Diaqua­bis­(pyrazine-2-carboxamide-κ² N ¹,O)cobalt(II) dinitrate

Abstract

The asymmetric unit of the title complex, [Co(C₅H₅N₃O)₂(H₂O)₂](NO₃)₂, contains one half of a Co^II cationic unit and a nitrate anion. The entire [Co(C₅H₅N₃O)₂(H₂O)₂]²⁺ cationic unit is completed by the application of inversion symmetry at the Co^II site, generating a six-coordinate distorted octa­hedral environment for the metal ion. The chelating pyrazine-2-carboxamide mol­ecules are bound to cobalt via N and O atoms, forming a square plane, while the remaining two trans positions in the octa­hedron are occupied by two coordinated water mol­ecules.

Related literature  

For the monodentate coordination mode of the pyrazine-2-carboxamide ligand, see: Azhdari Tehrani et al. (2010 ▶); Mir Mohammad Sadegh et al. (2010 ▶); Goher & Mautner (1999 ▶, 2001 ▶). For the chelating bidentate coordination mode, see: Tanase et al. (2008 ▶); Prins et al. (2007 ▶); Sekisaki (1973 ▶). For coordination by pyrazine carboxamide moieties, see: Hausmann & Brooker (2004 ▶); Cati & Stoeckli-Evans (2004 ▶).

Experimental  

Crystal data  

• [Co(C₅H₅N₃O)₂(H₂O)₂](NO₃)₂

• M _r = 465.22

• Monoclinic,

• a = 10.149 (5) Å

• b = 6.715 (3) Å

• c = 13.080 (5) Å

• β = 104.397 (4)°

• V = 863.4 (7) ų

• Z = 2

• Mo Kα radiation

• μ = 1.07 mm⁻¹

• T = 295 K

• 0.20 × 0.18 × 0.18 mm

Data collection  

• Rigaku R-AXIS IV++ diffractometer

• Absorption correction: multi-scan (CrystalClear; Rigaku, 2000 ▶) T _min = 0.815, T _max = 0.831

• 4254 measured reflections

• 1958 independent reflections

• 1831 reflections with I > 2σ(I)

• R _int = 0.023

Refinement  

• R[F ² > 2σ(F ²)] = 0.033

• wR(F ²) = 0.097

• S = 1.07

• 1958 reflections

• 140 parameters

• 2 restraints

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

• Δρ_max = 0.42 e Å⁻³

• Δρ_min = −0.55 e Å⁻³

Data collection: CrystalClear (Rigaku, 2000 ▶); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SIR92 (Altomare et al., 1993 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 (Farrugia, 1997 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶).

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
O1W—H1W⋯O4i	0.82 (1)	1.93 (1)	2.742 (2)	170 (3)
O1W—H2W⋯O4ii	0.82 (1)	1.92 (1)	2.722 (2)	164 (3)

Symmetry codes: (i) ; (ii) .

supplementary crystallographic information

Comment

The ligand pyrazine-2-carboxamide can coordinate to a metal center in a monodentate fashion through the pyrazine nitrogen atom which is meta to the carboxamide group. Alternatively, when the ligand uses both the carboxamide oxygen atom and the pyrazine nitrogen atom ortho to it for coordination, a stable five member ring is formed as a result of the ligand coordinating in chelating bidentate fashion.

In the present study we report the synthesis, molecular and crystal structure of an octahedral complex of Co^II with the pyrazine-2-carboxamide ligand, [Co(C₅H₅N₃O)₂(H₂O)₂](NO₃)₂. The molecular structure of this complex is shown in Fig. 1. In this complex, the Co^II atom lies on a center of inversion and adopts an octahedral geometry. Two pyrazine-2-carboxamide ligand molecules, each coordinating to the Co^II center in a chelating bidentate fashion and forming a stable five membered ring, form a square planar arrangement around the metal center. The remaining two trans positions in the octahedron are occupied by two coordinated water molecules. The crystal packing is dominated by O—H···O hydrogen bonding interactions between the complex molecules and the nitrate ions present in the crystal lattice which leads to the formation of a two-dimensional sheet parallel to the bc plane (Fig. 2, Table 1).

Experimental

A solution of pyrazine-2-carboxamide (0.246 g, 2.0 mmol) in ethanol (10 ml) was added to a solution of cobalt(II) nitrate hexahydrate (0.291 g, 1.0 mmol) in water (5 ml) at room temperature. After stirring the resulting solution for 3–4 h, an orange colored solid had formed which was filtered off and dried. Orange crystals of the title complex were obtained by slow evaporation from acetonitrile solution over two weeks.

Refinement

All non hydrogen atoms were refined anisotropically. The hydrogen atoms of the coordinated water molecules were located from the Fourier difference maps and included as riding contributions with O—H distances set to 0.82 Å with U_iso(H) = 1.2U_eq(O). All other H atoms were positioned geometrically with C–H = 0.93 and N—H = 0.86 Å and constrained to ride on their parent atoms, with U_iso(H) = 1.2U_eq(C,N).

Figures

Fig. 1.

The ORTEP diagram showing the molecular structure of the title complex. The ellipsoids are drawn at the 50% probability level. Unlabelled atoms are related to the labelled atoms by the symmetry transformation (-x, -y, -z + 1) .

Fig. 2.

The two dimensional sheet structure parallel to the bc plane is formed by O—H···O hydrogen bonding interactions between the complex cations and the nitrate ions. H-atoms other than those involved in H-bonding have been omitted for clarity. Hydrogen bonds are shown as dashed lines.

Crystal data

[Co(C5H5N3O)2(H2O)2](NO3)2	F(000) = 474
Mr = 465.22	Dx = 1.789 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71069 Å
Hall symbol: -P 2ybc	Cell parameters from 62 reflections
a = 10.149 (5) Å	θ = 1.6–30.1°
b = 6.715 (3) Å	µ = 1.07 mm−1
c = 13.080 (5) Å	T = 295 K
β = 104.397 (4)°	Block, orange
V = 863.4 (7) Å3	0.2 × 0.18 × 0.18 mm
Z = 2

Data collection

Rigaku R-AXIS IV++ diffractometer	1958 independent reflections
Confocal monochromator	1831 reflections with I > 2σ(I)
Detector resolution: 10 pixels mm-1	Rint = 0.023
φ scans	θmax = 30.1°, θmin = 1.6°
Absorption correction: multi-scan (CrystalClear; Rigaku, 2000)	h = −13→14
Tmin = 0.815, Tmax = 0.831	k = −7→9
4254 measured reflections	l = −13→18

Refinement

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)] = 0.033	H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.097	w = 1/[σ2(Fo2) + (0.0597P)2 + 0.1848P] where P = (Fo2 + 2Fc2)/3
S = 1.07	(Δ/σ)max < 0.001
1958 reflections	Δρmax = 0.42 e Å−3
140 parameters	Δρmin = −0.55 e Å−3
2 restraints	Extinction correction: SHELXL
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.058 (5)

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
C1	−0.13028 (17)	0.3679 (3)	0.37319 (14)	0.0252 (4)
H1	−0.045	0.4279	0.3917	0.03*
C2	−0.2368 (2)	0.4620 (3)	0.30214 (17)	0.0312 (4)
H2	−0.2209	0.5835	0.2733	0.037*
C3	−0.38018 (17)	0.2122 (3)	0.32023 (14)	0.0265 (4)
H3	−0.4668	0.1565	0.305	0.032*
C4	−0.27504 (15)	0.1155 (2)	0.38998 (12)	0.0187 (3)
C5	−0.28494 (16)	−0.0812 (3)	0.44282 (13)	0.0233 (4)
N1	−0.14921 (13)	0.1933 (2)	0.41483 (10)	0.0190 (3)
N2	−0.36101 (16)	0.3835 (3)	0.27411 (13)	0.0328 (4)
N3	−0.40489 (16)	−0.1673 (3)	0.42833 (14)	0.0338 (4)
H3A	−0.4122	−0.2795	0.4581	0.041*
H3B	−0.4758	−0.1112	0.3891	0.041*
N4	0.73095 (19)	−0.0030 (2)	0.13278 (13)	0.0257 (4)
O1	−0.17918 (12)	−0.1555 (2)	0.49866 (11)	0.0307 (3)
O2	0.67682 (16)	−0.1413 (2)	0.16811 (14)	0.0475 (4)
O3	0.67169 (18)	0.0854 (3)	0.05233 (14)	0.0574 (5)
O4	0.85161 (15)	0.0470 (2)	0.18035 (12)	0.0361 (3)
Co1	0	0	0.5	0.01880 (16)
O1W	0.00264 (16)	−0.1345 (2)	0.35909 (11)	0.0400 (4)
H2W	0.059 (2)	−0.215 (3)	0.349 (2)	0.048*
H1W	−0.045 (2)	−0.094 (4)	0.3028 (11)	0.048*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
C1	0.0174 (8)	0.0248 (9)	0.0307 (9)	−0.0021 (6)	0.0005 (7)	0.0021 (6)
C2	0.0257 (10)	0.0232 (8)	0.0405 (11)	0.0023 (7)	−0.0002 (8)	0.0086 (8)
C3	0.0129 (8)	0.0289 (9)	0.0322 (9)	0.0019 (6)	−0.0047 (7)	0.0007 (7)
C4	0.0136 (7)	0.0203 (8)	0.0204 (7)	0.0010 (6)	0.0008 (6)	−0.0017 (6)
C5	0.0165 (8)	0.0267 (9)	0.0240 (8)	−0.0016 (7)	0.0000 (6)	0.0020 (6)
N1	0.0124 (6)	0.0228 (7)	0.0194 (6)	0.0017 (5)	−0.0008 (5)	0.0004 (5)
N2	0.0210 (8)	0.0292 (8)	0.0409 (9)	0.0047 (6)	−0.0061 (7)	0.0078 (6)
N3	0.0166 (7)	0.0363 (9)	0.0426 (9)	−0.0074 (6)	−0.0040 (6)	0.0115 (7)
N4	0.0229 (9)	0.0313 (9)	0.0223 (8)	0.0009 (5)	0.0041 (7)	0.0009 (5)
O1	0.0150 (6)	0.0337 (7)	0.0383 (7)	−0.0011 (5)	−0.0027 (5)	0.0143 (6)
O2	0.0453 (9)	0.0434 (9)	0.0557 (10)	−0.0129 (7)	0.0163 (8)	0.0063 (7)
O3	0.0407 (9)	0.0808 (14)	0.0426 (9)	0.0083 (9)	−0.0048 (7)	0.0283 (9)
O4	0.0270 (8)	0.0405 (8)	0.0351 (8)	−0.0068 (6)	−0.0031 (6)	0.0039 (6)
Co1	0.0103 (2)	0.0237 (2)	0.0192 (2)	0.00234 (10)	−0.00225 (14)	0.00248 (10)
O1W	0.0415 (9)	0.0490 (9)	0.0237 (7)	0.0229 (7)	−0.0031 (6)	−0.0045 (6)

Geometric parameters (Å, º)

C1—N1	1.327 (2)	N3—H3A	0.86
C1—C2	1.390 (3)	N3—H3B	0.86
C1—H1	0.93	N4—O2	1.226 (2)
C2—N2	1.330 (3)	N4—O3	1.227 (2)
C2—H2	0.93	N4—O4	1.273 (2)
C3—N2	1.335 (3)	O1—Co1	2.0934 (14)
C3—C4	1.382 (2)	Co1—O1W	2.0586 (15)
C3—H3	0.93	Co1—O1Wi	2.0586 (15)
C4—N1	1.343 (2)	Co1—O1i	2.0934 (14)
C4—C5	1.505 (2)	Co1—N1i	2.0931 (14)
C5—O1	1.243 (2)	O1W—H2W	0.820 (2)
C5—N3	1.318 (2)	O1W—H1W	0.820 (2)
N1—Co1	2.0931 (14)
N1—C1—C2	120.52 (16)	O2—N4—O3	121.3 (2)
N1—C1—H1	119.7	O2—N4—O4	118.83 (18)
C2—C1—H1	119.7	O3—N4—O4	119.88 (17)
N2—C2—C1	122.04 (18)	C5—O1—Co1	115.20 (11)
N2—C2—H2	119	O1W—Co1—O1Wi	180
C1—C2—H2	119	O1W—Co1—O1i	91.24 (7)
N2—C3—C4	121.87 (16)	O1Wi—Co1—O1i	88.76 (7)
N2—C3—H3	119.1	O1W—Co1—O1	88.76 (7)
C4—C3—H3	119.1	O1Wi—Co1—O1	91.24 (7)
N1—C4—C3	120.57 (15)	O1i—Co1—O1	180
N1—C4—C5	113.48 (13)	O1W—Co1—N1	87.95 (6)
C3—C4—C5	125.94 (15)	O1Wi—Co1—N1	92.05 (6)
O1—C5—N3	122.68 (17)	O1i—Co1—N1	101.95 (6)
O1—C5—C4	118.41 (14)	O1—Co1—N1	78.05 (6)
N3—C5—C4	118.91 (15)	O1W—Co1—N1i	92.05 (6)
C1—N1—C4	118.09 (14)	O1Wi—Co1—N1i	87.95 (6)
C1—N1—Co1	127.39 (11)	O1i—Co1—N1i	78.05 (6)
C4—N1—Co1	113.95 (11)	O1—Co1—N1i	101.95 (6)
C2—N2—C3	116.81 (16)	N1—Co1—N1i	180
C5—N3—H3A	120	Co1—O1W—H2W	127 (2)
C5—N3—H3B	120	Co1—O1W—H1W	122 (2)
H3A—N3—H3B	120	H2W—O1W—H1W	110 (3)
N1—C1—C2—N2	0.8 (3)	N3—C5—O1—Co1	175.70 (14)
N2—C3—C4—N1	0.9 (3)	C4—C5—O1—Co1	−4.4 (2)
N2—C3—C4—C5	−177.61 (17)	C5—O1—Co1—O1W	−81.16 (14)
N1—C4—C5—O1	−3.1 (2)	C5—O1—Co1—O1Wi	98.84 (14)
C3—C4—C5—O1	175.52 (17)	C5—O1—Co1—N1	7.01 (13)
N1—C4—C5—N3	176.79 (15)	C5—O1—Co1—N1i	−172.99 (13)
C3—C4—C5—N3	−4.6 (3)	C1—N1—Co1—O1W	−90.46 (15)
C2—C1—N1—C4	−2.9 (2)	C4—N1—Co1—O1W	80.57 (12)
C2—C1—N1—Co1	167.77 (14)	C1—N1—Co1—O1Wi	89.54 (15)
C3—C4—N1—C1	2.1 (2)	C4—N1—Co1—O1Wi	−99.43 (12)
C5—C4—N1—C1	−179.19 (14)	C1—N1—Co1—O1i	0.38 (15)
C3—C4—N1—Co1	−169.81 (13)	C4—N1—Co1—O1i	171.41 (11)
C5—C4—N1—Co1	8.89 (17)	C1—N1—Co1—O1	−179.62 (15)
C1—C2—N2—C3	2.2 (3)	C4—N1—Co1—O1	−8.60 (11)
C4—C3—N2—C2	−3.0 (3)

Symmetry code: (i) −x, −y, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1W···O4ii	0.82 (1)	1.93 (1)	2.742 (2)	170 (3)
O1W—H2W···O4iii	0.82 (1)	1.92 (1)	2.722 (2)	164 (3)

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