Di-μ-nicotinato-κ2 N:O;κ2 O:N-bis­[aqua­(ethyl­enediamine-κ2 N,N′)(nicotinato-κN)cadmium(II)] dihydrate

Jan Moncol; Dušan Mikloš; Peter Segla; Marian Koman

doi:10.1107/S1600536808009756

. 2008 Apr 16;64(Pt 5):m665–m666. doi: 10.1107/S1600536808009756

Di-μ-nicotinato-κ² N:O;κ² O:N-bis[aqua(ethylenediamine-κ² N,N′)(nicotinato-κN)cadmium(II)] dihydrate

Jan Moncol ^a,^*, Dušan Mikloš ^a, Peter Segla ^a, Marian Koman ^a

PMCID: PMC2961096 PMID: 21202208

Abstract

The dinuclear molecule of the title compound, [Cd₂(C₆H₄NO₂)₄(C₂H₈N₂)₂(H₂O)₂]·2H₂O, lies on an inversion centre and forms 12-membered (CdNC₃O)₂ metallacycles with the two Cd²⁺ ions bridged by two nicotinate ligands. Both Cd²⁺ ions display coordination polyhedra with a distorted octahedral geometry that includes two pyridine N atoms from bridging and terminal nicotinate anions, two amine N atoms from chelating ethylenediamine ligands, carboxylate O atoms from bridging nicotinate anions and water O atoms. Intermolecular O—H⋯O and N—H⋯O hydrogen bonds result in the formation of a three-dimensional network, and π–π stacking interactions are observed between symmetry-related pyridine rings of bridging as well as terminal nicotinate anions (the centroid–centroid distances are 3.59 and 3.69 Å, respectively, and the distances between parallel planes of the stacked pyridine rings are 3.53 and 3.43 Å, respectively). The two methylene groups of the ethylenediamine ligand are disordered over two positions; the site occupancy factors are ca 0.8 and 0.2.

Related literature

For related literature, see: Bernstein et al. (1995 ▶); Chen (2003 ▶); Clegg et al. (1995 ▶); Evans & Lin (2001 ▶); Janiak (2000 ▶); Kang et al. (2007 ▶); Liang & Li (2005 ▶); Lu & Kohler (2002 ▶); Lu et al. (2007 ▶); Luo et al. (2004 ▶); Song et al. (2006 ▶); Xian et al. (2007 ▶); Zhang et al. (1996 ▶); Zhang et al. (2004 ▶). For related structures, see: Ayyappan et al. (2001 ▶); Abu-Youssef (2005 ▶); Chen et al. (2001 ▶, 2008 ▶); Lin et al. (2000 ▶); Liu et al. (2005 ▶); Madalan et al. (2005 ▶); Wang et al. (2002 ▶); Wasson & LaDuca (2007 ▶); Wu et al. (2003 ▶).

Experimental

Crystal data

[Cd₂(C₆H₄NO₂)₄(C₂H₈N₂)₂(H₂O)₂]·2H₂O
M _r = 905.18
Triclinic,
a = 7.678 (1) Å
b = 10.364 (1) Å
c = 11.984 (2) Å
α = 101.080 (1)°
β = 93.60 (1)°
γ = 109.63 (1)°
V = 873.1 (2) Å³
Z = 1
Mo Kα radiation
μ = 1.29 mm⁻¹
T = 294 (2) K
0.35 × 0.30 × 0.20 mm

Data collection

Siemens P4 diffractometer
Absorption correction: ψ scan (XEMP; Siemens, 1994 ▶) T _min = 0.652, T _max = 0.776
6118 measured reflections
5071 independent reflections
4491 reflections with I > 2σ(I)
R _int = 0.055
3 standard reflections every 97 reflections intensity decay: 2.0%

Refinement

R[F ² > 2σ(F ²)] = 0.030
wR(F ²) = 0.076
S = 1.06
5071 reflections
245 parameters
21 restraints
H-atom parameters constrained
Δρ_max = 0.57 e Å⁻³
Δρ_min = −0.62 e Å⁻³

Data collection: XSCANS (Siemens, 1994 ▶); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 (Farrugia, 1997 ▶); software used to prepare material for publication: enCIFer (Allen et al., 2004 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808009756/zl2107sup1.cif

e-64-0m665-sup1.cif^{(23.9KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808009756/zl2107Isup2.hkl

e-64-0m665-Isup2.hkl^{(243.5KB, hkl)}

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

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1W—H1W⋯O4ⁱ	0.82	1.84	2.659 (2)	174
O1W—H2W⋯O2ⁱⁱ	0.84	1.93	2.762 (3)	169
O2W—H3W⋯O2Wⁱⁱⁱ	0.84	2.25	3.041 (10)	158
O2W—H4W⋯O3^iv	0.82	1.97	2.742 (5)	157
N3—H3A⋯O2	0.89	2.37	3.099 (3)	139
N3—H3B⋯O4^v	0.90	2.11	2.966 (3)	160
N3—H3C⋯O2	0.89	2.36	3.099 (3)	141
N3—H3D⋯O4^v	0.90	2.24	2.966 (3)	138
N4—H4A⋯O3ⁱ	0.91	2.16	3.054 (3)	169
N4—H4B⋯O2W	0.91	2.22	2.975 (4)	140
N4—H4C⋯O3ⁱ	0.92	2.26	3.054 (3)	145
N4—H4D⋯O2W	0.90	2.13	2.975 (4)	157

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

Acknowledgments

We thank the Scientific Grant Agency of the Ministry of Education of the Slovak Republic and the Slovak Academy of Sciences (grant Nos. 1/4454/07 and 1/0353/08) for financial support.

supplementary crystallographic information

Comment

Several Cd^II coordination polymers that contain bridging 3-pyridylcarboxylate (nicotinate) ligands have been reported recently (Abu-Youssef, 2005; Evans & Lin, 2001; Chen, (2003); Clegg et al., 1995; Kang et al., 2007; Liang & Li, 2005; Lu & Kohler, 2002; Lu et al., 2007; Song et al., 2006; Xian et al. 2007; Zhang et al., 1996; Zhang et al., 2004). However, if the nicotinate anions are coordinated only as terminal ligands, the possibility of participating in a hydrogen-bonding network originates. As part of our efforts to investigate metal(II) complexes based on pyridine carboxylic acids, we report herein the crystal structure of the title compound, (I).

Figure 1 shows a representative ORTEP diagram for (I). The Cd centers are µ₂-bridged by two nicotinate ligands to form a twelve-membered (CdNC₃O)₂ ring with the Cd···Cdⁱ [symmetry code: (i) -x + 1, -y + 1, -z + 1] distance being 7.355 (1) Å. The two nicotinate ligands bridge two Cd centers through the pyridyl N atom and one of the carboxylate O atoms. The Cd²⁺ ion has a distorted octahedral coordination formed by the two pyridine N atoms of bridging [Cd–N1ⁱ = 2.349 (2) Å] and terminal [Cd–N2 = 2.406 (2) Å] nicotinate anions; the two N atoms of chelating 1,2-ethylenediamine ligands [Cd–N3 = 2.321 (2) Å and Cd–N4 = 2.345 (2) Å], and two O atoms in trans positions, one from the carboxylate group of a µ₂-bridging nicotinate ligand [Cd–O1 = 2.325 (2) Å] and one from the coordinated water molecule [Cd–O1W = 2.348 (2) Å].

The structure of (I) can be compared with two dimeric copper(II) complexes with a µ₂-bridging nicotinate ligand [Cu(µ₂-nic)(dien)]₂(nic)₂ (II) and [Cu(µ₂-nic)(dien)]₂(BF₄)₂.2MeOH (III) [dien is diethylenetriamine] (Chen et al., 2008). Both compounds (II-III) are dimeric complexes, where the nicotinate ligands are bridging two Cu centers to form similar twelve-membered (CuNC₃O)₂ rings (Table 2). On the other hand, the same (MNC₃O)₂ [M = Cu, Cd, Ni or Mn] rings are observed in some metal(II) nicotinate based coordination polymers, but the nicotinate ligands are µ₃-bridging ones. M···M distances and chromophores for dinuclear and polymeric complexes with twelve-membered (MNC₃O)₂ rings are compared in Table 2.

The hydrogen-bonding parameters of (I) are listed in Table 1. In the crystal structure, intermolecular O–H···O and N–H···O hydrogen-bonds (Table 1) link the molecules to form a three-dimensional network (Figures 2 and 3). One of the amine H atoms of the 1,2-ethylenediamine ligand forms an intramolecular hydrogen-bond [N3–H3A···O2 or N3–H3C···O2] and partipicates in creation of aan intramolecular metallocyclus with an S(6) pattern (Bernstein et al., 1995) (Figure 2). One O atom and one H atom of each of the uncoordinated water molecules, two amine groups of the 1,2-ethylenediamine ligands and one carboxylate O atom of each of the terminal nicotinate ligands are connected through hydrogen-bonds to rings with a graph set motif of R₆⁶(12) (Bernstein et al., 1995) [N4–H4B···O2W or N4–H4D···O2W; N4–H4A···O3ⁱⁱⁱ or N4–H4C···O3ⁱⁱⁱ; and O2W–H4W···O3ⁱ, symmetry codes: (i) -x + 1, -y + 1, -z + 1; (iii) x, y - 1, z] (Figure 2). The H atoms from the amine groups of the 1,2-ethylenediamine ligand and the H atoms from the coordinated water molecule are connected through hydrogen-bonds to the carboxylate O atoms of the terminal nicotinate ligands [N4–H4A···O3ⁱⁱⁱ or N4–H4C···O3ⁱⁱⁱ; O1W–H1W···O4ⁱⁱⁱ] and these groups create six-membered R₂²(8) rings (Bernstein et al., 1995) (Figure 2). The remaining hydrogen-bonds from the amine groups of the ethylendiamine ligands are connected to carboxylate O atoms of terminal nicotinate ligands of neighbouring complex molecules [N3–H3B···O4ⁱⁱ or N3–H3D···O4ⁱⁱ, symmetry codes: (ii) -x + 1, -y + 1, -z] (Figure 2). Further intermolecular hydrogen-bonds between uncoordinated water molecules [O2W–H3W···O2W^v, symmetry codes: (v) -x, -y, -z + 1], and between coordinated water molecules and carboxylate O atoms of bridging nicotinate ligands [O1W–H2W···O2^iv, symmetry codes: (iv) x + 1, y, z] are shown in Figure 3.

Additional interactions between the pyridine rigs of nicotinate ligands are π-π stacking interactions (Janiak, 2000) between the two adjacent pyridine rings of terminal nicotinate ligands [N2/C8—C12] (π_a-π_aⁱⁱ) (Figure 2), and between the two adjacent pyridine rings of bridging nicotinate ligands [N1/C2—C6] (π_b-π_b^vi) (Figure 3) [symmetry codes: (ii) -x + 1, -y + 1, -z; (vi) -x, -y + 1, -z - 1]. The centroid (C_g) distances C_g···C_g are 3.69 and 3.59 Å, respectively. The distances between parallel planes of the stacked pyridine rings are 3.43 and 3.53 Å, respectively.

Experimental

The title complex was formed in a methanolic solution (30 cm³) of Cd(nicotinate)₂.H₂O (1.25 mmol) by adding 1,2-ethylenediamine in the molar ratio of 1:1. The resulting solution was left to slowly evaporate at room temperature. Well shaped crystals, suitable for X-ray structure analysis were collected after a few days by filtration and finally dried in vacuo. Anal. Calc.: C, 37.14; H, 4.45; N, 12.37; Cd, 24.83; Found: C, 36.82; H, 4.53; N, 12.30; Cd, 24.65. Selected IR data (KBr) cm^-1: 1611 vs,br ν_as(COO^-); 1383 vs,br ν_s(COO^-); 643mδ(pyridine ring in-plane bending); 432mχ(pyridine ring out-of-plane bending).