catena-Poly[[[diaqua­nickel(II)]-μ-pyridine-2,4-dicarboxyl­ato-[tetraaqua­nickel(II)]-μ-pyridine-2,4-dicarboxyl­ato] dihydrate]

The asymmetric unit of the title coordination polymer, {[Ni₂(C₇H₃O₄N)₂(H₂O)₆]·2H₂O}_n, contains two crystallographically distinct Ni^II cations, located on inversion centres. One of the Ni ions exists in an octa­hedral coordination environment formed by two water mol­ecules and two pyridine­carboxyl­ate dianions that serve as N,O-donors. The other Ni ion is coordinated by four water mol­ecules and two monodentate pyridine­carboxyl­ate dianions with an octa­hedral geometry. The deprotonated pyridine-2,4-dicarboxylic acid (pdc²⁻) ligand bridges Ni^II ions to form the one-dimensional coordination polymer. Extensive hydrogen bonding helps to stabilize the crystal structure.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.005 Å
• R factor = 0.036
• wR factor = 0.092
• Data-to-parameter ratio = 11.8

checkCIF/PLATON results

No syntax errors found



Alert level B
            Crystal system given = triclinic
PLAT417_ALERT_2_B Short Inter D-H..H-D       H22B   ..  H23B    ..       1.98 Ang.
PLAT417_ALERT_2_B Short Inter D-H..H-D       H31B   ..  H31B    ..       1.80 Ang.

Alert level C
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor ....       2.35
PLAT369_ALERT_2_C Long   C(sp2)-C(sp2) Bond  C2     -   C5     ...       1.53 Ang.

Alert level G
PLAT794_ALERT_5_G Check Predicted Bond Valency for Ni1         (2)       2.03
PLAT794_ALERT_5_G Check Predicted Bond Valency for Ni2         (2)       2.04

   0 ALERT level A = In general: serious problem
   2 ALERT level B = Potentially serious problem
   2 ALERT level C = Check and explain
   2 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   4 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   2 ALERT type 5 Informative message, check

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S1. Comment

The use of multifunctional organic ligands such as 4,4'-bipyridine and 1,4-benzenedicarboxylic acid have been recognized as an efficient N, O donors toward the assembly of metal-organic coordination polymers (Kitagawa et al., 2004; Yaghi et al., 2003). Herein we demonstrate that a multifunctional bridging ligand, pyridine-2,4-dicarboxylic acid, not only serves as an efficient N, O donor ligand, but also exhibits versatile non-covalent interactions (e.g. hydrogen-bonding and π-π stacking interactions) towards the assembly of supramolecular coordination networks.

The asymmetric unit of (I) (Fig. 1) consists of two crystallographically distinct Ni^II cations, and both of the Ni^II ions exist in crystallographic inversion centers with site occupation factor of 0.5. The Ni1 ion exists in an octahedral coordination environment that is coordinated by two water molecules, and chelated by two pyridinecarboxylate groups that serve as N, O donors. The Ni1—O distances are 2.054 (3) Å and 2.099 (3) Å, and Ni—N distance is 2.063 (3) Å. The Ni2 ion is coordinated by four water molecules as well as two monodentate carboxylate groups to form an octahedral coordination environment. The Ni2—O distances range from 2.039 (3) to 2.074 (3) Å. The asymmetric unit consists of one deprotonated pyridine-2,4-dicarboxylic acid (H₂pdc) ligand. The observation of symmetrical carbon–oxygen bond lengths of 1.246 (4)/1.269 (4) Å and 1.245 (5)/1.249 (5) Å of the carboxyl groups reveals that the H₂pdc ligand is deprotonated to become pdc^2- anion. One lattice water molecule is also revealed from the difference Fourier map. Therefore, the formula of (I) become [Ni(C₇H₃O₄N)(H₂O)₃.H₂O]_n. The Niⁱⁱ cations are connected by the pdc^2- ligands to form one-dimensional chains (Fig. 2). There are π-π stacking interactions of the parallel 1-D chains. The distance between the pyridinedicarboxylate ligands of the neighboring parallel chains is about 3.23 Å. These 1-D chains also engage hydrogen-bonding interactions among themselves as well as lattice water molecules to result in a three-dimensional supramolecular network.

Related literature

For related literature, see: Kitagawa et al. (2004); Yaghi et al. (2003).

S2. Experimental

All reagents and solvents were used as obtained without further purification. Ni(NO₃)₂.6H₂O (1.0 mmol), pyridine-2,4-dicarboxylic acid (1.0 mmol) were dissolved in 5 ml benzyl alcohol and 5 ml distilled water. The mixture was sealed in a Teflon-lined stainless steel vessel and held at 413 K for 96 h. The vessel was gradually cooled to room temperature, and green crystals of (I) suitable for crystallographic analysis were obtained.

S3. Refinement

The C-bound H atoms were placed in calculated positions (C—H = 0.93 Å) and refined in the riding-model approximation with Uiso(H) = 1.2 Ueq(C). Water H atoms were located in a difference Fourier map, and refined as riding model with O—H distances range from 0.82 to 0.84 Å, and with Uiso(H) = 1.5Ueq(O). Due to the uncertainty in the assignment of one of the H atom (H31B) of the slightly disordered lattice water molecule (O31) from the difference Fourier map, its position is only approximate. No attempt was made to resolve the disordered nature of the lattice water molecule (O31). Diffraction data with 2θ angle higher than 50° were not collected due to the weakly diffracted crystal sample of (I).

Computing details

Data collection: XSCANS (Bruker, 1991); 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: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures

	Fig. 1. The asymmetric unit, expanded to show the complete coordination of the Ni^ii cations, with displacement ellipsoids drawn at the 50% probability level. [Symmetry codes: (i) 1 - x, -y, 1 - z; (ii) -x, -2 - y, -z].
	Fig. 2. Solid-state packing diagram of the one-dimensional coordination polymer of (I).

catena-Poly[[[diaquanickel(II)]-µ-pyridine-2,4-dicarboxylato- [tetraaquanickel(II)]-µ-pyridine-2,4-dicarboxylato] dihydrate]

Crystal data

[Ni2(C7H3O4N)2(H2O)6]·2H2O	Z = 1
Mr = 591.76	F(000) = 304
Triclinic, P1	Dx = 1.836 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 5.2115 (12) Å	Cell parameters from 23 reflections
b = 8.4001 (18) Å	θ = 8.1–12.5°
c = 13.107 (3) Å	µ = 1.85 mm^−1
α = 105.130 (17)°	T = 298 K
β = 95.953 (18)°	Block, green
γ = 101.584 (17)°	0.25 × 0.15 × 0.10 mm
V = 535.2 (2) Å^3

Data collection

Bruker P4 diffractometer	1354 reflections with I > 2σ(I)
Radiation source: sealed tube	Rint = 0.032
Graphite monochromator	θmax = 25.0°, θmin = 2.5°
2θ/ω scans	h = 0→6
Absorption correction: ψ scan (North et al., 1968)	k = −9→9
Tmin = 0.706, Tmax = 0.825	l = −14→14
2075 measured reflections	3 standard reflections every 97 reflections
1854 independent reflections	intensity decay: 1.0%

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	H-atom parameters constrained
R[F^2 > 2σ(F^2)] = 0.036	w = 1/[σ^2(Fo^2) + (0.0407P)^2 + 0.0365P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.092	(Δ/σ)max < 0.001
S = 1.01	Δρmax = 0.37 e Å^−3
1854 reflections	Δρmin = −0.35 e Å^−3
157 parameters

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.

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

	x	y	z	Uiso*/Ueq
Ni1	0.5	0	0.5	0.0203 (2)
Ni2	0	−1	0	0.0244 (2)
N1	0.4972 (6)	−0.2439 (3)	0.4134 (2)	0.0224 (7)
O1	0.1785 (5)	−0.0429 (3)	0.3831 (2)	0.0257 (6)
O2	−0.0586 (6)	−0.2348 (3)	0.2359 (2)	0.0313 (7)
O3	0.2226 (6)	−0.7857 (3)	0.1175 (2)	0.0345 (7)
O4	0.5387 (6)	−0.8362 (3)	0.2244 (2)	0.0394 (8)
O21	0.7520 (5)	0.1049 (3)	0.4072 (2)	0.0286 (6)
H21A	0.6818	0.1136	0.3489	0.043*
H21B	0.8732	0.0544	0.394	0.043*
O22	−0.2250 (6)	−0.8384 (3)	−0.0278 (2)	0.0380 (7)
H22A	−0.1825	−0.7389	0.009	0.057*
H22B	−0.3828	−0.869	−0.0589	0.057*
O23	0.2292 (5)	−0.9432 (3)	−0.1094 (2)	0.0308 (7)
H23A	0.1703	−0.8958	−0.1529	0.046*
H23B	0.2827	−1.0225	−0.1464	0.046*
O31	−0.2487 (8)	−0.5032 (4)	0.0507 (3)	0.0678 (11)
H31A	−0.2158	−0.4143	0.1023	0.102*
H31B	−0.158	−0.4738	0.0066	0.102*
C1	0.1279 (7)	−0.1862 (4)	0.3130 (3)	0.0216 (8)
C2	0.3949 (8)	−0.7462 (5)	0.1992 (3)	0.0262 (9)
C3	0.3027 (7)	−0.3048 (4)	0.3267 (3)	0.0205 (8)
C4	0.2634 (8)	−0.4659 (4)	0.2571 (3)	0.0245 (8)
H4	0.1278	−0.5048	0.1982	0.029*
C5	0.4299 (7)	−0.5695 (4)	0.2765 (3)	0.0229 (8)
C6	0.6267 (7)	−0.5059 (4)	0.3655 (3)	0.0243 (8)
H6	0.7405	−0.572	0.3808	0.029*
C7	0.6542 (8)	−0.3444 (4)	0.4317 (3)	0.0249 (8)
H7	0.7874	−0.3037	0.4915	0.03*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ni1	0.0228 (4)	0.0160 (3)	0.0175 (4)	0.0077 (3)	−0.0027 (3)	−0.0030 (3)
Ni2	0.0279 (4)	0.0193 (4)	0.0206 (4)	0.0088 (3)	−0.0037 (3)	−0.0032 (3)
N1	0.0257 (17)	0.0184 (15)	0.0213 (16)	0.0083 (13)	0.0008 (13)	0.0018 (12)
O1	0.0295 (15)	0.0183 (13)	0.0243 (14)	0.0105 (11)	−0.0031 (12)	−0.0035 (11)
O2	0.0352 (16)	0.0256 (14)	0.0266 (15)	0.0110 (12)	−0.0114 (13)	−0.0003 (12)
O3	0.0386 (17)	0.0243 (14)	0.0298 (16)	0.0104 (13)	−0.0100 (13)	−0.0067 (12)
O4	0.062 (2)	0.0324 (15)	0.0255 (15)	0.0318 (15)	−0.0015 (15)	−0.0012 (12)
O21	0.0296 (16)	0.0331 (15)	0.0248 (14)	0.0158 (12)	0.0013 (12)	0.0063 (12)
O22	0.0363 (17)	0.0236 (14)	0.0459 (18)	0.0116 (13)	−0.0092 (14)	−0.0013 (13)
O23	0.0411 (17)	0.0282 (14)	0.0257 (15)	0.0192 (13)	0.0039 (13)	0.0045 (11)
O31	0.087 (3)	0.0428 (19)	0.053 (2)	0.017 (2)	−0.013 (2)	−0.0136 (17)
C1	0.023 (2)	0.0219 (19)	0.0178 (19)	0.0067 (16)	−0.0017 (16)	0.0036 (15)
C2	0.032 (2)	0.024 (2)	0.022 (2)	0.0105 (18)	0.0044 (18)	0.0012 (16)
C3	0.0208 (19)	0.0184 (18)	0.0192 (18)	0.0050 (15)	−0.0008 (15)	0.0014 (14)
C4	0.026 (2)	0.022 (2)	0.0200 (18)	0.0080 (18)	−0.0057 (15)	−0.0029 (16)
C5	0.027 (2)	0.0190 (18)	0.0195 (18)	0.0068 (16)	0.0007 (16)	−0.0003 (15)
C6	0.026 (2)	0.0230 (19)	0.023 (2)	0.0110 (16)	−0.0021 (16)	0.0034 (15)
C7	0.026 (2)	0.0228 (19)	0.0189 (19)	0.0060 (16)	−0.0078 (16)	−0.0021 (15)

Geometric parameters (Å, º)

Ni1—O1	2.055 (3)	O21—H21A	0.8399
Ni1—O1^i	2.055 (3)	O21—H21B	0.8377
Ni1—N1	2.063 (3)	O22—H22A	0.8202
Ni1—N1^i	2.063 (3)	O22—H22B	0.8369
Ni1—O21	2.099 (3)	O23—H23A	0.8426
Ni1—O21^i	2.099 (3)	O23—H23B	0.8312
Ni2—O3^ii	2.074 (3)	O31—H31A	0.8395
Ni2—O3	2.074 (3)	O31—H31B	0.8387
Ni2—O22	2.039 (3)	C1—C3	1.510 (5)
Ni2—O22^ii	2.039 (3)	C2—C5	1.526 (5)
Ni2—O23	2.048 (3)	C3—C4	1.382 (5)
Ni2—O23^ii	2.048 (3)	C4—C5	1.396 (5)
N1—C7	1.335 (5)	C4—H4	0.93
N1—C3	1.353 (5)	C5—C6	1.380 (5)
O1—C1	1.268 (4)	C6—C7	1.377 (5)
O2—C1	1.247 (4)	C6—H6	0.93
O3—C2	1.249 (5)	C7—H7	0.93
O4—C2	1.245 (5)
O1—Ni1—O1^i	180.0000 (10)	C1—O1—Ni1	114.8 (2)
O1—Ni1—N1	80.69 (11)	C2—O3—Ni2	139.8 (3)
O1^i—Ni1—N1	99.31 (11)	Ni1—O21—H21A	117.6
O1—Ni1—N1^i	99.31 (11)	Ni1—O21—H21B	112.6
O1^i—Ni1—N1^i	80.69 (11)	H21A—O21—H21B	107.2
N1—Ni1—N1^i	180.00 (16)	Ni2—O22—H22A	119
O1—Ni1—O21	90.36 (11)	Ni2—O22—H22B	124.5
O1^i—Ni1—O21	89.64 (11)	H22A—O22—H22B	113.4
N1—Ni1—O21	91.84 (11)	Ni2—O23—H23A	118.4
N1^i—Ni1—O21	88.16 (11)	Ni2—O23—H23B	116.4
O1—Ni1—O21^i	89.64 (11)	H23A—O23—H23B	105.3
O1^i—Ni1—O21^i	90.36 (11)	H31A—O31—H31B	103
N1—Ni1—O21^i	88.16 (11)	O2—C1—O1	124.0 (3)
N1^i—Ni1—O21^i	91.84 (11)	O2—C1—C3	118.9 (3)
O21—Ni1—O21^i	180	O1—C1—C3	117.0 (3)
O22—Ni2—O22^ii	180.0000 (10)	O4—C2—O3	126.8 (3)
O22—Ni2—O23	90.28 (11)	O4—C2—C5	116.9 (3)
O22^ii—Ni2—O23	89.72 (11)	O3—C2—C5	116.3 (3)
O22—Ni2—O23^ii	89.72 (11)	N1—C3—C4	122.2 (3)
O22^ii—Ni2—O23^ii	90.28 (11)	N1—C3—C1	115.3 (3)
O23—Ni2—O23^ii	180	C4—C3—C1	122.5 (3)
O22—Ni2—O3^ii	96.62 (11)	C3—C4—C5	119.1 (3)
O22^ii—Ni2—O3^ii	83.38 (11)	C3—C4—H4	120.4
O23—Ni2—O3^ii	89.44 (12)	C5—C4—H4	120.4
O23^ii—Ni2—O3^ii	90.56 (12)	C6—C5—C4	118.0 (3)
O22—Ni2—O3	83.38 (11)	C6—C5—C2	121.9 (3)
O22^ii—Ni2—O3	96.62 (11)	C4—C5—C2	120.1 (3)
O23—Ni2—O3	90.56 (12)	C7—C6—C5	119.8 (3)
O23^ii—Ni2—O3	89.44 (11)	C7—C6—H6	120.1
O3^ii—Ni2—O3	180	C5—C6—H6	120.1
C7—N1—C3	118.2 (3)	N1—C7—C6	122.6 (3)
C7—N1—Ni1	129.6 (2)	N1—C7—H7	118.7
C3—N1—Ni1	112.2 (2)	C6—C7—H7	118.7

Symmetry codes: (i) −x+1, −y, −z+1; (ii) −x, −y−2, −z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O21—H21A···O4^iii	0.84	1.90	2.740 (4)	173
O21—H21B···O1^iv	0.84	1.93	2.763 (4)	172
O22—H22A···O31	0.82	2.02	2.767 (4)	151
O22—H22B···O23^v	0.84	1.98	2.807 (4)	171
O23—H23A···O2^vi	0.84	1.86	2.701 (4)	173
O23—H23B···O4^vii	0.83	1.82	2.644 (4)	168
O31—H31A···O2	0.84	1.96	2.775 (4)	164
O31—H31B···O31^vi	0.84	2.35	3.030 (8)	139

Symmetry codes: (iii) x, y+1, z; (iv) x+1, y, z; (v) x−1, y, z; (vi) −x, −y−1, −z; (vii) −x+1, −y−2, −z.