibenzyl, fluorene, and trans-stilbene having the general formula [(y6-arene)RuC1212were all prepared using a modification of the literature procedure.' NMR spectra were recorded on a Bruker AM-250 s ectrometer using either DMSO-& or CD3NO2 dried over 4 molecular sieves and referenced internally t o TMS. Crystallographic data were collected a t ambient temperature on either a Siemens R 3 m N diffractometer or an Enraf-Nonius CAD-4 instrument.
1
Preparation of dimeric [ (r,~~-arene)RuClzlz Complexes. In a typical reaction, a 100 mL flask was charged with 1.0 g (5) (a) Suravajiala, S.; Polam, J. R.; Porter, L. C. J . Organomet. Chem. 1993,461,201. (b) Polam, J. R.; Suravajiala, S.; Porter, L. C. Organometallics 1994,13,37. (c) Porter, L.C.; Polam, J. R.; Mahmoud, J . Organometallics 1994, 13,2092. (d) Porter, L. C.; Polam, J. R.; Bodige, S. Inorg. Chem. 1995,34,998. (e) Suravajiala, S.; Porter, L. C. Acta Crystallogr. 1994,C50, 1678. (6) Albers, M. 0.;Ashworth, T. V.; Oosthuizen, H. E.; Singleton, E. Inorg. Synth. 1987,26, 68. (7)(a)Pertici, P.; Vitulli, G.; Bigelli, C.; Lazzaroni, R. J. Organomet. Chem. 1984,275, 113. (b) Pertici, P.; Vitulli, G.; Lazzaroni, R.; Salvadori, P. J. Chem. SOC.,Dalton Trans. 1982,1019.
0276-7333/95/2314-4222$09.QQ/Q 0 1995 American Chemical Society
Organometallics, Vol. 14,No. 9,1995 4223
Bis(arene)ruthenium(II) Complexes
Table 1. Summary of Crystal Data for [(qs-biphenyl)2Ru1 [BF~IZ and [(qs-fluorene)zRu1[BF&
Chart 1
l2+
12+
d,,
Ril
1
W
2
I
empirical formula fw cryst syst space group a (A) b (A) c
(A)
P (deg)
v (A31
12+
1 2 +
z e (Mgm-3) ,u (mm-l)
radiation weighting scheme
3a
3b
Syn
Anti
1 2 +
4
of the [(1,5-C0D)RuCl~],,polymer, 2.0 g of the appropriate arene, 10.0 g (153 mmol) of zinc dust, and 20 mL of freshly distilled THF. The reaction mixture was refluxed for 24 h, after which the solvent was removed under reduced pressure. The residue was then treated with 40 mL of freshly distilled pentane and the pentane solution transferred via a cannula into a fresh 100 mL Schlenk flask. Removal of the solvent under reduced pressure resulted in the isolation of a n oily residue which was immediately dissolved in 10 mL of acetonitrile. To this was then added 4 mL of a l M HC1-etherate solution and the solution stirred for 24 h. Addition of 20 mL of diethyl ether to the reaction mixture resulted in the precipitation of the chloro-bridged dimer, which was then filtered, washed twice with two 10 mL aliquots of diethyl ether, and dried in umuo. Yields for the preparation of these dimeric complexes typically range from 10 to 20%, and full discussion of these complexes will be subject of a subsequent paper. Preparation of [(q6-biphenyl)zRu][BF412(1). Model Procedure for [(qs-arene)2Ru12+ Complexes. A mixture of 0.15 mmol of the chloro-bridged dimer, [(y6-biphenyl)RuC121~ and 0.60 mmol (0.177 g) of AgBF4 in 10 mL of acetone were stirred together for 15 min a t room temperature. The solution fraction was then transferred to a second Schlenk flask using a cannula, one end of which was covered with fine filter paper t o exclude the entrainment of any AgCl precipitate. Removal of the solvent under reduced pressure produced a n oily orangeyellow residue. To this was added was added 5 mL of trifluoroacetic acid followed by the 0.100 g (0.65 mmol) of biphenyl. The reaction mixture was refluxed for 5 min and cooled to room temperature. Removal of the solvent under reduced pressure resulted in the formation of a n oil which was triturated with 10 mL of methanol, producing a n off-white powder. The product was isolated by filtration and washed with 5 mL each of methanol and diethyl ether. The compound was recrystallized from a nitromethane-diethyl ether solution yielding 0.086 g of a white powder in 49% yield. Mp: 258260 "C dec. Anal. Calcd for Cz4HzoBzFsRu: C, 49.43; H, 3.46. Found: C, 48.71; H, 3.48. Preparation of [(q6-bibenzyl)zRu][BF4]2(2). This complex was prepared by following the procedure described for 1. Using 0.106 g (0.15 mmol) of the [(ys-bibenzyl)RuClz]2dimer, 0.117 g (0.60 mmol) of AgBF4, and 0.100 g (0.55 mmol) of bibenzyl, the off-white, air-stable compound 2 was isolated in
final R final R, goodness of fit
C24HzoB2FsRu 583.1 monoclinic P21h 12.206(6) 14.836(7) 13.479(6) 111.50(4) 2271(2) 4 1.705 0.751 Mo K a (0.710 73 A) w - l = &F) 0.0029F 0.062 0.0682 0.89
+
CzsHzoBzFsRu 607.1 monoclinic P21k 13.839(3) 18.829(4) 9.454(2) 106.96(3) 2356.3(9) 4 1.711 0.727 Mo K a (0.710 73 A) w-1 = $(F)
0.0037F 0.063 0.0959 1.27
+
56% (0.107 g) yield. Mp: 230-232 "C dec. Anal. Calcd for CzsHzsBzFsRu: C, 52.61; H, 4.42. Found: C, 51.82; H, 4.41. Preparation of [(qe-fluorene)zRu1[BF& (3). This complex was prepared by following the procedure described for 1. Using 0.100 g (0.15 mmol) of the [(y6-fluorene)RuClz]zcomplex, 0.117 g (0.60 mmol) of AgBF4, and 0.100 g (0.55 mmol) of fluorene, the yellow air-stable product 3 was isolated. The yield was 0.118 g (60%). Mp: 210-212 "C dec. Anal. Calcd for Cz,&oB2FsRu: C, 51.43; H, 3.33. Found: C, 51.18; H, 3.30. Preparation of [(q6-trans-stilbene)~Ru][BF4]2 (4). This complex was prepared by following the procedure described for 1. Using 0.105 g (0.15 mmol) of the [(r16-truns-stilbene)RuClzlz dimer, 0.117 g (0.60 mmol) ofAgBF4, and 0.100 g (0.55 mmol) of truns-stilbene, we isolated 0.118 g of a clean yellow powder in 62% yield. Mp: 300-302 "C dec. Anal. Calcd for C ~ ~ H Z ~ B ~ C, F ~52.94; R U : H, 3.81. Found: C, 52.69; H, 3.86.
Results Crystallographic Determination of the Structures. Details concerning the crystallographic experimental procedures are summarized in Table 1. Intensity data collection for the [(~6-fluorene)2R~l[BF& complex was carried out at 298 K using an Enraf-Nonius CAD-4 difiactometer. For the [(q6-biphenyl)2Rul[BF& complex a Siemens R3mN difiactometer also operating at room temperature was used. Both instruments were equipped with graphite-monochromated Mo Ka radiation. Structure solution and refinement was carried out using the SHELXTL-PC collection of crystallographic software8utilizing scattering factors that included terms for anomalous disper~ion.~ The data for both structures were corrected for Lorentz and polarization effects and for absorption. Structure determination of [(ps-biphenyl)zRul[BF& Crystals suitable for an X-ray crystal structure determination were obtained following crystallization from an acetone-nitromethane solution at room temperature. A single irregularly shaped pale yellow fragment was selected and mounted on the end of a glass fiber in a random orientation. Monoclinic symmetry was suggested on the basis of the interaxial angles and confirmed by axial rotation photographs. ( 8 ) Sheldrick, G. M. SHELXTL-PLUS (PC version): An Integrated System for Solving, Refining and Displaying Crystal Structures from Diffraction Data; University of Gottingen: Gottingen, Germany, 1990. (9) International Tables for X-ray Crystallography; Kynoch Press (present distributor D. Reidel, Dordrecht, The Netherlands): Birmingham, U.K., 1974;Vol. IV.
Porter et al.
4224 Organometallics, Vol. 14,No.9,1995 Refined cell parameters were determined from the setting angles of 35 reflections with 7" < 28 < 30". Three standards measured every 97 data showed only minor variations in intensity ( 3dZ). Structure Determination of [(qs-fluorene)zRul[BF& Amber, well-formed crystals suitable for an X-ray crystal structure determination were obtained following crystallization from a DMSO-water solution a t room temperature. A total of 4835 reflections (+h,+k,ltZ; hma, = 17, kma, = 23,,,I = 11)with 4.0" < 28 < 52.0" were collected using the 28-8 scanning technique and corrected for Lorentz and polarization effects. This led to 4629 unique reflections with Rint = 1.18% and 2692 observed reflections with Z > 241). Absorption corrections were applied empirically on the basis of azimuthal scans of several strong reflections spanning a range of 28 values. The structure was solved using direct methods; however, it quickly became apparent that the ligands of the structure (but not the transition metal) were disordered. This made it necessary to inspect very carefully the difference Fourier maps in order to correctly assign the regions of residual electron density t o the appropriate fluorene ligand. One of the problems that was encountered centered on the degree of overlap exhibited by several of the fluorene carbon atoms. This necessitated refining these atoms using only isotropic thermal parameters so that correlations between their temperature factors and fractional atomic coordinates were minimized. Hydrogen atoms were included in idealized positions with fixed isotropic U values of 0.08 A2. After the refinement had converged to a satisfactory state, the occupancies of the disordered carbon atoms were refined. This led to an increase in correlations between occupancy factors and thermal parameters but provided occupancies that indicated a 50:50 mix of the two isomers. Refinement was based on F using weights of the form w-l = [a2(F) + 0.0037(F)I. Convergence to conventional R values
+
Table 2. lH NlMR Absorptions of the Complexesa compd no. 1 2
3*
4
b
solvent
chem shift
DMSO-ds 6.96 (t, 2H, J = 5.41),7.06 (t, 4H, = 7.34 Hz), 7.29 (t, J = 6.66 Hz), 7.50 (m, 10H) DMSO-& 2.92 (s, 8H), 6.90 (m, lOH), 7.2-7.4 (m,lOH) CD3N02 2.88 (d, 2H, J = 23.60 Hz), 3.21 (d, 2H, J = 23.81 Hz), 3.82 (d, 2H, J = 23.78 Hz),3.92 (d, 2H, J = 23.82 Hz) 6.96 (m, 10H),7.10 (d, 2H, J = 7.63 Hz), 7.40 (m, 12H),7.64 (m, 6H), 7.83 (d, 2H, J = 7.71 Hz) DMSO-& 6.8 (d, 4H, J = 16.24 Hz), 6.85 (t, 2H, J = 5.82 Hz), 6.96 (t, 4H, J = 6.02 Hz),7.23 (m, 8H), 7.34 (d, 4H, J = 7.00 Hz), 7.55 (d, 2H, J = 16.32 Hz)
=Chemical shifts are given in ppm and J values in Hz. Combined data for both the syn and anti isomers.
of R = 0.0627 and R, = 0.0959 with a goodness of fit of 1.27 was obtained for 322 variable parameters and 2692 reflections with Z > 2a(Z). Discussion Four [2(q6-arene)2Ru12+sandwich complexes have been prepared using biphenyl, bibenzyl, fluorene, and trans-stilbene. Chloro-bridged (q6-arene)Ru" dimers having the general formula [(q6-arene)RuC1212were used as starting materials in each case. These dimers are readily cleaved by halide abstractionloa using 4 equiv of AgBF4 in acetone to give a tris(acetone1 complex of Ru" containing an v6-coordinated arene. The three molecules of acetone are only weakly coordinating and, hence, are easily displaced in the presence of the appropriate arene in refluxing trifluoroacetic acid.lob Elemental analyses consistent with structures having the formula [(q6-arene)2Ru1[BF412 were obtained for the complexes prepared in this investigation. All exhibited good solubility in nitromethane and DMSO and poor solubility in solvents such as methanol or halogenated solvents such as chloroform and dichloromethane. Overall yields typically were found to range from 40% to 60%, and in all instances the products were isolated as clean air-stable complexes. In these reactions the final step leading to the formation of the (q6-arene)2Ru" complex was essentially complete after a few minutes, and refluxing the reaction mixture for extended periods of time proved to be unnecessary. In fact, product yields decreased noticeably following prolonged heating using trifluoroacetic acid as the solvent. We suspect the reason for this reflects one or more competing side reactions, and while the exact nature of the products being formed under these conditions remains uncertain, 13C NMR data have in at least one instance revealed the presence of coordinated trifluoroacetate. lH and 13C NMR data were obtained for all the complexes, since a considerable amount of information concerning how the arene binds to the transition metal can be quickly obtained by examining the proton and carbon chemical shifts of the arene ligands. In the lH NMR spectra of all these complexes we find that the resonances for the protons associated with the bound carbons are shifted downfield slightly (Table 2). In contrast, the 13C NMR resonances (Table 3) for the (10) (a)Bennett, M. A,; Matheson, T. W. J . Organomet. Chem. 1979,
175,87. (b) Bennett, M. A,; Matheson, T. W.; Roberston, G . B.; Steffen,
W. L.; Turney, T. W. J . Chem. Soc., Chem. Commun. 1979,32.
Bis(arene)ruthenium(II) Complexes Table 3. compd no. 1 2
3b
4
l3C
Organometallics, Vol. 14, No. 9, 1995 4225
N M R Absorptions of the Complexesa
c1211
chem shift
solvent
DMSO-& 92.11,93.14,94.09, 112.17, 127.99, 128.51, 129.27, 132.05 DMSO-& 34.44. 35.62. 93.41. 94.17.94.26. 94.53. 126.51,128.43, i28.52,' 139.30 CD3N02 35.66, 35.74, 87.40, 87.51,92.07, 92.14, 92.62, 92.70, 92.76, 92.94, 115.74, 116.23, 116.49, 117.23, 125.47, 125.77, 127.50, 129.70, 130.29, 134.48, 134.63, 145.96 DMSO-& 90.6, 92.5, 93.7, 110.5, 117.9, 127.8, 128.7, 130.3, 134.4, 142.4
Chemical shifts are given in ppm. Combined data for both the syn and anti isomers.
Table 4. Atomic Coordinates ( x lo4) and Equivalent Isotropic Displacement Coefficients (biz-x lo3)for the Biphenyl Complex
4995(8) 4372(5) 5252(5) 347x41 715(7) -558(9) -1029(28) -1161(10) -632(28) -267(11) 292(22) 4511(8) -203(9) -2273(7) -3412(7) -3799(7) -3067(8) -1914(6) -1519(6) 341(6) 1509(6) 2067(6) 1446(6) 283(6) -300(6) 1344(6) 2500(7) 3135(6) 2602(6) 1444(6) 811(6) -859(7) -2008(8) -2693(8) -2246(7) - 1097(6) -416(5)
Cl221
10587(6) 9734(3) 11044(4) 11018(4) 8648(4) 8446(5) 8548(19) 8586(7) 7732(29) 7322(5) 7542(19) 10578(6) 8191(6) 9291(6) 9263(7) 8569(7) 7863(7) 7848(5) 8582(5) 7796(4) 7814(5) 8645(5) 9434(5) 9425(5) 8593(4) 794x51 7890(6) 8662(6) 9513(5) 9588(5) 8799(5) 8195(6) 8245(7) 8949(7) 9652(6) 9616(5) 8875(5)
8527(7) 7110(8) 7106(6) 7157(6) 3070(10) 3885(7) 3212(34) 2245(8) 2253(24) 2868(17) 3896(19) 7474(12) 3059(12) 5794(5) 5795(6) 6237(7) 6643(6) 6655(5) 6229(5) 6318(5) 6349(5) 6331(5) 6266(5) 6237(5) 6245(4) 9068(5) 9063(5) 9015(6) 8977(5) 8980(5) 9044(4) 9458(6) 9430(7) 8980(7) 8561(6) 8589(5) 9031(4)
a Equivalent isotropic U,defined as one-third of the trace of the orthogonalized U, tensor.
carbon atoms attached to the transition metal are found t o be shifted upfield ca. 10-20 ppm relative to the free arene. In the 'H and 13CNMR spectra of the fluorene complex, evidence for both the syn and anti isomers in solution was present. Careful peak integration of the methylene protons for the two isomers revealed that they were both present in solution in equal amounts. Description of the Structure of [(qe-biphenyl)&ul[BF& A cursory description of the structure of this complex has appeared; however not until now has a thorough crystallographic investigation of this complex been reported.'l Fractional atomic coordinates and selected bond angles and distances are given in Tables
C1131
C1231
Cl251
@ Rulll
c1321
c1331 Cl431 c'34'
U351
c1411
Cl421
Figure 1. View of the [(y6-biphenyl)~RulZ+ ion illustrating the coordination of the ruthenium atom and the atomic labeling scheme. Thermal ellipsoids have been drawn at the 50%probability level. The hydrogen atoms have been omitted for clarity. Table 5. Selected Bond lengths Biphenyl Complex Ru(l)-C(21) Ru(l)-C(23) Ru(l)-C(25) Ru(l)-C(31) Ru(l)-C(33) Ru(l)-C(35)
2.229(6) 2.200(9) 2.216(6) 2.220(7) 2.211(6) 2.232(7)
(A)for the
Ru(l)-C(22) Ru(l)-C(24) R~(l)-C(26) R~(l)-C(32) R~(l)-C(34) Ru(l)-C(36)
2.210(8) 2.198(8) 2.271(5) 2.196(7) 2.211(7) 2.262(7)
4 and 5, respectively, and in Figure 1 is shown a view of the complex. The structure of free biphenyl has been the subject of many investigations, both theoretical and experimental. From theoretical investigations of biphenyl in the gas phase there is found one energy minimum where the two arene rings display a torsion angle of 44.4"along with two energy maxima which occur at x = 0 and 90".l2 In the solid state biphenyl appears to be planar,13and the gas-phase energy barrier to rotation has been estimated to range from 6.5 to 9.2 kJ/"l.14 In the X-ray crystal structure of [($-biphenylhRuI[BF& the two phenyl rings are twisted with torsion angles that measure 24.6 and 25.0" for the two independent biphenyl groups, probably as a consequence of crystal-packing forces.15 Description of the X-ray Crystal Structure of [(qs-Fluorene)2Rul[BF~l~. In the X-ray crystal structure of the [(q6-fluorene)2Rul[BF412complex two isomers are present in equal proportion in the lattice. This complex therefore constitutes a rare example of conformational isomerization in which the two isomers cocrystallize. Views of the syn and anti isomers of [($fluorene)2Rul[BF& illustrating the atomic numbering scheme are presented in Figures 2 and 3. A listing of fractional atomic coordinates and a summary of pertinent bond angles and distances is given in Tables 6 and 7, respectively. An inspection of the figures of the two isomers shows that they differ with respect t o the relative orientations of the two methylene bridges and, to a lesser extent, (11)Plitzko, K.-D.; Wherle, G.; Gollas, B.; Rapko, B.; Dannheim, J.; Boekelheide, V. J . A m . Chem. Soc. 1990, 112, 6556. (12)Almenningen, A,; Bastiansen, 0.;Fernholt, L.; Cyvin, B. N.; Cyvin, S. J.; Samdal, S. J . Mol. Struct. 1985, 128, 59. (13) (a) Robertson, G. B. Nature 1961, 191, 593. (b) Charbonneau, G.-P.; Delugeard, Y. Acta Crystallogr. 1976, B33, 1586. ( c ) Charbonneau, G.-P.; Delugeard, Y. Acta Crystallogr. 1976, B32, 1420. (14)Hafelinger, G.; Regelmann, C. J . Comput. Chem. 1987,8,1057. (15) (a) Belsky, V. K.; Zavodnik, V. E.; Vozzhennikov, V. M. Acta Crystallogr. 1984, C40, 1210. (b) Gerkin, R. E.; Lundstedt, A. P.; Reppart, W. J. Acta Crystallogr. 1984, C40, 1892.
Porter et al.
4226 Organometallics, Vol. 14, No. 9, 1995 Cl231
Table 6. Atomic Coordinates ( x lo4) and Equivalent Isotropic Displacement Coefficients (Azx 10s) for the Fluorene ComDlex
CI22I
C1241
C1171 Cllll
c1151
c1111
CI4I
CI1)
Figure 2. View of the syn-[(~6-fluorene)~rRulz+ ion illustrating the coordination of the ruthenium atom and the atomic labeling scheme. Thermal ellipsoids have been drawn at the 50% probability level. The hydrogen atoms have been omitted for clarity. CI91
061
CIS1
CilOl
Cllll CI4I
CllSOl
C119ol
Figure 3. View of the anti-[(~6-fluorene)zRU12f ion with thermal ellipsoids drawn for all atoms, including those that are refined isotropically at the 50% probability level. The hydrogen atoms have been omitted for clarity.
4500(11) 5436(7) 5954(10) 5887(9) 742(8) 1218(11) -71(13) 1468(10) 5518(14) 824(15) 1900(8) 1744(7) 1978(9) 1791(9) 1348(9) 1138(7) 1337(6) 1219(6) 883(7) 837(8) 1111(9) 1445(9) 1523(7) 4062(11) 4022(13) 4372(23) 4288(15) 3842(16) 3420(11) 3606(10) 3285(20) 2917(22) 2922(20) 3232(22) 3632(17) 3602(13) 3100(24) 3593(16) 3748(24) 4132(17) 4334(14) 4181(21) 3834(17) 3445(17) 3663(18) 3400(19) 3116(20) 29 11(22) 3082(20)
11436(7) 11857(4) 11918(4) 10882(4) 8235(6) 9245(5) 8633(8) 8323(6) 11552(9) 8625(9) 10269(6) 9601(5) 8922(8) 8350(6) 8503(7) 9216(6) 9758(5) 10513(5) 10902(7) 11635(8) 11956(7) 11536(7) 10834(6) 10612(7) 9832(9) 9350(18) 8629(13) 8475(12) 9033(9) 9757(9) 10432(14) 10570(18) 11393(18) 11918(16) 11623(15) 10826(13) 9840(15) 9451(17) 8708(19) 8520(12) 9133(13) 9808(16) 9969(12 10482(15) 11107(17) 11844(13) 11789(19) 11157(18) 10642(13)
4480(14) 3146(7) 5593(8) 4478(10) -5764(10) -4621(17) -4196(17) -3414(12) 4410(15) -4569(17) 2825(12) 1932(10) 2383(13) 1345(16) -129(15) -624(12) 478(11) 261(11) -999(12) -825(17) 558(19) 1808(15) 1648(12) 1338(15) 985(29) 2054(37) 1452(26) -132(30) - 1236(16) -593(18) -1525(42) -2954(39) -2937(36) -1801(46) -244(27) -321(25) -2441(32) -929(25) -531(37) 936(33) 1869(22) 1591(37) 189(37) -957(35) 29(27) -886(39) -2397(35) -3197(36) -2341(41)
the angle of rotation that the fluorene ligands make with respect to each other. In the anti form of the complex the methylene bridges are located on opposite sides and the two fluorene rings are slightly staggered. In the syn isomer the methylene bridges are located on the same side; however, the carbon atoms of the two a Equivalent isotropic U,defined as one-third of the trace of the coordinated arene rings are nearly perfectly eclipsed. orthogonalized UGtensor. The syn and anti isomers are unique; neither can be Table 7. Selected Bond Lengths (A) for the interconverted by a simple rotation of the one of the Fluorene Complexa fluorene rings. In both isomers the Ru atom coordinates in an r6 manner to one of the arene rings of each of the Ru(1)-C(2) 2.267(11) Ru(l)-C(3) 2.210(4) Ru( 1)-C(4) 2.170(14) Ru(l)-C(5) 2.184(12) two fluorenes. In these two sandwich complexes we find Ru(l)-C(6) 2.208(9) Ru(l)-C(7) 2.253(9) the separation between the coordinated arene rings to Ru(lkC(15) 2.177(18) R~(l)-C(16) 2.296(28) measure 3.449-3.465 for the syn and anti isomers, Ru(l)-C(17) 2.245(21) R~(l)-C(18) 2.239(27) respectively. A similar range of values has been obRu(l)-C(19) 2.265(17) Ru(l)-C(20) 2.267(17) Ru(l)-C(15A) 2.258(27) Ru(l)-C(lGA) 2.175(39) served in the crystal structures of two isomeric forms Ru(l)-C(17A) 2.176(24) Ru(l)-C(18A) 2.164(17) of [~~6-4-(methylisopropyl)benzene)(~6-fluorene~l~BF~l~~~e Ru(l)-C(19A) 2.327(28) Ru(l)-C(2OA) 2.340(27) as well as other unsymmetrical Ru2+ sandwich comA complex listing of bond lengths and angles is available as plexes that have recently been prepared using a large part of the supporting information. polycyclic benzenoid aromatic as one of the ligand^.^ There are no substantial out-of-plane deviations of any structure of the syn isomer may reflect the effects of of the arene C atoms, and for both isomers the fluorene unfavorable steric interactions involving the bridging molecule is folded about the methylene bridge where methylene groups.15 the angles range from a minimum of 3.2"to a maximum Attempts were made to extend this work t o include of 4.3". In the crystal structure of free fluorene this fused-ring systems such as naphthalene, anthracene, angle is only 1.3";hence, the 4.3" angle seen in the and phenanthrene. In all instances we were unable to
a
Bis(arene)ruthenium(II) Complexes
isolate the needed chloro-bridged dimeric starting material, the reasons for which we are not completely certain. It may be possible to prepare dimeric complexes containing these ligands using the procedures described here; however, the yields are not likely t o be high. We find that fused-ring PAH’s tend to be inferior as ligands when compared t o the types of ligand systems used in these investigations.16 Alternately, it may be necessary t o develop a different synthetic approach that does not require as a principal step the preparation of the chlorobridged dimer. Investigations related to the preparation of new complexes containing other ligands such as fused polycyclic benzenoid aromatics are currently in progress. (16)Bennett, M. A,; Neuman, H.; Thomas, M.; Qiwang, X.; Pertici, P.; Vitulli, G.; Salvadori, P. Organometallics 1991,10, 3237.
Organometallics, Vol. 14, No. 9,1995 4227
Acknowledgment is made to the donors of the Petroleum Research Fund, administered by the American Chemical Society, and to the Robert A. Welch Foundation. We especially wish to thank Engelhard Corp. for their generous gift of ruthenium trichloride and F. Cervantes-Lee for assisting with the collection of the intensity data. Supporting Information Available: Tables of crystal data, bond lengths and angles for the BFI- anions, atomic positional parameters for hydrogen atoms, and anisotropic thermal parameters for the biphenyl and fluorene complexes (9 pages). Ordering information is given on any current masthead page. OM940954W
