Diaqua­bis­[4-(1H-imidazol-2-yl)pyridine-κN]bis­(nitrato-κO)cadmium

Abstract

In the title compound, [Cd(NO₃)₂(C₈H₇N₃)₂(H₂O)₂], the Cd^II cation is situated on an inversion center and is coordinated by the O atoms of two nitrate anions, by the N atoms of two 4-(imidazol-2-yl)pyridine ligands and by two water O atoms in a slightly distorted N₂O₄ octa­hedral geometry. The dihedral angle between the imidazole and pyridine rings is 1.6 (2)°. In the crystal, mol­ecules are linked by N—H⋯O, O—H⋯N and O—H⋯O hydrogen bonds, forming a three-dimensional network.

Related literature  

For background to compounds with metal-organic framework (MOF) structures, see: Batten & Robson (1998 ▶); Burrows (2011 ▶); Jin et al. (2010 ▶); Tanabe & Cohen (2011 ▶). For the use of N,N′-type ligands in MOFs, see: Custelcean (2010 ▶); Pschirer et al. (2002 ▶). For the structural analysis of an imidazole closely related to the ligand, see: Voss et al. (2008 ▶).

Experimental  

Crystal data  

• [Cd(NO₃)₂(C₈H₇N₃)₂(H₂O)₂]

• M _r = 562.78

• Monoclinic,

• a = 7.2508 (7) Å

• b = 12.1372 (12) Å

• c = 12.3509 (12) Å

• β = 102.278 (2)°

• V = 1062.07 (18) ų

• Z = 2

• Mo Kα radiation

• μ = 1.09 mm⁻¹

• T = 298 K

• 0.16 × 0.12 × 0.10 mm

Data collection  

• Bruker APEXII CCD area-detector diffractometer

• Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.845, T _max = 0.899

• 6543 measured reflections

• 2462 independent reflections

• 2272 reflections with I > 2σ(I)

• R _int = 0.046

Refinement  

• R[F ² > 2σ(F ²)] = 0.035

• wR(F ²) = 0.084

• S = 1.10

• 2462 reflections

• 157 parameters

• 3 restraints

• H atoms treated by a mixture of independent and constrained refinement

• Δρ_max = 0.73 e Å⁻³

• Δρ_min = −0.47 e Å⁻³

Data collection: APEX2 (Bruker, 2004 ▶); cell refinement: SAINT-Plus (Bruker, 2004 ▶); data reduction: SAINT-Plus; 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.

Supplementary Material

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
N3—H3⋯O3i	0.86	2.10	2.923 (3)	160
O4—H4B⋯N2ii	0.82 (1)	1.98 (1)	2.796 (3)	174 (4)
O4—H4A⋯O2iii	0.81 (1)	2.14 (1)	2.946 (4)	174 (4)
O4—H4A⋯O3iii	0.81 (1)	2.65 (3)	3.197 (3)	126 (3)

Symmetry codes: (i) ; (ii) ; (iii) .

supplementary crystallographic information

Comment

The construction of functional metal-organic frameworks is of great interest due to their intriguing network topologies and their potential applications as microporous, magnetism, catalysis, nonlinear optics, molecular separation, toxic materials adsorption and molecular sensors (Batten & Robson, 1998; Burrows, 2011; Jin et al., 2010; Tanabe & Cohen, 2011). The molecular geometry and flexibility of multidentate ligands play key roles in the field of supramolecular self-assemble on metal-organic frameworks. For example, 4, 4'-bipyridine, 1, 2- bis(4-pyridyl)ethane and trans-bis(4-pyridyl)ethene as ligands can form a lot of coordination polymers with different structure features (Custelcean, 2010; Pschirer et al., 2002). Our interest is to exploit the coordination chemistry of 2-pyridinyl-imidazole and its derivatives together with their potential application in material science.

In the report, the mono-nuclear cadmium(II) complex, [Cd(C₈H₇N₃)₂(NO₃)₂(H₂O)₂], was obtained via the reaction of 4-(1H-imidazol-2-yl)-pyridine and cadmium(II) nitrate. Single crystal X-ray diffraction analysis reveals that the cadmium(II) atom is six-coordinated in a slightly distorted octahedral geometry by two pyridine nitrogen atoms, two nitrate anions oxygen atoms and two aqua oxygen atoms forming N₂O₄ donor set (Figure 1). The cadmium atom is situated on an inversion center. Bond distances of Cd(1)—N(1), Cd(1)—O(1) and Cd(1)—O(4) are 2.276 (2), 2.503 (3) and 2.310 (2) Å, respectivity. The dihedral angle between the imidazole and pyridine rings is 1.6 (2)°. In the crystal, molecules are linked by N—H······O, O—H······N and O—H······O hydrogen bonds, forming a three-dimensional network (Figure 2).

Experimental

The organic ligand 4-(1H-imidazol-2-yl)-pyridine was prepared according to the previously reported literature methods (Voss et al., 2008). Cd(NO₃)₂ (24 mg, 0.1 mmol) dissolved in 5 ml ethanol and a solution of 4-(1H-imidazol-2-yl)-pyridine (29 mg, 0.2 mmol) in another 5 ml of ethanol were mixed, refluxed for 5 h and filtered. The filtrate was left at room temperature. Suitable single crystals for a X-ray diffraction study were obtained after a few days (yield: 73% based on Cd(II) salts).

Refinement

H atoms were positioned geometrically at distances of 0.93 (CH), and 0.86 (NH) from the respective parent atoms, a riding model was used during the refinement process. U_iso values were constrained to be 1.2 times U_eq of the carrier atom.

Figures

Fig. 1.

The molecular structure of (I) with atom labels and 30% probability displacement ellipsoids for non-H atoms.

Fig. 2.

The three-dimensional supramolecular packing architecture of (I) with hydrogen-bonds depicted as dashed lines.

Crystal data

[Cd(NO3)2(C8H7N3)2(H2O)2]	F(000) = 564
Mr = 562.78	Dx = 1.760 Mg m−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 4257 reflections
a = 7.2508 (7) Å	θ = 2.4–28.3°
b = 12.1372 (12) Å	µ = 1.09 mm−1
c = 12.3509 (12) Å	T = 298 K
β = 102.278 (2)°	Block, colorless
V = 1062.07 (18) Å3	0.16 × 0.12 × 0.10 mm
Z = 2

Data collection

Bruker APEXII CCD area-detector diffractometer	2462 independent reflections
Radiation source: fine-focus sealed tube	2272 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.046
phi and ω scans	θmax = 28.0°, θmin = 2.4°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −7→9
Tmin = 0.845, Tmax = 0.899	k = −15→15
6543 measured reflections	l = −14→16

Refinement

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.035	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.084	H atoms treated by a mixture of independent and constrained refinement
S = 1.10	w = 1/[σ2(Fo2) + (0.0252P)2 + 1.0694P] where P = (Fo2 + 2Fc2)/3
2462 reflections	(Δ/σ)max = 0.001
157 parameters	Δρmax = 0.73 e Å−3
3 restraints	Δρmin = −0.47 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
Cd1	1.0000	0.5000	0.5000	0.03811 (11)
C1	0.8396 (5)	0.6142 (2)	0.2671 (2)	0.0466 (7)
H1	0.8465	0.6754	0.3131	0.056*
C2	0.7823 (5)	0.6301 (2)	0.1550 (2)	0.0456 (7)
H2	0.7498	0.7002	0.1269	0.055*
C3	0.7732 (4)	0.5408 (2)	0.0842 (2)	0.0341 (5)
C4	0.8205 (5)	0.4390 (2)	0.1325 (2)	0.0499 (8)
H4	0.8146	0.3764	0.0885	0.060*
C5	0.8761 (5)	0.4304 (3)	0.2458 (2)	0.0497 (7)
H5	0.9086	0.3612	0.2762	0.060*
C6	0.7176 (4)	0.5554 (2)	−0.0359 (2)	0.0337 (5)
C7	0.6323 (5)	0.6241 (3)	−0.1984 (2)	0.0502 (7)
H7	0.5950	0.6748	−0.2552	0.060*
C8	0.6534 (5)	0.5154 (3)	−0.2132 (3)	0.0506 (8)
H8	0.6350	0.4779	−0.2803	0.061*
N1	0.8860 (4)	0.51635 (18)	0.3142 (2)	0.0396 (5)
N2	0.6733 (4)	0.6497 (2)	−0.08794 (19)	0.0426 (5)
N3	0.7075 (4)	0.4715 (2)	−0.1096 (2)	0.0427 (6)
H3	0.7309	0.4032	−0.0939	0.051*
N4	0.7084 (3)	0.6785 (2)	0.5340 (2)	0.0411 (5)
O1	0.8766 (3)	0.6853 (3)	0.5384 (2)	0.0747 (8)
O2	0.6297 (5)	0.5914 (2)	0.5037 (3)	0.0965 (11)
O3	0.6156 (3)	0.75586 (18)	0.5590 (2)	0.0562 (6)
O4	1.2220 (3)	0.63059 (19)	0.4800 (2)	0.0573 (6)
H4B	1.200 (5)	0.6945 (15)	0.461 (4)	0.086*
H4A	1.334 (2)	0.617 (3)	0.490 (4)	0.086*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
Cd1	0.05052 (19)	0.03477 (16)	0.02528 (16)	−0.00965 (11)	−0.00034 (11)	0.00115 (10)
C1	0.071 (2)	0.0372 (14)	0.0297 (13)	−0.0023 (14)	0.0073 (13)	−0.0033 (11)
C2	0.069 (2)	0.0356 (14)	0.0303 (14)	0.0046 (14)	0.0079 (13)	0.0017 (11)
C3	0.0388 (13)	0.0346 (12)	0.0279 (12)	−0.0030 (11)	0.0050 (10)	0.0008 (10)
C4	0.081 (2)	0.0318 (14)	0.0306 (14)	−0.0012 (14)	−0.0011 (14)	−0.0041 (11)
C5	0.074 (2)	0.0355 (14)	0.0333 (15)	−0.0032 (14)	−0.0040 (13)	0.0036 (12)
C6	0.0389 (13)	0.0332 (13)	0.0285 (12)	0.0001 (10)	0.0059 (10)	−0.0012 (10)
C7	0.065 (2)	0.0547 (18)	0.0284 (14)	0.0112 (15)	0.0049 (13)	0.0079 (12)
C8	0.069 (2)	0.0556 (19)	0.0252 (14)	0.0020 (15)	0.0045 (13)	−0.0020 (12)
N1	0.0523 (14)	0.0368 (12)	0.0267 (12)	−0.0080 (10)	0.0014 (10)	0.0007 (9)
N2	0.0578 (15)	0.0393 (12)	0.0303 (11)	0.0077 (11)	0.0083 (10)	0.0027 (9)
N3	0.0615 (16)	0.0356 (11)	0.0293 (12)	0.0016 (11)	0.0055 (11)	−0.0029 (9)
N4	0.0460 (13)	0.0387 (13)	0.0408 (13)	0.0056 (10)	0.0142 (10)	0.0112 (10)
O1	0.0446 (13)	0.111 (2)	0.0681 (17)	0.0082 (14)	0.0112 (12)	0.0077 (16)
O2	0.114 (3)	0.0367 (14)	0.151 (3)	−0.0131 (15)	0.055 (2)	−0.0218 (17)
O3	0.0654 (14)	0.0389 (11)	0.0700 (16)	0.0107 (11)	0.0271 (12)	0.0021 (10)
O4	0.0418 (11)	0.0386 (12)	0.0886 (18)	−0.0045 (9)	0.0075 (12)	0.0101 (12)

Geometric parameters (Å, º)

Cd1—N1	2.276 (2)	C5—N1	1.335 (4)
Cd1—N1i	2.276 (2)	C5—H5	0.9300
Cd1—O4	2.310 (2)	C6—N2	1.319 (3)
Cd1—O4i	2.310 (2)	C6—N3	1.357 (3)
Cd1—O1	2.503 (3)	C7—C8	1.345 (4)
Cd1—O1i	2.503 (3)	C7—N2	1.368 (4)
C1—N1	1.333 (4)	C7—H7	0.9300
C1—C2	1.371 (4)	C8—N3	1.364 (4)
C1—H1	0.9300	C8—H8	0.9300
C2—C3	1.386 (4)	N3—H3	0.8600
C2—H2	0.9300	N4—O1	1.211 (3)
C3—C4	1.384 (4)	N4—O2	1.222 (4)
C3—C6	1.463 (3)	N4—O3	1.232 (3)
C4—C5	1.374 (4)	O4—H4B	0.816 (10)
C4—H4	0.9300	O4—H4A	0.814 (10)
N1—Cd1—N1i	180.00 (4)	N1—C5—C4	123.4 (3)
N1—Cd1—O4	86.81 (9)	N1—C5—H5	118.3
N1i—Cd1—O4	93.19 (9)	C4—C5—H5	118.3
N1—Cd1—O4i	93.19 (9)	N2—C6—N3	110.6 (2)
N1i—Cd1—O4i	86.81 (9)	N2—C6—C3	125.8 (2)
O4—Cd1—O4i	180.0	N3—C6—C3	123.6 (2)
N1—Cd1—O1	92.58 (9)	C8—C7—N2	110.6 (3)
N1i—Cd1—O1	87.42 (9)	C8—C7—H7	124.7
O4—Cd1—O1	71.89 (9)	N2—C7—H7	124.7
O4i—Cd1—O1	108.11 (9)	C7—C8—N3	105.9 (3)
N1—Cd1—O1i	87.42 (9)	C7—C8—H8	127.1
N1i—Cd1—O1i	92.58 (9)	N3—C8—H8	127.1
O4—Cd1—O1i	108.11 (9)	C1—N1—C5	116.4 (3)
O4i—Cd1—O1i	71.89 (9)	C1—N1—Cd1	121.42 (18)
O1—Cd1—O1i	180.00 (7)	C5—N1—Cd1	121.97 (19)
N1—C1—C2	124.1 (3)	C6—N2—C7	105.5 (2)
N1—C1—H1	118.0	C6—N3—C8	107.4 (3)
C2—C1—H1	118.0	C6—N3—H3	126.3
C1—C2—C3	119.4 (3)	C8—N3—H3	126.3
C1—C2—H2	120.3	O1—N4—O2	118.2 (3)
C3—C2—H2	120.3	O1—N4—O3	122.4 (3)
C4—C3—C2	116.9 (2)	O2—N4—O3	119.4 (3)
C4—C3—C6	122.3 (3)	N4—O1—Cd1	109.1 (2)
C2—C3—C6	120.8 (2)	Cd1—O4—H4B	126 (3)
C5—C4—C3	119.9 (3)	Cd1—O4—H4A	123 (3)
C5—C4—H4	120.0	H4B—O4—H4A	111 (2)
C3—C4—H4	120.0
N1—C1—C2—C3	−0.9 (5)	O1i—Cd1—N1—C1	−161.4 (3)
C1—C2—C3—C4	1.1 (5)	N1i—Cd1—N1—C5	−114 (15)
C1—C2—C3—C6	−178.3 (3)	O4—Cd1—N1—C5	121.5 (3)
C2—C3—C4—C5	−1.0 (5)	O4i—Cd1—N1—C5	−58.5 (3)
C6—C3—C4—C5	178.4 (3)	O1—Cd1—N1—C5	−166.8 (3)
C3—C4—C5—N1	0.7 (6)	O1i—Cd1—N1—C5	13.2 (3)
C4—C3—C6—N2	−179.0 (3)	N3—C6—N2—C7	0.5 (3)
C2—C3—C6—N2	0.4 (4)	C3—C6—N2—C7	179.7 (3)
C4—C3—C6—N3	0.1 (4)	C8—C7—N2—C6	−0.6 (4)
C2—C3—C6—N3	179.4 (3)	N2—C6—N3—C8	−0.2 (4)
N2—C7—C8—N3	0.5 (4)	C3—C6—N3—C8	−179.4 (3)
C2—C1—N1—C5	0.6 (5)	C7—C8—N3—C6	−0.2 (4)
C2—C1—N1—Cd1	175.5 (3)	O2—N4—O1—Cd1	−6.3 (4)
C4—C5—N1—C1	−0.5 (5)	O3—N4—O1—Cd1	173.7 (2)
C4—C5—N1—Cd1	−175.3 (3)	N1—Cd1—O1—N4	77.8 (2)
N1i—Cd1—N1—C1	72 (15)	N1i—Cd1—O1—N4	−102.2 (2)
O4—Cd1—N1—C1	−53.1 (3)	O4—Cd1—O1—N4	163.6 (2)
O4i—Cd1—N1—C1	126.9 (3)	O4i—Cd1—O1—N4	−16.4 (2)
O1—Cd1—N1—C1	18.6 (3)	O1i—Cd1—O1—N4	29 (12)

Symmetry code: (i) −x+2, −y+1, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N3—H3···O3ii	0.86	2.10	2.923 (3)	160
O4—H4B···N2iii	0.82 (1)	1.98 (1)	2.796 (3)	174 (4)
O4—H4A···O2iv	0.81 (1)	2.14 (1)	2.946 (4)	174 (4)
O4—H4A···O3iv	0.81 (1)	2.65 (3)	3.197 (3)	126 (3)

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