Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270106032495/gd3041sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270106032495/gd3041Isup2.hkl |
CCDC reference: 625668
The Ni(OH)2.xH2O precipitate deposited from dropwise addition of 1 M NaOH (3.0 ml) to a stirred aqueous solution of NiCl2·6H2O (0.24 g, 1.0 mmol, in 7.0 ml H2O), followed by separation by centrifugation and washing with distilled water several times until no detectable Cl− anions remained in the supernatant. Subsequently, the precipitate was added to a stirred aqueous solution of H6chhc (0.17 g, 0.50 mmol) and 1,10-phenanthroline monohydrate (0.20 g, 1.0 mmol) in water (20.0 ml). The resulting mixture was further stirred for ca 30 minutes and then filtered. The green filtrate was allowed to stand at room temperature. Slow evaporation for several days afforded green plate-like crystals (yield ca 20% based on the initial NiCl2·6H2O input).
Compound (I) is monoclinic; space group C2/c was assumed and comfirmed by the analysis. H atoms attached to C atoms were placed in calculated positions and refined using a riding model [C—H = 0.93 or 0.98 Å, and Uiso(H) = 1.2Ueq(C)], while the H atom on atom O3 was observed in a difference Fourier map and was refined freely [O—H = 0.86 (4) Å].
Data collection: XSCANS (Siemens, 1996); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1997); software used to prepare material for publication: SHELXTL.
[Ni2(C12H8O12)(C12H8N2)2] | F(000) = 1680 |
Mr = 411.01 | Dx = 1.692 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -C 2yc | Cell parameters from 25 reflections |
a = 22.018 (4) Å | θ = 10–25° |
b = 8.9600 (18) Å | µ = 1.24 mm−1 |
c = 16.371 (3) Å | T = 298 K |
β = 92.49 (3)° | Plate, green |
V = 3226.6 (11) Å3 | 0.31 × 0.22 × 0.11 mm |
Z = 8 |
Bruker P4 diffractometer | 2959 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.030 |
Graphite monochromator | θmax = 27.5°, θmin = 1.9° |
ω/2θ scans | h = −1→28 |
Absorption correction: ψ scan (North et al., 1968) | k = −1→11 |
Tmin = 0.727, Tmax = 0.872 | l = −21→21 |
4519 measured reflections | 3 standard reflections every 97 reflections |
3715 independent reflections | intensity decay: none |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.036 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.087 | w = 1/[σ2(Fo2) + (0.0381P)2 + 3.2579P] where P = (Fo2 + 2Fc2)/3 |
S = 1.01 | (Δ/σ)max = 0.001 |
3715 reflections | Δρmax = 0.34 e Å−3 |
250 parameters | Δρmin = −0.29 e Å−3 |
0 restraints | Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.38 |
[Ni2(C12H8O12)(C12H8N2)2] | V = 3226.6 (11) Å3 |
Mr = 411.01 | Z = 8 |
Monoclinic, C2/c | Mo Kα radiation |
a = 22.018 (4) Å | µ = 1.24 mm−1 |
b = 8.9600 (18) Å | T = 298 K |
c = 16.371 (3) Å | 0.31 × 0.22 × 0.11 mm |
β = 92.49 (3)° |
Bruker P4 diffractometer | 2959 reflections with I > 2σ(I) |
Absorption correction: ψ scan (North et al., 1968) | Rint = 0.030 |
Tmin = 0.727, Tmax = 0.872 | 3 standard reflections every 97 reflections |
4519 measured reflections | intensity decay: none |
3715 independent reflections |
R[F2 > 2σ(F2)] = 0.036 | 0 restraints |
wR(F2) = 0.087 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.01 | Δρmax = 0.34 e Å−3 |
3715 reflections | Δρmin = −0.29 e Å−3 |
250 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 | ||
Ni | 0.902824 (12) | 0.35453 (3) | 0.857256 (16) | 0.01903 (10) | |
N1 | 0.81335 (9) | 0.2954 (2) | 0.83859 (12) | 0.0295 (4) | |
N2 | 0.86862 (9) | 0.4467 (2) | 0.96070 (11) | 0.0255 (4) | |
O1 | 0.94713 (8) | 0.15587 (18) | 0.89271 (9) | 0.0281 (4) | |
O2 | 0.93194 (8) | 0.21155 (19) | 0.76394 (9) | 0.0279 (4) | |
O3 | 1.01924 (8) | −0.1440 (2) | 0.95146 (10) | 0.0364 (4) | |
O4 | 0.91851 (9) | −0.1705 (2) | 0.95658 (11) | 0.0421 (5) | |
O5 | 0.90510 (7) | −0.44072 (18) | 0.79280 (10) | 0.0256 (3) | |
O6 | 0.98354 (7) | −0.52381 (17) | 0.86585 (9) | 0.0246 (3) | |
C1 | 0.78741 (13) | 0.2137 (4) | 0.77850 (17) | 0.0433 (7) | |
H1 | 0.8120 | 0.1670 | 0.7414 | 0.052* | |
C2 | 0.72423 (15) | 0.1962 (5) | 0.7695 (2) | 0.0590 (10) | |
H2 | 0.7073 | 0.1388 | 0.7271 | 0.071* | |
C3 | 0.68809 (13) | 0.2636 (5) | 0.8231 (2) | 0.0597 (10) | |
H3 | 0.6461 | 0.2524 | 0.8173 | 0.072* | |
C4 | 0.71318 (12) | 0.3502 (4) | 0.88740 (19) | 0.0470 (7) | |
C5 | 0.67951 (13) | 0.4271 (5) | 0.9478 (2) | 0.0634 (10) | |
H5 | 0.6373 | 0.4221 | 0.9448 | 0.076* | |
C6 | 0.70726 (15) | 0.5060 (5) | 1.0085 (2) | 0.0628 (10) | |
H6 | 0.6839 | 0.5556 | 1.0460 | 0.075* | |
C7 | 0.77247 (13) | 0.5151 (4) | 1.01667 (18) | 0.0438 (7) | |
C8 | 0.80477 (16) | 0.5896 (4) | 1.08044 (19) | 0.0540 (8) | |
H8 | 0.7838 | 0.6394 | 1.1203 | 0.065* | |
C9 | 0.86665 (15) | 0.5892 (4) | 1.08413 (17) | 0.0473 (7) | |
H9 | 0.8882 | 0.6360 | 1.1270 | 0.057* | |
C10 | 0.89725 (12) | 0.5168 (3) | 1.02188 (15) | 0.0329 (6) | |
H10 | 0.9395 | 0.5183 | 1.0239 | 0.039* | |
C11 | 0.80676 (10) | 0.4441 (3) | 0.95836 (14) | 0.0294 (5) | |
C12 | 0.77736 (10) | 0.3608 (3) | 0.89305 (15) | 0.0319 (5) | |
C13 | 0.95634 (10) | 0.1295 (2) | 0.81794 (13) | 0.0220 (4) | |
C14 | 0.99478 (10) | −0.0044 (2) | 0.79603 (13) | 0.0204 (4) | |
H14 | 1.0344 | 0.0046 | 0.8253 | 0.024* | |
C15 | 0.96382 (9) | −0.1480 (2) | 0.82531 (13) | 0.0199 (4) | |
H15 | 0.9217 | −0.1493 | 0.8032 | 0.024* | |
C16 | 0.96322 (11) | −0.1532 (3) | 0.91831 (14) | 0.0250 (5) | |
C17 | 0.99619 (9) | −0.2900 (2) | 0.79650 (12) | 0.0191 (4) | |
H17 | 1.0365 | −0.2954 | 0.8241 | 0.023* | |
C18 | 0.95958 (9) | −0.4275 (2) | 0.81973 (12) | 0.0197 (4) | |
H3A | 1.0186 (17) | −0.148 (4) | 1.004 (2) | 0.071 (12)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Ni | 0.01956 (14) | 0.01605 (15) | 0.02151 (15) | −0.00066 (12) | 0.00102 (10) | −0.00012 (12) |
N1 | 0.0278 (10) | 0.0308 (11) | 0.0296 (10) | −0.0075 (9) | −0.0013 (8) | 0.0036 (9) |
N2 | 0.0251 (9) | 0.0258 (10) | 0.0258 (9) | 0.0004 (8) | 0.0028 (7) | −0.0001 (8) |
O1 | 0.0426 (9) | 0.0212 (8) | 0.0207 (7) | 0.0064 (7) | 0.0032 (7) | 0.0005 (7) |
O2 | 0.0374 (9) | 0.0242 (8) | 0.0222 (8) | 0.0071 (7) | 0.0018 (7) | 0.0009 (7) |
O3 | 0.0387 (10) | 0.0494 (12) | 0.0209 (8) | 0.0039 (9) | −0.0014 (7) | −0.0004 (9) |
O4 | 0.0444 (11) | 0.0453 (12) | 0.0381 (10) | −0.0014 (9) | 0.0201 (8) | 0.0016 (9) |
O5 | 0.0230 (8) | 0.0216 (8) | 0.0318 (8) | 0.0000 (7) | −0.0042 (6) | 0.0054 (7) |
O6 | 0.0240 (8) | 0.0190 (8) | 0.0305 (8) | −0.0014 (6) | −0.0031 (6) | 0.0064 (7) |
C1 | 0.0442 (15) | 0.0444 (17) | 0.0406 (14) | −0.0171 (14) | −0.0072 (12) | −0.0021 (13) |
C2 | 0.0505 (19) | 0.074 (2) | 0.0510 (18) | −0.0301 (18) | −0.0175 (15) | 0.0028 (18) |
C3 | 0.0263 (14) | 0.084 (3) | 0.068 (2) | −0.0197 (16) | −0.0137 (14) | 0.018 (2) |
C4 | 0.0237 (12) | 0.062 (2) | 0.0551 (17) | −0.0061 (14) | −0.0014 (12) | 0.0182 (16) |
C5 | 0.0231 (13) | 0.089 (3) | 0.079 (2) | 0.0087 (17) | 0.0141 (15) | 0.017 (2) |
C6 | 0.0384 (17) | 0.083 (3) | 0.069 (2) | 0.0192 (18) | 0.0263 (16) | 0.004 (2) |
C7 | 0.0395 (15) | 0.0490 (18) | 0.0444 (15) | 0.0088 (13) | 0.0177 (12) | 0.0030 (14) |
C8 | 0.065 (2) | 0.056 (2) | 0.0430 (16) | 0.0114 (17) | 0.0211 (15) | −0.0141 (16) |
C9 | 0.065 (2) | 0.0473 (17) | 0.0300 (13) | −0.0022 (16) | 0.0042 (13) | −0.0126 (13) |
C10 | 0.0336 (13) | 0.0355 (14) | 0.0293 (12) | 0.0011 (11) | −0.0019 (10) | −0.0018 (11) |
C11 | 0.0245 (11) | 0.0321 (14) | 0.0317 (12) | 0.0033 (10) | 0.0036 (9) | 0.0053 (11) |
C12 | 0.0218 (11) | 0.0368 (14) | 0.0370 (13) | −0.0031 (11) | −0.0004 (9) | 0.0073 (12) |
C13 | 0.0293 (11) | 0.0137 (10) | 0.0234 (10) | −0.0027 (9) | 0.0043 (9) | −0.0005 (9) |
C14 | 0.0239 (11) | 0.0163 (10) | 0.0210 (10) | −0.0005 (9) | 0.0026 (8) | −0.0009 (8) |
C15 | 0.0209 (10) | 0.0161 (10) | 0.0227 (10) | 0.0009 (9) | 0.0018 (8) | 0.0005 (9) |
C16 | 0.0326 (12) | 0.0155 (10) | 0.0273 (11) | 0.0017 (10) | 0.0052 (9) | 0.0010 (9) |
C17 | 0.0211 (10) | 0.0150 (10) | 0.0213 (10) | 0.0003 (8) | 0.0004 (8) | 0.0006 (9) |
C18 | 0.0217 (10) | 0.0174 (10) | 0.0202 (10) | −0.0003 (9) | 0.0035 (8) | −0.0022 (9) |
Ni—N1 | 2.050 (2) | C4—C12 | 1.415 (3) |
Ni—N2 | 2.0561 (19) | C4—C5 | 1.437 (5) |
Ni—O6i | 2.0843 (16) | C5—C6 | 1.346 (5) |
Ni—O1 | 2.0994 (17) | C5—H5 | 0.9300 |
Ni—O2 | 2.1146 (16) | C6—C7 | 1.438 (4) |
Ni—O5i | 2.1181 (16) | C6—H6 | 0.9300 |
Ni—C18i | 2.412 (2) | C7—C11 | 1.396 (4) |
Ni—C13 | 2.436 (2) | C7—C8 | 1.406 (5) |
N1—C1 | 1.334 (3) | C8—C9 | 1.361 (5) |
N1—C12 | 1.352 (3) | C8—H8 | 0.9300 |
N2—C10 | 1.319 (3) | C9—C10 | 1.405 (4) |
N2—C11 | 1.361 (3) | C9—H9 | 0.9300 |
O1—C13 | 1.272 (3) | C10—H10 | 0.9300 |
O2—C13 | 1.253 (3) | C11—C12 | 1.435 (4) |
O3—C16 | 1.328 (3) | C13—C14 | 1.520 (3) |
O3—H3A | 0.86 (4) | C14—C14ii | 1.534 (4) |
O4—C16 | 1.200 (3) | C14—C15 | 1.542 (3) |
O5—C18 | 1.265 (3) | C14—H14 | 0.9800 |
O6—C18 | 1.248 (3) | C15—C16 | 1.524 (3) |
C1—C2 | 1.401 (4) | C15—C17 | 1.542 (3) |
C1—H1 | 0.9300 | C15—H15 | 0.9800 |
C2—C3 | 1.352 (5) | C17—C18 | 1.530 (3) |
C2—H2 | 0.9300 | C17—C17ii | 1.539 (4) |
C3—C4 | 1.401 (5) | C17—H17 | 0.9800 |
C3—H3 | 0.9300 | C18—Niiii | 2.412 (2) |
N1—Ni—N2 | 80.95 (8) | C8—C7—C6 | 124.5 (3) |
N1—Ni—O6i | 162.99 (8) | C9—C8—C7 | 120.3 (3) |
N2—Ni—O6i | 94.36 (7) | C9—C8—H8 | 119.8 |
N1—Ni—O1 | 104.71 (8) | C7—C8—H8 | 119.8 |
N2—Ni—O1 | 107.17 (7) | C8—C9—C10 | 118.7 (3) |
O6i—Ni—O1 | 92.30 (7) | C8—C9—H9 | 120.7 |
N1—Ni—O2 | 93.17 (8) | C10—C9—H9 | 120.7 |
N2—Ni—O2 | 166.35 (7) | N2—C10—C9 | 122.8 (3) |
O6i—Ni—O2 | 94.66 (7) | N2—C10—H10 | 118.6 |
O1—Ni—O2 | 62.24 (6) | C9—C10—H10 | 118.6 |
N1—Ni—O5i | 101.13 (7) | N2—C11—C7 | 122.9 (2) |
N2—Ni—O5i | 94.59 (7) | N2—C11—C12 | 116.6 (2) |
O6i—Ni—O5i | 62.75 (6) | C7—C11—C12 | 120.4 (2) |
O1—Ni—O5i | 148.35 (6) | N1—C12—C4 | 122.7 (3) |
O2—Ni—O5i | 98.65 (6) | N1—C12—C11 | 117.3 (2) |
N1—Ni—C13 | 102.66 (8) | C4—C12—C11 | 120.0 (2) |
C1—N1—C12 | 118.7 (2) | O2—C13—O1 | 119.2 (2) |
C1—N1—Ni | 129.01 (19) | O2—C13—C14 | 121.52 (19) |
C12—N1—Ni | 112.12 (16) | O1—C13—C14 | 119.19 (19) |
C10—N2—C11 | 118.3 (2) | O2—C13—Ni | 60.20 (11) |
C10—N2—Ni | 129.54 (17) | O1—C13—Ni | 59.50 (11) |
C11—N2—Ni | 111.83 (16) | C14—C13—Ni | 175.05 (16) |
C13—O1—Ni | 89.04 (13) | C13—C14—C14ii | 109.91 (16) |
C13—O2—Ni | 88.86 (13) | C13—C14—C15 | 109.07 (17) |
C16—O3—H3A | 110 (2) | C14ii—C14—C15 | 113.12 (14) |
C18—O5—Niiii | 87.13 (13) | C13—C14—H14 | 108.2 |
C18—O6—Niiii | 89.08 (13) | C14ii—C14—H14 | 108.2 |
N1—C1—C2 | 122.0 (3) | C15—C14—H14 | 108.2 |
N1—C1—H1 | 119.0 | C16—C15—C14 | 111.08 (18) |
C2—C1—H1 | 119.0 | C16—C15—C17 | 107.71 (17) |
C3—C2—C1 | 119.5 (3) | C14—C15—C17 | 112.13 (16) |
C3—C2—H2 | 120.3 | C16—C15—H15 | 108.6 |
C1—C2—H2 | 120.3 | C14—C15—H15 | 108.6 |
C2—C3—C4 | 120.7 (3) | C17—C15—H15 | 108.6 |
C2—C3—H3 | 119.7 | O4—C16—O3 | 124.3 (2) |
C4—C3—H3 | 119.7 | O4—C16—C15 | 124.7 (2) |
C3—C4—C12 | 116.5 (3) | O3—C16—C15 | 110.98 (19) |
C3—C4—C5 | 125.7 (3) | C18—C17—C17ii | 109.10 (14) |
C12—C4—C5 | 117.8 (3) | C18—C17—C15 | 109.46 (16) |
C6—C5—C4 | 122.0 (3) | C17ii—C17—C15 | 111.98 (14) |
C6—C5—H5 | 119.0 | C18—C17—H17 | 108.7 |
C4—C5—H5 | 119.0 | C17ii—C17—H17 | 108.7 |
C5—C6—C7 | 121.1 (3) | C15—C17—H17 | 108.7 |
C5—C6—H6 | 119.4 | O6—C18—O5 | 121.0 (2) |
C7—C6—H6 | 119.4 | O6—C18—C17 | 119.60 (19) |
C11—C7—C8 | 116.9 (3) | O5—C18—C17 | 119.37 (19) |
C11—C7—C6 | 118.6 (3) |
Symmetry codes: (i) x, y+1, z; (ii) −x+2, y, −z+3/2; (iii) x, y−1, z. |
D—H···A | D—H | H···A | D···A | D—H···A |
C6—H6···O4iv | 0.93 | 2.48 | 3.210 (4) | 136 |
O3—H3A···O1v | 0.86 (4) | 1.82 (3) | 2.628 (2) | 155 (4) |
C10—H10···O6v | 0.93 | 2.42 | 3.139 (3) | 134 |
Symmetry codes: (iv) −x+3/2, −y+1/2, −z+2; (v) −x+2, −y, −z+2. |
Experimental details
Crystal data | |
Chemical formula | [Ni2(C12H8O12)(C12H8N2)2] |
Mr | 411.01 |
Crystal system, space group | Monoclinic, C2/c |
Temperature (K) | 298 |
a, b, c (Å) | 22.018 (4), 8.9600 (18), 16.371 (3) |
β (°) | 92.49 (3) |
V (Å3) | 3226.6 (11) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 1.24 |
Crystal size (mm) | 0.31 × 0.22 × 0.11 |
Data collection | |
Diffractometer | Bruker P4 diffractometer |
Absorption correction | ψ scan (North et al., 1968) |
Tmin, Tmax | 0.727, 0.872 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 4519, 3715, 2959 |
Rint | 0.030 |
(sin θ/λ)max (Å−1) | 0.650 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.036, 0.087, 1.01 |
No. of reflections | 3715 |
No. of parameters | 250 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.34, −0.29 |
Computer programs: XSCANS (Siemens, 1996), XSCANS, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), SHELXTL (Bruker, 1997), SHELXTL.
D—H···A | D—H | H···A | D···A | D—H···A |
C6—H6···O4i | 0.93 | 2.48 | 3.210 (4) | 136 |
O3—H3A···O1ii | 0.86 (4) | 1.82 (3) | 2.628 (2) | 155 (4) |
C10—H10···O6ii | 0.93 | 2.42 | 3.139 (3) | 134 |
Symmetry codes: (i) −x+3/2, −y+1/2, −z+2; (ii) −x+2, −y, −z+2. |
In recent years, metal-organic coordination polymers have been attracting more and more attention owing to their potential application in many fields (Moulton & Zaworotko, 2001; MacGillivray et al., 1998). It is well known that the aromatic carboxylic acids, such as terephthalic acid (Chen et al., 2003), benzene-1,3,5-tricarboxylic acid (Chui et al., 1999), benzene-1,2,4,5- tetracarboxylic acid (Murugavel et al., 2002) and mellitic acid (Ranganathan et al., 2001), exhibit a variety of bridging modes and coordination fashions and have been widely used to construct coordination polymers with specific network topologies and interesting properties. Because of their greater conformational flexibility, the aliphatic carboxylic acids have also aroused much attention in the field of synthesis of coordination polymers (Zheng et al., 2004; Zheng & Kong, 2002). Comparably few naphthenic polycarboxylic acids have been explored as ligands for the construction of coordination polymers (Bi et al., 2003; Myunghyun et al., 2003; Kil & Myunghyun, 2001). In the present contribution, we report a new nickel coordination polymer, [Ni2(C12H8N2)2(H2chhc)], (I), resulting from self-assembly of Ni2+ ions, phenanthroline (phen) and a tetra-anion derived from 1,2,3,4,5,6-cyclohexanehexacarboxylic acid (H6chhc).
The asymmetric unit of the title compound consists of one Ni2+ cation, one phen ligand and one-half of a H2chhc4− anion lying across a twofold rotation axis. The Ni atoms are each in a distorted octahedral environment defined by four O atoms of two carboxylate groups from different H2chhc4− anions and two N atoms of one phen ligand. The Ni—N bond distances are 2.050 (2) Å and 2.056 (2) Å, respectively, and the Ni—O bond distances vary from 2.084 (2) Å to 2.118 (2) Å. Obviously, such bonding values fall in the normal region (Zheng et al., 2002). The H2chhc4− anions display a stable chair conformation with the two opposite carboxyl groups and four carboxylate groups orientating equatorially, similar to those reported in the literature (Bi et al., 2003; Myunghyun et al., 2003; Kil & Myunghyun, 2001). Each carboxylate group of the H2chhc4− anion chelates one Ni atom; as a result, the H2chhc4− anions are each coordinated to four [Ni(phen)]2+ units, leading to polymeric chains formulated as 1∞[Ni2(C12H8N2)2/2] running along the [010] direction with the phen ligands exo-orientated, as shown in Fig. 1. On the basis of the interchain C—H···O hydrogen bonds (Table 1) these chains are assembled into layers parallel to (101) (Fig. 2). The layers are further connected to form a three-dimensional framework via strong interlayer O—H···O hydrogen bonds and weak interchain C—H···O hydrogen bonds. The H2chhc4− anions exhibit the normal C—O bond distances (Kil & Myunghyun, 2001).