metal-organic compounds
μ-Bromido-dibromido-μ-hydroxido-bis[(4S)-2-halo-6-(4-isopropyl-4,5-dihydrooxazol-2-yl)pyridine]dicopper(II) (halo: Cl/Br = 3:1)
aInstitut für Organische Chemie und Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstrasse 21, D-79104 Freiburg, Germany
*Correspondence e-mail: bernhard.breit@organik.chemie.uni-freiburg.de
The 2Br3(OH)(C11H13Br0.5Cl1.5N2O)2], consists of two (2-halo-6-oxazolinyl)pyridine·CuBr units bridged by a Br atom and a hydroxide group. The CuII atoms are five-coordinate with an (N,N)BrCu(Br)(OH) distorted tetragonal–pyramidal core, and relatively short contacts to the bridging atoms (Cu—μ-OH and Cu—μ-Br). There are two symmetry-independent half-molecules in the which differ only in the arrangement of the isopropyl group. The molecules are located on a twofold rotation axes.
of the title complex, [CuRelated literature
For related literature, see: Chelucci & Thummel (2002); Fache et al. (2000); Karlin & Gultneh (1987); Kaim & Schwederski (1991); Lehn (1995); Mezei & Raptis (2004); Thompson et al. (1987); Walther et al. (1997).
Experimental
Crystal data
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Data collection: COLLECT (Nonius, 1997–2000); cell HKL SCALEPACK (Otwinowski & Minor 1997); data reduction: HKL DENZO (Otwinowski & Minor 1997) and SCALEPACK; program(s) used to solve structure: SIR97 (Altomare et al., 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97 and local programs.
Supporting information
https://doi.org/10.1107/S1600536807058862/sk3162sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536807058862/sk3162Isup2.hkl
A 3:1 mixture of (4S)-2-chloro-6-(4-isopropyl-4,5-dihydro-oxazol-2-yl)pyridine and (4S)-2-bromo-6-(4-isopropyl-4,5-dihydro-oxazol-2-yl)pyridine (15.1 mg, 56.1 µmol, 2.0 eq.) and CuBr.SMe2 (5.70 mg, 27.7 µmol) were dissolved in CDCl3 (0.7 ml) under argon atmosphere. The resulting deep red CuI complex could not be isolated and reacted with air to form a brown solution and a black precipitate after five days. The reaction mixture was allowed to evaporate in air at room temperature. Black crystals of (I) were separated from the filtrate after two weeks.
The two positions of the disordered Cl- versus Br-atoms were determined from the difference map and refined anisotropically with occupancies of 0.75 (Cl) and 0.25 (Br). All H atom bound to C atoms were placed in calculated positions (C — H = 0.95 or 0.98 or 0.99 or 1.00 Å) and refined as riding on their parent atoms with Uiso(H) = 1.2 Ueq(C) or 1.5 Ueq(C). The H atoms bound to the bridging OH groups were found in Fourier difference map, restrained with O—H = 0.85 (2) Å and refined with Uiso = 1.2Ueq(O)
Metal coordination and ligand geometry is essential in terms of activating and directing a metal-catalyzed process. Therefore, it is of interest to obtain a deeper insight into the structure of different coordination motifs and thus, this could help to enhance our understanding about the coordination behaviour and the scope and limitations of ligands applied in catalysis. Chiral oxazolines and pyridines are regarded as privileged ligands, which have found numerous applications in many asymmetric transformations (Fache et al., 2000; Chelucci & Thummel, 2002). Moreover, N-donor ligands are also found as component parts of enzymatic processes such as the fixation, activation and transport of oxygen (Kaim & Schwederski, 1991; Karlin & Gultneh, 1987), or they are used for studies concerning self-organizing phenomena (Lehn, 1995).
During our work in the field of supramolecular ligands and catalysts, the novel title compound (I) was isolated from a mixture of Cl- and Br-substituted oxazolinyl-pyridine ligands. This mixture was obtained from the oxazoline ring closure reaction of 2-bromo-6-(4-isopropyl-4,5-dihydro-oxazol-2-yl)pyridine under acidic conditions (HCl), and subsequent partial aromatic substitution of the bromine. After complexation with CuBr.SMe2, X-ray structure analysis reveales a 3:1 Cl/Br disorder ratio at the 2-halopyridine position, and the complex contains an unprecedented coordination motif of two [(2-halo-6-oxazolinyl)pyridine]CuIIBr units bridged by a Br atom and a hydroxide group. To the best of our knowledge there are various triple bridged dinuclear CuII complexes bearing different µ3-bridging ligands (µ-OH, µ-Br and µ-pyridazine) (Thompson et al., 1987), but only two double bridged dinuclear CuII complexes with Cl and OH as µ2-bridging anions have been reported (Walther et al., 1997; Mezei & Raptis, 2004).
In analogy to a previous report, complex (I) was obtained by aerial oxidation of a CDCl3 solution of a red oxazolinyl pyridine/CuBr complex (Walther et al., 1997). The X-ray structure analysis confirms a distorted tetragonal-pyramidal coordination geometry at the CuII centers of the dimeric complex. Both chiral oxazolinyl pyridine ligands act as a bidentate N,N-ligand, forming a five-membered chelate ring. Although all nitrogen atoms are sp2-hybridized, the bond lengths of the Cu — N(pyr) bonds [Cu11 — N102 = 2.362 (3) Å, Cu21 — N202 = 2.362 (3) Å] are significantly longer than the Cu — N(oxa) distance [Cu11 — N101 = 1.966 (3) Å, Cu21 — N201 = 1.97 (3) Å]. This presumably originates from dipole-dipole repulsion between the pyridinyl halides and the bridging ligands OH and Br.
Br(11) and Br(21) are bonded with somewhat shorter distances [Cu11 — Br11= 2.4069 (5) Å, Cu21 — Br21= 2.4280 (5) Å], and the bridging bromine Br12 and Br22 respectively are bonded by more distant contacts [Cu11 — Br12 = 2.5538 (5) Å, Cu21 — Br22 = 2.5321 (6) Å]. Although the atomic radii increase from Cl to Br, these Cu — Br bridging bonds and the Cu ··· Cu distances [Cu11 ··· Cu11a = 3.2480 (8) Å, Cu21 ··· Cu21a = 3.2415 (8) Å] in complex (I) are in the range of those observed in previous reported Cu ··· Cu contacts [3.1963 (7); Mezei & Raptis, 2004; 3.271 Å; Walther et al., 1997] and Cu — µCl bonds [2.409 (1) and 2.450 (1); Mezei & Raptis, 2004; 2.648 (2) Å and 2.507 (2) Å; Walther et al., 1997]. Moreover, the distance between the Cu atoms and the bridging hydroxo groups are slightly shorter [1.8716 (19) Å and 1.8705 (19) Å] when compared with both µ-Cl, µ-OH bridged CuII complexes [1.903 (3) and 1.905 (3); Mezei & Raptis, 2004; 1.914 (5) Å and 1.917 (5) Å; Walther et al., 1997]. The hydroxide bridge angles [120.5 (2)° and 120.1 (2)°] are substantially larger [114.2 (2)°; Mezei & Raptis, 2004; 117.3 (2)°; Walther et al., 1997], whereas the Cu — Br — Cu angle [78.98 (2)° and 79.59 (2)°] are in good agreement with one reported [78.7 (3)°; Walther et al., 1997] and smaller than the other [82.27 (4)°; Mezei & Raptis, 2004]. The compound (I) obtained provides a new motif in CuII pyridine and oxazoline chemistry, and represents the first example of a Br and OH µ2-bridged dinuclear (ligand)(halide)CuII complex.
Noteworthy is the absence of hydrogen bonds for the bridging OH-group. This OH-group is located in a "pocket" constituted by two Br and two Cl atoms of the same molecule. As a consequence no hydrogen-acceptor atom is accessible for hydrogen-bond formation. Although this hydrogen is on a restrained position, it is the only possible location.
For related literature, see: Chelucci & Thummel (2002); Fache et al. (2000); Karlin & Gultneh (1987); Kaim & Schwederski (1991); Lehn (1995); Mezei & Raptis (2004); Thompson et al. (1987); Walther et al. (1997).
Data collection: COLLECT (Nonius, 1997–2000); cell
HKL SCALEPACK (Otwinowski & Minor 1997); data reduction: HKL DENZO and SCALEPACK (Otwinowski & Minor 1997); program(s) used to solve structure: SIR97 (Altomare et al., 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997) and local programs.Fig. 1. The independent components of (I), showing the atom-labelling scheme. The structure contains a 3:1 Cl/Br disorder at the 2-halopyridine position. The figure displays the Cl-part of this disorder (Cl15). Displacement ellipsoids are drawn at the 50% probability level. | |
Fig. 2. CPK-plot of the bridging OH-group located in a pocket constituted by two Br (green) and two Cl (orange) atoms, illustrating no possibility for hydrogen bonding. |
[Cu2Br3(OH)(C11H13Br0.5Cl1.5N2O)2] | F(000) = 1668 |
Mr = 855.42 | Dx = 1.972 Mg m−3 |
Monoclinic, C2 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: C 2y | Cell parameters from 9966 reflections |
a = 23.2485 (5) Å | θ = 1.0–27.5° |
b = 7.9862 (1) Å | µ = 6.50 mm−1 |
c = 17.9187 (4) Å | T = 100 K |
β = 119.9850 (9)° | Irregular, green |
V = 2881.63 (10) Å3 | 0.20 × 0.20 × 0.10 mm |
Z = 4 |
Nonius KappaCCD diffractometer | 6381 independent reflections |
Radiation source: long-fine-focus sealed tube | 6086 reflections with I > 2σ(I) |
Horizonally mounted graphite crystal monochromator | Rint = 0.046 |
Detector resolution: 9 pixels mm-1 | θmax = 27.5°, θmin = 2.4° |
CCD scans | h = −29→26 |
Absorption correction: multi-scan (SORTAV; Blessing 1995) | k = −10→10 |
Tmin = 0.313, Tmax = 0.521 | l = −19→23 |
16751 measured reflections |
Refinement on F2 | Hydrogen site location: inferred from neighbouring sites |
Least-squares matrix: full | H atoms treated by a mixture of independent and constrained refinement |
R[F2 > 2σ(F2)] = 0.029 | w = 1/[σ2(Fo2) + (0.0381P)2 + 2.2361P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.070 | (Δ/σ)max = 0.003 |
S = 1.06 | Δρmax = 0.92 e Å−3 |
6381 reflections | Δρmin = −0.90 e Å−3 |
354 parameters | Extinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
3 restraints | Extinction coefficient: 0.00132 (10) |
Primary atom site location: structure-invariant direct methods | Absolute structure: Flack (1983), 2880 Friedel pairs |
Secondary atom site location: difference Fourier map | Absolute structure parameter: −0.002 (7) |
[Cu2Br3(OH)(C11H13Br0.5Cl1.5N2O)2] | V = 2881.63 (10) Å3 |
Mr = 855.42 | Z = 4 |
Monoclinic, C2 | Mo Kα radiation |
a = 23.2485 (5) Å | µ = 6.50 mm−1 |
b = 7.9862 (1) Å | T = 100 K |
c = 17.9187 (4) Å | 0.20 × 0.20 × 0.10 mm |
β = 119.9850 (9)° |
Nonius KappaCCD diffractometer | 6381 independent reflections |
Absorption correction: multi-scan (SORTAV; Blessing 1995) | 6086 reflections with I > 2σ(I) |
Tmin = 0.313, Tmax = 0.521 | Rint = 0.046 |
16751 measured reflections |
R[F2 > 2σ(F2)] = 0.029 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.070 | Δρmax = 0.92 e Å−3 |
S = 1.06 | Δρmin = −0.90 e Å−3 |
6381 reflections | Absolute structure: Flack (1983), 2880 Friedel pairs |
354 parameters | Absolute structure parameter: −0.002 (7) |
3 restraints |
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. |
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
C101 | 1.19690 (17) | 0.7710 (4) | 1.0541 (3) | 0.0261 (8) | |
H101 | 1.2314 | 0.8603 | 1.0820 | 0.031* | |
C102 | 1.2139 (2) | 0.6644 (6) | 0.9968 (3) | 0.0353 (9) | |
H10A | 1.2622 | 0.6676 | 1.0178 | 0.042* | |
H10B | 1.2003 | 0.5465 | 0.9957 | 0.042* | |
C103 | 1.12960 (19) | 0.8306 (4) | 0.9153 (3) | 0.0268 (8) | |
C104 | 1.0775 (2) | 0.9089 (5) | 0.8353 (3) | 0.0308 (9) | |
C105 | 1.0784 (3) | 0.9087 (6) | 0.7593 (3) | 0.0432 (12) | |
H105 | 1.1125 | 0.8517 | 0.7549 | 0.052* | |
C106 | 1.0294 (3) | 0.9923 (7) | 0.6900 (3) | 0.0498 (13) | |
H106 | 1.0298 | 0.9969 | 0.6373 | 0.060* | |
C107 | 0.9790 (3) | 1.0704 (6) | 0.6970 (3) | 0.0490 (14) | |
H107 | 0.9444 | 1.1295 | 0.6500 | 0.059* | |
C108 | 0.9812 (2) | 1.0585 (5) | 0.7764 (3) | 0.0342 (9) | |
C109 | 1.19183 (17) | 0.6747 (4) | 1.1239 (3) | 0.0259 (8) | |
H109 | 1.1518 | 0.6008 | 1.0957 | 0.031* | |
C110 | 1.1840 (2) | 0.7949 (5) | 1.1846 (3) | 0.0324 (8) | |
H11A | 1.2213 | 0.8739 | 1.2093 | 0.049* | |
H11B | 1.1836 | 0.7311 | 1.2311 | 0.049* | |
H11C | 1.1422 | 0.8566 | 1.1525 | 0.049* | |
C111 | 1.25314 (19) | 0.5648 (5) | 1.1744 (3) | 0.0378 (10) | |
H11D | 1.2568 | 0.4860 | 1.1351 | 0.057* | |
H11E | 1.2490 | 0.5023 | 1.2187 | 0.057* | |
H11F | 1.2929 | 0.6355 | 1.2020 | 0.057* | |
Br11 | 1.140591 (18) | 1.23282 (4) | 1.04093 (2) | 0.02632 (9) | |
Br12 | 1.0000 | 0.74718 (6) | 1.0000 | 0.02323 (11) | |
Br15 | 0.9118 (6) | 1.1501 (12) | 0.7897 (7) | 0.0444 (19) | 0.25 |
Cl15 | 0.9179 (4) | 1.1483 (8) | 0.7855 (5) | 0.0382 (12) | 0.75 |
Cu11 | 1.06770 (2) | 0.99397 (5) | 0.99464 (3) | 0.02011 (10) | |
N101 | 1.13358 (15) | 0.8501 (4) | 0.9880 (2) | 0.0242 (6) | |
N102 | 1.02942 (16) | 0.9853 (4) | 0.8453 (2) | 0.0279 (7) | |
O101 | 1.17680 (15) | 0.7393 (4) | 0.9118 (2) | 0.0357 (7) | |
O102 | 1.0000 | 1.1102 (5) | 1.0000 | 0.0269 (8) | |
H102 | 1.0000 | 1.215 (3) | 1.0000 | 0.05 (2)* | |
C201 | 0.83962 (18) | 0.8232 (4) | 0.5075 (2) | 0.0233 (7) | |
H201 | 0.8631 | 0.9209 | 0.4998 | 0.028* | |
C202 | 0.81820 (18) | 0.8714 (5) | 0.5736 (3) | 0.0283 (8) | |
H20A | 0.8190 | 0.9944 | 0.5807 | 0.034* | |
H20B | 0.7728 | 0.8303 | 0.5547 | 0.034* | |
C203 | 0.90193 (17) | 0.6897 (4) | 0.6330 (2) | 0.0211 (7) | |
C204 | 0.95679 (17) | 0.5943 (4) | 0.7024 (2) | 0.0216 (7) | |
C205 | 0.96634 (19) | 0.5830 (5) | 0.7843 (3) | 0.0268 (8) | |
H205 | 0.9363 | 0.6337 | 0.7990 | 0.032* | |
C206 | 1.0221 (2) | 0.4941 (5) | 0.8456 (3) | 0.0308 (8) | |
H206 | 1.0296 | 0.4793 | 0.9024 | 0.037* | |
C207 | 1.0657 (2) | 0.4288 (5) | 0.8229 (3) | 0.0314 (9) | |
H207 | 1.1043 | 0.3701 | 0.8637 | 0.038* | |
C208 | 1.05201 (18) | 0.4507 (4) | 0.7385 (3) | 0.0258 (8) | |
C209 | 0.78238 (19) | 0.7738 (5) | 0.4198 (3) | 0.0289 (8) | |
H209 | 0.7591 | 0.6755 | 0.4272 | 0.035* | |
C210 | 0.7332 (2) | 0.9214 (5) | 0.3837 (3) | 0.0340 (9) | |
H21A | 0.7564 | 1.0215 | 0.3808 | 0.051* | |
H21B | 0.7149 | 0.9432 | 0.4215 | 0.051* | |
H21C | 0.6971 | 0.8935 | 0.3258 | 0.051* | |
C211 | 0.8058 (2) | 0.7261 (6) | 0.3569 (3) | 0.0438 (11) | |
H21D | 0.8316 | 0.8186 | 0.3524 | 0.066* | |
H21E | 0.7672 | 0.7034 | 0.3002 | 0.066* | |
H21F | 0.8337 | 0.6257 | 0.3779 | 0.066* | |
Br21 | 0.868653 (17) | 0.29997 (4) | 0.49113 (3) | 0.02563 (9) | |
Br22 | 1.0000 | 0.78245 (7) | 0.5000 | 0.03828 (16) | |
Br25 | 1.1113 (5) | 0.3707 (13) | 0.7061 (8) | 0.0325 (13) | 0.25 |
Cl25 | 1.1087 (5) | 0.3860 (12) | 0.7098 (7) | 0.0410 (15) | 0.75 |
Cu21 | 0.94230 (2) | 0.53885 (5) | 0.52565 (3) | 0.02187 (10) | |
N201 | 0.88948 (14) | 0.6897 (4) | 0.5554 (2) | 0.0211 (6) | |
N202 | 0.99806 (15) | 0.5291 (4) | 0.6777 (2) | 0.0234 (6) | |
O201 | 0.86664 (13) | 0.7907 (3) | 0.65432 (17) | 0.0262 (5) | |
O202 | 1.0000 | 0.4219 (5) | 0.5000 | 0.0282 (8) | |
H202 | 1.0000 | 0.317 (3) | 0.5000 | 0.05 (2)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
C101 | 0.0164 (17) | 0.0216 (18) | 0.041 (2) | −0.0028 (13) | 0.0149 (16) | −0.0031 (15) |
C102 | 0.032 (2) | 0.033 (2) | 0.054 (3) | 0.0000 (17) | 0.031 (2) | −0.0058 (19) |
C103 | 0.0271 (19) | 0.0214 (18) | 0.043 (2) | −0.0101 (14) | 0.0258 (18) | −0.0072 (15) |
C104 | 0.035 (2) | 0.0281 (19) | 0.036 (2) | −0.0183 (17) | 0.0226 (19) | −0.0106 (16) |
C105 | 0.058 (3) | 0.044 (2) | 0.037 (2) | −0.032 (2) | 0.031 (2) | −0.0140 (19) |
C106 | 0.067 (4) | 0.048 (3) | 0.035 (2) | −0.036 (3) | 0.026 (2) | −0.012 (2) |
C107 | 0.056 (3) | 0.040 (3) | 0.028 (2) | −0.029 (2) | 0.003 (2) | 0.0048 (18) |
C108 | 0.036 (2) | 0.029 (2) | 0.028 (2) | −0.0167 (17) | 0.0080 (18) | 0.0003 (15) |
C109 | 0.0162 (16) | 0.0192 (16) | 0.037 (2) | 0.0020 (13) | 0.0098 (16) | 0.0008 (14) |
C110 | 0.0254 (19) | 0.0320 (19) | 0.036 (2) | 0.0065 (16) | 0.0121 (17) | −0.0001 (17) |
C111 | 0.022 (2) | 0.0246 (19) | 0.053 (3) | 0.0011 (16) | 0.0090 (19) | −0.0005 (18) |
Br11 | 0.02191 (18) | 0.02086 (17) | 0.0380 (2) | −0.00514 (13) | 0.01633 (16) | −0.00369 (14) |
Br12 | 0.0214 (2) | 0.0200 (2) | 0.0320 (3) | 0.000 | 0.0161 (2) | 0.000 |
Br15 | 0.033 (3) | 0.043 (3) | 0.044 (3) | −0.0047 (19) | 0.0094 (19) | 0.020 (2) |
Cl15 | 0.0285 (17) | 0.0254 (17) | 0.042 (2) | −0.0022 (11) | 0.0032 (15) | 0.0027 (15) |
Cu11 | 0.0165 (2) | 0.0181 (2) | 0.0272 (2) | −0.00104 (16) | 0.01203 (18) | −0.00062 (16) |
N101 | 0.0200 (15) | 0.0221 (15) | 0.0324 (17) | −0.0041 (11) | 0.0145 (14) | −0.0039 (12) |
N102 | 0.0321 (18) | 0.0205 (15) | 0.0292 (17) | −0.0113 (13) | 0.0139 (14) | −0.0019 (13) |
O101 | 0.0381 (16) | 0.0355 (15) | 0.0512 (18) | −0.0059 (13) | 0.0356 (15) | −0.0109 (14) |
O102 | 0.0208 (19) | 0.0166 (18) | 0.047 (2) | 0.000 | 0.0195 (17) | 0.000 |
C201 | 0.0204 (17) | 0.0166 (16) | 0.035 (2) | 0.0031 (13) | 0.0151 (16) | 0.0042 (14) |
C202 | 0.0216 (18) | 0.0266 (18) | 0.037 (2) | 0.0065 (15) | 0.0146 (17) | 0.0001 (16) |
C203 | 0.0189 (17) | 0.0148 (16) | 0.033 (2) | −0.0023 (12) | 0.0154 (16) | −0.0016 (13) |
C204 | 0.0185 (17) | 0.0151 (15) | 0.0294 (19) | −0.0060 (12) | 0.0108 (15) | −0.0032 (13) |
C205 | 0.028 (2) | 0.0230 (18) | 0.032 (2) | −0.0069 (15) | 0.0170 (17) | −0.0047 (14) |
C206 | 0.034 (2) | 0.0247 (18) | 0.030 (2) | −0.0062 (16) | 0.0130 (17) | −0.0029 (15) |
C207 | 0.027 (2) | 0.0198 (17) | 0.036 (2) | −0.0021 (14) | 0.0076 (18) | 0.0034 (15) |
C208 | 0.0213 (18) | 0.0187 (17) | 0.038 (2) | −0.0016 (13) | 0.0155 (17) | 0.0046 (14) |
C209 | 0.0258 (19) | 0.0223 (19) | 0.038 (2) | −0.0007 (14) | 0.0152 (17) | 0.0013 (15) |
C210 | 0.0221 (19) | 0.035 (2) | 0.041 (2) | 0.0059 (15) | 0.0133 (18) | 0.0032 (17) |
C211 | 0.051 (3) | 0.044 (2) | 0.032 (2) | 0.024 (2) | 0.018 (2) | 0.0063 (19) |
Br21 | 0.01980 (17) | 0.02221 (17) | 0.0378 (2) | −0.00142 (13) | 0.01654 (15) | 0.00206 (14) |
Br22 | 0.0538 (4) | 0.0178 (3) | 0.0731 (4) | 0.000 | 0.0542 (4) | 0.000 |
Br25 | 0.025 (2) | 0.0273 (19) | 0.052 (3) | 0.0113 (16) | 0.0246 (19) | 0.0141 (16) |
Cl25 | 0.032 (2) | 0.038 (2) | 0.059 (3) | 0.0180 (14) | 0.0271 (17) | 0.0128 (16) |
Cu21 | 0.0209 (2) | 0.0171 (2) | 0.0357 (2) | 0.00226 (16) | 0.0202 (2) | 0.00261 (17) |
N201 | 0.0202 (15) | 0.0163 (14) | 0.0312 (17) | 0.0039 (11) | 0.0160 (13) | 0.0028 (11) |
N202 | 0.0200 (15) | 0.0189 (15) | 0.0334 (17) | −0.0015 (11) | 0.0148 (13) | 0.0023 (12) |
O201 | 0.0233 (13) | 0.0276 (13) | 0.0330 (14) | 0.0021 (10) | 0.0180 (11) | −0.0025 (11) |
O202 | 0.029 (2) | 0.0177 (18) | 0.054 (2) | 0.000 | 0.033 (2) | 0.000 |
C101—N101 | 1.492 (5) | C201—N201 | 1.491 (4) |
C101—C109 | 1.522 (5) | C201—C209 | 1.518 (5) |
C101—C102 | 1.530 (5) | C201—C202 | 1.546 (5) |
C101—H101 | 1.0000 | C201—H201 | 1.0000 |
C102—O101 | 1.451 (6) | C202—O201 | 1.466 (5) |
C102—H10A | 0.9900 | C202—H20A | 0.9900 |
C102—H10B | 0.9900 | C202—H20B | 0.9900 |
C103—N101 | 1.268 (5) | C203—N201 | 1.271 (5) |
C103—O101 | 1.345 (5) | C203—O201 | 1.334 (4) |
C103—C104 | 1.476 (6) | C203—C204 | 1.472 (5) |
C104—N102 | 1.361 (5) | C204—N202 | 1.346 (5) |
C104—C105 | 1.372 (6) | C204—C205 | 1.375 (5) |
C105—C106 | 1.369 (8) | C205—C206 | 1.403 (6) |
C105—H105 | 0.9500 | C205—H205 | 0.9500 |
C106—C107 | 1.388 (8) | C206—C207 | 1.371 (6) |
C106—H106 | 0.9500 | C206—H206 | 0.9500 |
C107—C108 | 1.401 (7) | C207—C208 | 1.393 (6) |
C107—H107 | 0.9500 | C207—H207 | 0.9500 |
C108—N102 | 1.319 (5) | C208—N202 | 1.336 (5) |
C108—Cl15 | 1.715 (11) | C208—Cl25 | 1.715 (10) |
C108—Br15 | 1.891 (14) | C208—Br25 | 1.855 (12) |
C109—C111 | 1.527 (5) | C209—C211 | 1.524 (6) |
C109—C110 | 1.529 (5) | C209—C210 | 1.541 (5) |
C109—H109 | 1.0000 | C209—H209 | 1.0000 |
C110—H11A | 0.9800 | C210—H21A | 0.9800 |
C110—H11B | 0.9800 | C210—H21B | 0.9800 |
C110—H11C | 0.9800 | C210—H21C | 0.9800 |
C111—H11D | 0.9800 | C211—H21D | 0.9800 |
C111—H11E | 0.9800 | C211—H21E | 0.9800 |
C111—H11F | 0.9800 | C211—H21F | 0.9800 |
Br11—Cu11 | 2.4069 (5) | Br21—Cu21 | 2.4280 (5) |
Br12—Cu11 | 2.5538 (5) | Br22—Cu21 | 2.5321 (6) |
Br12—Cu11i | 2.5538 (5) | Br22—Cu21ii | 2.5321 (6) |
Cu11—O102 | 1.8706 (19) | Cu21—O202 | 1.8705 (19) |
Cu11—N101 | 1.966 (3) | Cu21—N201 | 1.974 (3) |
Cu11—N102 | 2.362 (3) | Cu21—N202 | 2.362 (3) |
O102—Cu11i | 1.8706 (19) | O202—Cu21ii | 1.8705 (19) |
O102—H102 | 0.83 (2) | O202—H202 | 0.84 (2) |
Cu11—Cu11i | 3.2480 (8) | Cu21—Cu21ii | 3.2415 (8) |
N101—C101—C109 | 114.6 (3) | N201—C201—C209 | 115.9 (3) |
N101—C101—C102 | 100.7 (3) | N201—C201—C202 | 101.1 (3) |
C109—C101—C102 | 115.0 (3) | C209—C201—C202 | 114.0 (3) |
N101—C101—H101 | 108.7 | N201—C201—H201 | 108.5 |
C109—C101—H101 | 108.7 | C209—C201—H201 | 108.5 |
C102—C101—H101 | 108.7 | C202—C201—H201 | 108.5 |
O101—C102—C101 | 104.9 (3) | O201—C202—C201 | 105.3 (3) |
O101—C102—H10A | 110.8 | O201—C202—H20A | 110.7 |
C101—C102—H10A | 110.8 | C201—C202—H20A | 110.7 |
O101—C102—H10B | 110.8 | O201—C202—H20B | 110.7 |
C101—C102—H10B | 110.8 | C201—C202—H20B | 110.7 |
H10A—C102—H10B | 108.8 | H20A—C202—H20B | 108.8 |
N101—C103—O101 | 118.1 (4) | N201—C203—O201 | 118.5 (3) |
N101—C103—C104 | 123.3 (3) | N201—C203—C204 | 123.4 (3) |
O101—C103—C104 | 118.5 (3) | O201—C203—C204 | 118.0 (3) |
N102—C104—C105 | 123.5 (4) | N202—C204—C205 | 124.4 (3) |
N102—C104—C103 | 113.0 (3) | N202—C204—C203 | 112.5 (3) |
C105—C104—C103 | 123.4 (4) | C205—C204—C203 | 123.0 (3) |
C106—C105—C104 | 118.7 (5) | C204—C205—C206 | 117.5 (4) |
C106—C105—H105 | 120.6 | C204—C205—H205 | 121.2 |
C104—C105—H105 | 120.6 | C206—C205—H205 | 121.2 |
C105—C106—C107 | 119.7 (4) | C207—C206—C205 | 119.4 (4) |
C105—C106—H106 | 120.2 | C207—C206—H206 | 120.3 |
C107—C106—H106 | 120.2 | C205—C206—H206 | 120.3 |
C106—C107—C108 | 117.3 (4) | C206—C207—C208 | 118.3 (4) |
C106—C107—H107 | 121.4 | C206—C207—H207 | 120.9 |
C108—C107—H107 | 121.4 | C208—C207—H207 | 120.9 |
N102—C108—C107 | 124.2 (5) | N202—C208—C207 | 123.8 (4) |
N102—C108—Cl15 | 117.8 (4) | N202—C208—Cl25 | 116.5 (5) |
C107—C108—Cl15 | 118.0 (5) | C207—C208—Cl25 | 119.7 (5) |
N102—C108—Br15 | 115.7 (5) | N202—C208—Br25 | 116.6 (5) |
C107—C108—Br15 | 120.1 (5) | C207—C208—Br25 | 119.6 (5) |
C101—C109—C111 | 110.2 (3) | C201—C209—C211 | 112.2 (3) |
C101—C109—C110 | 110.7 (3) | C201—C209—C210 | 108.6 (3) |
C111—C109—C110 | 110.2 (3) | C211—C209—C210 | 110.2 (3) |
C101—C109—H109 | 108.6 | C201—C209—H209 | 108.6 |
C111—C109—H109 | 108.6 | C211—C209—H209 | 108.6 |
C110—C109—H109 | 108.6 | C210—C209—H209 | 108.6 |
C109—C110—H11A | 109.5 | C209—C210—H21A | 109.5 |
C109—C110—H11B | 109.5 | C209—C210—H21B | 109.5 |
H11A—C110—H11B | 109.5 | H21A—C210—H21B | 109.5 |
C109—C110—H11C | 109.5 | C209—C210—H21C | 109.5 |
H11A—C110—H11C | 109.5 | H21A—C210—H21C | 109.5 |
H11B—C110—H11C | 109.5 | H21B—C210—H21C | 109.5 |
C109—C111—H11D | 109.5 | C209—C211—H21D | 109.5 |
C109—C111—H11E | 109.5 | C209—C211—H21E | 109.5 |
H11D—C111—H11E | 109.5 | H21D—C211—H21E | 109.5 |
C109—C111—H11F | 109.5 | C209—C211—H21F | 109.5 |
H11D—C111—H11F | 109.5 | H21D—C211—H21F | 109.5 |
H11E—C111—H11F | 109.5 | H21E—C211—H21F | 109.5 |
Cu11—Br12—Cu11i | 78.98 (2) | Cu21—Br22—Cu21ii | 79.59 (2) |
O102—Cu11—N101 | 173.95 (13) | O202—Cu21—N201 | 171.98 (13) |
O102—Cu11—N102 | 102.86 (9) | O202—Cu21—N202 | 102.67 (8) |
N101—Cu11—N102 | 77.15 (13) | N201—Cu21—N202 | 76.43 (11) |
O102—Cu11—Br11 | 93.13 (10) | O202—Cu21—Br21 | 92.64 (10) |
N101—Cu11—Br11 | 92.77 (9) | N201—Cu21—Br21 | 95.36 (9) |
N102—Cu11—Br11 | 102.44 (8) | N202—Cu21—Br21 | 100.29 (7) |
O102—Cu11—Br12 | 80.27 (10) | O202—Cu21—Br22 | 80.15 (10) |
N101—Cu11—Br12 | 93.71 (9) | N201—Cu21—Br22 | 92.17 (9) |
N102—Cu11—Br12 | 97.44 (8) | N202—Cu21—Br22 | 101.51 (7) |
Br11—Cu11—Br12 | 160.00 (2) | Br21—Cu21—Br22 | 158.06 (2) |
C103—N101—C101 | 107.5 (3) | C203—N201—C201 | 108.4 (3) |
C103—N101—Cu11 | 118.4 (3) | C203—N201—Cu21 | 117.6 (2) |
C101—N101—Cu11 | 133.5 (2) | C201—N201—Cu21 | 133.6 (2) |
C108—N102—C104 | 116.5 (4) | C208—N202—C204 | 116.5 (3) |
C108—N102—Cu11 | 135.2 (3) | C208—N202—Cu21 | 134.9 (3) |
C104—N102—Cu11 | 107.1 (3) | C204—N202—Cu21 | 107.2 (2) |
C103—O101—C102 | 104.3 (3) | C203—O201—C202 | 105.2 (3) |
Cu11i—O102—Cu11 | 120.5 (2) | Cu21ii—O202—Cu21 | 120.1 (2) |
Cu11i—O102—H102 | 119.76 (10) | Cu21ii—O202—H202 | 119.95 (10) |
Cu11—O102—H102 | 119.76 (9) | Cu21—O202—H202 | 119.95 (10) |
N101—C101—C102—O101 | 20.7 (3) | N201—C201—C202—O201 | 11.8 (3) |
C109—C101—C102—O101 | 144.4 (3) | C209—C201—C202—O201 | 136.9 (3) |
N101—C103—C104—N102 | −8.1 (5) | N201—C203—C204—N202 | 9.8 (5) |
O101—C103—C104—N102 | 174.5 (3) | O201—C203—C204—N202 | −165.2 (3) |
N101—C103—C104—C105 | 170.1 (4) | N201—C203—C204—C205 | −174.0 (3) |
O101—C103—C104—C105 | −7.3 (5) | O201—C203—C204—C205 | 11.0 (5) |
N102—C104—C105—C106 | 1.4 (6) | N202—C204—C205—C206 | −1.6 (5) |
C103—C104—C105—C106 | −176.7 (4) | C203—C204—C205—C206 | −177.4 (3) |
C104—C105—C106—C107 | −2.0 (6) | C204—C205—C206—C207 | 2.7 (5) |
C105—C106—C107—C108 | −0.1 (6) | C205—C206—C207—C208 | −1.3 (6) |
C106—C107—C108—N102 | 3.4 (6) | C206—C207—C208—N202 | −1.3 (6) |
C106—C107—C108—Cl15 | −178.0 (4) | C206—C207—C208—Cl25 | 174.7 (5) |
C106—C107—C108—Br15 | −176.4 (5) | C206—C207—C208—Br25 | 177.9 (5) |
N101—C101—C109—C111 | 166.2 (3) | N201—C201—C209—C211 | −62.8 (4) |
C102—C101—C109—C111 | 50.2 (4) | C202—C201—C209—C211 | −179.6 (3) |
N101—C101—C109—C110 | −71.6 (4) | N201—C201—C209—C210 | 175.1 (3) |
C102—C101—C109—C110 | 172.4 (3) | C202—C201—C209—C210 | 58.4 (4) |
Cu11i—Br12—Cu11—O102 | 0.0 | Cu21ii—Br22—Cu21—O202 | 0.0 |
Cu11i—Br12—Cu11—N101 | −179.35 (10) | Cu21ii—Br22—Cu21—N201 | 177.65 (9) |
Cu11i—Br12—Cu11—N102 | −101.85 (9) | Cu21ii—Br22—Cu21—N202 | 101.06 (7) |
Cu11i—Br12—Cu11—Br11 | 71.98 (6) | Cu21ii—Br22—Cu21—Br21 | −72.21 (5) |
O101—C103—N101—C101 | 4.5 (4) | O201—C203—N201—C201 | 5.6 (4) |
C104—C103—N101—C101 | −172.8 (3) | C204—C203—N201—C201 | −169.4 (3) |
O101—C103—N101—Cu11 | 176.6 (2) | O201—C203—N201—Cu21 | −179.9 (2) |
C104—C103—N101—Cu11 | −0.8 (5) | C204—C203—N201—Cu21 | 5.1 (4) |
C109—C101—N101—C103 | −139.6 (3) | C209—C201—N201—C203 | −134.4 (3) |
C102—C101—N101—C103 | −15.7 (4) | C202—C201—N201—C203 | −10.6 (4) |
C109—C101—N101—Cu11 | 50.1 (4) | C209—C201—N201—Cu21 | 52.3 (4) |
C102—C101—N101—Cu11 | 174.0 (3) | C202—C201—N201—Cu21 | 176.1 (3) |
N102—Cu11—N101—C103 | 5.2 (3) | N202—Cu21—N201—C203 | −10.5 (3) |
Br11—Cu11—N101—C103 | −96.9 (3) | Br21—Cu21—N201—C203 | 88.8 (3) |
Br12—Cu11—N101—C103 | 102.0 (3) | Br22—Cu21—N201—C203 | −111.8 (3) |
N102—Cu11—N101—C101 | 174.7 (3) | N202—Cu21—N201—C201 | 162.3 (3) |
Br11—Cu11—N101—C101 | 72.6 (3) | Br21—Cu21—N201—C201 | −98.3 (3) |
Br12—Cu11—N101—C101 | −88.5 (3) | Br22—Cu21—N201—C201 | 61.0 (3) |
C107—C108—N102—C104 | −4.0 (6) | C207—C208—N202—C204 | 2.4 (5) |
Cl15—C108—N102—C104 | 177.3 (4) | Cl25—C208—N202—C204 | −173.7 (5) |
Br15—C108—N102—C104 | 175.7 (4) | Br25—C208—N202—C204 | −176.8 (4) |
C107—C108—N102—Cu11 | 161.2 (3) | C207—C208—N202—Cu21 | −162.2 (3) |
Cl15—C108—N102—Cu11 | −17.5 (5) | Cl25—C208—N202—Cu21 | 21.7 (6) |
Br15—C108—N102—Cu11 | −19.1 (6) | Br25—C208—N202—Cu21 | 18.6 (6) |
C105—C104—N102—C108 | 1.6 (5) | C205—C204—N202—C208 | −0.9 (5) |
C103—C104—N102—C108 | 179.8 (3) | C203—C204—N202—C208 | 175.3 (3) |
C105—C104—N102—Cu11 | −167.5 (3) | C205—C204—N202—Cu21 | 167.7 (3) |
C103—C104—N102—Cu11 | 10.7 (3) | C203—C204—N202—Cu21 | −16.1 (3) |
O102—Cu11—N102—C108 | 11.1 (4) | O202—Cu21—N202—C208 | −7.7 (3) |
N101—Cu11—N102—C108 | −175.1 (4) | N201—Cu21—N202—C208 | −179.5 (3) |
Br11—Cu11—N102—C108 | −85.1 (4) | Br21—Cu21—N202—C208 | 87.4 (3) |
Br12—Cu11—N102—C108 | 92.7 (4) | Br22—Cu21—N202—C208 | −90.0 (3) |
O102—Cu11—N102—C104 | 177.2 (2) | O202—Cu21—N202—C204 | −173.2 (2) |
N101—Cu11—N102—C104 | −9.0 (2) | N201—Cu21—N202—C204 | 14.9 (2) |
Br11—Cu11—N102—C104 | 81.0 (2) | Br21—Cu21—N202—C204 | −78.1 (2) |
Br12—Cu11—N102—C104 | −101.1 (2) | Br22—Cu21—N202—C204 | 104.4 (2) |
N101—C103—O101—C102 | 9.7 (4) | N201—C203—O201—C202 | 2.8 (4) |
C104—C103—O101—C102 | −172.8 (3) | C204—C203—O201—C202 | 178.0 (3) |
C101—C102—O101—C103 | −18.8 (4) | C201—C202—O201—C203 | −9.4 (4) |
N102—Cu11—O102—Cu11i | 95.49 (8) | N202—Cu21—O202—Cu21ii | −99.70 (8) |
Br11—Cu11—O102—Cu11i | −160.99 (2) | Br21—Cu21—O202—Cu21ii | 159.13 (2) |
Br12—Cu11—O102—Cu11i | 0.0 | Br22—Cu21—O202—Cu21ii | 0.0 |
Symmetry codes: (i) −x+2, y, −z+2; (ii) −x+2, y, −z+1. |
Experimental details
Crystal data | |
Chemical formula | [Cu2Br3(OH)(C11H13Br0.5Cl1.5N2O)2] |
Mr | 855.42 |
Crystal system, space group | Monoclinic, C2 |
Temperature (K) | 100 |
a, b, c (Å) | 23.2485 (5), 7.9862 (1), 17.9187 (4) |
β (°) | 119.9850 (9) |
V (Å3) | 2881.63 (10) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 6.50 |
Crystal size (mm) | 0.20 × 0.20 × 0.10 |
Data collection | |
Diffractometer | Nonius KappaCCD |
Absorption correction | Multi-scan (SORTAV; Blessing 1995) |
Tmin, Tmax | 0.313, 0.521 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 16751, 6381, 6086 |
Rint | 0.046 |
(sin θ/λ)max (Å−1) | 0.649 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.029, 0.070, 1.06 |
No. of reflections | 6381 |
No. of parameters | 354 |
No. of restraints | 3 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.92, −0.90 |
Absolute structure | Flack (1983), 2880 Friedel pairs |
Absolute structure parameter | −0.002 (7) |
Computer programs: COLLECT (Nonius, 1997–2000), HKL SCALEPACK (Otwinowski & Minor 1997), HKL DENZO and SCALEPACK (Otwinowski & Minor 1997), SIR97 (Altomare et al., 1997), PLATON (Spek, 2003), SHELXL97 (Sheldrick, 1997) and local programs.
Br11—Cu11 | 2.4069 (5) | Br21—Cu21 | 2.4280 (5) |
Br12—Cu11 | 2.5538 (5) | Br22—Cu21 | 2.5321 (6) |
Cu11—O102 | 1.8706 (19) | Cu21—O202 | 1.8705 (19) |
Cu11—N101 | 1.966 (3) | Cu21—N201 | 1.974 (3) |
Cu11—N102 | 2.362 (3) | Cu21—N202 | 2.362 (3) |
Cu11—Cu11i | 3.2480 (8) | Cu21—Cu21ii | 3.2415 (8) |
Cu11—Br12—Cu11i | 78.98 (2) | Cu21—Br22—Cu21ii | 79.59 (2) |
Cu11i—O102—Cu11 | 120.5 (2) | Cu21ii—O202—Cu21 | 120.1 (2) |
Symmetry codes: (i) −x+2, y, −z+2; (ii) −x+2, y, −z+1. |
Acknowledgements
This work was supported by the Fonds der Chemischen Industrie, DFG (Int. Research Training Group GRK 1038), the Alfried Krupp Award for young university teachers of the Krupp Foundation (to BB), and BASF.
References
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This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
Metal coordination and ligand geometry is essential in terms of activating and directing a metal-catalyzed process. Therefore, it is of interest to obtain a deeper insight into the structure of different coordination motifs and thus, this could help to enhance our understanding about the coordination behaviour and the scope and limitations of ligands applied in catalysis. Chiral oxazolines and pyridines are regarded as privileged ligands, which have found numerous applications in many asymmetric transformations (Fache et al., 2000; Chelucci & Thummel, 2002). Moreover, N-donor ligands are also found as component parts of enzymatic processes such as the fixation, activation and transport of oxygen (Kaim & Schwederski, 1991; Karlin & Gultneh, 1987), or they are used for studies concerning self-organizing phenomena (Lehn, 1995).
During our work in the field of supramolecular ligands and catalysts, the novel title compound (I) was isolated from a mixture of Cl- and Br-substituted oxazolinyl-pyridine ligands. This mixture was obtained from the oxazoline ring closure reaction of 2-bromo-6-(4-isopropyl-4,5-dihydro-oxazol-2-yl)pyridine under acidic conditions (HCl), and subsequent partial aromatic substitution of the bromine. After complexation with CuBr.SMe2, X-ray structure analysis reveales a 3:1 Cl/Br disorder ratio at the 2-halopyridine position, and the complex contains an unprecedented coordination motif of two [(2-halo-6-oxazolinyl)pyridine]CuIIBr units bridged by a Br atom and a hydroxide group. To the best of our knowledge there are various triple bridged dinuclear CuII complexes bearing different µ3-bridging ligands (µ-OH, µ-Br and µ-pyridazine) (Thompson et al., 1987), but only two double bridged dinuclear CuII complexes with Cl and OH as µ2-bridging anions have been reported (Walther et al., 1997; Mezei & Raptis, 2004).
In analogy to a previous report, complex (I) was obtained by aerial oxidation of a CDCl3 solution of a red oxazolinyl pyridine/CuBr complex (Walther et al., 1997). The X-ray structure analysis confirms a distorted tetragonal-pyramidal coordination geometry at the CuII centers of the dimeric complex. Both chiral oxazolinyl pyridine ligands act as a bidentate N,N-ligand, forming a five-membered chelate ring. Although all nitrogen atoms are sp2-hybridized, the bond lengths of the Cu — N(pyr) bonds [Cu11 — N102 = 2.362 (3) Å, Cu21 — N202 = 2.362 (3) Å] are significantly longer than the Cu — N(oxa) distance [Cu11 — N101 = 1.966 (3) Å, Cu21 — N201 = 1.97 (3) Å]. This presumably originates from dipole-dipole repulsion between the pyridinyl halides and the bridging ligands OH and Br.
Br(11) and Br(21) are bonded with somewhat shorter distances [Cu11 — Br11= 2.4069 (5) Å, Cu21 — Br21= 2.4280 (5) Å], and the bridging bromine Br12 and Br22 respectively are bonded by more distant contacts [Cu11 — Br12 = 2.5538 (5) Å, Cu21 — Br22 = 2.5321 (6) Å]. Although the atomic radii increase from Cl to Br, these Cu — Br bridging bonds and the Cu ··· Cu distances [Cu11 ··· Cu11a = 3.2480 (8) Å, Cu21 ··· Cu21a = 3.2415 (8) Å] in complex (I) are in the range of those observed in previous reported Cu ··· Cu contacts [3.1963 (7); Mezei & Raptis, 2004; 3.271 Å; Walther et al., 1997] and Cu — µCl bonds [2.409 (1) and 2.450 (1); Mezei & Raptis, 2004; 2.648 (2) Å and 2.507 (2) Å; Walther et al., 1997]. Moreover, the distance between the Cu atoms and the bridging hydroxo groups are slightly shorter [1.8716 (19) Å and 1.8705 (19) Å] when compared with both µ-Cl, µ-OH bridged CuII complexes [1.903 (3) and 1.905 (3); Mezei & Raptis, 2004; 1.914 (5) Å and 1.917 (5) Å; Walther et al., 1997]. The hydroxide bridge angles [120.5 (2)° and 120.1 (2)°] are substantially larger [114.2 (2)°; Mezei & Raptis, 2004; 117.3 (2)°; Walther et al., 1997], whereas the Cu — Br — Cu angle [78.98 (2)° and 79.59 (2)°] are in good agreement with one reported [78.7 (3)°; Walther et al., 1997] and smaller than the other [82.27 (4)°; Mezei & Raptis, 2004]. The compound (I) obtained provides a new motif in CuII pyridine and oxazoline chemistry, and represents the first example of a Br and OH µ2-bridged dinuclear (ligand)(halide)CuII complex.
Noteworthy is the absence of hydrogen bonds for the bridging OH-group. This OH-group is located in a "pocket" constituted by two Br and two Cl atoms of the same molecule. As a consequence no hydrogen-acceptor atom is accessible for hydrogen-bond formation. Although this hydrogen is on a restrained position, it is the only possible location.