Tetra­aqua­bis(nicotinamide-κN 1)nickel(II) bis­(2-fluoro­benzoate)

Tuncer Hökelek; Hakan Dal; Barış Tercan; F Elif Özbek; Hacali Necefoğlu

doi:10.1107/S1600536809040392

. 2009 Oct 10;65(Pt 11):m1330–m1331. doi: 10.1107/S1600536809040392

Tetraaquabis(nicotinamide-κN ¹)nickel(II) bis(2-fluorobenzoate)

Tuncer Hökelek ^a,^*, Hakan Dal ^b, Barış Tercan ^c, F Elif Özbek ^d, Hacali Necefoğlu ^d

PMCID: PMC2970982 PMID: 21578089

Abstract

The asymmetric unit of the title complex, [Ni(C₆H₆N₂O)₂(H₂O)₄](C₇H₄FO₂)₂, contains one-half of the complex cation with the Ni^II atom located on an inversion center, and a 2-fluorobenzoate (FB) counter-anion. The four O atoms in the equatorial plane around the Ni atom form a slightly distorted square-planar arrangement with an average Ni—O bond length of 2.079 Å, and the slightly distorted octahedral coordination is completed by the two N atoms of the nicotinamide (NA) ligands in the axial positions. The dihedral angle between the carboxyl group and the attached benzene ring is 28.28 (11)°, while the pyridine and benzene rings are oriented at a dihedral angle of 8.31 (4)°. In the crystal structure, O—H⋯O, N—H⋯O, C—H⋯O, and C—H⋯F hydrogen bonds link the molecules into a three-dimensional network. π–π Contacts between the pyridine and benzene rings [centroid–centroid distance = 3.626 (1) Å] may further stabilize the crystal structure. The 2-fluorobenzoate anion is disordered over two orientations, with an occupancy ratio of 0.85:0.15.

Related literature

For niacin, see: Krishnamachari (1974 ▶) and for the nicotinic acid derivative N,N-diethylnicotinamide, see: Bigoli et al. (1972 ▶). For related structures, see: Hökelek et al. (2009 ▶); Sertçelik et al. (2009 ▶).

Experimental

Crystal data

[Ni(C₆H₆N₂O)₂(H₂O)₄](C₇H₄FO₂)₂
M _r = 653.23
Triclinic,
a = 7.2529 (1) Å
b = 7.3315 (1) Å
c = 14.3831 (3) Å
α = 82.115 (2)°
β = 77.332 (2)°
γ = 63.664 (1)°
V = 668.05 (2) Å³
Z = 1
Mo Kα radiation
μ = 0.81 mm⁻¹
T = 100 K
0.33 × 0.28 × 0.18 mm

Data collection

Bruker Kappa APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ▶) T _min = 0.768, T _max = 0.868
12196 measured reflections
3339 independent reflections
3241 reflections with I > 2σ(I)
R _int = 0.020

Refinement

R[F ² > 2σ(F ²)] = 0.026
wR(F ²) = 0.071
S = 1.04
3339 reflections
221 parameters
7 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.55 e Å⁻³
Δρ_min = −0.70 e Å⁻³

Data collection: APEX2 (Bruker, 2007 ▶); cell refinement: SAINT (Bruker, 2007 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶) and PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809040392/xu2610sup1.cif

e-65-m1330-sup1.cif^{(19.3KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809040392/xu2610Isup2.hkl

e-65-m1330-Isup2.hkl^{(160.4KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Selected bond lengths (Å).

Ni1—O4	2.0925 (10)
Ni1—O5	2.0658 (10)
Ni1—N1	2.0834 (11)

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Table 2. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N2—H2A⋯O1ⁱ	0.86	2.03	2.8875 (17)	171
N2—H2B⋯O2ⁱⁱ	0.86	2.23	3.0654 (16)	164
O4—H4A⋯O3ⁱⁱⁱ	0.887 (16)	2.01 (3)	2.8372 (15)	155 (2)
O4—H4B⋯O3^iv	0.887 (16)	1.87 (2)	2.7288 (15)	163 (2)
O5—H5A⋯O2ⁱⁱ	0.887 (16)	1.82 (2)	2.7001 (15)	175 (3)
O5—H5B⋯O3^v	0.887 (15)	1.94 (2)	2.7774 (15)	157 (2)
C10—H10⋯O2ⁱⁱ	0.93	2.52	3.339 (2)	147
C12—H12⋯F1^vi	0.93	2.51	3.4314 (19)	173

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) ; (v) ; (vi) .

Acknowledgments

The authors are indebted to Anadolu University and the Medicinal Plants and Medicine Research Centre of Anadolu University, Eskişehir, Turkey, for the use of X-ray diffractometer. This work was supported financially by Kafkas University Research Fund (grant No. 2009-FEF-03).

supplementary crystallographic information

Comment

As a part of our ongoing investigation on transition metal complexes of nicotinamide (NA), one form of niacin (Krishnamachari, 1974), and/or the nicotinic acid derivative N,N-diethylnicotinamide (DENA), an important respiratory stimulant (Bigoli et al., 1972), the title compound was synthesized and its crystal structure is reported herein.

The title compound is a monomeric complex, with Ni^II ion on a centre of symmetry, consisting of two NA ligands, four coordinated water molecules and one FB molecule. The structures of some DENA and/or NA complexes of Ni^II ion, [Ni(C₆H₆N₂O)₂(H₂O)₄](C₈H₅O₃)₂.2H₂O (Hökelek et al., 2009) and [Ni(C₈H₅O₃)₂(C₁₀H₁₄N₂O)₂(H₂O)₂] (Sertçelik et al., 2009) have also been determined.

In the title compound, NA ligands are monodentate. The four O atoms (O4, O5, and the symmetry-related atoms, O4', O5') in the equatorial plane around the Ni atom form a slightly distorted square-planar arrangement, while the slightly distorted octahedral coordination is completed by the two pyridine N atoms (N1, N1') of the NA ligands at 2.0834 (11) Å from the Ni atom in the axial positions (Table 1, Fig. 1). The average Ni—O bond length is 2.0792 (10) Å. The dihedral angle between the planar carboxylate group (O2/O3/C13) and the benzene ring B (C7—C12) is 28.28 (11)°, while that between rings A (N1/C1—C5) and B is 8.31 (4)°. In the crystal structure, O—H···O, N—H···O, C—H···O and C—H···F hydrogen bonds (Table 2) link the molecules into a three-dimensional network, in which they may be effective in the stabilization of the structure. The π–π contact between the pyridine and benzene rings, Cg1—Cg2, [where Cg1 and Cg2 are centroids of the rings A (N1/C1—C5) and B (C7—C12), respectively] may further stabilize the structure, with centroid-centroid distance of 3.626 (1) Å.

Experimental

The title compound was prepared by the reaction of NiSO₄.6H₂O (1.31 g, 5 mmol) in H₂O (20 ml) and NA (1.22 g, 10 mmol) in H₂O (20 ml) with sodium 2-fluorobenzoate (1.62 g, 10 mmol) in H₂O (50 ml). The mixture was filtered and set aside to crystallize at ambient temperature for five days, giving blue single crystals.