trans-Diaqua­bis­[2-(2-pyrid­yl)acetato-κ²N,O]nickel(II)

In the centrosymmetric title complex, [Ni(C₇H₆NO₂)₂(H₂O)₂], the Ni^II atom, located on an inversion center, is six-coordinated in a distorted octa­hedral geometry defined by two N and four O atoms from the two chelating 2-(2-pyrid­yl)acetate ligands and two aqua ligands. The mol­ecules form a three-dimensional framework by O—H...O hydrogen bonds and aromatic π–π stacking inter­actions, with a centroid–centroid distance of 3.506 (3) Å.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.023
• wR factor = 0.067
• Data-to-parameter ratio = 14.3

checkCIF/PLATON results

No syntax errors found





Alert level A
PLAT900_ALERT_1_A No Matching Reflection File Found ..............          !
PLAT900_ALERT_1_A No Matching Reflection File Found ..............          !
PLAT902_ALERT_1_A No (Interpretable) Reflections found in FCF ....          !

Alert level B
PLAT112_ALERT_2_B ADDSYM Detects Additional (Pseudo) Symm. Elem...          I

Alert level C
PLAT232_ALERT_2_C Hirshfeld Test Diff (M-X)  Ni1    --  O2      ..       6.30 su

Alert level G
PLAT128_ALERT_4_G Alternate Setting of Space-group P21/c   .......      P21/n
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported   _diffrn_ambient_temperature        293 K
PLAT720_ALERT_4_G Number of Unusual/Non-Standard Labels ..........          2

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

   5 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   2 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
   2 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

---

S1. Comment

(2-Pyridinyl)acetic acid is a common ligand. Here we report the synthesis of [Ni(C₅H₄NCH₂CO₂)₂(H₂O)₂], in which the Ni(II) ion coordination environment is the same as in [Zn(C₅H₄NCH₂CO₂)₂(H₂O)₂] reported earlier (Faure & Loiseleur,1972). The Zn and Ni complexes show a high degree of isostructurality.

As shown in Fig. 1, the Ni(II) coordination geometry can be considered as a distorted octahedral with N₂O₄ donor set. Due to a special position of Ni(II), the complex molecule is centrosymmetric. The atoms N1, O2, N1ⁱ, O2ⁱ (symmetry code i: -x + 2, -y + 2, -z) from the (2-pyridinyl)acetate ligand are located in the equatorial plane, while O1W and O1Wⁱ are in the axial positions. In the title complex the (2-pyridinyl)acetate anion acts as a chelating bidentate ligand.

Two kinds of intermolecular O—H···O hydrogen bonds (Table 1) were found which link the neighboring molecules into two dimensional layers parallel to the ab plane. The two-dimensional layers are assembled via weak aromatic π-π stacking interactions into three-dimensional network with a centroid-to-centroid distance of 3.506 (3) Å.

Related literature

For similar structures, see: Faure & Loiseleur (1972, 1975).

S2. Experimental

All the chemicals and solvents used for the syntheses were of reagent grade and used without further purification. Ni(CH₃COO)₂.4H₂O (24.88 mg, 0.1 mmol) was dissolved in 5 ml of H₂O, while (2-pyridinyl)acetic acid (27.4 mg, 0.2 mmol) was dissolved in 5 ml of methanol at room temperature. The mixture was stirred for one hour. Pale-green single crystals of the title compound suitable for X-ray analysis were obtained by slow evaporation at room temperature for two weeks.

S3. Refinement

The H atoms bonded to O1W atoms were located in a difference Fourier map and fully refined (positional and isotropic displacement parameters ). Other H atoms were calculated geometrically with C-H distances of 0.93-0.97 Å and were allowed to ride on the C atoms to which they were bonded with U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: APEX2 (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures

	Fig. 1. The molecular structure of the title complex with the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. H-atoms have been omitted. Symmetry code for the atoms with the A label: 2-x, 2-y, -z.
	Fig. 2. Crystal packing diagram with hydrogen bonds shown by dashed lines.

trans-Diaquabis[2-(2-pyridyl)acetato-κ²N,O]nickel(II)

Crystal data

[Ni(C7H6NO2)2(H2O)2]	F(000) = 380
Mr = 367.00	Dx = 1.746 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 804 reflections
a = 8.3346 (12) Å	θ = 3.1–27.8°
b = 7.100 (1) Å	µ = 1.43 mm^−1
c = 12.1023 (18) Å	T = 293 K
β = 102.977 (2)°	Block, pale-green
V = 697.87 (17) Å^3	0.22 × 0.15 × 0.11 mm
Z = 2

Data collection

Bruker APEXII 1K CCD area-detector diffractometer	1627 independent reflections
Radiation source: fine-focus sealed tube	1471 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.017
φ and ω scans	θmax = 28.2°, θmin = 2.7°
Absorption correction: multi-scan (SADABS; Bruker, 2004)	h = −10→11
Tmin = 0.774, Tmax = 0.855	k = −8→9
4515 measured reflections	l = −16→15

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)] = 0.023	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.067	H atoms treated by a mixture of independent and constrained refinement
S = 1.00	w = 1/[σ^2(Fo^2) + (0.0413P)^2 + 0.1727P] where P = (Fo^2 + 2Fc^2)/3
1627 reflections	(Δ/σ)max < 0.001
114 parameters	Δρmax = 0.34 e Å^−3
0 restraints	Δρmin = −0.20 e Å^−3

Special details

Experimental. 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 > 2sigma(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.

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	1.0000	1.0000	0.0000	0.01966 (10)
O1	0.73292 (15)	0.53276 (15)	−0.14497 (10)	0.0320 (3)
O1W	0.87262 (14)	1.17222 (17)	−0.13481 (9)	0.0315 (2)
H1WA	0.820 (2)	1.274 (3)	−0.1354 (18)	0.046 (6)*
H1WB	0.838 (3)	1.115 (4)	−0.199 (2)	0.072 (7)*
O2	0.89799 (12)	0.77910 (14)	−0.09898 (9)	0.0275 (2)
N1	0.79922 (16)	0.99744 (14)	0.07548 (10)	0.0221 (3)
C1	0.70767 (17)	0.8430 (2)	0.08078 (11)	0.0238 (3)
C2	0.56827 (18)	0.8517 (2)	0.12662 (12)	0.0302 (3)
H2A	0.5061	0.7438	0.1297	0.036*
C3	0.5230 (2)	1.0201 (2)	0.16721 (14)	0.0331 (4)
H3A	0.4307	1.0270	0.1983	0.040*
C4	0.61676 (17)	1.1788 (2)	0.16100 (13)	0.0313 (3)
H4A	0.5885	1.2946	0.1871	0.038*
C5	0.75331 (17)	1.1610 (2)	0.11506 (12)	0.0272 (3)
H5A	0.8168	1.2676	0.1113	0.033*
C6	0.76151 (18)	0.6580 (2)	0.04071 (12)	0.0277 (3)
H6A	0.6757	0.5660	0.0412	0.033*
H6B	0.8592	0.6165	0.0950	0.033*
C7	0.79960 (16)	0.65785 (18)	−0.07716 (11)	0.0229 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ni1	0.02185 (15)	0.01823 (15)	0.01945 (15)	−0.00105 (8)	0.00579 (10)	−0.00173 (8)
O1	0.0420 (7)	0.0236 (5)	0.0281 (6)	−0.0050 (4)	0.0029 (5)	−0.0058 (4)
O1W	0.0397 (6)	0.0257 (6)	0.0263 (6)	0.0069 (5)	0.0012 (5)	0.0001 (4)
O2	0.0320 (5)	0.0251 (5)	0.0268 (5)	−0.0052 (4)	0.0099 (4)	−0.0056 (4)
N1	0.0236 (6)	0.0223 (6)	0.0203 (6)	0.0003 (4)	0.0049 (5)	−0.0012 (4)
C1	0.0261 (7)	0.0270 (8)	0.0173 (6)	−0.0018 (5)	0.0030 (5)	0.0007 (5)
C2	0.0271 (7)	0.0385 (9)	0.0247 (7)	−0.0067 (6)	0.0055 (6)	0.0014 (6)
C3	0.0244 (7)	0.0487 (10)	0.0276 (8)	0.0015 (6)	0.0087 (6)	−0.0019 (6)
C4	0.0297 (7)	0.0367 (8)	0.0274 (7)	0.0063 (6)	0.0064 (6)	−0.0068 (6)
C5	0.0284 (7)	0.0251 (7)	0.0279 (7)	0.0006 (6)	0.0060 (6)	−0.0037 (6)
C6	0.0360 (8)	0.0212 (7)	0.0265 (7)	−0.0050 (6)	0.0082 (6)	0.0008 (5)
C7	0.0255 (6)	0.0179 (7)	0.0240 (6)	0.0035 (5)	0.0028 (5)	−0.0009 (5)

Geometric parameters (Å, º)

Ni1—O2	2.0397 (10)	C2—C3	1.378 (2)
Ni1—N1	2.0789 (13)	C2—H2A	0.9300
Ni1—O1W	2.1228 (11)	C3—C4	1.383 (2)
O1—C7	1.2515 (17)	C3—H3A	0.9300
O1W—H1WA	0.84 (2)	C4—C5	1.380 (2)
O1W—H1WB	0.87 (3)	C4—H4A	0.9300
O2—C7	1.2572 (17)	C5—H5A	0.9300
N1—C5	1.3444 (17)	C6—C7	1.5294 (19)
N1—C1	1.3454 (17)	C6—H6A	0.9700
C1—C2	1.397 (2)	C6—H6B	0.9700
C1—C6	1.503 (2)
O2^i—Ni1—N1^i	88.90 (4)	C1—C2—H2A	120.0
O2^i—Ni1—N1	91.10 (4)	C2—C3—C4	118.97 (15)
N1^i—Ni1—N1	180	C2—C3—H3A	120.5
O2^i—Ni1—O1W	94.53 (4)	C4—C3—H3A	120.5
N1—Ni1—O1W	91.70 (5)	C5—C4—C3	118.35 (14)
O2^i—Ni1—O1W^i	85.47 (5)	C5—C4—H4A	120.8
N1—Ni1—O1W^i	88.30 (5)	C3—C4—H4A	120.8
O1W—Ni1—O1W^i	180	N1—C5—C4	123.29 (14)
Ni1—O1W—H1WA	132.0 (14)	N1—C5—H5A	118.4
Ni1—O1W—H1WB	115.2 (17)	C4—C5—H5A	118.4
H1WA—O1W—H1WB	109 (2)	C1—C6—C7	116.18 (11)
C5—N1—C1	118.50 (13)	C1—C6—H6A	108.2
C5—N1—Ni1	118.07 (9)	C7—C6—H6A	108.2
C1—N1—Ni1	123.31 (9)	C1—C6—H6B	108.2
N1—C1—C2	120.96 (13)	C7—C6—H6B	108.2
N1—C1—C6	118.88 (12)	H6A—C6—H6B	107.4
C2—C1—C6	120.11 (13)	O1—C7—O2	124.25 (13)
C3—C2—C1	119.92 (14)	O1—C7—C6	117.23 (12)
C3—C2—H2A	120.0	O2—C7—C6	118.50 (12)

Symmetry code: (i) −x+2, −y+2, −z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1WA···O1^ii	0.84 (2)	1.97 (2)	2.8035 (17)	169.7 (19)
O1W—H1WB···O1^iii	0.87 (3)	1.93 (3)	2.7936 (17)	169 (2)

Symmetry codes: (ii) x, y+1, z; (iii) −x+3/2, y+1/2, −z−1/2.