catena-Poly[bis­[(1,10-phenanthro­line)nickel(II)]-μ-3,6-dicarboxy­cyclo­hexane-1,2,4,5-tetra­carboxyl­ato]

In the title compound, [Ni₂(C₁₂H₈O₁₂)(C₁₂H₈N₂)₂]_n, the 3,6-dicarboxy­cyclo­hexane-1,2,4,5-tetra­carboxyl­ate (H₂chhc⁴⁻) anion has crystallographically imposed C₂ symmetry and bridges the six-coordinate Ni atoms to generate polymeric [Ni₂(H₂chhc)_2/2(C₁₂H₈N₂)₂] chains extending in the [010] direction. The coordination polymer chains are linked into a three-dimensional framework by O—H...O and C—H...O hydrogen bonds.

S1. Comment

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).

S2. Experimental

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).

S3. Refinement

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 U_iso(H) = 1.2U_eq(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].

Computing details

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.

Figures

	Fig. 1. A fragment of the one-dimensional ^1∞[Ni2(phen)2(H2chhc)2/2] polymeric chain. Displacement ellipsoids are drawn at the 45% probability level. H atoms have been omitted.
	Fig. 2. The two-dimensional supramolecular layer in (I) parallel to (101). Hydrogen bonds are indicated by dashed lines.
	Fig. 3. The packing of (I). Hydrogen bonds are indicated by dashed lines.

catena-Poly-[bis[(1,10-phenanthroline)nickel(II)]-µ- 3,6-dicarboxycyclohexane-1,2,4,5-tetracarboxylato]

Crystal data

[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) Å^3	0.31 × 0.22 × 0.11 mm
Z = 8

Data collection

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

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.036	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.087	w = 1/[σ^2(Fo^2) + (0.0381P)^2 + 3.2579P] where P = (Fo^2 + 2Fc^2)/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+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.38

Special details

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	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)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
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)

Geometric parameters (Å, º)

Ni—N1	2.050 (2)	C4—C12	1.415 (3)
Ni—N2	2.0561 (19)	C4—C5	1.437 (5)
Ni—O6^i	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—O5^i	2.1181 (16)	C6—H6	0.9300
Ni—C18^i	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—C14^ii	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—C17^ii	1.539 (4)
C3—C4	1.401 (5)	C17—H17	0.9800
C3—H3	0.9300	C18—Ni^iii	2.412 (2)
N1—Ni—N2	80.95 (8)	C8—C7—C6	124.5 (3)
N1—Ni—O6^i	162.99 (8)	C9—C8—C7	120.3 (3)
N2—Ni—O6^i	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)
O6^i—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)
O6^i—Ni—O2	94.66 (7)	N2—C10—H10	118.6
O1—Ni—O2	62.24 (6)	C9—C10—H10	118.6
N1—Ni—O5^i	101.13 (7)	N2—C11—C7	122.9 (2)
N2—Ni—O5^i	94.59 (7)	N2—C11—C12	116.6 (2)
O6^i—Ni—O5^i	62.75 (6)	C7—C11—C12	120.4 (2)
O1—Ni—O5^i	148.35 (6)	N1—C12—C4	122.7 (3)
O2—Ni—O5^i	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—C14^ii	109.91 (16)
C13—O2—Ni	88.86 (13)	C13—C14—C15	109.07 (17)
C16—O3—H3A	110 (2)	C14^ii—C14—C15	113.12 (14)
C18—O5—Ni^iii	87.13 (13)	C13—C14—H14	108.2
C18—O6—Ni^iii	89.08 (13)	C14^ii—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—C17^ii	109.10 (14)
C12—C4—C5	117.8 (3)	C18—C17—C15	109.46 (16)
C6—C5—C4	122.0 (3)	C17^ii—C17—C15	111.98 (14)
C6—C5—H5	119.0	C18—C17—H17	108.7
C4—C5—H5	119.0	C17^ii—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.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C6—H6···O4^iv	0.93	2.48	3.210 (4)	136
O3—H3A···O1^v	0.86 (4)	1.82 (3)	2.628 (2)	155 (4)
C10—H10···O6^v	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.