Bis[(1S*,2S*)-trans-1,2-bis­(diphenyl­phosphin­oxy)cyclo­hexa­ne]chlorido­ruthenium(II) trifluoro­methane­sulfonate dichloro­methane disolvate

George R Clark; Cornelis Lensink; Angela T Slade; L James Wright

doi:10.1107/S1600536809023034

. 2009 Jun 20;65(Pt 7):m804–m805. doi: 10.1107/S1600536809023034

Bis[(1S,2S)-trans-1,2-bis(diphenylphosphinoxy)cyclohexane]chloridoruthenium(II) trifluoromethanesulfonate dichloromethane disolvate

George R Clark ^a,^*, Cornelis Lensink ^b, Angela T Slade ^a, L James Wright ^a

PMCID: PMC2969446 PMID: 21582729

Abstract

The crystal structure of a racemic mixture of the title ruthenium(II) complex, [RuCl(C₃₀H₃₀O₂P₂)₂]CF₃SO₃·2CH₂Cl₂, reveals that the coordination geometry about the coordinatively unsaturated metal centre is approximately trigonal-pyramidal, with the chlorine atom occupying one of the equatorial positions. The axial Ru—P bonds are longer than the equatorial Ru—P bonds and there is an acute P—Ru—P angle.

Related literature

For the syntheses and properties of chiral asymmetric hydrogenation catalysts, see: Knowles & Noyori (2007 ▶); Zhang et al. (2007 ▶); Zhang (2004 ▶). For the syntheses and properties of chiral diphosphinite complexes, see: Au-Yeung & Chan (2004 ▶); Falshaw et al. (2007 ▶); Clark et al. (2009 ▶). For a decription of the Cambridge Structural Database, see: Allen (2002 ▶).

Experimental

Crystal data

[RuCl(C₃₀H₃₀O₂P₂)₂]CF₃SO₃·2CH₂Cl₂
M _r = 1424.40
Orthorhombic,
a = 16.7887 (5) Å
b = 22.9766 (6) Å
c = 32.6782 (9) Å
V = 12605.5 (6) Å³
Z = 8
Mo Kα radiation
μ = 0.66 mm⁻¹
T = 85 K
0.32 × 0.18 × 0.10 mm

Data collection

Siemens SMART CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.808, T _max = 0.930
70582 measured reflections
12041 independent reflections
8363 reflections with I > 2σ(I)
R _int = 0.049

Refinement

R[F ² > 2σ(F ²)] = 0.059
wR(F ²) = 0.136
S = 1.06
12041 reflections
757 parameters
H-atom parameters constrained
Δρ_max = 1.10 e Å⁻³
Δρ_min = −1.16 e Å⁻³

Data collection: SMART (Siemens, 1995 ▶); cell refinement: SAINT (Siemens, 1995 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-III (Burnett & Johnson, 1996 ▶); software used to prepare material for publication: SHELXTL (Sheldrick, 2008 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809023034/lh2843sup1.cif

e-65-0m804-sup1.cif^{(36.6KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809023034/lh2843Isup2.hkl

e-65-0m804-Isup2.hkl^{(576.9KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Selected geometric parameters (Å, °).

Ru—P2	2.2237 (13)
Ru—P3	2.2430 (13)
Ru—Cl1	2.3838 (13)
Ru—P1	2.3935 (12)
Ru—P4	2.4170 (13)

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P2—Ru—P3	87.81 (5)
P2—Ru—Cl1	131.42 (5)
P3—Ru—Cl1	140.73 (5)
P2—Ru—P1	89.44 (4)
P3—Ru—P1	99.68 (4)
Cl1—Ru—P1	84.49 (4)
P2—Ru—P4	99.48 (4)
P3—Ru—P4	89.39 (4)
Cl1—Ru—P4	83.10 (4)
P1—Ru—P4	167.55 (4)

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Acknowledgments

We thank the Tertiary Education Commission, administered by Auckland UniServices Limited, for granting an Enterprise Scholarship to ATS, and Industrial Research Limited New Zealand for partial support of this work. We also thank the University of Auckland for partial support of this work through grants-in-aid.

supplementary crystallographic information

Comment

The development and study of new asymmetric hydrogenation catalysts continues to be a very active area of research (Knowles & Noyori, 2007). Reasons for this interest include the commercial importance of producing enantiomerically pure organic materials (especially for the pharmaceutical industry) and the fact that successful catalysts tend to be substrate-specific rather than being generally useful for a wide range of prochiral substrates (Zhang et al., 2007, Zhang, 2004). Many of the successful catalysts that have been developed contain chiral phosphane or phosphinite ligands (Au-Yeung & Chan, 2004). In our recent studies in this area we have synthesized and studied a range of new chiral ruthenium complexes that are potential asymmetric hydrogenation catalysts (Falshaw et al., 2007, Clark et al., 2009). These complexes all contain chiral diphosphinite ligands that have either chiro-inositol or cyclohexane backbones. During these investigations we prepared a racemic mixture of the cationic, chiral ruthenium complexes [RuCl{(1S,2S)-trans-(OPPh₂)₂(C₆H₁₀)}₂]O₃SCF₃ and [RuCl{(1R,2R) -trans-(OPPh₂)₂(C₆H₁₀)}₂]O₃SCF₃((rac)-3) through treatment of a racemic mixture of the corresponding hydride complexes ((rac)-2) with triflic acid (see Figure 1). (rac)-2, in turn, was prepared by heating a solution of [RuCl₂(COD)]_n with NEt₃ and a racemic mixture of the diphosphinite ligands (1R,2R)-1,2-trans-bis-(O-diphenylphosphino)cyclohexane and (1S,2S)-1,2-trans-bis-(O-diphenylphosphino)cyclohexane ((rac)-1). We now report the details of the structure of (rac)-3 which crystallizes with four molecules of each enantiomer in the unit cell. The bond lengths and angles for each enantiomer are crystallographically identical and the structure of [RuCl{(1S,2S)-trans-(OPPh₂)₂(C₆H₁₀)}₂]O₃SCF₃ only is depicted in Figure 2. The geometry about the ruthenium(II) centre in this coordinatively unsaturated complex is approximately trigonal bipyramidal with chloride occupying one of the equatorial positions. It is noteworthy that the isomer of [RuCl{(1S,2S)-trans-(OPPh₂)₂(C₆H₁₀)} ₂]O₃SCF₃ that has the opposite configuration at the metal centre was not present in the crystal. As expected, the two phosphorus atoms in the axial positions (P1 and P4; P1—Ru—P4 = 167.55 (4)°) form slightly longer bonds to ruthenium (Ru—P1 = 2.3935 (13), Ru—P4 = 2.4170 (13) Å) than the two phosphorus atoms (P2 and P3) that are in the equatorial positions (Ru—P2 = 2.2237 (13), Ru—P3 = 2.2430 (13) Å). However, all Ru—P distances fall within the normal range for compounds of this type [Cambridge Structure Database Version 5.30; Allen (2002); average Ru-P(OR)Ph₂ distance = 2.288Å (SD = 0.042Å]. Similarly, the Ru—Cl distance (2.3838 (13) Å) is normal. The P2—Ru—P3 angle is small at 87.81 (5)°. The crystals also contain two dichloromethane molecules of crystallization per molecule of complex.

Experimental

Synthesis of a racemic mixture of chlorobis{(1S,2S)-1,2-trans-bis-(O-diphenylphosphino)cyclohexane}ruthenium(II) trifluoromethanesulfonate and chlorobis{(1R,2R)-1,2-trans-bis-(O-diphenylphosphino)cyclohexane}ruthenium(II) trifluoromethanesulfonate (rac-3). Triflic acid (0.049 ml, 0.56 mmol) was added under nitrogen to a racemic mixture of RuHCl{(1S,2S)-trans-(OPPh₂)₂(C₆H₁₀)}₂ and RuHCl{(1R,2R)- trans-(OPPh₂)₂(C₆H₁₀)}₂ (0.21 g, 0.19 mmol) in THF (10 ml) and toluene (1 ml). The solution was stirred for 15 minutes at R.T. and the solvents were removed under reduced pressure to give a red product that was recrystallized from dichloromethane/hexane. MS (m/z): Calcd for C₆₀H₆₀³⁵ ClO₄P₄¹⁰²Ru (M⁺) 1105.21741 m/z. Found: 1105.21644. ¹H NMR (CDCl₃, δ): 0.74–2.40 (m, 16H, CH₂), 3.70–4.90 (m, 4H, CH), 6.58–7.90 (m, 40H, Ph). ¹³C NMR (CDCl₃, δ): 22.4 (CH₂), 23.3 (CH₂), 31.7 (CH₂), 32.8 (CH₂), 77.9 (CH), 83.1 (CH), 126.0–136.0 (multiple signals, Ph). ³¹P{¹H} NMR (CDCl₃,δ): 126.18 (t, ²J_PP = 29.6 Hz), 157.19 (t, ²J_PP = 29.6 Hz).