Bis(μ-nitrito-κ2O:O)bis­[bis­(1-methyl-1H-imidazole-κN3)(nitrito-κO)copper(II)]

Zhu, R.-Q.

doi:10.1107/S1600536812009804

metal-organic compounds

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ISSN: 2056-9890

Volume 68| Part 4| April 2012| Page m398

doi:10.1107/S1600536812009804

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Bis(μ-nitrito-κ²O:O)bis[bis(1-methyl-1H-imidazole-κN³)(nitrito-κO)copper(II)]

Run-Qiang Zhu ^a ^*

^aOrdered Matter Science Research Center, College of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, People's Republic of China
^*Correspondence e-mail: zhurunqiang@163.com

(Received 25 February 2012; accepted 6 March 2012; online 10 March 2012)

In the binuclear title compound, [Cu₂(NO₂)₄(C₄H₆N₂)₄], centrosymmetrically related complex molecules are linked via weak Cu—O interactions, forming dimeric units. The Cu^II atom displays an elongated square-pyramidal CuN₂O₃ coordination geometry with a slight tetrahedral distortion of the basal plane [maximum deviation = 0.249 (2) Å]. The dihedral angle formed by the imidazole rings is 26.20 (10)°.

Related literature

The structure of the title compound was determined as part of our ongoing study of potential ferroelectric phase change materials. For general background to ferroelectric compounds with metal-organic framework structures, see: Fu et al. (2009 ); Ye et al. (2006 ); Zhang et al. (2008 , 2010 ). For a related structure, see: Costes et al. (1995 ).

Experimental

Crystal data

[Cu₂(NO₂)₄(C₄H₆N₂)₄]
M_r = 639.55
Triclinic, $[P \overline 1]$
a = 7.8281 (16) Å
b = 8.4873 (17) Å
c = 10.054 (2) Å
α = 80.35 (3)°
β = 77.72 (3)°
γ = 79.46 (3)°
V = 635.9 (2) Å³
Z = 1
Mo Kα radiation
μ = 1.74 mm⁻¹
T = 293 K
0.29 × 0.23 × 0.20 mm

Data collection

Rigaku SCXmini diffractometer
Absorption correction: multi-scan (CrystalClear; Rigaku, 2005 ) T_min = 0.625, T_max = 0.706
6578 measured reflections
2900 independent reflections
2465 reflections with I > 2σ(I)
R_int = 0.035

Refinement

R[F² > 2σ(F²)] = 0.037
wR(F²) = 0.091
S = 1.05
2900 reflections
174 parameters
H-atom parameters constrained
Δρ_max = 0.40 e Å⁻³
Δρ_min = −0.29 e Å⁻³

Data collection: CrystalClear (Rigaku, 2005); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg & Putz, 2005 ); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536812009804/rz2715sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536812009804/rz2715Isup2.hkl

checkCIF report

Comment top

As part of our ongoing study of potential ferroelectric phase change materials we have determined the structures of several copper complexes and examined the changes in their dielectric constants with temperature, which is the usual method for detecting such behaviour (Fu et al., 2009; Ye et al., 2006; Zhang et al., 2008; Zhang et al., 2010). Unfortunately, the dielectric constant of the title compound indicates the onset of a ferroelectric phase change over the range 80–298 K.

As show in Fig. 1, the copper ion adopts an elongated square pyramidal geometry with a slight tetrahedral distortion in the basal plane (maximum deviation 0.249 (2) Å for atom N4) which is primarily associated with the coordination of the nitrite ions (O2—Cu1—O3 = 167.15 (8)°). As observed in a related compound (Costes et al., 1995), this geometry displaces atom O2 from the ideal coordination plane towards the centrosymmetrically related Cu1ⁱ copper atom [symmetry code: (i) 1-x, 1-y, -z] resulting in an O2—Cu1 distance of 2.578 (5) Å. While this distance is considerably longer than those in basal plane (Cu1—O2 and Cu1—O3 are 2.0221 (19) and 2.0085 (19) Å, respectively), the direction of the displacement of atom O2 and the orientations of the two nitrite ligands which place both atoms O1 and O3 on the opposite side of the coordination plane, suggest that there is a weak association of one complex molecule with its centrosymmetrically related. The dihedral angle formed by the trans-arranged imidazole rings is 26.20 (10)°. The crystal packing (Fig. 2) is governed only by van der Waals interactions.

Related literature top

The structure of the title compound was determined part of our ongoing study of potential ferroelectric phase change materials. For general background to ferroelectric metal-organic frameworks, see: Fu et al. (2009); Ye et al. (2006); Zhang et al. (2008, 2010). For a related structure, see: Costes et al. (1995).

Experimental top

An aqueous solution of 1-methylimidazole (2.0 g, 25 mmol) and H₂SO₄ (12.5 mmol) was treated with CuSO₄ (250 g, 12.5 mmol). After the mixture was stirred for a few minutes, Ba(NO₂)₂ (6.18 g, 25 mmol) was added to give a blue solution. Slow evaporation of the solution following removal of the precipitated BaSO₄ yielded blue crystals after a few days. M. p. 319–329 K.

Structure description top

Computing details top

Data collection: CrystalClear (Rigaku, 2005); cell refinement: CrystalClear (Rigaku, 2005); data reduction: CrystalClear (Rigaku, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top

	Fig. 1. Partial packing diagram of the title compound, with displacement ellipsoids drawn at the 30% probability level. The weak Cu—O interactions are shown as dashed lines. Primed atoms are generated by the symmetry operator: (') 1-x, 1-y, -z.
	Fig. 2. Packing diagram of the title compound. The weak Cu—O interactions are shown as dashed lines.

Bis(µ-nitrito-κ²O:O)bis[bis(1-methyl-1H-imidazole- κN³)(nitrito-κO)copper(II)] top

Crystal data top

[Cu₂(NO₂)₄(C₄H₆N₂)₄]	Z = 1
M_r = 639.55	F(000) = 326
Triclinic, P1	D_x = 1.670 Mg m⁻³
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 7.8281 (16) Å	Cell parameters from 2900 reflections
b = 8.4873 (17) Å	θ = 2.3–27.5°
c = 10.054 (2) Å	µ = 1.74 mm⁻¹
α = 80.35 (3)°	T = 293 K
β = 77.72 (3)°	Prism, blue
γ = 79.46 (3)°	0.29 × 0.23 × 0.20 mm
V = 635.9 (2) Å³

Data collection top

Rigaku SCXmini diffractometer	2465 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.035
Graphite monochromator	θ_max = 27.5°, θ_min = 3.0°
ω scans	h = −10→10
Absorption correction: multi-scan (CrystalClear; Rigaku, 2005)	k = −11→11
T_min = 0.625, T_max = 0.706	l = −13→13
6578 measured reflections	2 standard reflections every 150 reflections
2900 independent reflections	intensity decay: none

Refinement top

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)] = 0.037	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.091	H-atom parameters constrained
S = 1.05	w = 1/[σ²(F_o²) + (0.0423P)² + 0.1143P] where P = (F_o² + 2F_c²)/3
2900 reflections	(Δ/σ)_max = 0.001
174 parameters	Δρ_max = 0.40 e Å⁻³
0 restraints	Δρ_min = −0.29 e Å⁻³

Crystal data top

[Cu₂(NO₂)₄(C₄H₆N₂)₄]	γ = 79.46 (3)°
M_r = 639.55	V = 635.9 (2) Å³
Triclinic, P1	Z = 1
a = 7.8281 (16) Å	Mo Kα radiation
b = 8.4873 (17) Å	µ = 1.74 mm⁻¹
c = 10.054 (2) Å	T = 293 K
α = 80.35 (3)°	0.29 × 0.23 × 0.20 mm
β = 77.72 (3)°

Data collection top

Rigaku SCXmini diffractometer	2465 reflections with I > 2σ(I)
Absorption correction: multi-scan (CrystalClear; Rigaku, 2005)	R_int = 0.035
T_min = 0.625, T_max = 0.706	2 standard reflections every 150 reflections
6578 measured reflections	intensity decay: none
2900 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.037	0 restraints
wR(F²) = 0.091	H-atom parameters constrained
S = 1.05	Δρ_max = 0.40 e Å⁻³
2900 reflections	Δρ_min = −0.29 e Å⁻³
174 parameters

Special details top

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 (Å²) top

	x	y	z	U_iso*/U_eq
C1	0.7413 (4)	0.2449 (4)	0.4825 (3)	0.0549 (8)
H1A	0.7735	0.1313	0.4761	0.082*
H1B	0.7220	0.2619	0.5769	0.082*
H1C	0.8349	0.3012	0.4302	0.082*
C2	0.5675 (3)	0.4011 (3)	0.3090 (3)	0.0365 (6)
H2	0.6629	0.4389	0.2480	0.044*
C3	0.3061 (4)	0.3554 (4)	0.4028 (3)	0.0496 (8)
H3	0.1847	0.3553	0.4178	0.059*
C4	0.4134 (4)	0.2788 (4)	0.4889 (3)	0.0520 (8)
H4	0.3803	0.2185	0.5738	0.062*
C5	−0.1244 (4)	0.9207 (4)	−0.2032 (3)	0.0490 (8)
H5A	−0.2148	0.8597	−0.1523	0.074*
H5B	−0.0952	0.8978	−0.2964	0.074*
H5C	−0.1667	1.0341	−0.2020	0.074*
C6	0.0619 (3)	0.7480 (3)	−0.0451 (3)	0.0341 (6)
H6	−0.0165	0.6746	−0.0090	0.041*
C7	0.2892 (4)	0.8716 (3)	−0.0865 (3)	0.0384 (6)
H7	0.3984	0.8980	−0.0837	0.046*
C8	0.1763 (4)	0.9545 (3)	−0.1664 (3)	0.0411 (6)
H8	0.1925	1.0480	−0.2277	0.049*
N1	0.6145 (3)	0.7315 (3)	0.0924 (3)	0.0485 (6)
N3	0.5793 (3)	0.3061 (3)	0.4283 (2)	0.0376 (5)
N2	−0.0346 (3)	0.5775 (3)	0.2749 (3)	0.0495 (7)
N4	0.4024 (3)	0.4338 (3)	0.2893 (2)	0.0334 (5)
N5	0.2167 (3)	0.7405 (2)	−0.0090 (2)	0.0314 (5)
N6	0.0336 (3)	0.8755 (3)	−0.1406 (2)	0.0355 (5)
O1	0.5052 (3)	0.7955 (3)	0.1808 (2)	0.0541 (5)
O2	0.5618 (2)	0.6202 (2)	0.04605 (19)	0.0402 (4)
O3	0.0807 (3)	0.4952 (2)	0.1912 (2)	0.0422 (5)
O4	0.0182 (3)	0.6897 (3)	0.3082 (2)	0.0542 (6)
Cu1	0.31394 (4)	0.57713 (4)	0.13253 (3)	0.02903 (12)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0475 (18)	0.067 (2)	0.0476 (18)	0.0037 (15)	−0.0230 (15)	0.0039 (16)
C2	0.0324 (13)	0.0429 (16)	0.0316 (14)	−0.0020 (11)	−0.0056 (11)	−0.0021 (11)
C3	0.0389 (15)	0.063 (2)	0.0424 (17)	−0.0159 (14)	−0.0080 (13)	0.0158 (14)
C4	0.0492 (18)	0.066 (2)	0.0363 (16)	−0.0152 (15)	−0.0087 (14)	0.0143 (14)
C5	0.0434 (16)	0.0549 (19)	0.0458 (17)	0.0069 (14)	−0.0183 (14)	−0.0016 (14)
C6	0.0320 (13)	0.0338 (14)	0.0361 (14)	−0.0022 (10)	−0.0103 (11)	−0.0019 (11)
C7	0.0386 (14)	0.0354 (15)	0.0410 (15)	−0.0103 (11)	−0.0087 (12)	0.0016 (12)
C8	0.0473 (16)	0.0341 (15)	0.0391 (15)	−0.0068 (12)	−0.0096 (13)	0.0051 (12)
N1	0.0425 (14)	0.0497 (16)	0.0550 (16)	−0.0166 (12)	−0.0174 (12)	0.0094 (13)
N3	0.0383 (12)	0.0435 (13)	0.0294 (11)	−0.0013 (10)	−0.0103 (10)	−0.0004 (9)
N2	0.0326 (13)	0.0622 (18)	0.0475 (15)	−0.0074 (12)	−0.0065 (11)	0.0092 (13)
N4	0.0328 (11)	0.0378 (12)	0.0275 (11)	−0.0043 (9)	−0.0053 (9)	−0.0007 (9)
N5	0.0299 (11)	0.0318 (11)	0.0313 (11)	−0.0036 (9)	−0.0056 (9)	−0.0023 (9)
N6	0.0368 (12)	0.0352 (12)	0.0324 (11)	0.0020 (9)	−0.0093 (9)	−0.0032 (9)
O1	0.0652 (14)	0.0489 (13)	0.0529 (13)	−0.0133 (11)	−0.0137 (11)	−0.0116 (10)
O2	0.0361 (10)	0.0439 (11)	0.0383 (10)	−0.0065 (8)	−0.0062 (8)	0.0008 (8)
O3	0.0395 (10)	0.0432 (11)	0.0450 (11)	−0.0135 (9)	−0.0125 (9)	0.0041 (9)
O4	0.0547 (13)	0.0539 (14)	0.0501 (13)	−0.0016 (11)	−0.0062 (10)	−0.0076 (11)
Cu1	0.02605 (17)	0.03196 (19)	0.02820 (18)	−0.00537 (12)	−0.00609 (12)	0.00075 (12)

Geometric parameters (Å, º) top

C1—N3	1.460 (4)	C6—N5	1.325 (3)
C1—H1A	0.9600	C6—N6	1.341 (3)
C1—H1B	0.9600	C6—H6	0.9300
C1—H1C	0.9600	C7—C8	1.344 (4)
C2—N4	1.321 (3)	C7—N5	1.385 (3)
C2—N3	1.339 (3)	C7—H7	0.9300
C2—H2	0.9300	C8—N6	1.363 (3)
C3—C4	1.341 (4)	C8—H8	0.9300
C3—N4	1.370 (3)	N1—O1	1.219 (3)
C3—H3	0.9300	N1—O2	1.286 (3)
C4—N3	1.356 (4)	N2—O4	1.225 (3)
C4—H4	0.9300	N2—O3	1.286 (3)
C5—N6	1.466 (3)	N4—Cu1	1.989 (2)
C5—H5A	0.9600	N5—Cu1	1.985 (2)
C5—H5B	0.9600	O2—Cu1	2.0221 (19)
C5—H5C	0.9600	O3—Cu1	2.0085 (19)

N3—C1—H1A	109.5	N5—C7—H7	125.5
N3—C1—H1B	109.5	C7—C8—N6	107.0 (2)
H1A—C1—H1B	109.5	C7—C8—H8	126.5
N3—C1—H1C	109.5	N6—C8—H8	126.5
H1A—C1—H1C	109.5	O1—N1—O2	114.3 (2)
H1B—C1—H1C	109.5	C2—N3—C4	107.2 (2)
N4—C2—N3	111.1 (2)	C2—N3—C1	126.1 (2)
N4—C2—H2	124.4	C4—N3—C1	126.8 (2)
N3—C2—H2	124.4	O4—N2—O3	114.5 (2)
C4—C3—N4	109.7 (3)	C2—N4—C3	105.2 (2)
C4—C3—H3	125.2	C2—N4—Cu1	126.73 (18)
N4—C3—H3	125.2	C3—N4—Cu1	127.94 (19)
C3—C4—N3	106.8 (2)	C6—N5—C7	105.6 (2)
C3—C4—H4	126.6	C6—N5—Cu1	125.75 (18)
N3—C4—H4	126.6	C7—N5—Cu1	128.63 (18)
N6—C5—H5A	109.5	C6—N6—C8	107.5 (2)
N6—C5—H5B	109.5	C6—N6—C5	125.5 (2)
H5A—C5—H5B	109.5	C8—N6—C5	127.0 (2)
N6—C5—H5C	109.5	N1—O2—Cu1	115.28 (17)
H5A—C5—H5C	109.5	N2—O3—Cu1	114.51 (17)
H5B—C5—H5C	109.5	N5—Cu1—N4	173.10 (8)
N5—C6—N6	110.9 (2)	N5—Cu1—O3	90.30 (8)
N5—C6—H6	124.6	N4—Cu1—O3	89.99 (9)
N6—C6—H6	124.6	N5—Cu1—O2	90.40 (8)
C8—C7—N5	109.1 (2)	N4—Cu1—O2	90.85 (8)
C8—C7—H7	125.5	O3—Cu1—O2	167.15 (8)

N4—C3—C4—N3	−1.2 (4)	C7—C8—N6—C5	179.9 (3)
N5—C7—C8—N6	−0.5 (3)	O1—N1—O2—Cu1	−0.8 (3)
N4—C2—N3—C4	−0.9 (3)	O4—N2—O3—Cu1	−1.9 (3)
N4—C2—N3—C1	179.4 (3)	C6—N5—Cu1—O3	−9.1 (2)
C3—C4—N3—C2	1.3 (3)	C7—N5—Cu1—O3	168.4 (2)
C3—C4—N3—C1	−179.0 (3)	C6—N5—Cu1—O2	158.1 (2)
N3—C2—N4—C3	0.2 (3)	C7—N5—Cu1—O2	−24.4 (2)
N3—C2—N4—Cu1	177.04 (17)	C2—N4—Cu1—O3	168.7 (2)
C4—C3—N4—C2	0.7 (4)	C3—N4—Cu1—O3	−15.1 (3)
C4—C3—N4—Cu1	−176.2 (2)	C2—N4—Cu1—O2	1.6 (2)
N6—C6—N5—C7	0.1 (3)	C3—N4—Cu1—O2	177.7 (2)
N6—C6—N5—Cu1	178.14 (16)	N2—O3—Cu1—N5	−82.48 (18)
C8—C7—N5—C6	0.3 (3)	N2—O3—Cu1—N4	90.62 (18)
C8—C7—N5—Cu1	−177.67 (19)	N2—O3—Cu1—O2	−175.6 (3)
N5—C6—N6—C8	−0.5 (3)	N1—O2—Cu1—N5	90.08 (18)
N5—C6—N6—C5	−179.8 (2)	N1—O2—Cu1—N4	−83.13 (18)
C7—C8—N6—C6	0.6 (3)	N1—O2—Cu1—O3	−176.8 (3)

Experimental details

Crystal data
Chemical formula	[Cu₂(NO₂)₄(C₄H₆N₂)₄]
M_r	639.55
Crystal system, space group	Triclinic, P1
Temperature (K)	293
a, b, c (Å)	7.8281 (16), 8.4873 (17), 10.054 (2)
α, β, γ (°)	80.35 (3), 77.72 (3), 79.46 (3)
V (Å³)	635.9 (2)
Z	1
Radiation type	Mo Kα
µ (mm⁻¹)	1.74
Crystal size (mm)	0.29 × 0.23 × 0.20

Data collection
Diffractometer	Rigaku SCXmini
Absorption correction	Multi-scan (CrystalClear; Rigaku, 2005)
T_min, T_max	0.625, 0.706
No. of measured, independent and observed [I > 2σ(I)] reflections	6578, 2900, 2465
R_int	0.035
(sin θ/λ)_max (Å⁻¹)	0.649

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.037, 0.091, 1.05
No. of reflections	2900
No. of parameters	174
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.40, −0.29

Computer programs: CrystalClear (Rigaku, 2005), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg & Putz, 2005).

Acknowledgements

This work was supported by Southeast University.

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