research communications
H-purin-7-ido-κN7)cobalt(II)
of tetraaquabis(1,3-dimethyl-2,6-dioxo-7aEquipe Metallation, Complexes Moleculaires et Applications, Universite Moulay, Ismail, Faculte des Sciences, Meknes, BP 11201 Zitoune, 50000 Meknes, Morocco, bLaboratoire de Chimie de Coordination du CNRS, 205, route de Narbonne, BP 44099, F-31077 Toulouse Cedex 4, France, and cUniversité de Toulouse, UPS, INPT, F-31077 Toulouse Cedex 4, France
*Correspondence e-mail: elhamdanihicham41@gmail.com
The title complex, [Co(C7H7N4O2)2(H2O)4], comprises mononuclear molecules consisting of a CoII ion, two deprotonated theophylline ligands (systematic name: 1,3-dimethyl-7H-purine-2,6-dione) and four coordinating water molecules. The CoII atom lies on an inversion centre and has a slightly distorted octahedral coordination environment, with two N atoms of two trans-oriented theophylline ligands and the O atoms of four water molecules. An intramolecular hydrogen bond stabilizes this conformation. A three-dimensional supramolecular network structure is formed by intermolecular O—H⋯O and O—H⋯N hydrogen bonds.
Keywords: crystal structure; theophylline; cobalt; hydrogen bonding.
CCDC reference: 1566195
1. Chemical context
Theophylline (systematic name: 1,3-dimethyl-7H-purine-2,6-dione) belongs to the family of xanthines, which are purine derivatives. It is related to dietary xanthines caffeine and theobromine and is an important pharmacologic compound (Shukla & Mishra, 1994). Usually, synthetic drugs of theophylline are used for the treatment of disorder in the physiological functions of the pulmonary system (Childs, 2004) because theophylline is a bronchodilator that is given against asthma and bronchospasm in adults (Chen et al., 2007).
The complexing ability of theophylline has been studied towards modelling metal interactions with the guanine base of et al., 1988). Theophylline can be deprotonated in basic or neutral media. In the majority of cases, the resulting anionic ligand is monodentate and coordinates through the N7 atom of theophylline (Marzilli et al., 1973; Begum & Manohar, 1994; Bombicz et al., 1997; Buncel et al., 1985), while only in a few cases has a different coordination behaviour been reported, e.g. through the N9 atom of the imidazole ring (Aoki & Yamazaki, 1980). In addition, deprotonated theophylline may act as a bidentate ligand, where the initial metal bonding to N7 is supplemented by coordination to the O6 atom, forming an N7/O6 chelate (Cozak et al., 1986).
(OrbellIn this study, we reacted theophylline with the CoII ion to yield the title complex, [Co(C7H7N4O2)2(H2O)4].
2. Structural commentary
The molecular structure of the title complex is shown in Fig. 1. The complex lies across an inversion centre, with the CoII atom being coordinated in a slightly distorted octahedral environment by four aqua ligands in the equatorial sites and the imidazole ring N atoms of two 1,3-dimethyl-2,6-dioxo-7H-purin-7-ide ligands [N1 and N1i; see Table 1 for symmetry code], in the axial sites. The Co—O bond lengths are shorter than the Co—N bond length (Table 1). The purine ring system is essentially planar, with a maximum deviation of 0.029 Å for N5; methyl atoms C10 and C12 deviate from this mean plane by −0.117 and 0.12 Å, respectively. The molecular conformation is stabilized by an intramolecular O—H⋯O hydrogen bond between a water molecule (O15) and a carbonyl O atom (O13) (Table 2), leading to an S(7) graph-set motif (Bernstein et al., 1995).
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3. Supramolecular features
In the crystal, the mononuclear units are connected into a layered arrangement parallel to (010). The coordinating water molecules are involved in various hydrogen-bonding interactions (Table 2), including R42(8) graph-set motifs that are formed through (O14⋯O11ii = 2.817 (2) Å and O14⋯O11iii = 2.773 (2) Å; see Table 2 for symmetry codes) between a coordinating water molecule and the carbonyl groups of symmetry-related theophylline ligands (Fig. 2). In addition, water molecule O15 is hydrogen bonded to the nonmethylated N atom of the imidazole group (O15⋯N3iv = 2.799 (2) Å; see Table 2 for symmetry code), leading to an overall three-dimensional network.
4. Synthesis and crystallization
Theophylline (360 mg, 2 mmol) was dissolved in water (20 ml). An aqueous solution (10 ml) of NaOH (80 mg, 2 mmol) was added slowly. CoCl2·6H2O (237 mg, 1 mmol) in water (10 ml) was then added. Pink single crystals of the title compound suitable for X-ray analysis were obtained after several months by slow evaporation of the solvent at room temperature.
5. Refinement
Details of data collection and structure . The calculated strategy was based on monoclinic chiral symmetry, with a completeness of 100%, an average multiplicity of 11.4 and no missing reflections. However, some reflections were still missing after data collection, thus reducing the completeness to less than 100%. All H atoms were located in a difference map, but those attached to C atoms were repositioned geometrically. The H atoms were refined with soft restraints on bond lengths and angles to regularize their geometry (C—H = 0.93–0.98 Å, N—H = 0.86–0.89 Å, N—H = 0.86 Å and O—H = 0.82 Å) and Uiso(H) values (in the range 1.2–1.5 times Ueq of the parent atom), after which the positions were refined with riding constraints (Cooper et al., 2010).
are summarized in Table 3Supporting information
CCDC reference: 1566195
https://doi.org/10.1107/S2056989017011379/wm5408sup1.cif
contains datablocks global, New_Global_Publ_Block, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989017011379/wm5408Isup2.hkl
Data collection: COLLECT (Nonius, 2001).; cell
DENZO/SCALEPACK (Otwinowski & Minor, 1997); data reduction: APEX2 (Bruker, 2006); program(s) used to solve structure: SUPERFLIP (Palatinus & Chapuis, 2007); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003); molecular graphics: CAMERON (Watkin et al., 1996); software used to prepare material for publication: CRYSTALS (Betteridge et al., 2003).[Co(C7H7N4O2)2(H2O)4] | F(000) = 506 |
Mr = 489.31 | Dx = 1.729 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 9823 reflections |
a = 7.6304 (3) Å | θ = 3–25° |
b = 13.1897 (6) Å | µ = 0.98 mm−1 |
c = 9.6670 (4) Å | T = 175 K |
β = 104.9744 (17)° | Block, pale pink |
V = 939.87 (7) Å3 | 0.20 × 0.20 × 0.15 mm |
Z = 2 |
Nonius KappaCCD diffractometer | 1704 reflections with I > 2.0σ(I) |
Graphite monochromator | Rint = 0.028 |
φ & ω scans | θmax = 25.4°, θmin = 2.7° |
Absorption correction: multi-scan (DENZO/SCALEPACK; Otwinowski & Minor, 1997) | h = −9→9 |
Tmin = 0.81, Tmax = 0.86 | k = −15→15 |
41453 measured reflections | l = −11→11 |
1736 independent reflections |
Refinement on F | Primary atom site location: other |
Least-squares matrix: full | Hydrogen site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.021 | H-atom parameters constrained |
wR(F2) = 0.023 | Method = Quasi-Unit weights W = 1.0 or 1./4Fsq |
S = 1.00 | (Δ/σ)max = 0.0003458 |
1686 reflections | Δρmax = 0.29 e Å−3 |
142 parameters | Δρmin = −0.22 e Å−3 |
0 restraints |
Experimental. The crystal was placed in the cold stream of an Oxford Cryosystems open-flow nitrogen cryostat (Cosier & Glazer, 1986) with a nominal stability of 0.1 K. Cosier, J. & Glazer, A.M., 1986. J. Appl. Cryst. 105-107. |
x | y | z | Uiso*/Ueq | ||
N1 | 0.05846 (17) | 0.45527 (9) | 0.72491 (13) | 0.0126 | |
N3 | 0.04606 (18) | 0.33836 (10) | 0.89795 (13) | 0.0151 | |
N5 | 0.24314 (17) | 0.42364 (10) | 1.10036 (13) | 0.0143 | |
N7 | 0.34987 (17) | 0.58201 (10) | 1.04872 (13) | 0.0139 | |
C2 | −0.0068 (2) | 0.36737 (12) | 0.75802 (16) | 0.0143 | |
C4 | 0.1522 (2) | 0.41609 (11) | 0.95762 (15) | 0.0124 | |
C6 | 0.3386 (2) | 0.50912 (12) | 1.14880 (16) | 0.0145 | |
C8 | 0.2695 (2) | 0.57724 (11) | 0.89958 (16) | 0.0136 | |
C9 | 0.16404 (19) | 0.48879 (11) | 0.85772 (15) | 0.0119 | |
C10 | 0.2355 (2) | 0.34042 (13) | 1.19853 (17) | 0.0218 | |
C12 | 0.4475 (2) | 0.67528 (12) | 1.10615 (17) | 0.0196 | |
O11 | 0.41386 (15) | 0.52183 (9) | 1.27770 (11) | 0.0188 | |
O13 | 0.29724 (16) | 0.64754 (8) | 0.82313 (12) | 0.0206 | |
O14 | 0.26896 (14) | 0.46163 (9) | 0.50496 (11) | 0.0197 | |
O15 | 0.08751 (15) | 0.64646 (8) | 0.55927 (11) | 0.0172 | |
Co1 | 0.0000 | 0.5000 | 0.5000 | 0.0103 | |
H21 | −0.0864 | 0.3279 | 0.6895 | 0.0161* | |
H103 | 0.3447 | 0.3423 | 1.2769 | 0.0336* | |
H101 | 0.1296 | 0.3467 | 1.2352 | 0.0345* | |
H102 | 0.2316 | 0.2770 | 1.1486 | 0.0330* | |
H121 | 0.4345 | 0.7242 | 1.0325 | 0.0318* | |
H122 | 0.4018 | 0.7025 | 1.1814 | 0.0314* | |
H123 | 0.5741 | 0.6614 | 1.1459 | 0.0311* | |
H142 | 0.3487 | 0.4654 | 0.5786 | 0.0298* | |
H151 | 0.1601 | 0.6467 | 0.6392 | 0.0273* | |
H141 | 0.3056 | 0.4824 | 0.4383 | 0.0306* | |
H152 | 0.0280 | 0.6987 | 0.5575 | 0.0275* |
U11 | U22 | U33 | U12 | U13 | U23 | |
N1 | 0.0148 (6) | 0.0118 (6) | 0.0100 (6) | −0.0004 (5) | 0.0012 (5) | −0.0006 (5) |
N3 | 0.0188 (7) | 0.0135 (6) | 0.0124 (6) | −0.0009 (5) | 0.0031 (5) | 0.0011 (5) |
N5 | 0.0164 (6) | 0.0158 (6) | 0.0094 (6) | 0.0006 (5) | 0.0010 (5) | 0.0024 (5) |
N7 | 0.0138 (6) | 0.0148 (6) | 0.0114 (6) | −0.0019 (5) | 0.0003 (5) | −0.0019 (5) |
C2 | 0.0163 (7) | 0.0135 (7) | 0.0122 (7) | −0.0016 (6) | 0.0019 (6) | −0.0014 (6) |
C4 | 0.0125 (7) | 0.0136 (7) | 0.0109 (7) | 0.0021 (6) | 0.0026 (6) | 0.0001 (6) |
C6 | 0.0112 (7) | 0.0191 (8) | 0.0129 (7) | 0.0028 (6) | 0.0026 (6) | −0.0008 (6) |
C8 | 0.0127 (7) | 0.0150 (7) | 0.0122 (7) | 0.0020 (6) | 0.0015 (6) | −0.0008 (6) |
C9 | 0.0124 (7) | 0.0129 (7) | 0.0097 (7) | 0.0015 (6) | 0.0014 (5) | 0.0002 (6) |
C10 | 0.0312 (9) | 0.0187 (8) | 0.0139 (8) | 0.0009 (7) | 0.0030 (7) | 0.0065 (6) |
C12 | 0.0216 (8) | 0.0177 (8) | 0.0171 (8) | −0.0042 (7) | 0.0004 (6) | −0.0049 (6) |
O11 | 0.0170 (5) | 0.0280 (6) | 0.0089 (5) | −0.0012 (5) | −0.0008 (4) | −0.0012 (5) |
O13 | 0.0272 (6) | 0.0171 (6) | 0.0141 (5) | −0.0082 (5) | −0.0008 (5) | 0.0032 (5) |
O14 | 0.0146 (5) | 0.0329 (7) | 0.0105 (5) | 0.0010 (5) | 0.0012 (4) | 0.0005 (5) |
O15 | 0.0236 (6) | 0.0119 (5) | 0.0125 (5) | 0.0007 (5) | −0.0021 (4) | −0.0016 (4) |
Co1 | 0.01218 (14) | 0.00993 (14) | 0.00793 (14) | −0.00056 (11) | 0.00085 (10) | −0.00020 (11) |
N1—C2 | 1.333 (2) | C8—C9 | 1.416 (2) |
N1—C9 | 1.3994 (18) | C8—O13 | 1.2375 (19) |
N1—Co1 | 2.1847 (12) | C10—H103 | 0.971 |
N3—C2 | 1.363 (2) | C10—H101 | 0.966 |
N3—C4 | 1.341 (2) | C10—H102 | 0.962 |
N5—C4 | 1.3786 (19) | C12—H121 | 0.947 |
N5—C6 | 1.358 (2) | C12—H122 | 0.955 |
N5—C10 | 1.4620 (19) | C12—H123 | 0.961 |
N7—C6 | 1.382 (2) | O14—Co1 | 2.1022 (11) |
N7—C8 | 1.4149 (19) | O14—H142 | 0.810 |
N7—C12 | 1.4706 (19) | O14—H141 | 0.813 |
C2—H21 | 0.933 | O15—Co1 | 2.0756 (10) |
C4—C9 | 1.380 (2) | O15—H151 | 0.826 |
C6—O11 | 1.2414 (18) | O15—H152 | 0.823 |
C2—N1—C9 | 102.52 (12) | H103—C10—H102 | 108.8 |
C2—N1—Co1 | 118.74 (10) | H101—C10—H102 | 109.7 |
C9—N1—Co1 | 138.49 (10) | N7—C12—H121 | 110.0 |
C2—N3—C4 | 101.73 (12) | N7—C12—H122 | 110.7 |
C4—N5—C6 | 119.43 (13) | H121—C12—H122 | 109.2 |
C4—N5—C10 | 120.08 (13) | N7—C12—H123 | 110.6 |
C6—N5—C10 | 120.48 (13) | H121—C12—H123 | 109.2 |
C6—N7—C8 | 126.39 (13) | H122—C12—H123 | 107.1 |
C6—N7—C12 | 115.76 (12) | Co1—O14—H142 | 120.9 |
C8—N7—C12 | 117.76 (13) | Co1—O14—H141 | 115.7 |
N3—C2—N1 | 116.71 (13) | H142—O14—H141 | 110.0 |
N3—C2—H21 | 121.3 | Co1—O15—H151 | 110.6 |
N1—C2—H21 | 122.0 | Co1—O15—H152 | 129.6 |
N5—C4—N3 | 125.28 (14) | H151—O15—H152 | 104.5 |
N5—C4—C9 | 122.90 (14) | N1—Co1—N1i | 180 |
N3—C4—C9 | 111.81 (13) | N1—Co1—O14i | 92.00 (4) |
N7—C6—N5 | 117.44 (13) | N1i—Co1—O14i | 88.00 (4) |
N7—C6—O11 | 120.82 (14) | N1—Co1—O14 | 88.00 (4) |
N5—C6—O11 | 121.74 (14) | N1i—Co1—O14 | 92.00 (4) |
N7—C8—C9 | 113.12 (13) | O14i—Co1—O14 | 180 |
N7—C8—O13 | 118.63 (13) | N1—Co1—O15i | 89.53 (4) |
C9—C8—O13 | 128.25 (14) | N1i—Co1—O15i | 90.47 (4) |
C8—C9—N1 | 132.26 (13) | O14i—Co1—O15i | 88.58 (4) |
C8—C9—C4 | 120.50 (13) | O14—Co1—O15i | 91.42 (4) |
N1—C9—C4 | 107.23 (13) | N1—Co1—O15 | 90.47 (4) |
N5—C10—H103 | 108.5 | N1i—Co1—O15 | 89.53 (4) |
N5—C10—H101 | 110.6 | O14i—Co1—O15 | 91.42 (4) |
H103—C10—H101 | 110.0 | O14—Co1—O15 | 88.58 (4) |
N5—C10—H102 | 109.2 | O15i—Co1—O15 | 180 |
Symmetry code: (i) −x, −y+1, −z+1. |
D—H···A | D—H | H···A | D···A | D—H···A |
O14—H142···O11ii | 0.81 | 1.99 | 2.773 (2) | 164 |
O15—H151···O13 | 0.83 | 1.82 | 2.638 (2) | 173 |
O14—H141···O11iii | 0.81 | 2.01 | 2.817 (2) | 174 |
O15—H152···N3iv | 0.82 | 2.01 | 2.799 (2) | 162 |
Symmetry codes: (ii) −x+1, −y+1, −z+2; (iii) x, y, z−1; (iv) −x, y+1/2, −z+3/2. |
Acknowledgements
The authors would like to thank the LCC CNRS (Laboratory of Chemistry of Coordination) for their help.
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