Highly Diastereoselective Preparation of ... - ACS Publications

Frédéric Pezet, Jean-Claude Daran, Isabelle Sasaki, Hassan Aıt-Haddou,*,† and. Gilbert G. A. Balavoine. Laboratoire de Chimie de Coordination CNR...
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Organometallics 2000, 19, 4008-4015

Articles Highly Diastereoselective Preparation of Ruthenium Bis(diimine) Sulfoxide Complexes: New Concept in the Preparation of Optically Active Octahedral Ruthenium Complexes Fre´de´ric Pezet, Jean-Claude Daran, Isabelle Sasaki, Hassan Aı¨t-Haddou,*,† and Gilbert G. A. Balavoine Laboratoire de Chimie de Coordination CNRS, UPR 8241, 205 Route de Narbonne, 31077, Toulouse Cedex 4, France Received March 27, 2000

Microwave irradiation of racemic cis-[Ru(bpy)2(Cl)2] (bpy ) 2,2′-bipyridine) or racemic cis[Ru(phen)2(Cl)2] (phen ) phenanthroline) with either (R)-(+)- or (S)-(-)-methyl p-tolyl sulfoxide yielded the ruthenium bis(diimine) sulfoxide complexes with a high level of asymmetric induction (73-76% de). Stereochemistry at the metal center for the major isomer was determined by X-ray study of [Ru(bpy)2(dmbpy)]‚2PF6, obtained by reaction of complex 3 with 4,4′-dimethyl-2,2′-bipyridine and confirmed by X-ray study of the complex 7. The absolute configuration at the metal center for the minor isomer was established by X-ray study of the minor isomer derived from the reaction of cis-[Ru(bpy)2(Cl)2] with (S)-(-)-methyl p-tolyl sulfoxide. Structural analysis of ∆-7 (major isomer) revealed the presence of two intramolecular interactions, oxygen-hydrogen interaction and π-π stacking of the pyridyltolyl rings, while the structural analysis of ∆-5 (minor isomer) showed only the presence of the oxygen-hydrogen interaction. The importance of these interactions in this transformation was confirmed by the reaction of cis-[Ru(2,9-dimethyl-1,10-phenanthroline)2Cl2] with (R)(+)-methyl p-tolyl sulfoxide, which gave, in acetonitrile, the complex cis-[Ru(2,9-dimethyl1,10-phenanthroline)2(CH3CN)2]‚2PF6, 10. Oxygen-hydrogen and π-π interactions are used to explain both the reactivity of cis-[Ru(diimine)2Cl2] with the sulfoxide and the stability of the major isomer when enantiomerically pure sulfoxide was used. Introduction Contrary to the highly developed asymmetric synthesis in organic chemistry, asymmetric inorganic synthesis has only recently become the subject of a few investigations. These studies have been spurred on by several applications that require the inorganic complexes in enantiomerically enriched form. Optically pure octahedral ruthenium complexes have been known for many years1 and are promising new † Current address: University of Texas at Austin, Department of Chemistry and Biochemistry, Austin, TX 78712-167. Fax: (001) 512471-7791. E-mail: [email protected]. (1) (a) Burstall, F. H. J. Chem. Soc. 1936, 173. (b) Knof, U.; von Zelewsky, A. Angew. Chem., Int. Ed. 1999, 38, 302. (2) Keene, F. R. Coord. Chem. Rev. 1997, 166, 121. (b) Ziegler, M.; von Zelewsky, A. Coord. Chem. Rev. 1998, 177, 257. (3) (a) Dwyer, F. P.; Gyarfas, E. C. J. Proc. R. Chem. Soc. N. S. W. 1949, 83, 170. (b) Rutherford, T. J.; Quagliotto, M. G.; Keene, F. R. Inorg. Chem. 1995, 34, 3857. (c) Hua, X.; von Zelewsky, A. Inorg. Chem. 1995, 34, 5791. (d) Watson, R. T.; Jackson, J. L.; Harper, J. D.; KaneMaguire, K. A.; Kane-Maguire, L. A. P.; Kane-Maguire, N. A. P. Inorg. Chim. Acta 1996, 249, 5. (e) Dwyer, F. P.; Gyarfas, E. C. J. Proc. R. Chem. Soc. N. S. W. 1949, 83, 263. (f) Bosnich, B.; Dwyer, F. P. Aust. J. Chem. 1966, 19, 2229. (g) Sagues, J. A. A.; Gillard, R. D.; Smalley, D. H.; Williams, P. A. Inorg. Chem. Acta 1980, 43, 211. (h) Hiort, C.; Lincoln, P.; Norden, B. J. Am. Chem. Soc. 1993, 115, 3448.

materials in several scientific fields.2 However, there are few existing methods for their preparation. Generally, the procedures used for the preparation of optically pure bis(diimine)- or tris(diimine) ruthenium complexes rely on chromatographic separation3 or optical resolution.4 The first asymmetric synthesis of ruthenium bipyridine complexes was reported by von Zelewsky and coworkers5 using well-defined chiral ligands, “Chiragen”. This method afforded the octahedral ruthenium complexes with high diastereoselectivities; however, it is somewhat limited because the final product must contain the chiral ligand. In connection with our work concerning the applica(4) (a) Patterson, B. T.; Keene, F. R. Inorg. Chem. 1998, 37, 645. (b) Naing, K.; Takahashi, M.; Taniguchi, M.; Yamagishi A. Bull. Chem. Soc. Jpn. 1994, 67, 2424. (c) Aldrich-Wright, J. R.; Greguric, I.; Vagg, R. S.; Vickery, K.; Williams, P. A. J. Chromatogr. 1995, 718, 436. (d) Dupureur, C. M.; Barton, J. K. Inorg. Chem. 1997, 36, 33. (e) Greguric, I.; Aldrich-Wright, J. R.; Collins, J. G. J. Am. Chem. Soc. 1997, 119, 3621. (f) Shelton, C. M.; Seaver, K. E.; Wheeler, J. F.; Kane-Maguire, N. A. P. Inorg. Chem. 1997, 36, 1532. (g) Rutherford, T. J.; Pellegrini, P. A.; Aldrich-Wright, J. R.; Junk, P. C.; Keene, F. R. Eur J. Inorg. Chem. 1998, 1677. (h) Fletcher, N. C.; Junk, P. C.; Reitsma, D. A.; Keene, F. R. J. Chem. Soc., Dalton Trans. 1998, 133. (i) Hesek, D.; Inoue, Y.; Everitt, S. R. L.; Ishida, H.; Kunieda, M.; Drew, M. G. B. Chem. Commun. 1999, 403.

10.1021/om000255l CCC: $19.00 © 2000 American Chemical Society Publication on Web 09/07/2000

Preparation of Ru Bis(diimine) Sulfoxide Complexes Scheme 1. Formation of ∆- and Λ-Isomers by Reaction of cis-[Ru(bipyridine)2(Cl)2] with an Enantiomerically Pure Sulfoxide

tion of octahedral ruthenium complexes as catalysts in the epoxidation of olefins,6 we decided to investigate new procedures for the synthesis of such complexes. In this paper we wish to describe our results concerning the investigation of the thermal reaction of racemic cis-[Ru(bpy)2(Cl)2] or racemic cis-[Ru(phen)2(Cl)2] with (R)-(+)or (S)-(-)-methyl p-tolyl sulfoxide.7 Results and Discussions On the basis of the work of Inoue and co-workers4i on cis-[Ru(bpy)2(DMSO)(Cl)]+, we reasoned that the substitution of one of two chloride ligands by homochiral sulfoxide would lead to the formation of ∆ and Λ isomers in 50:50 ratio (Scheme 1), which could be separated. Reaction of these optically pure ruthenium complexes with an achiral bidentate nucleophile would give other ruthenium complexes with retention of optical activity, as previously demonstrated with the resolved form of cis-[Ru(bpy)2(DMSO)(Cl)]+. Thus, cis-[Ru(bpy)2(Cl)2] was heated with 1 equiv of the enantiomerically pure (R)sulfoxide 2 in EtOH/AcOH (8:1) at 80 °C for 24 h to give a solid orange complex, which was isolated in 70% yield (Scheme 2). To our surprise, proton NMR analysis of this crude material revealed the presence of two isomers (∆ and Λ), one major and one minor. A 62% de was determined using chiral phase HPLC. During our efforts to separate the two isomers, we found that the major isomer can be isolated by washing the crude product with ethanol. Unfortunately, our attempts to grow crystallographic quality crystals in order to elucidate (5) (a) Muerner, H.; Besler, P.; von Zelewsky, A. J. Am. Chem. Soc. 1996, 118, 7989. (b) Fletcher, N. C.; Keene, F. R.; Viebrok, H.; von Zelewsky, A. Inorg. Chem. 1997, 36, 1113. (c) Hayoz, P.; von Zelewsky, A.; Stoekli-Evans, H. J. Am. Chem. Soc. 1993, 115, 5111. (6) Pezet, F.; Sasaki, I.; Daran, J.-C.; Balavoine, G. G. A.; Aı¨tHaddou, H. Unpublished results. (7) While the manuscript was being written, a related study appeared; see: Hesek, D.; Inoue, Y.; Everitt, S. R. L.; Ishida, H.; Kunieda, M.; Drew, M. G. B. Inorg. Chem. 2000, 39, 317-324. In this paper, the thermal reaction of cis- and trans-Ru(diimine)2Cl2 (diiminie ) 2,2′-bipyridine or 4,4′-dimethyl-2,2′-bipyridine) with (R)- or (S)methyl-p-tolylsulfoxide was investigated in dimethylformamide in direct analogy with our work. In their very informative study, the authors described a low diastereoselectivity (49-59% de). The separation of both diastereoisomers was achieved by preparative chiral HPLC and spectroscopic methods, and calculations were used to determine the stereochemistry at the metal center of the ruthenium sulfoxide complexes and to establish the factors governing the stability of the major isomer. No X-ray structure of ruthenium bis(bipyridine) chiral sulfoxide complex or of the product of its reaction with other bidentate ligands was reported to confirm these spectroscopic results.

Organometallics, Vol. 19, No. 20, 2000 4009 Scheme 2. Reaction of cis-[Ru(bipyridine)2(Cl)2] with Either (R)- or (S)-Methyl p-Tolyl Sulfoxide: Diastereoselective Synthesis of Ruthenium Bis(bipyridine) Chiral Sulfoxide Complexes

stereochemistry at the metal center by X-ray crystallography were unsuccessful due to the instability of this compound in organic solvents. However, the ∆-selectivity at the metal center was determined by X-ray analysis of crystals of [Ru(bpy)2(dmbpy)]‚2PF6 obtained from the reaction of the major isomer with 4,4′-dimethyl-2,2′-bipyridine. Knowing that the optically resolved form of cis-[Ru(bpy)2(DMSO)(Cl)]+ reacts with 4,4′dimethyl-2,2′-bipyridine with retention of absolute configuration at the metal center4i allows us to conclude that the ruthenium (bipyridine) sulfoxide complex 3 possesses the same absolute configuration at the metal as cis-∆-[Ru(bpy)2(dmbpy)]‚2PF6.8 To ascertain whether this observed diastereomeric excess was due to selective decomposition or asymmetric induction, optimization experiments were undertaken to evaluate reaction conditions (solvents, temperatures, concentrations, and 1:2 ratios). Optimal conditions involved heating 1:2 (2 equiv) in ethylene glycol for 6 h at 150 °C, which gave the two isomers in 95% yield with an apparent ∆: Λ ratio of ca. 84:16 (68% de). During this optimization, we decided to examine the merit of microwave irradiation as a nonconventional energy source for this transformation.9-12 The results obtained are summarized in Table 1. The microwave-irradiated reactions provided excellent yields and high reaction rates with a notable increase in the observed diastereoisomeric excess. Furthermore, comparison of entries 1, 2, 3, and 4 reveals a significant effect of the cis-[Ru(bpy)2(Cl)2]:2 ratio on both the diastereoselectivities and yields of this transformation. In the case of cis-[Ru(bpy)2(Cl)2], full conversion (8) The crystallographic data (atomic coordinates and bonding parameters) have been placed in the Supporting Information. (9) For the flash-heating by microwave for the acceleration of organic reactions, see: (a) Gabriel, C.; Gabriel, S.; Grant, E. H.; Halstead, B. S. J.; Mingos, D. M. P. Chem. Soc. Rev. 1998, 27, 213. (b) Mingos, D. M. P.; Baghurst, D. R. Chem. Soc. Rev. 1991, 20, 1. (10) For the use of microwave in Heck reactions, see: (a) Garg, N.; Larhed, M.; Hallberg, A. J. Org. Chem. 1998, 63, 4158. (b) Dı´az-Ortiz, A.; Prieto, P.; Va´squez, E. Synlett 1997, 269. (c) Li, J.; Mau, A. W.-H.; Strauss, C. R. J. Chem. Soc., Chem. Commun. 1997, 1275. (11) For the use of microwave in asymmetric allylic alkylation, see: Bremberg, U.; Larhed, M.; Moberg, C.; Hallberg, A. J. Org. Chem. 1999, 64, 1082. (12) For the use of microwave in the preparation of [Ru(terpy)2]‚ 2PF6, see: Sasaki, I.; Daran, J.-C.; Aı¨t-Haddou, H.; Balavoine, G. G. A. Inorg. Chem. Commun. 1998, 1, 354.

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Table 1. Results Obtained for Microwave-Induced Diastereoselective Reactiona entry

[Ru]

Sulb

[Ru]:Sul

time (min)

de (%)c

yield (%)d

1 2 3 4 5 6 7 8

Ru(bpy)2Cl2 Ru(bpy)2Cl2 Ru(bpy)2Cl2 Ru(bpy)2Cl2 Ru(bpy)2Cl2 Ru(bpy)2Cl2 Ru(Phen)2Cl2 Ru(Phen)2Cl2

R R R R R S R S

1:0.5 1:1 1:2 1:3 1:2 1:2 1:2 1:2

2 2 2 2 4 2 4 4

57 70 73.7 51 73.5 73.9 76 73.7

39 75 97 95 96 97 99 98

a Reactions were conducted under continuous microwave irradiation (375 W). The reaction scale is 0.1 mmol of ruthenium bis(diimine) complex for all the entries. b Sul ) methyl p-tolyl sulfoxide. c The de values were determined by HPLC using a chiral column (Pharmacir 4C-R, flow rate 1 mL min-1, aqueous solution of NH4PF6 (0.1 M)/acetonitrile 1:1). d Yields are based on the engaged ruthenium bis(diimine) complex.

Scheme 3. Diastereoselective Synthesis of Ruthenium Bis(phenanthroline) Chiral Sulfoxide Complexes

Figure 1. Molecular structure of complex 7 with atomlabeling scheme. Ellipsoids are drawn at 50% probability.

atom. Each phenanthroline, named I (N(11),N(21)) and II (N(31),N(41)), is essentially planar, with the largest deviations from the plane being 0.027 and 0.107 Å for I and II, respectively. They are approximately perpendicular to each other with a dihedral angle of 85.5°. The distances and angles within the phenanthroline ligands are as expected.13 As anticipated, this complex is enantiomerically pure and crystallizes in the P21 enantiomorphous space group (Table 2). The absolute configuration was obtained by refining the Flack’s enantiopole parameter14 x defined as

Fo2 ) (1 - x)F(h)2 + xF(-h)2

was obtained in 2.0 min at 375 W (entry 3) by using a 1:2 molar ratio of ruthenium complex and 2. This procedure gave cis-∆-[Ru(bpy)2(2)(Cl)]‚PF6 with 73.9% de as judged by chiral HPLC, which was easily isolated in 77% yield (de ) 96%). Little change was noted with a prolongation of the reaction time (compare entries 3 and 5). No amelioration was observed when the reaction was preformed in an ethylene glycol/ethanol mixture (1: 1) under these conditions. The reaction of cis-[Ru(bpy)2(Cl)2] with the enantiomerically pure (S)-sulfoxide 4 (entry 6) afforded cis-Λ-[Ru(bpy)2(4)(Cl)]‚PF6 5 (73.7% de) as the major product (Scheme 2). However, when racemic cis-[Ru(phen)2(Cl)2] was used as a starting material, 4.0 min was necessary for a complete conversion (Scheme 3). The observed de’s are similar to those obtained with Ru(bpy)2Cl2 (entries 7 and 8). The purification of both isomers was achieved by complete precipitation of the Λ-isomer, 8, from a concentrated dichloromethane solution of the crude material. Single crystals of 7 were obtained, and its X-ray structure was studied to confirm its absolute configuration at the metal center and to determine the structural factors governing its stability. The molecular structure of complex 7 determined by X-ray analysis (Figure 1) shows a chiral near-octahedral geometry for the ruthenium, which is bonded to two bidentate 1,10-phenanthroline ligands, a chloride ion, and a methyl p-tolyl sulfoxide ligand through the sulfur

The absolute configuration is ∆ at the metal center1b and S at the sulfur atom due to the coordination to the ruthenium (change of substituent priorities). It is worth noting that the absolute configuration at the sulfur (Rmethyl p-tolyl sulfoxide) has been retained. This structure is closely related to previously reported ruthenium bis(bipyridine) dimethyl sulfoxide complexes.15 The RuN(41) bond trans to the Cl atom is ca. 0.03 Å shorter than the three other Ru-N bonds (Table 3), and the oxygen atom of the sulfoxide forms a hydrogen bond to H(111) from ligand I (C-H ) 0.954 Å, C- - -O ) 2.974(5) Å; H- - -O ) 2.163(3) Å, C-H- - -O ) 142.0(2)°). However, the O(1)-S(1)-Ru(1)-N(11) torsion angle, 7.71°, is much smaller than the values observed in the dimethyl sulfoxide complexes, 25.2°, resulting in a shorter O- - -H distance of 2.163(3) versus 2.26 Å. The nearly parallel arrangement of the tolyl and pyridyl N(31) rings is also noteworthy. The two rings project nearly perfectly on each other, and the distance between them, 3.752 Å, falls within the expected range for π-π interactions.16 In the case of the minor isomer, we also tried to examine the presence or absence of the intramolecular interactions observed in 7 (in the crystal). We were able to grow crystallographic quality crystals for the minor isomer obtained from a concentrated dichloromethane (13) Deacon, G. B.; Kepert, C. M.; Sahely, N.; Skelton, B. W.; Spiccia, L.; Thomas, N. C.; White, A. H. J. Chem. Soc., Dalton Trans. 1999, 275. (14) Flack, H. Acta Crystallogr. 1983, A39, 876. (15) Hesek, D.; Inoue, Y.; Everitt, S. R. L.; Ishida, H.; Kunieda, M.; Drew, M. G. B. J. Chem. Soc., Dalton Trans. 1999, 3701. (16) Mamula, O.; von Zelewsky, A.; Bark, T.; Bernardinelli, G. Angew. Chem., Int. Ed. 1999, 38, 2945.

Preparation of Ru Bis(diimine) Sulfoxide Complexes

Organometallics, Vol. 19, No. 20, 2000 4011

Table 2. Crystal Data formula fw(g) cryst size, mm cryst system space gp a, Å b, Å c, Å β, deg V, Å3 Z Dcalcd, g cm-3 µ(Mo KR), cm-1 temperature, K no. of rflns collected no. of unique rflns (Rint) refinement method no. of data/params R (I>1σ(I)) Rw (I>1σ(I)) GOF

formula fw cryst size, mm cryst system space gp a, Å b, Å c, Å β, deg V, Å3 Z Dcalcd, g cm-3 µ(Mo KR), cm-1 temperature, K no. of rflns collected no. of unique rflns (Rint) refinement method no. of data/params R (I>2σ(I)) Rw (I>2σ(I)) GOF

7

[Ru(bpy)2(dmbpy)]

C32H26ClF6N4OPRuS 796.13 0.35, 0.25, 0.02 monoclinic P21 7.6710(8) 12.6410(16) 16.4750(18) 98.43(1) 1580.3(3) 2 1.673 7.675 160(2) 12863 4735 (0.034)

C34H31F12N7P2Ru 928.66 0.40, 0.075, 0.05 orthorhombic P212121 13.3764(12) 13.4899(14) 20.340(3) 90.0 3670.3(7) 4 1.681 6.131 160(2) 30018 5848 (0.15)

full-matrix on F 4211/426 0.0250 0.0280 1.043

full-matrix on F 3892/507 0.0569 0.0598 0.983

10

∆-5

C19H21F6N3OPRu0.5 502.89 0.50, 0.50, 0.05 monoclinic C2/c 12.9783(17) 20.2849(24) 16.6265(23) 106.52(2) 4196.4(9) 8 1.592 5.456 160(2) 20733 4059 (0.0282)

C28H26ClF6N7OPRuS 748.07 0.56, 0.20, 0.10 orthorhombic P212121 10.1642(15) 14.4657(22) 20.301(3) 2984.9(8) 4 1.665 8.064 160(2) 29575 5768 (0.1188)

full-matrix on F 3626/298 0.0314 0.0364 1.122

full-matrix on F 4595/426 0.0378 0.0440 1.022

solution of the crude material obtained from the reaction of cis-[Ru(bpy)2(Cl)2] with the enantiomerically pure (S)sulfoxide, 4. As for complex 7, the molecular structure of this minor isomer represented in Figure 2 shows a chiral near-octahedral geometry for the ruthenium, which is bonded to two bidentate 2,2′-bipyridine ligands, a chloride ion, and a methyl p-tolyl sulfoxide ligand through the sulfur atom. Each bipyridine is essentially planar, with the largest deviations from the plane being 0.034 and 0.102 Å, respectively. They are approximately perpendicular to each other, with a dihedral angle of 88.3°. The distances and angles within these ligands are as expected. As anticipated, this complex is enantiomerically pure and crystallizes in the P212121 space group (Table 2). The absolute configuration is ∆ at the metal center and R at the sulfur atom due to the coordination to the ruthenium (change of the priority). It is worth noting that the absolute configuration at the sulfur (S-methyl p-tolyl sulfoxide) has been retained. As noted in complex 7, the Ru-N(41) bond trans to the Cl atom is ca. 0.03 Å shorter than the three other Ru-N bonds (Table 3) and the oxygen atom of the sulfoxide forms a hydrogen bond

Figure 2. Molecular structure of complex ∆-5 with atomlabeling scheme. Ellipsoids are drawn at 50% probability.

to H(111) (C-H ) 0.96 Å, C- - -O ) 3.008(6) Å; H- - -O ) 2.148(4) Å, C-H- - -O ) 148.5(3)°). The O(1)-S(1)Ru(1)-N(11) torsion of -11.4° compares well with complex 7. However, contrary to what was observed in ∆-7, there is no π-π overlap between the tolyl and the pyridyl rings in ∆-5; the tolyl ring has rotated away from the bipyridine N(31)-N(41). This is evidenced by the large values observed for the C(111)-S(1)-Ru(1)-N(31) and C(111)-S(1)-Ru(1)-N(41) torsion angles of -71.8° and -151.06°, respectively, compared with the corresponding values of -19.6° and 59.3° in 7. According to the X-ray study on these two complexes, we speculate that the formation of the ruthenium bis(diimine) sulfoxide complexes may be related to the strong oxygen-hydrogen interaction, which precludes the formation of the ruthenium bis(diimine) bis(sulfoxide) complex. To confirm the role of this intramolecular interaction, we decided to investigate the application of Ru(2,9-dimethyl-phen)2Cl2 (2,9-dimethylphen ) 2,9-dimethyl-1,10-phenanthroline), 9, in this reaction (Scheme 4). Thus, the reaction of this ruthenium fragment with R-sulfoxide 2 under microwave irradiation resulted in the formation of [Ru(2,9-dimethyl-phen)2(R-2)2]2+. This complex in acetonitrile gave [Ru(dmphen)2(CH3CN)2]‚ 2PF6, 10,17 which was characterized by X-ray study as a racemic complex. A molecular view of complex 10 is shown in Figure 3. The complex comprises two asymmetric units, each containing half of the molecule, arranged around a 2-fold axis. The ruthenium has a pseudo-octahedral geometry with two 2,9-dimethyl-1,10-phenanthroline ligands and two acetonitrile ligands in cis-arrangement (Table 2). A similar cis-arrangement of acetonitrile ligand has already been reported for the related cis-bis(acetonitrile)bis(2,2′-bipyridine)ruthenium(II) bis(hexafluorophosphate).18 As observed in related ruthenium(II) phenanthroline complexes,19 the phenanthroline is not (17) Collin, J. P.; Sauvage, J. P. Inorg. Chem. 1986, 25, 135.

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Scheme 4. Formation of the Ruthenium Bisacetonitrile Complex 10 by Reaction of [Ru(2,9-dmphen)2Cl2] with the Chiral Sulfoxide 2

planar but appears to be folded around the central ring by 7.2° and 6.3°, resulting in a dihedral angle between the pyridyl rings of 12.4° (Table 3). This deformation is certainly related to steric hindrance, the methyl groups having a tendency to move away from the metal center as shown by the distortion of the Ru(1)-N(11)-C(15)C(25)-N(21) metallacycle: the Ru(1),N(11),N(21) and N(11),C(15),C(25),N(21) planes make a dihedral angle of 21.7°. Thus it is clear that this O- - -H interaction is the most important factor governing the reaction of [Ru(diimine)2(Cl)2] with the sulfoxide leading to the ruthenium mono sulfoxide complex by preventing the substitution of the second chloride ligand. Additionally, it appears from the X-ray studies of the major isomer ∆-7 and the minor isomer ∆-5 that the observed diastereoselectivities in this system are fundamentally influenced by this O- - -H interaction and by the pyridyl-tolyl rings’ π-π overlap. The major isomer is favored due to the cooperation between both interactions. These observations are in agreement with the molecular modeling proposed by Inoue.7 The mechanistic interpretation of substitution reactions of octahedral complexes is difficult because several parameters could be involved. However, the predominant mechanism for this transformation is likely the reaction of the complexing agent with the pentacoordinate intermediate generated in situ after the dissociative process.20 In our case, the reaction of [Ru(bpy)2(DMSO)(Cl)]+ with (R)-2 under the microwave conditions yielded the two isomers of cis-[Ru(bpy)2(2)(Cl)]+ in 96% yield, with the ∆-isomer in 65% de. According to our experimental conditions (use of protic solvent), the sixcoordinated species resulting from a weak bond between a solvent molecule and the pentacoordinated species could also be considered. However, at this stage, we do not have experimental information to favor either of these two hypotheses. (18) Heeg, M. J.; Kroener, R.; Deutsch, E. Acta Crystallogr., Sect. C 1985, 41, 684. (19) (a) Ichida, H.; Tachiyashiki, S.; Sasaki, Y. Chem. Lett. 1989, 1579. (b) Reibenspies, J. H.; Darensbourg, D. J.; Benyei, A. C. Z. Kristallogr. 1996, 211, 977. (20) (a) Wilkins, R. G. Kinetics and Mechanism of Reactions of Transitions Metal Complexes; 2nd ed.; VCH: Weinheim, 1991. (b) Atwood, J. D. Inorganic and Organometallic Reaction Mechanism, 2nd ed.; Wiley-VCH: New York, 1997.

Pezet et al.

In conclusion, the aforementioned results introduce a new approach to the synthesis of optically active octahedral ruthenium complexes. This was reached by microwave irradiation of cis-[Ru(diimine)2(Cl)2] with an enantiomerically pure sulfoxide. This source of energy improves both yields and reaction rates with a very good diastereoselectivity (73-76% de). This represents a significant advance in the asymmetric synthesis of octahedral ruthenium complexes. We have also demonstrated that these complexes are useful precursors for the preparation of optically pure tris(diimine) ruthenium complexes. X-ray studies of complex 7, complex ∆-5, and the result of the reaction of [Ru(2,9-dimethylphen)2(Cl)2] with the chiral sulfoxide clearly demonstrate the fundamental role of the intramolecular O- - H interaction in the reactivity of [Ru(diimine)2(Cl)2] with the sulfoxide. The observed asymmetric induction is likely due to the stability of the major isomer resulting from the contribution of the two intramolecular interactions. Work is in progress to investigate the effect of the nature of the chiral sulfoxide on this system and to determine the origin of the diastereoselectivity. Experimental Section All reagents used were reagent grade or better and used without further purification. cis-[Ru(bpy)2Cl2], cis-[Ru(phen)2Cl2],21 [Ru(2,9-dmphen)2Cl2],17 and (R)-methyl-p-tolylsulfoxide22 were prepared according to published procedures. IR spectra were obtained using a KBr disk in a PerkinElmer IRTF 1725X. NMR spectra were recorded on a DPX 400 (400 MHz for 1H and 100.6 MHz for 13C) spectrometer. Optical rotations were measured on a Perkin-Elmer 241 MC. DCI mass spectra were recorded with a quadripolar Nermag R 1010H instrument. Elemental analyses were performed by Laure Donnadieu-Noe´ on a Perkin-Elmer 2400 series II. Diastereoisomeric and enantiomeric excesses were determined with an analytical HPLC (Waters 600) equipped with an analytical chiral column (PHARMACIR 4C-R). An aqueous solution of NH4PF6 (0.1 M) and acetonitrile were used as eluent with a flow rate of 1 mL‚min-1. General Procedure for Bis(bipyridine) Sulfoxide Ruthenium Complexes. Method A. A suspension of Ru(bpy)2Cl2‚2H2O (52.0 mg, 0.10 mmol) and chiral methyl-ptolylsulfoxide (31.0 mg, 0.20 mmol) in ethylene glycol (1 mL) was heated for 2.0 min in a microwave oven (375 W). After cooling, a saturated aqueous ammonium hexafluorophosphate solution was added. The precipitate was filtered, washed with water and diethyl ether, and dried overnight to yield the two diastereoisomers as an orange powder (75 mg, >99%). Method B. A suspension of Ru(bipy)2Cl2‚2H2O (52.0 mg, 0.10 mmol) and (R)-methyl-p-tolylsulfoxide (31.0 mg, 0.20 mmol) in ethylene glycol (5 mL) was heated for 6 h at 150 °C. After cooling, a saturated aqueous ammonium hexafluorophosphate solution was added. The precipitate was filtered, washed with water and diethyl ether, and dried overnight to yield both isomers as an orange powder (72 mg, 95%). cis-∆-[Ru(bpy)2(2)(Cl)]‚PF6 (3). The separation of cis-∆[Ru(bpy)2(2)(Cl)]‚PF6 (3) can be achieved by three successive washings of the crude material with ethanol (2 mL). The resulting precipitate led to 3 with de ) 96% (yield ) 77%). IR: 1096 cm-1 stretching band S-O bond.23 [R]D -160° (acetone, c 0.125). UV-vis: λ 290 ( 17500), λ 424 ( 2050). 1H NMR (CD2Cl2, 400 MHz): δ 10.39 (d, J ) 5.6 Hz, 1H), 9,67 (d, J ) 5.6 Hz, 1H), 8.35 (d, J ) 8.1 Hz, 1H), 8.28 (d, J ) 8.1 Hz, 1H), (21) Lay, P. A.; Sargerson, A. M.; Taube, H. Inorg. Synth. 1986, 24, 291. (22) Anderson, K. K. Tetrahedron Lett. 1962, 18, 93.

Preparation of Ru Bis(diimine) Sulfoxide Complexes

Organometallics, Vol. 19, No. 20, 2000 4013

Table 3. Important Bond Lengths (Å) and Bond Angles (deg) with Esd’s in Parentheses complex 7 Ru(1)-Cl(1) Ru(1)-S(1) Ru(1)-N(11) Ru(1)-N(21) Ru(1)-N(41) Ru(1)-N(31) S(1)-O(1) S(1)-C(111) S(1)-C(121) N(11)-C(11) N(11)-C(15) N(12)-C(21) N(12)-C(25) N(31)-C(31) N(31)-C(35) N(41)-C(41) N(41)-C(45) Cl(1)-Ru(1)-S(1) Cl(1)-Ru(1)-N(11) Cl(1)-Ru(1)-N(21) Cl(1)-Ru(1)-N(31) Cl(1)-Ru(1)-N(41) S(1)-Ru(1)-N(11) S(1)-Ru(1)-N(21) S(1)-Ru(1)-N(31) S(1)-Ru(1)-N(41) N(11)-Ru(1)-N(21) N(11)-Ru(1)-N(31) N(11)-Ru(1)-N(41) N(21)-Ru(1)-N(31) N(21)-Ru(1)-N(41) N(31)-Ru(1)-N(41) Ru(1)-S(1)-O(1) Ru(1)-S(1)-C(111) Ru(1)-S(1)-C(121) O(1)-S(1)-C(111) O(1)-S(1)-C(121) C(111)-S(1)-C(121) Ru(1)-N(11)-C(11) Ru(1)-N(11)-C(15) Ru(1)-N(21)-C(21) Ru(1)-N(21)-C(25) Ru(1)-N(31)-C(31) Ru(1)-N(31)-C(35) Ru(1)-N(41)-C(41) Ru(1)-N(41)-C(45)

complex ∆-5 2.4256(9) 2.271(1) 2.088(3) 2.088(3) 2.057(3) 2.088(3) 1.490(3) 1.780(4) 1.774(4) 1.333(5) 1.381(5) 1.315(5) 1.380(4) 1.333(5) 1.363(5) 1.338(5) 1.361(5)

Ru(1)-Cl(1) Ru(1)-S(1) Ru(1)-N(11) Ru(1)-N(21) Ru(1)-N(41) Ru(1)-N(31) S(1)-O(1) S(1)-C(111) S(1)-C(121) N(11)-C(15) N(11)-C(11) N(21)-C(25) N(21)-C(21) N(41)-C(45) N(41)-C(41) N(31)-C(35) N(31)-C(31)

90.50(4) 89.63(9) 85.95(8) 95.26(9) 171.52(9) 97.67(9) 175.48(9) 87.14(9) 95.64(9) 79.53(12) 173.12(13) 95.32(12) 95.96(12) 88.18(11) 79.26(12) 119.04(12) 110.78(13) 112.05(14) 106.18(18) 104.7(2) 102.6(2) 129.9(3) 113.1(3) 128.9(2) 112.8(2) 129.0(3) 113.2(2) 127.7(3) 114.4(2)

Cl(1)-Ru(1)-S(1) Cl(1)-Ru(1)-N(11) Cl(1)-Ru(1)-N(21) Cl(1)-Ru(1)-N(31) Cl(1)-Ru(1)-N(41) S(1)-Ru(1)-N(11) S(1)-Ru(1)-N(21) S(1)-Ru(1)-N(31) S(1)-Ru(1)-N(41) N(11)-Ru(1)-N(21) N(11)-Ru(1)-N(31) N(11)-Ru(1)-N(41) N(21)-Ru(1)-N(31) N(21)-Ru(1)-N(41) N(31)-Ru(1)-N(41) Ru(1)-S(1)-O(1) Ru(1)-S(1)-C(111) Ru(1)-S(1)-C(121) O(1)-S(1)-C(111) O(1)-S(1)-C(121) C(111)- S(1)-C(121) Ru(1)-N(11)-C(11) Ru(1)-N(11)-C(15) Ru(1)-N(21)-C(21) Ru(1)-N(21)-C(25) Ru(1)-N(31)-C(31) Ru(1)-N(31)-C(35) Ru(1)-N(41)-C(41) Ru(1)-N(41)-C(45)

2.395(1) 2.2647(11) 2.098(4) 2.082(4) 2.054(3) 2.070(3) 1.491(3) 1.783(5) 1.766(5) 1.358(6) 1.356(6) 1.343(6) 1.364(6) 1.366(6) 1.336(6) 1.357(6) 1.336(6) 92.27(4) 90.48(11) 85.4(1) 94.49(11) 173.4(1) 99.86(11) 176.37(11) 91.99(11) 90.58(11) 77.42(14) 166.97(14) 94.85(14) 90.96(15) 92.03(14) 79.50(14) 119.12(16) 113.28(15) 112.03(19) 105.6(2) 104.2(3) 100.6(2) 126.7(3) 115.1(3) 125.5(3) 117.2(3) 126.1(3) 114.3(3) 126.2(3) 114.4(3)

Complex 10 Ru(1)-N(1) Ru(1)-N(11) Ru(1)-N(21) N(1)-C(1) N(11)-C(11) N(1)-Ru(1)-N(1) N(1)-Ru(1)-N(11) N(1)-Ru(1)-N(11)′a N(11)-Ru(1)-N(11)′ N(1)-Ru(1)-N(21) N(1)-Ru(1)-N(21)′ N(11)-Ru(1)-N(21) N(11)-Ru(1)-N(21)′ a

2.0428(19) 2.1062(18) 2.0756(17) 1.134(3) 1.332(3) 84.6(1) 84.09(7) 95.06(7) 178.86(9) 88.92(7) 172.16(7) 79.90(7) 100.86(7)

N(11)-C(15) N(21)-C(21) N(21)-C(25) C(1)-C(2) Ru(1)-N(1)-C(1) Ru(1)-N(11)-C(11) Ru(1)-N(11)-C(15) C(11)-N(11)-C(15) Ru(1)-N(21)-C(21) Ru(1)-N(21)-C(25) C(21)-N(21)-C(25) N(1)-C(1)-C(2)

1.380(3) 1.337(3) 1.383(3) 1.456(3) 172.26(19) 132.01(15) 109.60(13) 117.96(19) 131.04(14) 110.29(13) 118.15(18) 175.7(3)

′Symmetry transformations used to generate equivalent atoms: 1 - x, y, 3/2 - z.

8.15 (td, J ) 8.0 Hz and 1.4 Hz, 1H), 8.03 (td, J ) 8.0 Hz and 1.4 Hz, 1H), 7.94-7.91 (m, 2H), 7.84 (t, J ) 8 Hz, 1H), 7.79 (d, J ) 6.5 Hz, 3H), 7.66 (t, J ) 6.0 Hz, 1H), 7.26-7.15 (m, 3H), 6.82 (d, J ) 8.0 Hz, 2H), 6.47 (d, J ) 8.0 Hz, 2H), 3.60 (s, 3H), 2.26 (s, 3H). 13C NMR (CD2Cl2, 100.6 MHz): δ 155.1, 152.5, 149.0, 137.6, 137.3, 137.0, 136.4, 128.8, 126.6, 126.4, 125.9, 122.3, 122.1, 43.2, 20.2. MS (FAB, mNBA); m/z (%): 603 (39) [M - PF6], 449 (100) [M - PF6 - sulfoxide]. Anal. Calcd (23) Evans, I. P.; Spencer, A.; Wilkinson, G. J. Chem. Soc., Dalton Trans. 1973, 204.

for C28H26F6ClN4OSPRu‚1/2H2O: C, 44.4; H, 3.59; N, 7.40; S, 4.23. Found: C, 44.65; H, 3.68; N, 7.32; S 4.05. Retention times: 9.60 min for cis-∆-[Ru(bpy)2(2)(Cl)]‚PF6 (3) (6.25 min for the minor diastereoisomer), 9.16 min for cis-Λ-[Ru(bpy)2(4)(Cl)]‚PF6 (5) (8.47 min for the minor diastereoisomer). cis-∆-[Ru(bpy)2(4)(Cl)]‚PF6. The crystallization of cis-∆[Ru(bpy)2(4)(Cl)]‚PF6, ∆-5, can be achieved from a concentrated solution of the crude material in the dichloromethane. IR: 1096 cm-1 stretching band S-O bond. [R]D +185° (acetone, c 0.15). 1H NMR (acetone-d , 400 MHz): δ 9.75 (d, J ) 5.6 Hz, 1H), 6

4014

Organometallics, Vol. 19, No. 20, 2000

Figure 3. Molecular structure of complex 10 with atomlabeling scheme. Ellipsoids are drawn at 50% probability. 9.42 (d, J ) 5.6 Hz, 1H), 8.75 (d, J ) 8.3 Hz, 1H), 8.64 (d, J ) 8.3 Hz, 1H), 8.62 (d, J ) 8.3 Hz, 1H), 8.60 (d, J ) 8.3 Hz, 1H), 8.32 (t, J ) 7.8 Hz, 1H), 8.18 (t, J ) 7.8 Hz, 1H), 8.12 (d, J ) 5.6 Hz, 1H), 8.04 (m, 2H), 7.75 (t, J ) 5.8 Hz, 1H), 7.64 (t, J ) 5.8 Hz, 1H), 7.49 (d, J ) 7.8 Hz, 2H), 7.42 (d, J ) 5.8 Hz, 1H), 7.37 (m, 2H), 7.24 (d, J ) 7.8 Hz, 2H), 2.74 (s, 3H), 2.39 (s, 3H). 13C NMR (acetone-d6, 100.6 MHz): δ 158.5, 158.1, 157.8, 156.7, 155.7, 153.6, 153.1, 149.8, 141.8, 141.5, 138.4, 138.2, 137.6, 137.4, 129.6, 127.6, 126.4, 125.3, 124.2, 124.1, 123.6, 123.2, 43.4, 20.4. Anal. Calcd for C28H26F6ClN4OSPRu‚ 1/2H2O: C, 44.4; H, 3.59; N, 7.40; S, 4.23. Found: C, 44.38; H, 3.70; N, 7.24; S, 4.35. General Procedure for Bis(phenanthroline) Sulfoxide Ruthenium Complexes. A suspension of Ru(phen)2Cl2‚H2O (52.0 mg, 0.10 mmol) and chiral methyl-p-tolylsulfoxide (31.0 mg, 0.20 mmol) in ethylene glycol (1 mL) was heated for 4.0 min in a microwave oven (375 W). After cooling, a saturated ammonium hexafluorophosphate aqueous solution was added. The precipitate was filtered, washed with water and diethyl ether, and dried overnight to yield 1 as an orange powder (80.0 mg, 97%). The minor diastereoisomer was slowly precipitated from a concentrated solution of the crude product in dichloromethane. cis-∆-[Ru(phen)2(2)(Cl)]‚PF6 (7) or cis-Λ-[Ru(phen)2(4)(Cl)]‚PF6. [R]D -2.25° (acetone, c 0.034) for complex 7. 1H NMR (CD2Cl2, 400 MHz): δ 10.81 (dd, J ) 5.4 Hz and 1.3 Hz, 1H), 10.01 (dd, J ) 5.4 Hz and 1.0 Hz, 1H), 8.67 (dd, J ) 8.0 Hz and 1.0 Hz, 1H), 8.56 (dd, J ) 8.0 Hz and 1.0 Hz, 1H), 8.36 (dd, J ) 7.0 Hz and 2.5 Hz, 1H), 8.25-7.85 (m, 9H), 7.447.30 (m, 2H), 6.37 (d, J ) 8.0 Hz, 2H), 6.11 (d, J ) 8.0 Hz, 2H), 3.68 (s, 3H), 2.14 (s, 3H). 13C NMR (CD2Cl2, 100.6 MHz): δ 158.3, 155.5, 155.2, 152.0, 148.8, 143.0, 139.1, 138.7, 138.6, 137.6, 123.3, 130.2, 130.0, 129.6, 129.2, 127.8, 127.6, 127.2, 127.0, 126.8, 123.4, 45.3, 22.4. MS (FAB, mNBA) m/z (%): 651 (29) [M - PF6], 497 (100) [M - PF6 - sulfoxide]. Anal. Calcd for C32H26F6ClN4OSPRu‚H2O: C, 47.21; H, 3.47; N, 6.88; S, 3.94. Found: C, 47.00; H, 3.54; N, 6.70; S, 3.89. Retention

Pezet et al. times: 16.60 min for cis-∆-[Ru(phen)2(2)(Cl)]‚PF6 (7) and 15.60 min for cis-Λ-[Ru(phen)2(4)(Cl)]‚PF6. cis-Λ-[Ru(phen)2(2)(Cl)]‚PF6 (8) or cis-∆-[Ru(phen)2(4) (Cl)]‚PF6 (minor diastereoisomer). 1H NMR (acetone-d6, 400 MHz): δ 10.18 (dd, J ) 5.5 Hz and 1.0 Hz, 1H), 9.65(dd, J ) 5.5 Hz and 1.0 Hz, 1H), 9.13 (dd, J ) 8.0 Hz and 1.0 Hz, 1H), 8.75 (td, J ) 8.0 Hz and 1.0 Hz, 2H), 8.54 (t, J ) 8.0 Hz, 2H), 8.44 (dd, J ) 8.0 Hz and 5.5 Hz, 2H), 8.34 (d, J ) 8.0 Hz, 2H), 8.29-8.20 (m, 2H), 7.61-7.53 (m, 3H), 7.38 (d, J ) 8.0 Hz, 2H), 7.23 (d, J ) 8.0 Hz, 2H), 2.70 (s, 3H), 2.42 (s, 3H). 13 C NMR (acetone-d6, 100.6 MHz): δ 156.7, 154.8, 154.2, 150.7, 148.9, 148.8, 147.1, 142.0, 141.7, 137.5, 137.1, 136.6, 131.3, 131.2, 131.0, 130.4, 129.3, 128.3, 128.2, 127.6, 126.6, 126.0, 125.7, 125.5, 125.4, 43.6, 20.6. Retention times: 12.50 min for cis-Λ-[Ru(phen)2(2)(Cl)]‚PF6 (8) and 13.41 min for cis-∆-[Ru(phen)2(4)(Cl)]‚PF6. [Ru(2,9-dimethylphenanthroline)2(CH3CN)2]‚2PF6‚ 2H2O (10). A suspension of Ru(2,9-dmphen)2Cl2 (60.0 mg, 0.10 mmol) and chiral methyl-p-tolylsulfoxide (31.0 mg, 0.20 mmol) in ethylene glycol (1 mL) was heated for 2 min in the microwave oven (375 W). After cooling, a saturated aqueous ammonium hexafluorophosphate solution was added. The precipitate was filtered, washed with water and ether, and then treated with acetonitrile (5 mL) at room temperature for 1 h. The solvent was evaporated, and the resulting product was washed with water and ether to lead to 10 as a red powder (55.0 mg, 70%). This complex was crystallized in acetonitrile. 1H NMR (CD CN, 400 MHz): δ 8.62 (d, J ) 8.3 Hz, 2H), 8.22 3 (d, J ) 8.3 Hz, 2H), 8.08 (d, J ) 8.7 Hz, 2H), 7.94 (d, J ) 8.3 Hz, 2H), 7.29 (d, J ) 8.7 Hz, 2H), 3.30 (s, 6H), 2.18 (s, 6H), 1.71 (s,6H). 13C NMR (CD3CN, 100.6 MHz): δ 138.7, 138.0, 127.6, 127.3, 126.9, 124.6, 27.6, 24.5, 4.5. MS (FAB, mNBA) m/z (%): [M - 2CH3CN] 518 (100). Anal. Calcd for C32H30F6N6PRu: C, 51.75; H, 4.10; N, 11.25. Found: C, 51.61; H, 4.06; N, 11.29. X-ray Crystallographic Study. All the data were collected on a Stoe IPDS (imaging plate diffraction system) diffractometer. The final unit cell parameters were obtained by the least-squares refinement of 5000 reflections. Only statistical fluctuations were observed in the intensity monitors over the course of the data collection. The structures were solved by direct methods (SIR92)24 and refined by least-squares procedures on Fobs. H atoms were located on difference Fourier maps. The H atoms were introduced in the calculations in idealized positions (d(CH) ) 0.96 Å), and their atomic coordinates were recalculated after each cycle. They were given isotropic thermal parameters 20% higher than those of the carbon to which they were attached. The PF6 anion in ∆-5 and one PF6 in 11 were disordered. Four fluorine atoms forming an equatorial plane were distributed over two different sites; these disordered F atoms were restrained to have reasonable geometry. Least-squares refinements were carried out by minimizing the function ∑w(|Fo| |Fc|)2, where Fo and Fc are the observed and calculated structure factors. The weighting scheme used in the last refinement cycles was w ) w′[1 - {∆F/6σ(Fo)}2]2 where w′ ) 1/∑ln ArTr(x) with three coefficients Ar for the Chebyshev polynomial ArTr(x) where x was Fc/Fc(max).25 Models reached convergence with R ) ∑(|Fo| - |Fc|)/∑(|Fo|) and Rw ) ∑w(|Fo| - |Fc|)2/∑w(Fo)2]1/2, having values listed in Table 1. Criteria for a satisfactory complete analysis were the ratios of rms shift to standard deviation less than 0.1 and no significant features in final difference maps. The calculations were carried out with the CRYSTALS (24) Altomare, A.; Cascarano, G.; Giacovazzo, G.; Guagliardi, A.; Burla, M. C.; Polidori, G.; Camalli, M. SIR92-a program for automatic solution of crystal structures by direct methods. J. Appl. Crystallogr. 1994, 27, 435. (25) Prince, E. Mathematical Techniques in Crystallography; SpringerVerlag: Berlin, 1982.

Preparation of Ru Bis(diimine) Sulfoxide Complexes package program.26 The drawing of the molecule was realized with the help of CAMERON.27 Crystallographic data (excluding structure factors) for the structures reported in this paper have been deposited at the Cambridge Crystallographic Data Center as supplementary publication no. XXXX. Copies of the data can be obtained free of charge on application to CCDC, 12 Union Road, Cambridge CB2 IEZ, UK [fax: int. code + 44(1223)336-033; e-mail: [email protected]]. (26) Watkin, D. J.; Prout, C. K.; Carruthers, J. R.; Betteridge P. W. CRYSTALS Issue 10; Chemical Crystallography Laboratory, University of Oxford: Oxford, 1996. (27) Watkin, D. J.; Prout, C. K.; Pearce, L. J. CAMERON; Chemical Crystallography Laboratory, University of Oxford: Oxford, 1999.

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Acknowledgment. This work was supported by the Centre National de Recherche Scientifique (CNRS) and the “Ministe`re de l’Education Nationale, de la Recherche et de la Technologie” with a doctoral fellowship for F.P. Supporting Information Available: Selected HPLC data for the chiral sulfoxide-containing complexes 3, 7, 8, and [Ru(bpy)2(dmbpy)]‚2PF6, tables of crystal data, fractional atomic coordinates, anisotropic thermal parameters for non-hydrogen atoms, and atomic coordinates for H atoms. This material is available free in charge via the Internet at http://pubs.acs.org. OM000255L