Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807030978/cv2264sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536807030978/cv2264Isup2.hkl |
CCDC reference: 648017
The proton-transfer compound was prepared by a reaction between propane-1,3-diamine and benzene-1,2,4,5-tetracarboxylic acid (Aghabozorg et al., 2007). Starting with a 1:1 molar ratio of the reactants in THF, a puffy white precipitate was obtained. By recrystallization in an aqueous solution, pale-yellow crystals were obtained. A solution of Ni(NO3)2.6H2O (143 mg, 0.5 mmol) in water (15 ml) was added to an aqueous solution of (pnH2)2(btc).2H2O (253 mg, 1.0 mmol) in water (15 ml) in a 1:2 molar ratio. Crystals of (I) suitable for X-ray characterization were obtained after a few days at room temperature.
The value of the Flack parameter of 0.412 (17) indicates that the absolute structure in this case cannot be determined unambiguously due to the specific centrosymmetric arrangement of the anionic pattern. The refinement of the structure in the centrosymmetric space group Imma gives rise to disodering of the dication.
The hydrogen atoms of coordinate water molecules and –NH3 groups were localized in difference Fourier synthesis, but placed in idealized positions (O—H 0.90 Å, N—H 0.90–0.92 Å). C-bound H atoms were placed in calculated positions (C—H 0.95–0.99 Å). The crystalline water molecule was treated as disordered between two positions related by a mirror plane with the occupancies of 0.25 (for O6) The attached H atoms were positioned geometrically (O—H 0.96, 0.97 Å). All H atoms were refined in a riding model with Uiso(H)=1.2–1.3Ueq of the parent atom.
Just as there is a field of molecular chemistry based on the covalent bond, there is a field of supramolecular chemistry, the chemistry of molecular assemblies and intermolecular interactions. The importance of weak hydrogen bonds in the context of crystal engineering, molecular recognition and supramolecular chemistry have been well recognized in recent years. In this regard, we have reported cases in which proton transfer from pyridine-2,6-dicarboxylic acid (pydcH2) and benzene-1,2,4,5-tetracarboxylicacid (btcH4) to piperazine (pipz), propane-1,3-diamine and 1,10-phenanthroline (phen) resulted in the formation of novel self-assembled (pipzH2)(pydc), (pnH2)2(btc).2H2O (Aghabozorg, et al., 2007) and (phenH)4(btcH3)2(btcH2) (Aghabozorg, Ghadermazi & Gharamaleki, 2006) systems, respectively. The resulting compounds with some remaining sites as electron donors can coordinate to metallic ions (Aghabozorg, Ghasemikhah et al., 2006; Aghabozorg, Zabihi et al., 2006).
Here we report a new polymeric compound obtained from reaction of (pnH2)2(btc).2H2O with nickel(II) nitrate. The crystal structure of the title polymeric compound is shown in Fig. 1. The intermolecular hydrogen bond distances are listed in the Table. The negative charge of the anionic complex is neutralized by dicationic propane-1,3-diaminium species. According to the crystal structure of (I), the coordination around NiII is distorted octahedral. A considerable feature of the compound (I) is the presence of C—H···π stacking interactions between C—H groups of (pnH2)2+ cations and aromatic rings of (btc)4– fragments. The C—H···π distances (measured to the centre of phenyl ring) are 2.60 Å for C8—H8A···Cg1 and 2.97 Å for C7—H7A···Cg1 with the angles of 142° and 137°, respectively [Cg1 is a centroid of C1—C4/C2i/C3i; symmetry code: (i) 1/2 + x, -1/2 + y, -1/2 + z]. The most important features of the crystal structure of (I) is a number of O—H···O, N—H···O and C—H···O hydrogen bonds between (pnH2)2+ and [Ni(H2O)2(btc)]2– fragments and uncoordinated water molecules with D···A distances ranging from 2.668 (2) Å to 3.242 (2) Å (Table). Ion pairing, C—H···π stacking and van der Waals forces are also effective in the stabilization of the crystal structure, resulting in the formation of an interesting supramolecular structure (Fig. 2).
For details of the preparation of related proton-transfer compounds, see: Aghabozorg et al. (2007); Aghabozorg, Ghadermazi & Attar Gharamaleki (2006). For the crystal structures of related complexes, see: Aghabozorg, Ghasemikhah et al. (2006); Aghabozorg, Zabihi et al. (2006).
Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT-Plus (Bruker, 2001); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXTL (Sheldrick, 2001); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.
Fig. 1. The structure of (I), showing the atom-numbering scheme and displacement ellipsoids at the 50% probability level. | |
Fig. 2. The crystal packing of (I). Hydrogen bonds are shown as dashed lines. |
(C3H12N2)[Ni(C10H2O8)(H2O)2]·0.5H2O | F(000) = 892 |
Mr = 430.01 | Dx = 1.716 Mg m−3 |
Orthorhombic, Ima2 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: I 2 -2a | Cell parameters from 6046 reflections |
a = 16.3724 (6) Å | θ = 2.5–30.0° |
b = 7.1673 (4) Å | µ = 1.23 mm−1 |
c = 14.1857 (8) Å | T = 100 K |
V = 1664.63 (15) Å3 | Prism, colourless |
Z = 4 | 0.30 × 0.30 × 0.20 mm |
Bruker SMART APEXII CCD area-detector diffractometer | 2424 independent reflections |
Radiation source: fine-focus sealed tube | 2353 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.022 |
φ and ω scans | θmax = 30.0°, θmin = 2.5° |
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) | h = −23→22 |
Tmin = 0.710, Tmax = 0.792 | k = −10→10 |
10153 measured reflections | l = −19→19 |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: mixed |
R[F2 > 2σ(F2)] = 0.028 | H-atom parameters constrained |
wR(F2) = 0.073 | w = 1/[σ2(Fo2) + (0.05P)2 + 1.1P] where P = (Fo2 + 2Fc2)/3 |
S = 1.00 | (Δ/σ)max < 0.001 |
2424 reflections | Δρmax = 0.44 e Å−3 |
132 parameters | Δρmin = −0.24 e Å−3 |
1 restraint | Absolute structure: Flack (1983), 1113 Friedel pairs |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: 0.412 (17) |
(C3H12N2)[Ni(C10H2O8)(H2O)2]·0.5H2O | V = 1664.63 (15) Å3 |
Mr = 430.01 | Z = 4 |
Orthorhombic, Ima2 | Mo Kα radiation |
a = 16.3724 (6) Å | µ = 1.23 mm−1 |
b = 7.1673 (4) Å | T = 100 K |
c = 14.1857 (8) Å | 0.30 × 0.30 × 0.20 mm |
Bruker SMART APEXII CCD area-detector diffractometer | 2424 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) | 2353 reflections with I > 2σ(I) |
Tmin = 0.710, Tmax = 0.792 | Rint = 0.022 |
10153 measured reflections |
R[F2 > 2σ(F2)] = 0.028 | H-atom parameters constrained |
wR(F2) = 0.073 | Δρmax = 0.44 e Å−3 |
S = 1.00 | Δρmin = −0.24 e Å−3 |
2424 reflections | Absolute structure: Flack (1983), 1113 Friedel pairs |
132 parameters | Absolute structure parameter: 0.412 (17) |
1 restraint |
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) | |
N1 | 0.59831 (9) | 0.2336 (2) | 0.13471 (12) | 0.0224 (3) | |
H1A | 0.5517 | 0.2517 | 0.1007 | 0.027* | |
H1B | 0.6023 | 0.3068 | 0.1862 | 0.027* | |
H1C | 0.5982 | 0.1168 | 0.1618 | 0.027* | |
C7 | 0.67406 (11) | 0.2598 (3) | 0.07757 (14) | 0.0223 (4) | |
H7A | 0.6754 | 0.3883 | 0.0521 | 0.027* | |
H7B | 0.6737 | 0.1719 | 0.0237 | 0.027* | |
C8 | 0.7500 | 0.2259 (4) | 0.1374 (2) | 0.0227 (4) | |
H8A | 0.7500 | 0.0960 | 0.1611 | 0.027* | |
H8B | 0.7500 | 0.3113 | 0.1922 | 0.027* | |
Ni1 | 0.5000 | 0.5000 | 0.35324 (4) | 0.01460 (8) | |
O1 | 0.40867 (9) | 0.4393 (2) | 0.44765 (10) | 0.0196 (3) | |
O2 | 0.46016 (8) | 0.19013 (19) | 0.52250 (10) | 0.0223 (3) | |
O3 | 0.41573 (8) | 0.0581 (2) | 0.74825 (10) | 0.0186 (3) | |
O4 | 0.43957 (8) | 0.36127 (18) | 0.71826 (10) | 0.0217 (2) | |
O5 | 0.54310 (7) | 0.22702 (15) | 0.35648 (11) | 0.0198 (2) | |
H5A | 0.5196 | 0.1739 | 0.3058 | 0.024* | |
H5B | 0.5204 | 0.1936 | 0.4118 | 0.024* | |
C1 | 0.2500 | 0.3097 (4) | 0.50968 (18) | 0.0180 (5) | |
H1 | 0.2500 | 0.3499 | 0.4459 | 0.022* | |
C2 | 0.32398 (11) | 0.2805 (3) | 0.55610 (13) | 0.0166 (3) | |
C3 | 0.32397 (11) | 0.2229 (2) | 0.65041 (13) | 0.0164 (3) | |
C4 | 0.2500 | 0.1941 (4) | 0.69672 (17) | 0.0161 (4) | |
H4 | 0.2500 | 0.1544 | 0.7606 | 0.019* | |
C5 | 0.40460 (11) | 0.3053 (3) | 0.50457 (12) | 0.0179 (3) | |
C6 | 0.40005 (11) | 0.2128 (2) | 0.70882 (13) | 0.0162 (3) | |
O6 | 0.7040 (7) | 0.0338 (19) | 0.3588 (14) | 0.088 (4) | 0.25 |
H6A | 0.7500 | −0.0326 | 0.3312 | 0.105* | 0.50 |
H6B | 0.6575 | −0.0252 | 0.3298 | 0.105* | 0.25 |
U11 | U22 | U33 | U12 | U13 | U23 | |
N1 | 0.0173 (6) | 0.0238 (7) | 0.0261 (7) | −0.0001 (5) | 0.0008 (5) | −0.0031 (6) |
C7 | 0.0207 (7) | 0.0201 (8) | 0.0261 (9) | −0.0002 (6) | 0.0001 (6) | −0.0003 (7) |
C8 | 0.0197 (10) | 0.0217 (11) | 0.0266 (11) | 0.000 | 0.000 | −0.0006 (9) |
Ni1 | 0.01386 (12) | 0.01624 (12) | 0.01370 (12) | −0.00143 (8) | 0.000 | 0.000 |
O1 | 0.0189 (6) | 0.0204 (6) | 0.0194 (6) | 0.0014 (5) | 0.0036 (5) | 0.0037 (5) |
O2 | 0.0193 (6) | 0.0244 (6) | 0.0233 (6) | 0.0033 (5) | 0.0031 (5) | 0.0027 (5) |
O3 | 0.0186 (6) | 0.0191 (6) | 0.0181 (6) | 0.0010 (5) | −0.0030 (5) | 0.0009 (5) |
O4 | 0.0202 (5) | 0.0209 (6) | 0.0240 (6) | −0.0022 (5) | −0.0049 (5) | 0.0026 (5) |
O5 | 0.0211 (5) | 0.0205 (5) | 0.0177 (5) | −0.0003 (4) | −0.0020 (6) | −0.0010 (5) |
C1 | 0.0179 (11) | 0.0218 (11) | 0.0145 (11) | 0.000 | 0.000 | 0.0021 (9) |
C2 | 0.0160 (7) | 0.0181 (8) | 0.0157 (8) | −0.0012 (6) | 0.0027 (7) | 0.0021 (6) |
C3 | 0.0146 (7) | 0.0164 (7) | 0.0181 (8) | −0.0006 (6) | 0.0001 (6) | −0.0002 (6) |
C4 | 0.0156 (10) | 0.0151 (10) | 0.0175 (12) | 0.000 | 0.000 | 0.0009 (8) |
C5 | 0.0154 (7) | 0.0210 (8) | 0.0173 (8) | −0.0020 (6) | 0.0014 (6) | −0.0016 (6) |
C6 | 0.0144 (7) | 0.0199 (8) | 0.0144 (7) | 0.0010 (6) | 0.0013 (6) | 0.0005 (6) |
O6 | 0.071 (6) | 0.137 (10) | 0.055 (6) | 0.048 (6) | −0.004 (8) | −0.008 (8) |
N1—C7 | 1.493 (2) | O2—C5 | 1.254 (2) |
N1—H1A | 0.9121 | O3—C6 | 1.268 (2) |
N1—H1B | 0.9011 | O4—C6 | 1.253 (2) |
N1—H1C | 0.9210 | O5—H5A | 0.9000 |
C7—C8 | 1.525 (3) | O5—H5B | 0.9011 |
C7—H7A | 0.9900 | C1—C2 | 1.394 (2) |
C7—H7B | 0.9900 | C1—H1 | 0.9500 |
C8—C7i | 1.525 (3) | C2—C3 | 1.400 (2) |
C8—H8A | 0.9900 | C2—C5 | 1.519 (3) |
C8—H8B | 0.9900 | C3—C4 | 1.393 (2) |
Ni1—O1 | 2.0540 (15) | C3—C6 | 1.498 (3) |
Ni1—O3ii | 2.0724 (14) | C4—H4 | 0.9500 |
Ni1—O5 | 2.0804 (11) | O6—H6A | 0.9729 |
O1—C5 | 1.257 (2) | O6—H6B | 0.9631 |
C7—N1—H1A | 112.9 | O5iii—Ni1—O5 | 177.46 (10) |
C7—N1—H1B | 107.8 | C5—O1—Ni1 | 128.29 (13) |
H1A—N1—H1B | 114.0 | C6—O3—Ni1v | 128.88 (12) |
C7—N1—H1C | 110.0 | Ni1—O5—H5A | 103.6 |
H1A—N1—H1C | 110.4 | Ni1—O5—H5B | 97.4 |
H1B—N1—H1C | 101.0 | H5A—O5—H5B | 114.0 |
N1—C7—C8 | 110.80 (16) | C2vi—C1—C2 | 120.6 (2) |
N1—C7—H7A | 109.5 | C2—C1—H1 | 119.7 |
C8—C7—H7A | 109.5 | C1—C2—C3 | 119.7 (2) |
N1—C7—H7B | 109.5 | C1—C2—C5 | 120.65 (17) |
C8—C7—H7B | 109.5 | C3—C2—C5 | 119.63 (19) |
H7A—C7—H7B | 108.1 | C4—C3—C2 | 119.6 (2) |
C7—C8—C7i | 109.3 (2) | C4—C3—C6 | 117.06 (17) |
C7—C8—H8A | 109.8 | C2—C3—C6 | 122.88 (19) |
C7—C8—H8B | 109.8 | C3vi—C4—C3 | 120.8 (2) |
H8A—C8—H8B | 108.3 | C3—C4—H4 | 119.6 |
O1iii—Ni1—O1 | 98.61 (9) | O2—C5—O1 | 126.49 (17) |
O1—Ni1—O3ii | 86.64 (5) | O2—C5—C2 | 117.11 (16) |
O1—Ni1—O3iv | 174.74 (7) | O1—C5—C2 | 116.40 (17) |
O3ii—Ni1—O3iv | 88.12 (8) | O4—C6—O3 | 126.22 (17) |
O1—Ni1—O5iii | 86.44 (6) | O4—C6—C3 | 116.58 (16) |
O1—Ni1—O5 | 91.91 (6) | O3—C6—C3 | 117.07 (16) |
O3ii—Ni1—O5 | 93.02 (6) | H6A—O6—H6B | 103.0 |
O3iv—Ni1—O5 | 88.81 (6) | ||
N1—C7—C8—C7i | −178.27 (13) | Ni1—O1—C5—O2 | 8.0 (3) |
O1iii—Ni1—O1—C5 | −66.36 (16) | Ni1—O1—C5—C2 | −171.57 (12) |
O3ii—Ni1—O1—C5 | 113.24 (18) | C1—C2—C5—O2 | −140.7 (2) |
O5iii—Ni1—O1—C5 | −157.75 (17) | C3—C2—C5—O2 | 37.6 (2) |
O5—Ni1—O1—C5 | 20.32 (17) | C1—C2—C5—O1 | 39.0 (3) |
C2vi—C1—C2—C3 | −0.6 (4) | C3—C2—C5—O1 | −142.72 (16) |
C2vi—C1—C2—C5 | 177.70 (17) | Ni1v—O3—C6—O4 | 8.7 (3) |
C1—C2—C3—C4 | 0.5 (2) | Ni1v—O3—C6—C3 | −166.96 (12) |
C5—C2—C3—C4 | −177.8 (2) | C4—C3—C6—O4 | −113.8 (2) |
C1—C2—C3—C6 | −171.7 (2) | C2—C3—C6—O4 | 58.6 (2) |
C5—C2—C3—C6 | 10.0 (2) | C4—C3—C6—O3 | 62.3 (2) |
C2—C3—C4—C3vi | −0.3 (3) | C2—C3—C6—O3 | −125.31 (17) |
C6—C3—C4—C3vi | 172.29 (15) |
Symmetry codes: (i) −x+3/2, y, z; (ii) x, −y+1/2, z−1/2; (iii) −x+1, −y+1, z; (iv) −x+1, y+1/2, z−1/2; (v) x, −y+1/2, z+1/2; (vi) −x+1/2, y, z. |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1A···O2ii | 0.91 | 1.91 | 2.819 (2) | 174 |
N1—H1B···O3iv | 0.90 | 2.03 | 2.838 (2) | 149 |
N1—H1C···O4vii | 0.92 | 2.09 | 2.985 (2) | 163 |
O5—H5A···O4ii | 0.90 | 1.82 | 2.668 (2) | 156 |
O5—H5B···O2 | 0.90 | 1.85 | 2.731 (2) | 164 |
O6—H6B···O4vii | 0.96 | 2.39 | 3.321 (3) | 164 |
C7—H7A···Cg(C1-C4/C2i/C3i)viii | 0.99 | 2.97 | 3.757 (2) | 137 |
C8—H8A···Cg(C1-C4/C2i/C3i)ix | 0.99 | 2.60 | 3.433 (2) | 142 |
Symmetry codes: (ii) x, −y+1/2, z−1/2; (iv) −x+1, y+1/2, z−1/2; (vii) −x+1, y−1/2, z−1/2; (viii) x+1/2, y+1/2, z−1/2; (ix) x+1/2, y−1/2, z−1/2. |
Experimental details
Crystal data | |
Chemical formula | (C3H12N2)[Ni(C10H2O8)(H2O)2]·0.5H2O |
Mr | 430.01 |
Crystal system, space group | Orthorhombic, Ima2 |
Temperature (K) | 100 |
a, b, c (Å) | 16.3724 (6), 7.1673 (4), 14.1857 (8) |
V (Å3) | 1664.63 (15) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 1.23 |
Crystal size (mm) | 0.30 × 0.30 × 0.20 |
Data collection | |
Diffractometer | Bruker SMART APEXII CCD area-detector |
Absorption correction | Multi-scan (SADABS; Sheldrick, 2003) |
Tmin, Tmax | 0.710, 0.792 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 10153, 2424, 2353 |
Rint | 0.022 |
(sin θ/λ)max (Å−1) | 0.704 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.028, 0.073, 1.00 |
No. of reflections | 2424 |
No. of parameters | 132 |
No. of restraints | 1 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.44, −0.24 |
Absolute structure | Flack (1983), 1113 Friedel pairs |
Absolute structure parameter | 0.412 (17) |
Computer programs: APEX2 (Bruker, 2005), SAINT-Plus (Bruker, 2001), SAINT-Plus, SHELXTL (Sheldrick, 2001), SHELXTL.
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1A···O2i | 0.91 | 1.91 | 2.819 (2) | 174 |
N1—H1B···O3ii | 0.90 | 2.03 | 2.838 (2) | 149 |
N1—H1C···O4iii | 0.92 | 2.09 | 2.985 (2) | 163 |
O5—H5A···O4i | 0.90 | 1.82 | 2.668 (2) | 156 |
O5—H5B···O2 | 0.90 | 1.85 | 2.731 (2) | 164 |
O6—H6B···O4iii | 0.96 | 2.39 | 3.321 (3) | 164 |
C7—H7A···Cg(C1-C4/C2i/C3i)iv | 0.99 | 2.97 | 3.757 (2) | 137 |
C8—H8A···Cg(C1-C4/C2i/C3i)v | 0.99 | 2.60 | 3.433 (2) | 142 |
Symmetry codes: (i) x, −y+1/2, z−1/2; (ii) −x+1, y+1/2, z−1/2; (iii) −x+1, y−1/2, z−1/2; (iv) x+1/2, y+1/2, z−1/2; (v) x+1/2, y−1/2, z−1/2. |
Just as there is a field of molecular chemistry based on the covalent bond, there is a field of supramolecular chemistry, the chemistry of molecular assemblies and intermolecular interactions. The importance of weak hydrogen bonds in the context of crystal engineering, molecular recognition and supramolecular chemistry have been well recognized in recent years. In this regard, we have reported cases in which proton transfer from pyridine-2,6-dicarboxylic acid (pydcH2) and benzene-1,2,4,5-tetracarboxylicacid (btcH4) to piperazine (pipz), propane-1,3-diamine and 1,10-phenanthroline (phen) resulted in the formation of novel self-assembled (pipzH2)(pydc), (pnH2)2(btc).2H2O (Aghabozorg, et al., 2007) and (phenH)4(btcH3)2(btcH2) (Aghabozorg, Ghadermazi & Gharamaleki, 2006) systems, respectively. The resulting compounds with some remaining sites as electron donors can coordinate to metallic ions (Aghabozorg, Ghasemikhah et al., 2006; Aghabozorg, Zabihi et al., 2006).
Here we report a new polymeric compound obtained from reaction of (pnH2)2(btc).2H2O with nickel(II) nitrate. The crystal structure of the title polymeric compound is shown in Fig. 1. The intermolecular hydrogen bond distances are listed in the Table. The negative charge of the anionic complex is neutralized by dicationic propane-1,3-diaminium species. According to the crystal structure of (I), the coordination around NiII is distorted octahedral. A considerable feature of the compound (I) is the presence of C—H···π stacking interactions between C—H groups of (pnH2)2+ cations and aromatic rings of (btc)4– fragments. The C—H···π distances (measured to the centre of phenyl ring) are 2.60 Å for C8—H8A···Cg1 and 2.97 Å for C7—H7A···Cg1 with the angles of 142° and 137°, respectively [Cg1 is a centroid of C1—C4/C2i/C3i; symmetry code: (i) 1/2 + x, -1/2 + y, -1/2 + z]. The most important features of the crystal structure of (I) is a number of O—H···O, N—H···O and C—H···O hydrogen bonds between (pnH2)2+ and [Ni(H2O)2(btc)]2– fragments and uncoordinated water molecules with D···A distances ranging from 2.668 (2) Å to 3.242 (2) Å (Table). Ion pairing, C—H···π stacking and van der Waals forces are also effective in the stabilization of the crystal structure, resulting in the formation of an interesting supramolecular structure (Fig. 2).