A polymorph of diaqua-bis(pyrazine-2-carboxyl-ato-κN,O)copper(II).

The title compound, [Cu(C(5)H(3)N(2)O(2))(2)(H(2)O)(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-carboxyl-ate ligands and by two water mol-ecules in a distorted octa-hedral geometry with the water mol-ecules occupying the axial sites. Inter-molecular O-H⋯O, O-H⋯N and C-H⋯O hydrogen bonds connect the complex mol-ecules into a two-dimensional layer parallel to (10), 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 = 345.76

Monoclinic,

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 (; 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[F 2 > 2σ(F 2)] = 0.024

wR(F 2) = 0.071

S = 1.10

1212 reflections

98 parameters

H-atom parameters constrained

Δρmax = 0.24 e Å−3

Δρmin = −0.27 e Å−3

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.

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

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

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

[Cu(C5H3N2O2)2(H2O)2]	F(000) = 350
Mr = 345.76	Dx = 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

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

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(Fo2) + (0.0427P)2 + 0.1736P] where P = (Fo2 + 2Fc2)/3
S = 1.10	(Δ/σ)max < 0.001
1212 reflections	Δρmax = 0.24 e Å−3
98 parameters	Δρmin = −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)

	x	y	z	Uiso*/Ueq
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*

	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)

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)

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

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) ; (ii) .