catena-Poly[[[bis­[aqua­nickel(II)]bis­(μ-pyridine-2,6-dicarboxyl­ato N-oxide)]-μ-1,2-di-4-pyridylethane] tetra­hydrate]

In the title compound, {[Ni₂(C₇H₃NO₅)₂(C₁₂H₁₂N₂)(H₂O)₂]·4H₂O}_n, two Ni^II ions, two tridentate pyridine-2,6-dicarboxyl­ate N-oxide ligands and two coordinated water mol­ecules form centrosymmetric dinuclear units, which are further bridged by centrosymmetric 1,2-di-4-pyridylethane ligands into polymeric chains along [210]. Each Ni^II ion has a distorted square-pyramidal environment, with the basal plane formed by three O [Ni—O = 1.9290 (16)–1.9588 (10) Å] and one N [Ni—N = 1.9828 (18) Å] atoms and the apical position occupied by the water mol­ecule [Ni—O = 2.2643 (11) Å]. The water mol­ecules are involved in the formation of O—H...O hydrogen bonds.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.028
• wR factor = 0.063
• Data-to-parameter ratio = 14.3

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT232_ALERT_2_B Hirshfeld Test Diff (M-X)  Ni1    --  O1W     ..      11.02 su
PLAT417_ALERT_2_B Short Inter D-H..H-D       H4W    ..  H5W     ..       2.06 Ang.

Alert level C
PLAT232_ALERT_2_C Hirshfeld Test Diff (M-X)  Ni1    --  O1      ..       7.01 su
PLAT232_ALERT_2_C Hirshfeld Test Diff (M-X)  Ni1    --  O3      ..       6.51 su
PLAT232_ALERT_2_C Hirshfeld Test Diff (M-X)  Ni1    --  N1      ..       5.09 su
PLAT232_ALERT_2_C Hirshfeld Test Diff (M-X)  Ni1    --  O4_a    ..       7.00 su
PLAT041_ALERT_1_C Calc. and Rep. SumFormula Strings    Differ ....          ?
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?
PLAT045_ALERT_1_C Calculated and Reported Z Differ by ............       2.00 Ratio
PLAT154_ALERT_1_C The su's on the Cell Angles are Equal  (x 10000)        200 Deg.

Alert level G
FORMU01_ALERT_1_G  There is a discrepancy between the atom counts in the
            _chemical_formula_sum and _chemical_formula_moiety. This is
            usually due to the moiety formula being in the wrong format.
            Atom count from _chemical_formula_sum:   C26 H30 N4 Ni2 O16
            Atom count from _chemical_formula_moiety:C26 H30 N4 Ni2 O12
PLAT804_ALERT_5_G ARU-Pack Problem in PLATON Analysis ............          1 Times

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

   5 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   6 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
   1 ALERT type 5 Informative message, check

---

S1. Comment

The complexation of metal ions by dicarboxylate acid (pyridine-2,6-dicarboxylic acid) has been extensively studied (Laine et al., 1995a,b). Owing to the unique ability of the ligand to form stable chelates with various coordination modes and its biological activity, many crystal structures have been determined. Pyridine-2,6-dicarboxylic acid N-oxide (pydco), has limited steric hindrance and weak stacking interactions and can offer possibilities to form complicated coordination polymers through polycarboxylate ligands. However, the coordination chemistry and structural properties of metal polymers containing pydco ligands have seldom been documented to date (Nathan et al., 1985; Lin et al., 2006; Wen et al., 2005). In this paper, we report the synthesis and crystal structure of the title compound, (I).

In (I) (Fig. 1), each Ni^II atom is coordinated by three oxygen atoms from the carboxylato groups and one N-oxide entity from two pydco anions and one N atom from bridging 1,2-di-4-pyridylethane (bpa) ligand to form the basal plane, and further it coordinated by one apical oxygen atom from one water molecule to form a quasi-square pyramidal environment. Each carboxylato group is coordinated to the Ni atom in a monodentate fashion and the two carboxyl groups are out of coplanarity with the correspondingly linking pyridine rings, with the dihedral angles between them being ca 46° and 39°, respectively. They are very different from those in the free H₂pydco, in which the carboxyl groups are found to be essentially coplanar with the pyridine rings. Owing to the monodentate coordination modes of carboxylate groups, a binuclear [Ni₂(pydco)₂] unit was formed. Finally, bpa ligands connect the dimeric units into polymeric zigzag chain.

The crystalline water molecules contribute to intermolecular O—H···O hydrogen bonds (Table 1), which stabilize the crystal packing.

Related literature

For related structures, see: Laine et al. (1995a,b); Lin et al. (2006); Nathan et al. (1985); Wen et al. (2005).

S2. Experimental

Ni(AC)₂ (25 mg, 0.07 mmol), H₂pydco (31 mg, 0.15 mmol), bpa (19 mg, 0.09 mmol) were added in a solvent of acetonitrile, the mixture was heated for two hours under reflux. during the process stirring and influx were required. The resultant was kept at room temperature for six weeks, when single crystals were obtained.

S3. Refinement

C-bound H atoms were geometrically positioned (C—H 0.93-0.97 Å). The O-bound H atoms were located on a Fourier difference map with O—H 0.84-0.86 °. All H atoms were refined as riding, with U_iso(H) = 1.2-1.5U_eq of the parent atom.

Computing details

Data collection: APEX2 (Bruker, 2004); cell refinement: APEX2 (Bruker, 2004); data reduction: APEX2 (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEPIII (Burnett & Johnson, 1996), ORTEP-3 for Windows (Farrugia, 1997) and PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures

Fig. 1. A portion of the crystal structure of (I) showing the atomic numbering scheme and 40% probability displacement ellipsoids [symmetry codes: (i) -x, -y, 2 - z; (ii) -x, -y, 1 - z' (iii) -x, 1 - y, 1 - z].

catena-Poly[[[bis[aquanickel(II)]bis(µ-pyridine-2,6-dicarboxylato N-oxide)]-µ-1,2-di-4-pyridylethane] tetrahydrate]

Crystal data

[Ni2(C7H3NO5)2(C12H12N2)(H2O)2]·4H2O	Z = 1
Mr = 771.96	F(000) = 398
Triclinic, P1	Dx = 1.594 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 8.2803 (16) Å	Cell parameters from 2850 reflections
b = 10.3542 (15) Å	θ = 2.1–25.2°
c = 11.1326 (16) Å	µ = 1.25 mm^−1
α = 113.727 (2)°	T = 298 K
β = 104.282 (2)°	Block, green
γ = 100.255 (2)°	0.25 × 0.19 × 0.16 mm
V = 804.4 (2) Å^3

Data collection

Bruker APEXII area-detector diffractometer	2850 independent reflections
Radiation source: fine-focus sealed tube	2180 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.033
ϕ and ω scans	θmax = 25.2°, θmin = 2.1°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −9→9
Tmin = 0.745, Tmax = 0.825	k = −12→12
4146 measured reflections	l = −13→12

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.028	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.063	H-atom parameters constrained
S = 0.83	w = 1/[σ^2(Fo^2) + (0.0269P)^2 + 0.19P] where P = (Fo^2 + 2Fc^2)/3
2850 reflections	(Δ/σ)max < 0.001
199 parameters	Δρmax = 0.35 e Å^−3
0 restraints	Δρmin = −0.29 e Å^−3

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
Ni1	0.19610 (4)	0.10188 (3)	0.85792 (3)	0.03124 (11)
O1	0.0912 (2)	0.1451 (2)	0.70832 (19)	0.0473 (5)
O2	−0.1257 (2)	0.1548 (2)	0.5550 (2)	0.0600 (6)
O3	−0.03449 (19)	0.0177 (2)	0.85274 (17)	0.0433 (4)
N1	0.4335 (2)	0.2138 (2)	0.8837 (2)	0.0376 (5)
N2	−0.1753 (2)	−0.0555 (2)	0.7358 (2)	0.0354 (5)
C1	−0.0673 (3)	0.1028 (3)	0.6318 (3)	0.0401 (6)
C2	−0.2011 (3)	−0.0227 (3)	0.6272 (3)	0.0368 (6)
C3	−0.3544 (3)	−0.1043 (3)	0.5128 (3)	0.0489 (7)
H3	−0.3736	−0.0847	0.4369	0.059*
C4	−0.4795 (4)	−0.2144 (3)	0.5092 (3)	0.0570 (8)
H4	−0.5824	−0.2686	0.4315	0.068*
C5	−0.4508 (3)	−0.2433 (3)	0.6215 (3)	0.0492 (7)
H5	−0.5343	−0.3172	0.6205	0.059*
C6	−0.2980 (3)	−0.1624 (3)	0.7350 (3)	0.0366 (6)
C8	0.5711 (3)	0.1727 (3)	0.9306 (3)	0.0490 (7)
H8	0.5514	0.0953	0.9529	0.059*
C9	0.7394 (3)	0.2397 (3)	0.9470 (3)	0.0507 (7)
H9	0.8307	0.2077	0.9798	0.061*
C10	0.7726 (3)	0.3553 (3)	0.9144 (3)	0.0436 (6)
C11	0.9551 (3)	0.4316 (3)	0.9304 (3)	0.0518 (7)
H11A	1.0234	0.3635	0.9215	0.062*
H11B	0.9488	0.4587	0.8559	0.062*
C12	0.6307 (3)	0.3995 (3)	0.8690 (3)	0.0479 (7)
H12	0.6474	0.4782	0.8482	0.058*
C13	0.46548 (10)	0.32671 (9)	0.85477 (8)	0.0442 (7)
H13	0.3722	0.3577	0.8236	0.053*
O1W	0.22201 (10)	−0.11885 (9)	0.72089 (8)	0.0584 (5)
H1W	0.1610	−0.1939	0.7212	0.088*
H2W	0.2045	−0.1367	0.6357	0.088*
O2W	0.15515 (10)	0.41900 (9)	0.61420 (8)	0.0944 (8)
H3W	0.0828	0.3364	0.5887	0.142*
H4W	0.1122	0.489	0.6354	0.142*
O3W	0.03080 (10)	0.37588 (9)	0.33371 (8)	0.0875 (7)
H6W	0.0820	0.3592	0.2741	0.131*
H5W	0.1116	0.4510	0.4044	0.131*
C7	−0.25478 (10)	−0.18425 (9)	0.86469 (8)	0.0374 (6)
O4	−0.28538 (10)	−0.09359 (9)	0.96606 (8)	0.0401 (4)
O5	−0.19822 (10)	−0.28825 (9)	0.85957 (8)	0.0540 (5)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ni1	0.02697 (17)	0.0386 (2)	0.03728 (19)	0.00914 (13)	0.01384 (14)	0.02526 (16)
O1	0.0408 (10)	0.0605 (12)	0.0545 (12)	0.0133 (9)	0.0172 (9)	0.0406 (11)
O2	0.0654 (13)	0.0709 (14)	0.0579 (13)	0.0196 (11)	0.0122 (10)	0.0495 (12)
O3	0.0302 (9)	0.0632 (12)	0.0351 (10)	0.0041 (8)	0.0070 (8)	0.0286 (9)
N1	0.0335 (11)	0.0434 (13)	0.0472 (13)	0.0122 (10)	0.0175 (10)	0.0297 (11)
N2	0.0296 (11)	0.0454 (13)	0.0341 (12)	0.0114 (10)	0.0107 (10)	0.0218 (11)
C1	0.0484 (16)	0.0430 (16)	0.0361 (15)	0.0176 (13)	0.0183 (13)	0.0219 (13)
C2	0.0388 (14)	0.0456 (16)	0.0335 (14)	0.0180 (12)	0.0152 (12)	0.0221 (13)
C3	0.0471 (16)	0.0630 (19)	0.0386 (16)	0.0170 (15)	0.0102 (14)	0.0285 (15)
C4	0.0403 (16)	0.073 (2)	0.0413 (17)	0.0064 (15)	0.0009 (14)	0.0243 (16)
C5	0.0403 (15)	0.0570 (19)	0.0440 (17)	0.0067 (13)	0.0102 (13)	0.0241 (15)
C6	0.0319 (13)	0.0431 (16)	0.0374 (15)	0.0096 (12)	0.0129 (12)	0.0219 (13)
C8	0.0419 (15)	0.0528 (18)	0.070 (2)	0.0182 (13)	0.0246 (15)	0.0413 (16)
C9	0.0376 (15)	0.0531 (18)	0.070 (2)	0.0172 (13)	0.0220 (14)	0.0340 (16)
C10	0.0384 (14)	0.0430 (16)	0.0456 (16)	0.0072 (12)	0.0191 (13)	0.0172 (14)
C11	0.0420 (16)	0.0497 (18)	0.0549 (18)	0.0048 (13)	0.0224 (14)	0.0172 (14)
C12	0.0497 (16)	0.0403 (16)	0.0560 (18)	0.0061 (13)	0.0202 (14)	0.0270 (15)
C13	0.0400 (15)	0.0445 (16)	0.0553 (17)	0.0127 (13)	0.0167 (13)	0.0305 (15)
O1W	0.0732 (13)	0.0580 (13)	0.0531 (12)	0.0221 (11)	0.0286 (11)	0.0301 (11)
O2W	0.1038 (19)	0.0682 (16)	0.113 (2)	0.0268 (14)	0.0349 (16)	0.0454 (15)
O3W	0.127 (2)	0.0742 (16)	0.0925 (17)	0.0440 (15)	0.0679 (16)	0.0463 (14)
C7	0.0256 (13)	0.0449 (17)	0.0418 (16)	0.0028 (12)	0.0102 (12)	0.0249 (14)
O4	0.0350 (9)	0.0520 (11)	0.0420 (10)	0.0147 (8)	0.0165 (8)	0.0278 (9)
O5	0.0675 (13)	0.0502 (12)	0.0608 (13)	0.0252 (10)	0.0269 (11)	0.0360 (11)

Geometric parameters (Å, º)

Ni1—O3	1.9290 (16)	C8—C9	1.373 (3)
Ni1—O1	1.9373 (16)	C8—H8	0.9300
Ni1—O4^i	1.9588 (10)	C9—C10	1.386 (3)
Ni1—N1	1.9828 (18)	C9—H9	0.9300
Ni1—O1W	2.2643 (11)	C10—C12	1.390 (3)
O1—C1	1.258 (3)	C10—C11	1.506 (3)
O2—C1	1.230 (3)	C11—C11^ii	1.501 (5)
O3—N2	1.331 (2)	C11—H11A	0.9700
N1—C13	1.3332 (19)	C11—H11B	0.9700
N1—C8	1.345 (3)	C12—C13	1.376 (3)
N2—C6	1.358 (3)	C12—H12	0.9300
N2—C2	1.361 (3)	C13—H13	0.9300
C1—C2	1.525 (3)	O1W—H1W	0.85
C2—C3	1.379 (3)	O1W—H2W	0.86
C3—C4	1.377 (4)	O2W—H3W	0.84
C3—H3	0.9300	O2W—H4W	0.84
C4—C5	1.375 (3)	O3W—H6W	0.85
C4—H4	0.9300	O3W—H5W	0.86
C5—C6	1.371 (3)	C7—O5	1.2351 (14)
C5—H5	0.9300	C7—O4	1.2618 (12)
C6—C7	1.517 (3)	O4—Ni1^i	1.9588 (10)
O3—Ni1—O1	89.83 (7)	N2—C6—C5	120.3 (2)
O3—Ni1—O4^i	86.14 (5)	N2—C6—C7	116.2 (2)
O1—Ni1—O4^i	167.38 (6)	C5—C6—C7	123.6 (3)
O3—Ni1—N1	172.23 (8)	N1—C8—C9	123.1 (2)
O1—Ni1—N1	90.76 (7)	N1—C8—H8	118.5
O4^i—Ni1—N1	91.65 (6)	C9—C8—H8	118.5
O3—Ni1—O1W	94.95 (6)	C8—C9—C10	119.7 (2)
O1—Ni1—O1W	97.00 (6)	C8—C9—H9	120.2
O4^i—Ni1—O1W	95.30 (6)	C10—C9—H9	120.2
N1—Ni1—O1W	92.67 (6)	C9—C10—C12	117.0 (2)
C1—O1—Ni1	129.11 (16)	C9—C10—C11	121.5 (2)
N2—O3—Ni1	123.58 (13)	C12—C10—C11	121.5 (2)
C13—N1—C8	117.39 (17)	C11^ii—C11—C10	111.5 (3)
C13—N1—Ni1	123.82 (12)	C11^ii—C11—H11A	109.3
C8—N1—Ni1	118.78 (15)	C10—C11—H11A	109.3
O3—N2—C6	114.80 (18)	C11^ii—C11—H11B	109.3
O3—N2—C2	123.49 (19)	C10—C11—H11B	109.3
C6—N2—C2	121.6 (2)	H11A—C11—H11B	108.0
O2—C1—O1	124.3 (2)	C13—C12—C10	120.0 (2)
O2—C1—C2	115.3 (2)	C13—C12—H12	120.0
O1—C1—C2	120.5 (2)	C10—C12—H12	120.0
N2—C2—C3	118.2 (2)	N1—C13—C12	122.78 (15)
N2—C2—C1	121.5 (2)	N1—C13—H13	118.6
C3—C2—C1	120.3 (2)	C12—C13—H13	118.6
C4—C3—C2	121.1 (2)	Ni1—O1W—H1W	115.3
C4—C3—H3	119.5	Ni1—O1W—H2W	114.2
C2—C3—H3	119.5	H1W—O1W—H2W	108.3
C5—C4—C3	119.4 (3)	H3W—O2W—H4W	113.1
C5—C4—H4	120.3	H6W—O3W—H5W	99.6
C3—C4—H4	120.3	O5—C7—O4	127.3 (1)
C6—C5—C4	119.5 (2)	O5—C7—C6	117.9 (2)
C6—C5—H5	120.3	O4—C7—C6	114.9 (2)
C4—C5—H5	120.3	C7—O4—Ni1^i	114.7 (1)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1W···O3W^iii	0.85	1.99	2.8144 (15)	162
O1W—H2W···O2^iii	0.86	1.98	2.824 (2)	168
O3W—H6W···O5^iii	0.85	1.94	2.7791 (13)	170
O3W—H5W···O2W	0.86	2.44	2.8527 (13)	110
O2W—H3W···O2	0.84	2.15	2.976 (2)	167
O2W—H4W···O3W^iv	0.84	1.97	2.7985 (14)	169

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