A polymorph of diaqua­bis(pyrazine-2-carboxyl­ato-κ2N1,O)copper(II)

Wang, G.-H.; He, R.-L.; Meng, F.-J.; Hu, N.-H.; Xu, J.-W.

doi:10.1107/S1600536809045371

metal-organic compounds

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Volume 65| Part 12| December 2009| Page m1511

doi:10.1107/S1600536809045371

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A polymorph of diaquabis(pyrazine-2-carboxylato-κ²N¹,O)copper(II)

Guan-Hua Wang,^a Ren-Ling He,^a Fan-Jin Meng,^a Ning-Hai Hu ^a ^* and Jing-Wei Xu ^a ^*

^aThe State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, People's Republic of China
^*Correspondence e-mail: hunh@ciac.jl.cn, jwxu@ciac.jl.cn

(Received 26 October 2009; accepted 29 October 2009; online 4 November 2009)

The title compound, [Cu(C₅H₃N₂O₂)₂(H₂O)₂], is a new polymorph of the previously reported compound [Klein et al. (1982 ). Inorg. Chem. 21, 1891–1897]. The Cu^II atom, lying on an inversion center, is coordinated by two N atoms and two O atoms from two pyrazine-2-carboxylate ligands and by two water molecules in a distorted octahedral geometry with the water molecules occupying the axial sites. Intermolecular O—H⋯O, O—H⋯N and C—H⋯O hydrogen bonds connect the complex molecules into a two-dimensional layer parallel to (10 $[\overline{1}]$ ), whereas the previously reported polymorph exhibits a three-dimensional hydrogen-bonded network.

Related literature

For general background to metal complexes of pyrazinecarboxylates, see: Dong et al. (2000 ); Kubota et al. (2006 ); Luo et al. (2004 ); Ptasiewicz-Bak et al. (1995 ). For the previously reported polymorph, see: Klein et al. (1982). For a related structure, see: Chutia et al. (2009 ).

Experimental

Crystal data

[Cu(C₅H₃N₂O₂)₂(H₂O)₂]
M_r = 345.76
Monoclinic, P 2₁ /n
a = 6.7066 (12) Å
b = 7.9041 (14) Å
c = 12.030 (2) Å
β = 105.036 (2)°
V = 615.88 (19) Å³
Z = 2
Mo Kα radiation
μ = 1.81 mm⁻¹
T = 293 K
0.29 × 0.25 × 0.20 mm

Data collection

Bruker SMART APEX CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ) T_min = 0.626, T_max = 0.711
3322 measured reflections
1212 independent reflections
1119 reflections with I > 2σ(I)
R_int = 0.014

Refinement

R[F² > 2σ(F²)] = 0.024
wR(F²) = 0.071
S = 1.10
1212 reflections
98 parameters
H-atom parameters constrained
Δρ_max = 0.24 e Å⁻³
Δρ_min = −0.27 e Å⁻³

Table 1
Selected bond lengths (Å)

Cu1—O1	1.9486 (12)
Cu1—N1	1.9753 (14)
Cu1—O1W	2.6143 (14)

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1W—H1A⋯O2ⁱ	0.82	1.99	2.796 (2)	168
O1W—H1B⋯N2ⁱⁱ	0.82	2.33	3.041 (2)	145
C1—H1⋯O2ⁱⁱ	0.93	2.42	3.226 (2)	144
Symmetry codes: (i) $[x+{\script{1\over 2}}, -y+{\script{3\over 2}}, z+{\script{1\over 2}}]$ ; (ii) $[x+{\script{1\over 2}}, -y+{\script{1\over 2}}, z+{\script{1\over 2}}]$ .

Data collection: SMART (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: SHELXTL (Sheldrick, 2008) and Mercury (Macrae et al., 2006 ); software used to prepare material for publication: SHELXTL.

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809045371/is2480sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809045371/is2480Isup2.hkl

checkCIF report

Comment top

Pyrazinecarboxylates have been extensively studied as excellent bridging ligands in the coordination chemistry research (Dong et al., 2000; Kubota et al., 2006; Luo et al., 2004; Ptasiewicz-Bak et al., 1995). The structure and magnetic properties of a copper(II) complex with the pyrazine-2-carboxylate (pzc) ligand (polymorph I) has been reported by Klein et al. (1982). We report here the structure of a new polymorph (polymorph II) of the title compound.

The polymorph II crystallizes in the monoclinic space group P2₁/n (polymorph I in P2₁/c). The Cu^II atom, lying on an inversion center, is six-coordinated in a distorted octahedral geometry, defined by two O atoms and two N atoms from two pzc ligands in the equatorial plane and two water molecules in the axial positions (Table 1 and Fig. 1). Weak coordination exists between the Cu^II center and the coordinated water molecule, with a Cu—O distance of 2.6143 (14) Å, due to Jahn-Teller effects. The bond lengths and angles are in normal ranges (Chutia et al., 2009; Klein et al., 1982). The coordinated water molecule donates its two H atoms to an uncoordinated carboxylate O atom and a pyrazine N atom of the neighboring molecules (Table 2 and Fig. 2). One complex molecule is linked to four neighboring molecules through these O—H···O and O—H···N hydrogen bonds, forming a two-dimensional layer in the (1 0 1) plane. Weak C—H···O hydrogen bond (Table 2) stabilizes the layer structure. In the previously reported polymorph I, the water molecule forms two O—H···O hydrogen bonds with a coordinated carboxylate O atom and an uncoordinated carboxylate O atom. One complex molecule is linked to six neighboring molecules, leading to a three-dimensional network.

Related literature top

For general background to metal complexes of pyrazinecarboxylates, see: Dong et al. (2000); Kubota et al. (2006); Luo et al. (2004); Ptasiewicz-Bak et al. (1995). For the previously reported polymorph, see: Klein et al. (1982). For a related structure, see: Chutia et al. (2009).

Experimental top

Aqueous triethylamine (0.05 ml) was added to a suspending solution of Hpzc (0.012 g, 0.1 mmol) in H₂O (7 ml), followed by dropwise addition of a solution of Cu(NO₃)₂.3H₂O (0.024 g, 0.1 mmol) in H₂O (3 ml). The mixture was stirred and sealed in a 15 ml Teflon-lined stainless steel autoclave and heated at 413 K for 3 d under autogenous pressure. When the mixture was cooled to room temperature, blue block crystals of the title compound were obtained (yield 0.029 g, 85% based on Cu).

Computing details top

Data collection: SMART (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008) and Mercury (Macrae et al., 2006); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top

	Fig. 1. The molecular structure of the title compound. Displacement ellipsoids are drawn at the 30% probability level. [Symmetry code: (i) -x, 1 - y, 2 - z.]
	Fig. 2. A part of the two-dimensional layer structure in the title compound. Dashed lines denote hydrogen bonds.

diaquabis(pyrazine-2-carboxylato-κ²N¹,O)copper(II) top

Crystal data top

[Cu(C₅H₃N₂O₂)₂(H₂O)₂]	F(000) = 350
M_r = 345.76	D_x = 1.864 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 2148 reflections
a = 6.7066 (12) Å	θ = 3.1–26.1°
b = 7.9041 (14) Å	µ = 1.81 mm⁻¹
c = 12.030 (2) Å	T = 293 K
β = 105.036 (2)°	Block, blue
V = 615.88 (19) Å³	0.29 × 0.25 × 0.20 mm
Z = 2

Data collection top

Bruker SMART APEX CCD diffractometer	1212 independent reflections
Radiation source: sealed tube	1119 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.014
ϕ and ω scans	θ_max = 26.1°, θ_min = 3.1°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −8→8
T_min = 0.626, T_max = 0.711	k = −8→9
3322 measured reflections	l = −7→14

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.024	H-atom parameters constrained
wR(F²) = 0.071	w = 1/[σ²(F_o²) + (0.0427P)² + 0.1736P] where P = (F_o² + 2F_c²)/3
S = 1.10	(Δ/σ)_max < 0.001
1212 reflections	Δρ_max = 0.24 e Å⁻³
98 parameters	Δρ_min = −0.27 e Å⁻³
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.015 (3)

Crystal data top

[Cu(C₅H₃N₂O₂)₂(H₂O)₂]	V = 615.88 (19) Å³
M_r = 345.76	Z = 2
Monoclinic, P2₁/n	Mo Kα radiation
a = 6.7066 (12) Å	µ = 1.81 mm⁻¹
b = 7.9041 (14) Å	T = 293 K
c = 12.030 (2) Å	0.29 × 0.25 × 0.20 mm
β = 105.036 (2)°

Data collection top

Bruker SMART APEX CCD diffractometer	1212 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	1119 reflections with I > 2σ(I)
T_min = 0.626, T_max = 0.711	R_int = 0.014
3322 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.024	0 restraints
wR(F²) = 0.071	H-atom parameters constrained
S = 1.10	Δρ_max = 0.24 e Å⁻³
1212 reflections	Δρ_min = −0.27 e Å⁻³
98 parameters

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Cu1	0.0000	0.5000	1.0000	0.03498 (16)
O1	−0.0727 (2)	0.61455 (15)	0.85150 (10)	0.0366 (3)
O2	−0.1196 (2)	0.56084 (18)	0.66400 (11)	0.0410 (3)
N1	0.0637 (2)	0.30822 (17)	0.90970 (11)	0.0281 (3)
N2	0.0994 (2)	0.0660 (2)	0.74999 (14)	0.0379 (4)
C1	0.1310 (3)	0.1525 (2)	0.94293 (15)	0.0323 (4)
H1	0.1685	0.1252	1.0208	0.039*
C2	0.1451 (3)	0.0321 (2)	0.86246 (19)	0.0388 (4)
H2	0.1880	−0.0765	0.8874	0.047*
C3	0.0352 (3)	0.2226 (2)	0.71834 (15)	0.0334 (4)
H3	0.0033	0.2509	0.6407	0.040*
C4	0.0146 (2)	0.3439 (2)	0.79692 (14)	0.0277 (4)
C5	−0.0665 (3)	0.5207 (2)	0.76592 (16)	0.0299 (4)
O1W	0.3669 (2)	0.63676 (18)	1.04173 (12)	0.0483 (4)
H1A	0.3551	0.7207	1.0796	0.058*
H1B	0.4636	0.5788	1.0781	0.058*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cu1	0.0529 (2)	0.0279 (2)	0.0235 (2)	0.00894 (12)	0.00891 (15)	−0.00016 (10)
O1	0.0516 (8)	0.0285 (6)	0.0285 (7)	0.0070 (5)	0.0085 (5)	0.0008 (5)
O2	0.0550 (8)	0.0383 (7)	0.0252 (7)	0.0039 (6)	0.0022 (6)	0.0042 (6)
N1	0.0298 (7)	0.0275 (7)	0.0256 (7)	0.0002 (5)	0.0050 (5)	0.0003 (6)
N2	0.0438 (9)	0.0331 (8)	0.0380 (9)	0.0012 (7)	0.0127 (7)	−0.0059 (7)
C1	0.0343 (9)	0.0327 (9)	0.0287 (9)	0.0030 (7)	0.0059 (7)	0.0043 (7)
C2	0.0417 (10)	0.0292 (9)	0.0468 (12)	0.0066 (7)	0.0139 (9)	0.0022 (8)
C3	0.0356 (9)	0.0352 (9)	0.0287 (9)	−0.0023 (7)	0.0073 (7)	−0.0023 (7)
C4	0.0271 (8)	0.0292 (8)	0.0258 (8)	−0.0022 (6)	0.0049 (6)	−0.0005 (6)
C5	0.0299 (8)	0.0287 (8)	0.0292 (10)	−0.0006 (6)	0.0039 (7)	0.0010 (7)
O1W	0.0578 (9)	0.0406 (8)	0.0456 (8)	0.0054 (6)	0.0116 (7)	−0.0037 (6)

Geometric parameters (Å, º) top

Cu1—O1	1.9486 (12)	C1—C2	1.378 (3)
Cu1—N1	1.9753 (14)	C1—H1	0.9300
Cu1—O1W	2.6143 (14)	C2—H2	0.9300
O1—C5	1.279 (2)	C3—C4	1.379 (2)
O2—C5	1.227 (2)	C3—H3	0.9300
N1—C1	1.336 (2)	C4—C5	1.510 (2)
N1—C4	1.340 (2)	O1W—H1A	0.82
N2—C3	1.333 (3)	O1W—H1B	0.82
N2—C2	1.335 (3)

O1ⁱ—Cu1—O1	180.0	N1—C1—H1	119.8
O1ⁱ—Cu1—N1ⁱ	83.73 (5)	C2—C1—H1	119.8
O1—Cu1—N1ⁱ	96.27 (5)	N2—C2—C1	122.29 (18)
O1ⁱ—Cu1—N1	96.27 (5)	N2—C2—H2	118.9
O1—Cu1—N1	83.73 (5)	C1—C2—H2	118.9
N1ⁱ—Cu1—N1	180.0	N2—C3—C4	122.17 (16)
O1W—Cu1—N1	95.50 (5)	N2—C3—H3	118.9
O1W—Cu1—O1	89.03 (5)	C4—C3—H3	118.9
O1W—Cu1—N1ⁱ	84.50 (5)	N1—C4—C3	120.37 (16)
O1W—Cu1—O1ⁱ	90.97 (5)	N1—C4—C5	115.01 (15)
C5—O1—Cu1	114.57 (11)	C3—C4—C5	124.60 (16)
C1—N1—C4	118.16 (14)	O2—C5—O1	126.37 (16)
C1—N1—Cu1	130.31 (12)	O2—C5—C4	118.61 (16)
C4—N1—Cu1	111.33 (11)	O1—C5—C4	115.02 (15)
C3—N2—C2	116.61 (16)	H1A—O1W—H1B	109
N1—C1—C2	120.36 (16)

Symmetry code: (i) −x, −y+1, −z+2.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1A···O2ⁱⁱ	0.82	1.99	2.796 (2)	168
O1W—H1B···N2ⁱⁱⁱ	0.82	2.33	3.041 (2)	145
C1—H1···O2ⁱⁱⁱ	0.93	2.42	3.226 (2)	144

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

Experimental details

Crystal data
Chemical formula	[Cu(C₅H₃N₂O₂)₂(H₂O)₂]
M_r	345.76
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	293
a, b, c (Å)	6.7066 (12), 7.9041 (14), 12.030 (2)
β (°)	105.036 (2)
V (Å³)	615.88 (19)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	1.81
Crystal size (mm)	0.29 × 0.25 × 0.20

Data collection
Diffractometer	Bruker SMART APEX CCD diffractometer
Absorption correction	Multi-scan (SADABS; Sheldrick, 1996)
T_min, T_max	0.626, 0.711
No. of measured, independent and observed [I > 2σ(I)] reflections	3322, 1212, 1119
R_int	0.014
(sin θ/λ)_max (Å⁻¹)	0.618

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.024, 0.071, 1.10
No. of reflections	1212
No. of parameters	98
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.24, −0.27

Computer programs: SMART (Bruker, 2007), SAINT (Bruker, 2007), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008) and Mercury (Macrae et al., 2006), SHELXTL (Sheldrick, 2008).

Selected bond lengths (Å) top

Cu1—O1	1.9486 (12)	Cu1—O1W	2.6143 (14)
Cu1—N1	1.9753 (14)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1A···O2ⁱ	0.82	1.99	2.796 (2)	168
O1W—H1B···N2ⁱⁱ	0.82	2.33	3.041 (2)	145
C1—H1···O2ⁱⁱ	0.93	2.42	3.226 (2)	144

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

Acknowledgements

The authors thank Changchun Institute of Applied Chemistry for supporting this work.

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