metal-organic compounds
(2,2′-Bipyridine)bis(3-carboxypyrazine-2-carboxylato)copper(II) dihydrate
aDepartment of Chemistry, Tarbiat Moallem University, 49 Mofateh Avenue, Tehran, Iran, bDepartment of Chemistry, Islamic Azad University, North Tehran Branch, Tehran, Iran, and cDepartment of Biology, Faculty of Science, Shahed University, Opposite Imam Khomeini's Shrine, Tehran-Qom Highway, Tehran, Iran
*Correspondence e-mail: haghabozorg@yahoo.com
The title six-coordinated distorted octahedral complex, [Cu(C6H3N2O4)2(C10H8N2)]·2H2O, consists of two 3-carboxypyrazine-2-carboxylate anions and one 2,2′-bipyridine ligand. There is a twofold rotation axis positioned at the CuII center. The N atoms of the pyrazine ring occupy the axial positions and two proton-transferred O atoms of tbe acid together with the two N atoms of the 2,2′-bipyridine ligand complete the equatorial plane. The interactions existing in the are intermolecular O—H⋯O hydrogen bonds, and C—H⋯O and C—O⋯π interactions (O⋯π =3.145 Å, C—O⋯π = 149.75°).
Related literature
There are several compounds made from pyrazine-2,3-dicarboxylic acid, but most of them are in a polymeric form; see, for example: Tombul et al. (2007, 2008). For related literature, see: Egli & Sarkhel (2007).
Experimental
Crystal data
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Refinement
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Data collection: APEX2 (Bruker, 2007); cell SAINT (Bruker, 2007); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.
Supporting information
10.1107/S1600536808022885/om2248sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536808022885/om2248Isup2.hkl
To a 10 ml of a stirring aqueous solution of pyrazine-2,3-dicarboxylic acid (0.084 g, 0.5 mmol) and 2,2'- bipyridine (0.078 g, 0.5 mmol), was added a 0.5 molar equivalent of CuSO4. 5 H2O (0.062 g, 0.25 mmol) at room temperature. A neutral copper(II) complex, [Cu(pzdcH)2(2,2'- bpy)]. 2H2O, was isolated as very light blue crystals. Slow evaporation of the solvent result in product complex in a week.
Data collection: APEX2 (Bruker, 2007); cell
SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).[Cu(C6H3N2O4)2(C10H8N2)]·2H2O | F(000) = 1204 |
Mr = 589.96 | Dx = 1.686 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -C 2yc | Cell parameters from 9557 reflections |
a = 18.3080 (8) Å | θ = 2.6–30.5° |
b = 9.2168 (4) Å | µ = 1.01 mm−1 |
c = 16.3235 (7) Å | T = 100 K |
β = 122.480 (5)° | Prism, colourless |
V = 2323.59 (18) Å3 | 0.20 × 0.20 × 0.20 mm |
Z = 4 |
Bruker SMART APEXII diffractometer | 3500 independent reflections |
Radiation source: fine-focus sealed tube | 3289 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.017 |
ϕ and ω scans | θmax = 30.5°, θmin = 2.6° |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | h = −26→26 |
Tmin = 0.823, Tmax = 0.823 | k = −13→13 |
14982 measured reflections | l = −23→23 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.023 | Hydrogen site location: mixed |
wR(F2) = 0.063 | H-atom parameters constrained |
S = 1.04 | w = 1/[σ2(Fo2) + (0.04P)2 + 1.2P] where P = (Fo2 + 2Fc2)/3 |
3500 reflections | (Δ/σ)max = 0.001 |
177 parameters | Δρmax = 0.49 e Å−3 |
0 restraints | Δρmin = −0.31 e Å−3 |
[Cu(C6H3N2O4)2(C10H8N2)]·2H2O | V = 2323.59 (18) Å3 |
Mr = 589.96 | Z = 4 |
Monoclinic, C2/c | Mo Kα radiation |
a = 18.3080 (8) Å | µ = 1.01 mm−1 |
b = 9.2168 (4) Å | T = 100 K |
c = 16.3235 (7) Å | 0.20 × 0.20 × 0.20 mm |
β = 122.480 (5)° |
Bruker SMART APEXII diffractometer | 3500 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 3289 reflections with I > 2σ(I) |
Tmin = 0.823, Tmax = 0.823 | Rint = 0.017 |
14982 measured reflections |
R[F2 > 2σ(F2)] = 0.023 | 0 restraints |
wR(F2) = 0.063 | H-atom parameters constrained |
S = 1.04 | Δρmax = 0.49 e Å−3 |
3500 reflections | Δρmin = −0.31 e Å−3 |
177 parameters |
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 | ||
Cu1 | 1.0000 | 0.367362 (16) | 0.2500 | 0.01104 (5) | |
O1 | 0.91326 (4) | 0.21893 (8) | 0.16501 (5) | 0.01386 (13) | |
O2 | 0.85176 (5) | 0.08782 (9) | 0.02861 (6) | 0.02271 (16) | |
O3 | 0.90660 (5) | 0.00760 (8) | −0.12364 (6) | 0.02014 (15) | |
H3O | 0.8658 | −0.0282 | −0.1804 | 0.024* | |
O4 | 0.81385 (5) | 0.19258 (9) | −0.16881 (6) | 0.02211 (16) | |
N1 | 1.02854 (5) | 0.32913 (9) | 0.12702 (6) | 0.01404 (15) | |
N2 | 1.01283 (6) | 0.27792 (10) | −0.05007 (6) | 0.01888 (17) | |
N3 | 0.91587 (5) | 0.53313 (8) | 0.19274 (6) | 0.01230 (14) | |
C1 | 0.96492 (6) | 0.24626 (10) | 0.05929 (7) | 0.01255 (15) | |
C2 | 0.95681 (6) | 0.22146 (10) | −0.02994 (7) | 0.01416 (16) | |
C3 | 1.07722 (7) | 0.35806 (12) | 0.01940 (8) | 0.01958 (19) | |
H3A | 1.1187 | 0.3983 | 0.0079 | 0.023* | |
C4 | 1.08554 (7) | 0.38463 (11) | 0.10811 (8) | 0.01748 (18) | |
H4A | 1.1321 | 0.4426 | 0.1556 | 0.021* | |
C5 | 0.90413 (6) | 0.17769 (10) | 0.08456 (7) | 0.01334 (16) | |
C6 | 0.88379 (7) | 0.13731 (10) | −0.11323 (7) | 0.01512 (17) | |
C7 | 0.82914 (6) | 0.52122 (10) | 0.13793 (7) | 0.01459 (16) | |
H7A | 0.8039 | 0.4274 | 0.1197 | 0.018* | |
C8 | 0.77532 (6) | 0.64164 (10) | 0.10722 (7) | 0.01620 (18) | |
H8A | 0.7142 | 0.6307 | 0.0692 | 0.019* | |
C9 | 0.81274 (6) | 0.77869 (11) | 0.13324 (7) | 0.01659 (17) | |
H9A | 0.7773 | 0.8630 | 0.1126 | 0.020* | |
C10 | 0.90229 (6) | 0.79146 (10) | 0.18959 (7) | 0.01464 (17) | |
H10A | 0.9289 | 0.8843 | 0.2076 | 0.018* | |
C11 | 0.95228 (5) | 0.66600 (10) | 0.21923 (6) | 0.01133 (15) | |
O5 | 0.80282 (5) | 0.09628 (8) | 0.20844 (6) | 0.01843 (14) | |
H5A | 0.8335 | 0.1329 | 0.1897 | 0.022* | |
H5B | 0.7644 | 0.1614 | 0.1957 | 0.022* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Cu1 | 0.01075 (8) | 0.00986 (8) | 0.01153 (8) | 0.000 | 0.00533 (6) | 0.000 |
O1 | 0.0162 (3) | 0.0146 (3) | 0.0136 (3) | −0.0032 (2) | 0.0099 (3) | −0.0027 (2) |
O2 | 0.0255 (4) | 0.0255 (4) | 0.0199 (4) | −0.0116 (3) | 0.0140 (3) | −0.0098 (3) |
O3 | 0.0209 (3) | 0.0171 (3) | 0.0184 (3) | 0.0053 (3) | 0.0079 (3) | −0.0022 (3) |
O4 | 0.0193 (3) | 0.0250 (4) | 0.0179 (3) | 0.0082 (3) | 0.0072 (3) | −0.0017 (3) |
N1 | 0.0152 (3) | 0.0137 (3) | 0.0149 (4) | 0.0000 (3) | 0.0092 (3) | 0.0009 (3) |
N2 | 0.0181 (4) | 0.0255 (4) | 0.0168 (4) | 0.0038 (3) | 0.0118 (3) | 0.0035 (3) |
N3 | 0.0119 (3) | 0.0124 (3) | 0.0118 (3) | 0.0001 (3) | 0.0058 (3) | 0.0001 (3) |
C1 | 0.0141 (4) | 0.0121 (4) | 0.0132 (4) | 0.0018 (3) | 0.0085 (3) | 0.0013 (3) |
C2 | 0.0149 (4) | 0.0154 (4) | 0.0132 (4) | 0.0040 (3) | 0.0082 (3) | 0.0019 (3) |
C3 | 0.0171 (4) | 0.0257 (5) | 0.0204 (5) | 0.0016 (3) | 0.0131 (4) | 0.0045 (4) |
C4 | 0.0156 (4) | 0.0196 (4) | 0.0184 (4) | −0.0010 (3) | 0.0099 (4) | 0.0018 (3) |
C5 | 0.0146 (4) | 0.0134 (4) | 0.0133 (4) | −0.0003 (3) | 0.0083 (3) | −0.0002 (3) |
C6 | 0.0178 (4) | 0.0169 (4) | 0.0133 (4) | 0.0035 (3) | 0.0101 (4) | 0.0005 (3) |
C7 | 0.0122 (4) | 0.0142 (4) | 0.0154 (4) | −0.0007 (3) | 0.0060 (3) | −0.0004 (3) |
C8 | 0.0120 (4) | 0.0171 (4) | 0.0162 (4) | 0.0008 (3) | 0.0054 (3) | −0.0010 (3) |
C9 | 0.0138 (4) | 0.0149 (4) | 0.0171 (4) | 0.0027 (3) | 0.0057 (3) | −0.0008 (3) |
C10 | 0.0144 (4) | 0.0122 (4) | 0.0153 (4) | 0.0006 (3) | 0.0067 (3) | −0.0010 (3) |
C11 | 0.0114 (4) | 0.0126 (4) | 0.0100 (4) | 0.0000 (3) | 0.0057 (3) | 0.0003 (3) |
O5 | 0.0213 (3) | 0.0156 (3) | 0.0244 (4) | 0.0041 (3) | 0.0163 (3) | 0.0056 (3) |
Cu1—O1 | 1.9880 (7) | C2—C6 | 1.5117 (14) |
Cu1—N3 | 2.0085 (8) | C3—C4 | 1.3940 (15) |
Cu1—N1 | 2.3565 (8) | C3—H3A | 0.9500 |
O1—C5 | 1.2890 (11) | C4—H4A | 0.9500 |
O2—C5 | 1.2243 (12) | C7—C8 | 1.3869 (13) |
O3—C6 | 1.3072 (12) | C7—H7A | 0.9500 |
O3—H3O | 0.8844 | C8—C9 | 1.3903 (13) |
O4—C6 | 1.2142 (12) | C8—H8A | 0.9500 |
N1—C1 | 1.3340 (12) | C9—C10 | 1.3886 (13) |
N1—C4 | 1.3386 (12) | C9—H9A | 0.9500 |
N2—C3 | 1.3362 (15) | C10—C11 | 1.3904 (13) |
N2—C2 | 1.3388 (12) | C10—H10A | 0.9500 |
N3—C7 | 1.3446 (11) | C11—C11i | 1.4754 (17) |
N3—C11 | 1.3496 (12) | O5—H5A | 0.8419 |
C1—C2 | 1.4012 (13) | O5—H5B | 0.8612 |
C1—C5 | 1.5169 (12) | ||
O1—Cu1—O1i | 93.03 (4) | C4—C3—H3A | 118.9 |
O1—Cu1—N3i | 166.86 (3) | N1—C4—C3 | 120.57 (10) |
O1—Cu1—N3 | 94.19 (3) | N1—C4—H4A | 119.7 |
O1i—Cu1—N3 | 166.86 (3) | C3—C4—H4A | 119.7 |
N3i—Cu1—N3 | 80.95 (4) | O2—C5—O1 | 125.49 (9) |
O1—Cu1—N1i | 91.84 (3) | O2—C5—C1 | 118.30 (8) |
N3—Cu1—N1i | 92.57 (3) | O1—C5—C1 | 116.20 (8) |
O1—Cu1—N1 | 76.24 (3) | O4—C6—O3 | 124.67 (10) |
N3—Cu1—N1 | 100.53 (3) | O4—C6—C2 | 121.68 (9) |
N1i—Cu1—N1 | 162.80 (4) | O3—C6—C2 | 113.34 (8) |
C5—O1—Cu1 | 122.13 (6) | N3—C7—C8 | 122.08 (9) |
C6—O3—H3O | 109.2 | N3—C7—H7A | 119.0 |
C1—N1—C4 | 118.00 (9) | C8—C7—H7A | 119.0 |
C1—N1—Cu1 | 107.29 (6) | C7—C8—C9 | 118.61 (9) |
C4—N1—Cu1 | 134.12 (7) | C7—C8—H8A | 120.7 |
C3—N2—C2 | 116.72 (9) | C9—C8—H8A | 120.7 |
C7—N3—C11 | 119.40 (8) | C10—C9—C8 | 119.48 (9) |
C7—N3—Cu1 | 125.73 (6) | C10—C9—H9A | 120.3 |
C11—N3—Cu1 | 114.69 (6) | C8—C9—H9A | 120.3 |
N1—C1—C2 | 120.85 (8) | C9—C10—C11 | 118.84 (9) |
N1—C1—C5 | 117.05 (8) | C9—C10—H10A | 120.6 |
C2—C1—C5 | 122.07 (8) | C11—C10—H10A | 120.6 |
N2—C2—C1 | 121.62 (9) | N3—C11—C10 | 121.57 (8) |
N2—C2—C6 | 113.75 (8) | N3—C11—C11i | 114.75 (5) |
C1—C2—C6 | 124.57 (8) | C10—C11—C11i | 123.67 (5) |
N2—C3—C4 | 122.22 (9) | H5A—O5—H5B | 104.5 |
N2—C3—H3A | 118.9 | ||
O1i—Cu1—O1—C5 | −96.65 (7) | C3—N2—C2—C6 | 177.66 (9) |
N3i—Cu1—O1—C5 | 26.65 (17) | N1—C1—C2—N2 | 0.90 (14) |
N3—Cu1—O1—C5 | 94.33 (7) | C5—C1—C2—N2 | −177.34 (9) |
N1i—Cu1—O1—C5 | −172.96 (7) | N1—C1—C2—C6 | −175.91 (9) |
N1—Cu1—O1—C5 | −5.49 (7) | C5—C1—C2—C6 | 5.84 (14) |
O1—Cu1—N1—C1 | 8.79 (6) | C2—N2—C3—C4 | −1.13 (15) |
O1i—Cu1—N1—C1 | 101.46 (6) | C1—N1—C4—C3 | 1.09 (14) |
N3i—Cu1—N1—C1 | −164.26 (6) | Cu1—N1—C4—C3 | −168.92 (7) |
N3—Cu1—N1—C1 | −82.99 (6) | N2—C3—C4—N1 | 0.34 (16) |
N1i—Cu1—N1—C1 | 55.98 (14) | Cu1—O1—C5—O2 | −179.47 (8) |
O1—Cu1—N1—C4 | 179.57 (10) | Cu1—O1—C5—C1 | 1.41 (11) |
O1i—Cu1—N1—C4 | −87.76 (10) | N1—C1—C5—O2 | −171.48 (9) |
N3i—Cu1—N1—C4 | 6.52 (10) | C2—C1—C5—O2 | 6.83 (14) |
N3—Cu1—N1—C4 | 87.79 (10) | N1—C1—C5—O1 | 7.71 (12) |
N1i—Cu1—N1—C4 | −133.24 (9) | C2—C1—C5—O1 | −173.98 (9) |
O1—Cu1—N3—C7 | 15.90 (8) | N2—C2—C6—O4 | −96.00 (11) |
O1i—Cu1—N3—C7 | −107.29 (14) | C1—C2—C6—O4 | 81.03 (13) |
N3i—Cu1—N3—C7 | −176.39 (10) | N2—C2—C6—O3 | 77.89 (11) |
N1i—Cu1—N3—C7 | −76.14 (8) | C1—C2—C6—O3 | −105.07 (11) |
N1—Cu1—N3—C7 | 92.66 (8) | C11—N3—C7—C8 | 0.14 (14) |
O1—Cu1—N3—C11 | −169.01 (6) | Cu1—N3—C7—C8 | 175.02 (7) |
O1i—Cu1—N3—C11 | 67.81 (15) | N3—C7—C8—C9 | 0.79 (15) |
N3i—Cu1—N3—C11 | −1.30 (5) | C7—C8—C9—C10 | −0.57 (15) |
N1i—Cu1—N3—C11 | 98.96 (6) | C8—C9—C10—C11 | −0.53 (15) |
N1—Cu1—N3—C11 | −92.25 (7) | C7—N3—C11—C10 | −1.31 (13) |
C4—N1—C1—C2 | −1.68 (14) | Cu1—N3—C11—C10 | −176.74 (7) |
Cu1—N1—C1—C2 | 170.83 (7) | C7—N3—C11—C11i | 178.90 (9) |
C4—N1—C1—C5 | 176.65 (8) | Cu1—N3—C11—C11i | 3.47 (12) |
Cu1—N1—C1—C5 | −10.84 (9) | C9—C10—C11—N3 | 1.50 (14) |
C3—N2—C2—C1 | 0.53 (14) | C9—C10—C11—C11i | −178.73 (10) |
Symmetry code: (i) −x+2, y, −z+1/2. |
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H3O···O5ii | 0.88 | 1.66 | 2.5390 (12) | 170 |
O5—H5A···O1 | 0.84 | 1.89 | 2.7218 (13) | 173 |
O5—H5B···O4iii | 0.86 | 1.84 | 2.6989 (13) | 177 |
C7—H7A···O2iii | 0.95 | 2.57 | 3.1144 (14) | 117 |
C8—H8A···O2iii | 0.95 | 2.45 | 3.0433 (13) | 121 |
C9—H9A···O5iv | 0.95 | 2.55 | 3.2168 (13) | 127 |
Symmetry codes: (ii) x, −y, z−1/2; (iii) −x+3/2, −y+1/2, −z; (iv) x, y+1, z. |
Experimental details
Crystal data | |
Chemical formula | [Cu(C6H3N2O4)2(C10H8N2)]·2H2O |
Mr | 589.96 |
Crystal system, space group | Monoclinic, C2/c |
Temperature (K) | 100 |
a, b, c (Å) | 18.3080 (8), 9.2168 (4), 16.3235 (7) |
β (°) | 122.480 (5) |
V (Å3) | 2323.59 (18) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 1.01 |
Crystal size (mm) | 0.20 × 0.20 × 0.20 |
Data collection | |
Diffractometer | Bruker SMART APEXII diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 1996) |
Tmin, Tmax | 0.823, 0.823 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 14982, 3500, 3289 |
Rint | 0.017 |
(sin θ/λ)max (Å−1) | 0.714 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.023, 0.063, 1.04 |
No. of reflections | 3500 |
No. of parameters | 177 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.49, −0.31 |
Computer programs: APEX2 (Bruker, 2007), SAINT (Bruker, 2007), SHELXTL (Sheldrick, 2008).
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H3O···O5i | 0.88 | 1.66 | 2.5390 (12) | 170 |
O5—H5A···O1 | 0.84 | 1.89 | 2.7218 (13) | 173 |
O5—H5B···O4ii | 0.86 | 1.84 | 2.6989 (13) | 177 |
C7—H7A···O2ii | 0.95 | 2.57 | 3.1144 (14) | 117 |
C8—H8A···O2ii | 0.95 | 2.45 | 3.0433 (13) | 121 |
C9—H9A···O5iii | 0.95 | 2.55 | 3.2168 (13) | 127 |
Symmetry codes: (i) x, −y, z−1/2; (ii) −x+3/2, −y+1/2, −z; (iii) x, y+1, z. |
References
Bruker (2007). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Egli, M. & Sarkhel, S. (2007). Acc. Chem. Res. 40, 197–205. Web of Science CrossRef PubMed CAS Google Scholar
Sheldrick, G. M. (1996). SADABS. University of Göttingen, Germany. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Tombul, M., Güven, K. & Büyükgüngör, O. (2007). Acta Cryst. E63, m1783–m1784. Web of Science CSD CrossRef IUCr Journals Google Scholar
Tombul, M., Güven, K. & Svoboda, I. (2008). Acta Cryst. E64, m246–m247. Web of Science CSD CrossRef IUCr Journals Google Scholar
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The structure consists of [Cu(2,3-pzdcH)2(2,2'- bpy)]. 2H2O, where pzdcH2 and 2,2'-bpy are pyrazine-2,3-dicarboxylic acid and 2,2'-bipyridine, respectively. The presence of bidentate mono anionic (pzdcH)- and neutral 2,2'-bipyridine ligands results in a neutral complex. The asymmetric unit is given in Fig. 1. The obtained hexacoordinated geometry is distorted octahedral. The bond lengths and angles around the CuII center are all in accordance with the geometrical steric effects.
There is a 2-fold rotation axis positioned at CuII center, transforming one half of the compound to the other.
The main interaction responsible for stabilizing such a framework is O–H···O hydrogen bonds. The water molecule participates in two hydrogen bonds relating two neighboring complexes. There is also a weaker C–H···O which joins the third complex to the series.
The O3–H3O···O5(x, -y, z - 1/2, 1.664 Å) and O5–H5B···O4 (-x + 3/2, -y + 1/2, -z, 1.839 Å) form hydrogen-bonded chains described by C22(14) graph-set descriptor (Fig. 2). Expansion of these chains results in layer. Furthermore, the C–H···O interactions between the complexes themselves help in the stabilization of the layers. In the third dimension, there is a similar layer at about a 4.1 Å distance. These layers are connected to each other via a fascinating C–O···π interaction by C6–O3 and a pyrazine ring (Fig. 3). All factors including O···π distance (3.145 Å), C–O···π angle (α = 149.75°) and dihedral angle between the planes defined by X2C–O and the aromatic system (ω = 79.18°), are in the mentioned range as in the reference [Egli & Sarkhel, 2007].
Figure 4 represents the packing diagram of this crystal lattice.