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Acta Cryst. (2007). E63, m2292-m2293    [ doi:10.1107/S1600536807037919 ]

trans-Bis[(S)-2-(4-ethyl-4,5-dihydro-1,3-oxazol-2-yl)phenolato-[kappa]2N,O]copper(II)

Y. Zhang, T.-F. Liu, W.-G. Xu, B.-T. Zhao and J.-G. Wang

Abstract top

In the title centrosymmetric compound, [Cu(C11H12NO2)2], the coordination geometry of the CuII atom, which is on an inversion centre, is distorted square planar, with a Cu-N distance of 1.9541 (14) and a Cu-O distance of 1.9083 (14) Å. The crystal packing is stabilized by [pi]-[pi] interactions, with a centroid-to-centroid distance of 3.7953 (12) Å, and by C-H...[pi] interactions.

Comment top

Over the last decade, C2-symmetric chiral oxazoline metal complexes have been recognized as an effective class of chiral catalyst in a variety of transition metal catalyzed asymmetric reactions (Ghosh et al., 1998). High catalytic activities and enantiomeric excesses have been obtained using C2-symmetric chiral ligands in conjunction with suitable transition metal ion, for example, the hydrosilylation of ketone (Imai et al., 1996), allylic alkylation (Chelucci 1997), Michael addition (Ji et al., 1999), Diels-Alder cycloaddition, and cyclopropanation. Thus, the design and synthesis of new chiral oxazoline ligands and their complexes have inspired many scientists to work with great efforts (Du et al., 2003; Zhang et al., 2007).

We report here the crystal structure of the title compound, (I), a CuII complex with the chiral (S)-2-(4-ethyl-4,5-dihydrooxazol −2-yl)phenol, as the coordination ligand.

The title compound, contains one centrosymmetric tetra-coordinated copper(II) complex (Fig 1). The copper atom is coordinated by two 2-(4-ethyl- 4,5-dihydrooxazol-2-yl)-phenol anions, which bind to the metal centre via the N atom and the phenolyl O atom. Pairs of equivalent ligands lie trans to each other in a slightly distorted square planar geometry about the copper(II) atom (see Table 1).

The aryl and oxazoline least-squares planes are linked by π-π stacking interactions with Cg-Cgii distances 3.7953 (12) Å (symmetry code ii: 1 − x, 1 − y, 1 − z). The C—H···Cg (aryl ring) interactions are observed with H9Aiii···Cg = 2.94 Å (symmetry code iii: x, 1/2 − y, −1/2 + z) and H9Ai···Cg = 2.89 Å (Fig 2) (Spek, 2003).

Related literature top

For related literature, see Chelucci (1997); Du et al. (2003); Ghosh et al. (1998); Ji et al. (1999); Imai et al. (1996); Zhang et al. (2007). For synthesis, see: Serrano et al. (1995).

Experimental top

The chiral ligand, (S)-2-(4-ethyl-4,5-dihydrooxazol-2-yl)phenol was prepared from 2-hydroxybenzonitrile and (S)-2-aminobutan-1-ol as literature reported (Serrano et al., 1995).

A solution of (S)-2-(4-ethyl-4,5-dihydrooxazol-2-yl)phenol (30.56 mg, 0.16 mmol) in methanol (1.60 ml) was added to a stirred solution of CuCl23H2O (34.10 mg, 0.2 mmol) in methanol(2.00 ml). Crystals suitable for diffraction analysis were obtained after a few days.

Refinement top

H atoms were positioned geometrically (aromatic C—H = 0.93 Å, aliphatic C—H = 0.96–0.98 Å) and refined with the riding model approximation, with Uiso(H) = 1.2Ueq(C) [1.5Ueq(C) for methyl H].

Computing details top

Data collection: SMART (Bruker, 2003); cell refinement: SAINT (Bruker, 2003); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1999); software used to prepare material for publication: SHELXTL and PLATON (Spek, 2003).

Figures top
[Figure 1] Fig. 1. ORTEP plot of [Cu(C11H12NO2)2]; displacement ellipsoids are drawn at the 30% probability level. (suffix A denotes symmetry code: −x, −y, −z + 1).
[Figure 2] Fig. 2. The π–π stacking interactions and C—H···π interactions between ligands. Non-interaction hydrogen atoms are omitted for clarity.
trans-Bis[(S)-2-(4-ethyl-4,5-dihydro-1,3-oxazol-2-yl)phenolato- κ2N,O]copper(II) top
Crystal data top
[Cu(C11H12N1O2)2]F000 = 462
Mr = 443.97Dx = 1.443 Mg m−3
Monoclinic, P21/cMo Kα radiation
λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 3198 reflections
a = 6.6645 (9) Åθ = 2.4–26.7º
b = 14.5796 (19) ŵ = 1.10 mm−1
c = 10.5615 (14) ÅT = 291 (2) K
β = 95.1630 (10)ºBlock, dark green
V = 1022.1 (2) Å30.48 × 0.27 × 0.19 mm
Z = 2
Data collection top
Bruker SMART CCD area-detector
diffractometer		1882 independent reflections
Radiation source: fine-focus sealed tube1652 reflections with I > 2σ(I)
Monochromator: graphiteRint = 0.013
Detector resolution: 0 pixels mm-1θmax = 25.5º
T = 291(2) Kθmin = 2.4º
φ and ω scansh = −8→8
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)		k = −17→17
Tmin = 0.621, Tmax = 0.821l = −12→12
6062 measured reflections
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.026H-atom parameters constrained
wR(F2) = 0.077  w = 1/[σ2(Fo2) + (0.0434P)2 + 0.1918P]
where P = (Fo2 + 2Fc2)/3
S = 1.08(Δ/σ)max < 0.001
1882 reflectionsΔρmax = 0.19 e Å−3
134 parametersΔρmin = −0.19 e Å−3
Primary atom site location: structure-invariant direct methodsExtinction correction: none
Crystal data top
[Cu(C11H12N1O2)2]V = 1022.1 (2) Å3
Mr = 443.97Z = 2
Monoclinic, P21/cMo Kα
a = 6.6645 (9) ŵ = 1.10 mm−1
b = 14.5796 (19) ÅT = 291 (2) K
c = 10.5615 (14) Å0.48 × 0.27 × 0.19 mm
β = 95.1630 (10)º
Data collection top
Bruker SMART CCD area-detector
diffractometer		1882 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)		1652 reflections with I > 2σ(I)
Tmin = 0.621, Tmax = 0.821Rint = 0.013
6062 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.026134 parameters
wR(F2) = 0.077H-atom parameters constrained
S = 1.08Δρmax = 0.19 e Å−3
1882 reflectionsΔρmin = −0.19 e Å−3
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Cu10.00000.50000.50000.05203 (14)
O10.0943 (2)0.53611 (12)0.66862 (13)0.0721 (4)
O20.5047 (2)0.64456 (9)0.42505 (13)0.0618 (4)
N10.2068 (2)0.57490 (10)0.43014 (14)0.0491 (3)
C10.2700 (3)0.56981 (13)0.71016 (18)0.0552 (4)
C20.3213 (3)0.57523 (15)0.84174 (19)0.0688 (5)
H20.22710.55730.89670.083*
C30.5071 (4)0.60636 (15)0.8920 (2)0.0726 (6)
H30.53630.60890.97970.087*
C40.6509 (3)0.63390 (15)0.8124 (2)0.0715 (6)
H40.77740.65340.84620.086*
C50.6042 (3)0.63190 (14)0.6845 (2)0.0609 (5)
H50.69980.65130.63130.073*
C60.4154 (3)0.60134 (12)0.62996 (17)0.0490 (4)
C70.3682 (3)0.60446 (12)0.49455 (17)0.0487 (4)
C80.2135 (3)0.60125 (12)0.29532 (16)0.0504 (4)
H80.19460.54680.24110.060*
C90.4282 (3)0.63686 (15)0.2930 (2)0.0632 (5)
H9A0.50910.59440.24850.076*
H9B0.42890.69610.25120.076*
C100.0526 (3)0.67215 (15)0.2555 (2)0.0665 (5)
H10A−0.07640.65100.27990.080*
H10B0.08480.72930.29980.080*
C110.0365 (4)0.68926 (19)0.1130 (2)0.0902 (8)
H11A0.16560.70750.08790.135*
H11B−0.06000.73700.09200.135*
H11C−0.00620.63400.06900.135*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cu10.0521 (2)0.0579 (2)0.0478 (2)−0.01417 (13)0.01397 (14)−0.00670 (13)
O10.0673 (9)0.0990 (11)0.0521 (8)−0.0319 (8)0.0174 (7)−0.0150 (8)
O20.0532 (7)0.0665 (9)0.0667 (9)−0.0141 (6)0.0114 (6)0.0104 (7)
N10.0506 (8)0.0491 (8)0.0487 (8)−0.0064 (6)0.0097 (6)−0.0020 (6)
C10.0607 (11)0.0506 (10)0.0548 (10)−0.0062 (8)0.0081 (8)−0.0073 (8)
C20.0817 (14)0.0709 (13)0.0545 (11)−0.0105 (11)0.0097 (10)−0.0077 (10)
C30.0901 (16)0.0666 (13)0.0580 (12)−0.0029 (11)−0.0105 (11)−0.0065 (10)
C40.0680 (13)0.0644 (13)0.0779 (15)−0.0036 (10)−0.0173 (11)−0.0024 (11)
C50.0542 (11)0.0533 (11)0.0742 (13)−0.0025 (8)0.0007 (9)0.0033 (9)
C60.0515 (9)0.0390 (9)0.0564 (10)0.0012 (7)0.0041 (8)−0.0013 (7)
C70.0489 (9)0.0373 (9)0.0613 (11)0.0005 (7)0.0132 (8)0.0020 (7)
C80.0578 (10)0.0462 (9)0.0489 (9)−0.0023 (8)0.0141 (8)−0.0009 (8)
C90.0633 (12)0.0657 (12)0.0623 (12)−0.0030 (9)0.0154 (9)0.0145 (10)
C100.0670 (13)0.0693 (13)0.0634 (12)0.0140 (10)0.0076 (10)−0.0008 (10)
C110.1026 (19)0.0967 (19)0.0690 (14)0.0271 (15)−0.0048 (13)0.0096 (13)
Geometric parameters (Å, °) top
Cu1—O1i1.9083 (14)C4—H40.9300
Cu1—O11.9083 (14)C5—C61.408 (3)
Cu1—N11.9541 (14)C5—H50.9300
Cu1—N1i1.9541 (14)C6—C71.437 (3)
O1—C11.309 (2)C8—C101.521 (3)
O2—C71.352 (2)C8—C91.524 (3)
O2—C91.446 (3)C8—H80.9800
N1—C71.294 (2)C9—H9A0.9700
N1—C81.479 (2)C9—H9B0.9700
C1—C21.403 (3)C10—C111.520 (3)
C1—C61.419 (3)C10—H10A0.9700
C2—C31.379 (3)C10—H10B0.9700
C2—H20.9300C11—H11A0.9600
C3—C41.390 (3)C11—H11B0.9600
C3—H30.9300C11—H11C0.9600
C4—C51.359 (3)
O1i—Cu1—O1180C1—C6—C7120.29 (16)
O1i—Cu1—N189.19 (6)N1—C7—O2115.27 (16)
O1—Cu1—N190.81 (6)N1—C7—C6127.55 (16)
O1i—Cu1—N1i90.81 (6)O2—C7—C6117.16 (16)
O1—Cu1—N1i89.19 (6)N1—C8—C10111.15 (14)
N1—Cu1—N1i180N1—C8—C9102.36 (14)
C1—O1—Cu1128.74 (12)C10—C8—C9113.79 (17)
C7—O2—C9107.09 (14)N1—C8—H8109.8
C7—N1—C8108.87 (14)C10—C8—H8109.8
C7—N1—Cu1124.68 (12)C9—C8—H8109.8
C8—N1—Cu1126.31 (11)O2—C9—C8105.14 (14)
O1—C1—C2118.93 (18)O2—C9—H9A110.7
O1—C1—C6124.03 (17)C8—C9—H9A110.7
C2—C1—C6117.03 (18)O2—C9—H9B110.7
C3—C2—C1122.0 (2)C8—C9—H9B110.7
C3—C2—H2119.0H9A—C9—H9B108.8
C1—C2—H2119.0C11—C10—C8111.75 (17)
C2—C3—C4120.4 (2)C11—C10—H10A109.3
C2—C3—H3119.8C8—C10—H10A109.3
C4—C3—H3119.8C11—C10—H10B109.3
C5—C4—C3119.1 (2)C8—C10—H10B109.3
C5—C4—H4120.5H10A—C10—H10B107.9
C3—C4—H4120.5C10—C11—H11A109.5
C4—C5—C6122.0 (2)C10—C11—H11B109.5
C4—C5—H5119.0H11A—C11—H11B109.5
C6—C5—H5119.0C10—C11—H11C109.5
C5—C6—C1119.43 (18)H11A—C11—H11C109.5
C5—C6—C7120.26 (17)H11B—C11—H11C109.5
O1i—Cu1—O1—C1−70 (4)C2—C1—C6—C7−175.30 (18)
N1—Cu1—O1—C1−20.2 (2)C8—N1—C7—O2−4.4 (2)
N1i—Cu1—O1—C1159.8 (2)Cu1—N1—C7—O2171.45 (11)
O1i—Cu1—N1—C7−161.26 (15)C8—N1—C7—C6173.99 (16)
O1—Cu1—N1—C718.74 (15)Cu1—N1—C7—C6−10.1 (3)
N1i—Cu1—N1—C7−143 (7)C9—O2—C7—N1−3.2 (2)
O1i—Cu1—N1—C813.88 (15)C9—O2—C7—C6178.17 (16)
O1—Cu1—N1—C8−166.12 (15)C5—C6—C7—N1176.24 (18)
N1i—Cu1—N1—C832 (7)C1—C6—C7—N1−5.5 (3)
Cu1—O1—C1—C2−167.87 (16)C5—C6—C7—O2−5.4 (3)
Cu1—O1—C1—C611.8 (3)C1—C6—C7—O2172.87 (16)
O1—C1—C2—C3177.2 (2)C7—N1—C8—C10−112.28 (18)
C6—C1—C2—C3−2.4 (3)Cu1—N1—C8—C1071.94 (19)
C1—C2—C3—C40.2 (4)C7—N1—C8—C99.56 (19)
C2—C3—C4—C51.6 (3)Cu1—N1—C8—C9−166.22 (12)
C3—C4—C5—C6−1.0 (3)C7—O2—C9—C89.1 (2)
C4—C5—C6—C1−1.3 (3)N1—C8—C9—O2−11.01 (19)
C4—C5—C6—C7176.96 (18)C10—C8—C9—O2109.00 (18)
O1—C1—C6—C5−176.67 (19)N1—C8—C10—C11−171.40 (18)
C2—C1—C6—C53.0 (3)C9—C8—C10—C1173.7 (2)
O1—C1—C6—C75.1 (3)
Symmetry codes: (i) −x, −y+1, −z+1.
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C9—H9A···Cgii0.972.893.632 (2)134
C9—H9A···Cgiii0.972.943.814 (2)151
Symmetry codes: (ii) −x+1, −y+1, −z+1; (iii) x, −y+3/2, z−1/2.
Table 1
Selected geometric parameters (Å, °) top
Cu1—O11.9083 (14)Cu1—N11.9541 (14)
O1i—Cu1—O1180O1—Cu1—N1i89.19 (6)
O1—Cu1—N190.81 (6)
Symmetry codes: (i) −x, −y+1, −z+1.
Table 2
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C9—H9A···Cgii0.972.893.632 (2)134
C9—H9A···Cgiii0.972.943.814 (2)151
Symmetry codes: (ii) −x+1, −y+1, −z+1; (iii) x, −y+3/2, z−1/2.
Acknowledgements top

The authors acknowledge support from the Natural Science Foundation Council of China (NSFC) (grant No. 20401003) and the Excellent Young Scholars Research Fund of Beijing Institute of Technology (grant No. 000Y07–26).

references
References top

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