trans-Tetra­aqua­bis­(pyridine-4-carboxyl­ate-κN)nickel(II)

The title complex, [Ni(C₆H₄NO₂)₂(H₂O)₄], consists of Ni atoms coordinated to two trans pyridyl­carboxyl­ate ligands, coordinated through the N atoms, and four water ligands. The Ni atom lies on a centre of symmetry. Extensive inter-complex hydrogen bonding occurs between the water ligands and the carboxyl­ate groups, resulting in a three-dimensional network.

Key indicators

• Single-crystal X-ray study
• T = 123 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.025
• wR factor = 0.058
• Data-to-parameter ratio = 13.3

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

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S1. Comment

Pyridylcarboxylate ligands have recently been used in the construction of novel new coordination polymers with interesting microporous and non-linear optical properties (Lin et al., 1998; Evans, Xiong et al., 1999; Evans, Wang et al., 1999; Evans & Lin, 2000). A feature of this class of bridging ligand is the presence of two different coordinating functionalities – a pyridyl group and a carboxylate group. The ligands also offer the possibility of participating in hydrogen-bonding networks if monodentate coordination occurs. We report here the structure of NiL₂(H₂O)₄ (L is pyridyl-4-carboxylate), (I), in which such a hydrogen-bonded network is found.

The structure of (I) is isomorphous with the previously reported manganese(II) (Hauptmann et al., 2000), iron(II) (Liu et al., 1999), cobalt(II) (Waizumi et al., 1998), copper(II) (Okabe et al., 1993; Waizumi et al., 1998), zinc(II) (Cingi et al., 1971) and cadmium(II) (Cingi et al., 1971) structures. It consists of mononuclear nickel complexes in which the metal ion is coordinated to the N atoms of two trans pyridyl-4-carboxylate ligands, and to four water ligands (Fig. 1). The octahedrally coordinated Ni atom (Table 1) lies on a centre of symmetry. The carboxylate group of the ligand is twisted slightly from the plane of the pyridyl group [the angle between the two planes is 13.93 (8)°].

Extensive hydrogen bonding between the water ligands and the uncoordinated carboxylate groups generates a complex three-dimensional network (Fig. 2). Each carboxylate O atom is hydrogen bonded to two separate water ligands (Table 2), and each water ligand hydrogen bonds to two separate carboxylates. Each complex is thus connected to six neighbours via 16 O—H···O hydrogen bonds.

S2. Experimental

The title compound was obtained from an aqueous solution containing nickel nitrate, sodium dicyanamide and pyridyl-4-carboxylic acid.

S3. Refinement

All H atoms were observed in difference syntheses, however only those of the water ligands were allowed to refine freely.

Computing details

Data collection: COLLECT (Hooft, 1998); cell refinement: DENZO-SMN (Otwinowski & Minor, 1997); data reduction: DENZO-SMN; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPIII (Burnett & Johnson, 1996); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. Atom-numbering scheme for (I). Displacement ellipsoids are drawn at the 50% probability level.
	Fig. 2. Crystal packing in (I), showing the extensive hydrogen bonding between complexes.

trans-Bis(pyridine-4-carboxylate)tetraaquonickel(II)

Crystal data

[Ni(C6H4NO2)2(H2O)4]	Z = 1
Mr = 374.98	F(000) = 194
Triclinic, P1	Dx = 1.822 Mg m^−3
a = 6.2862 (3) Å	Mo Kα radiation, λ = 0.71073 Å
b = 6.8598 (2) Å	Cell parameters from 3694 reflections
c = 9.2394 (4) Å	θ = 2.4–28.3°
α = 96.511 (3)°	µ = 1.47 mm^−1
β = 104.929 (2)°	T = 123 K
γ = 113.692 (3)°	Plate, blue
V = 341.77 (2) Å^3	0.18 × 0.13 × 0.05 mm

Data collection

Nonius KappaCCD diffractometer	1626 independent reflections
Radiation source: fine-focus sealed tube	1558 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.029
Detector resolution: 9 pixels mm^-1	θmax = 28.3°, θmin = 2.4°
ϕ and ω scans	h = −8→8
Absorption correction: integration (XPREP; Siemens, 1994)	k = −8→8
Tmin = 0.835, Tmax = 0.940	l = −11→12
3694 measured reflections

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)] = 0.025	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.058	H atoms treated by a mixture of independent and constrained refinement
S = 1.15	w = 1/[σ^2(Fo^2) + (0.0023P)^2 + 0.1806P] where P = (Fo^2 + 2Fc^2)/3
1626 reflections	(Δ/σ)max < 0.001
122 parameters	Δρmax = 0.34 e Å^−3
0 restraints	Δρmin = −0.52 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. All hydrogen atoms were found, however only those of the water ligands were allowed to refine freely.

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

	x	y	z	Uiso*/Ueq
Ni1	0.5000	0.5000	0.5000	0.00985 (10)
O1	0.3201 (2)	0.68358 (19)	0.54174 (13)	0.0133 (2)
H11	0.233 (4)	0.716 (3)	0.448 (2)	0.022 (5)*
H12	0.406 (5)	0.799 (4)	0.603 (3)	0.038 (7)*
O2	0.2785 (2)	0.23654 (19)	0.57230 (13)	0.0146 (2)
H21	0.357 (5)	0.179 (4)	0.621 (3)	0.031 (6)*
H22	0.169 (6)	0.232 (5)	0.609 (3)	0.051 (8)*
N1	0.2618 (2)	0.3588 (2)	0.27200 (14)	0.0115 (3)
C1	0.0173 (3)	0.2869 (3)	0.23226 (18)	0.0146 (3)
H1A	−0.0535	0.2808	0.3119	0.017*
C2	−0.1366 (3)	0.2211 (2)	0.08009 (18)	0.0133 (3)
H2A	−0.3090	0.1709	0.0566	0.016*
C3	−0.0356 (3)	0.2294 (2)	−0.03765 (17)	0.0113 (3)
C4	0.2166 (3)	0.2947 (2)	0.00326 (18)	0.0127 (3)
H4A	0.2911	0.2962	−0.0742	0.015*
C5	0.3569 (3)	0.3571 (2)	0.15742 (17)	0.0125 (3)
H5A	0.5287	0.4009	0.1839	0.015*
C6	−0.1921 (3)	0.1762 (2)	−0.20519 (18)	0.0127 (3)
O3	−0.4223 (2)	0.08506 (19)	−0.23781 (13)	0.0176 (2)
O4	−0.0777 (2)	0.2321 (2)	−0.29873 (13)	0.0183 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ni1	0.00868 (14)	0.01290 (15)	0.00829 (15)	0.00532 (11)	0.00296 (10)	0.00170 (10)
O1	0.0129 (5)	0.0160 (6)	0.0113 (5)	0.0083 (5)	0.0023 (4)	0.0013 (4)
O2	0.0127 (5)	0.0171 (6)	0.0164 (6)	0.0071 (5)	0.0069 (5)	0.0072 (4)
N1	0.0113 (6)	0.0131 (6)	0.0103 (6)	0.0059 (5)	0.0033 (5)	0.0024 (5)
C1	0.0133 (7)	0.0178 (8)	0.0141 (7)	0.0071 (6)	0.0069 (6)	0.0033 (6)
C2	0.0102 (7)	0.0133 (7)	0.0156 (8)	0.0053 (6)	0.0042 (6)	0.0011 (6)
C3	0.0129 (7)	0.0079 (7)	0.0127 (7)	0.0051 (6)	0.0028 (6)	0.0023 (5)
C4	0.0139 (7)	0.0126 (7)	0.0129 (7)	0.0062 (6)	0.0060 (6)	0.0034 (6)
C5	0.0101 (7)	0.0150 (7)	0.0132 (7)	0.0063 (6)	0.0041 (6)	0.0031 (6)
C6	0.0147 (7)	0.0106 (7)	0.0134 (7)	0.0076 (6)	0.0030 (6)	0.0019 (5)
O3	0.0124 (5)	0.0210 (6)	0.0161 (6)	0.0065 (5)	0.0019 (4)	0.0036 (4)
O4	0.0177 (6)	0.0286 (7)	0.0129 (6)	0.0131 (5)	0.0065 (5)	0.0071 (5)

Geometric parameters (Å, º)

Ni1—O1	2.0669 (11)	C1—C2	1.386 (2)
Ni1—O1^i	2.0669 (11)	C1—H1A	0.9500
Ni1—N1^i	2.0890 (13)	C2—C3	1.389 (2)
Ni1—N1	2.0891 (13)	C2—H2A	0.9500
Ni1—O2^i	2.0932 (11)	C3—C4	1.392 (2)
Ni1—O2	2.0932 (11)	C3—C6	1.515 (2)
O1—H11	1.00 (2)	C4—C5	1.379 (2)
O1—H12	0.80 (3)	C4—H4A	0.9500
O2—H21	0.83 (3)	C5—H5A	0.9500
O2—H22	0.83 (3)	C6—O3	1.2575 (19)
N1—C1	1.342 (2)	C6—O4	1.2591 (19)
N1—C5	1.344 (2)
O1—Ni1—O1^i	180.0	C1—N1—C5	117.60 (13)
O1—Ni1—N1^i	88.10 (5)	C1—N1—Ni1	122.94 (10)
O1^i—Ni1—N1^i	91.90 (5)	C5—N1—Ni1	119.18 (10)
O1—Ni1—N1	91.90 (5)	N1—C1—C2	122.89 (14)
O1^i—Ni1—N1	88.10 (5)	N1—C1—H1A	118.6
N1^i—Ni1—N1	180.0	C2—C1—H1A	118.6
O1—Ni1—O2^i	86.76 (5)	C1—C2—C3	119.19 (15)
O1^i—Ni1—O2^i	93.24 (5)	C1—C2—H2A	120.4
N1^i—Ni1—O2^i	90.76 (5)	C3—C2—H2A	120.4
N1—Ni1—O2^i	89.24 (5)	C2—C3—C4	117.91 (14)
O1—Ni1—O2	93.24 (5)	C2—C3—C6	121.39 (14)
O1^i—Ni1—O2	86.76 (5)	C4—C3—C6	120.68 (14)
N1^i—Ni1—O2	89.24 (5)	C5—C4—C3	119.29 (14)
N1—Ni1—O2	90.76 (5)	C5—C4—H4A	120.4
O2^i—Ni1—O2	180.000 (1)	C3—C4—H4A	120.4
Ni1—O1—H11	114.6 (12)	N1—C5—C4	123.00 (14)
Ni1—O1—H12	114.8 (18)	N1—C5—H5A	118.5
H11—O1—H12	106 (2)	C4—C5—H5A	118.5
Ni1—O2—H21	112.3 (16)	O3—C6—O4	126.02 (15)
Ni1—O2—H22	126.5 (19)	O3—C6—C3	117.62 (14)
H21—O2—H22	109 (2)	O4—C6—C3	116.34 (14)

Symmetry code: (i) −x+1, −y+1, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H11···O4^ii	1.00 (2)	1.64 (2)	2.634 (2)	177 (2)
O1—H12···O3^iii	0.80 (2)	2.00 (3)	2.793 (2)	172 (2)
O2—H21···O3^iv	0.83 (3)	2.00 (3)	2.825 (2)	171 (2)
O2—H22···O4^v	0.83 (3)	1.96 (3)	2.786 (2)	178 (3)
C1—H1A···O1^vi	0.95	2.47	3.381 (2)	160

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