supplementary materials


hy2621 scheme

Acta Cryst. (2013). E69, m263-m264    [ doi:10.1107/S1600536813009355 ]

(3,3'-{(1E,1'E)-1,1'-[Ethane-1,2-diylbis(azan-1-yl-1-ylidene-[kappa]N)]bis(ethan-1-yl-1-ylidene)}dipyrazine 1-oxide-[kappa]N4)bis(nitrato-[kappa]O)nickel(II) monohydrate

M. A. S. Omer and J.-C. Liu

Abstract top

In the title complex, [Ni(NO3)2(C14H16N6O2)]·H2O, the NiII atom, lying on a twofold rotation axis, is coordinated by a tetradentate 3,3'-{(1E,1'E)-1,1'-[ethane-1,2-diylbis(azan-1-yl-1-ylidene)]bis(ethan-1-yl-1-ylidene)}dipyrazine 1-oxide ligand and two mutually trans monodentate nitrate anions in a distorted octahedral geometry. The lattice water molecule is located on a twofold rotation axis. The complex molecules are linked by the water molecules through O-H...O hydrogen bonds into a chain along [001]. Further C-H...O hydrogen bonds lead to the formation of a three-dimensional network.

Comment top

Interest in heterocyclic aromatic N-oxides has flourished because of their practical impact on biological activity (Sarma et al., 2010). Several aromatic N-oxide derivatives capable of forming biologically active metal complexes have been reported (Nizhnik et al., 2008). Indeed, most coordinative studies of N-oxide donors have been carried out using pyridine-N-oxide (Karayannis et al., 1973) or bipyridine-N,N'-bisoxide. However, complexes containing ligands with pyrazine single N-oxide site are few (Chupakhin et al., 2011). Herein, we synthesize a new bipyrazine N-oxide Schiff base 3,3'-(1E,1'E)-1,1'-[ethane-1,2-diylbis(azan-1-yl-1-ylidene)] bis(ethan-1-yl-1-ylidene)dipyrazine-1-oxide (L) and its Ni(II) complex.

In the title complex, the NiII atom, lying on a twofold rotation axis, exhibits a distorted octahedral geometry, defined by four N atoms from the L ligand, occupying the equatorial plane, and two axial O atoms from two monodentate nitrate anions (Fig. 1). The equatorial Ni—N distances [Ni1—N1 = 2.0855 (19) and Ni1—N3 = 2.0183 (19) Å] are in a normal range for this class of compounds and also very similar to those of Ni—N(pyridine) and Ni—N(imine) found in analogue complexes (Banerjee et al., 2004; Padhi & Manivannan, 2007). Hydrogen bonding plays an important role in the formation of the crystal structure (Table 1). The lattice water molecule is located on a twofold rotation axis and connect two symmetry-related complex molecules through O—H···O hydrogen bonds, so forming a chain structure along [001] (Fig. 2). C—H···O hydrogen bonds lead to a three-dimensional network (Fig. 3).

Related literature top

For background to complexes with heterocyclic aromatic N-oxide ligands, see: Chupakhin et al. (2011); Karayannis et al. (1973); Nizhnik et al. (2008); Sarma et al. (2010). For related structures, see: Banerjee et al. (2004); Padhi & Manivannan (2007).

Experimental top

Synthesis of 2-acetylpyrazine-N-oxide: 2-Acetylpyrazine (12.2 g, 0.1 mol), glacial acetic acid (75 ml) and 30% hydrogen peroxide (14 ml) were heated with reflux at 70–80°C for 3 h. Additional 30% H2O2 (10 ml) was added and the temperature was maintained at 70–80°C for a further 10 h. The solvent was removed by rotary evaporation and upon standing brown yellow solid was formed, filtered and dried.

Synthesis of the L ligand : 1,2-Diaminoethane (0.100 g, 1.66 mmol) in 5 cm3 methanol was added dropwise to a hot stirred solution of 2-acetylpyrazine-N-oxide (0.455 g, 3.3 mmol) in 25 ml of methanol. The mixture was refluxed for 5 h. Brown precipitate was filtered, washed with methanol and air dried (yield: 0.68 g, 68.7%).

Synthesis of the title complex: Ni(NO3)2.6H2O (0.290 g, 0.1 mmol) in 5 cm3 of CH3CN was added dropwise to a hot stirred solution of the ligand L (0.030 g, 0.1 mmol) in a mixture of CH3OH/CH3CN (v/v = 2:1) and the mixture was stirred for 30 min. Diethyl ether was slowly diffused into the solution and block brown crystals suitable for X-ray diffraction analysis were collected by filtration within two weeks.

Refinement top

C-bound H atoms were positioned geometrically and refined as riding atoms, with C—H = 0.93 (aromatic), 0.97 (CH2) and 0.96 (CH3) Å and with Uiso(H)= 1.2(1.5 for methyl)Ueq(C). The water H atom was located on a difference Fourier map and refined isotropically.

Computing details top

Data collection: APEX2 (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: DIAMOND (Brandenburg, 1999); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title complex. Displacement ellipsoids are drawn at the 30% probability level. H atoms and water molecule have been omitted for clarity. [Symmetry code: (i) -x, y, -z+1/2.]
[Figure 2] Fig. 2. : O—H···O hydrogen bonds (dashed lines) between water molecule and two adjacent complex molecules, which lead to a chain along [001]. H atoms not involved in hydrogen bonds are omitted for clarity.
[Figure 3] Fig. 3. The crystal packing of the title complex, viewed along the c axis. Hydrogen bonds are shown as dashed lines.
(3,3'-{(1E,1'E)-1,1'-[Ethane-1,2-diylbis(azan-1-yl-1-ylidene-κN)]bis(ethan-1-yl-1-ylidene)}dipyrazine 1-oxide-κN4)bis(nitrato-κO)nickel(II) monohydrate top
Crystal data top
[Ni(NO3)2(C14H16N6O2)]·H2OF(000) = 1032
Mr = 501.05Dx = 1.697 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2ycCell parameters from 2097 reflections
a = 16.993 (5) Åθ = 2.5–23.4°
b = 16.218 (5) ŵ = 1.06 mm1
c = 7.754 (2) ÅT = 293 K
β = 113.427 (3)°Block, brown
V = 1960.8 (10) Å30.23 × 0.21 × 0.19 mm
Z = 4
Data collection top
Bruker APEXII CCD
diffractometer
1828 independent reflections
Radiation source: fine-focus sealed tube1515 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.034
φ and ω scansθmax = 25.5°, θmin = 2.5°
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
h = 2020
Tmin = 0.793, Tmax = 0.824k = 1918
6930 measured reflectionsl = 99
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.032Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.070H atoms treated by a mixture of independent and constrained refinement
S = 1.04 w = 1/[σ2(Fo2) + (0.0282P)2 + 1.9388P]
where P = (Fo2 + 2Fc2)/3
1828 reflections(Δ/σ)max < 0.001
151 parametersΔρmax = 0.26 e Å3
1 restraintΔρmin = 0.23 e Å3
Crystal data top
[Ni(NO3)2(C14H16N6O2)]·H2OV = 1960.8 (10) Å3
Mr = 501.05Z = 4
Monoclinic, C2/cMo Kα radiation
a = 16.993 (5) ŵ = 1.06 mm1
b = 16.218 (5) ÅT = 293 K
c = 7.754 (2) Å0.23 × 0.21 × 0.19 mm
β = 113.427 (3)°
Data collection top
Bruker APEXII CCD
diffractometer
1828 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
1515 reflections with I > 2σ(I)
Tmin = 0.793, Tmax = 0.824Rint = 0.034
6930 measured reflectionsθmax = 25.5°
Refinement top
R[F2 > 2σ(F2)] = 0.032H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.070Δρmax = 0.26 e Å3
S = 1.04Δρmin = 0.23 e Å3
1828 reflectionsAbsolute structure: ?
151 parametersFlack parameter: ?
1 restraintRogers parameter: ?
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
xyzUiso*/Ueq
Ni10.00000.22687 (3)0.25000.02616 (14)
C10.11963 (16)0.08324 (15)0.4745 (4)0.0364 (6)
H10.07980.04640.39470.044*
C20.19290 (17)0.05229 (17)0.6107 (4)0.0461 (7)
H20.20220.00430.62140.055*
C30.23627 (16)0.18666 (15)0.7095 (3)0.0352 (6)
H3A0.27600.22380.78840.042*
C40.16163 (14)0.21473 (14)0.5717 (3)0.0282 (5)
C50.13925 (15)0.30501 (15)0.5473 (3)0.0308 (5)
C60.19245 (18)0.36564 (17)0.6900 (4)0.0528 (8)
H6A0.17070.42020.65150.079*
H6B0.25070.36250.70150.079*
H6C0.19020.35330.80910.079*
C70.03112 (17)0.40247 (15)0.3526 (4)0.0397 (6)
H7A0.07460.44440.37310.048*
H7B0.00060.41500.43190.048*
H1W0.961 (7)0.337 (9)0.670 (19)0.65 (10)*
N10.10253 (12)0.16371 (12)0.4506 (3)0.0289 (5)
N20.25192 (14)0.10433 (13)0.7301 (3)0.0437 (6)
N30.07187 (12)0.32112 (11)0.4021 (3)0.0302 (5)
N40.08220 (14)0.16354 (17)0.4974 (3)0.0462 (6)
O10.32056 (13)0.07731 (13)0.8616 (3)0.0739 (7)
O20.06595 (11)0.22970 (11)0.4291 (2)0.0413 (4)
O30.11896 (19)0.16980 (18)0.6043 (4)0.0997 (10)
O40.06439 (14)0.09594 (13)0.4506 (3)0.0603 (6)
O51.00000.3575 (3)0.75000.0993 (13)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Ni10.0253 (2)0.0206 (2)0.0280 (2)0.0000.00583 (18)0.000
C10.0348 (14)0.0261 (14)0.0407 (14)0.0021 (11)0.0071 (12)0.0025 (11)
C20.0413 (16)0.0265 (14)0.0576 (18)0.0033 (12)0.0059 (14)0.0085 (13)
C30.0284 (14)0.0325 (14)0.0376 (14)0.0053 (11)0.0055 (11)0.0030 (11)
C40.0262 (12)0.0287 (13)0.0288 (12)0.0019 (10)0.0100 (10)0.0012 (10)
C50.0292 (14)0.0282 (13)0.0336 (13)0.0052 (11)0.0110 (11)0.0025 (10)
C60.0490 (18)0.0387 (17)0.0501 (17)0.0044 (14)0.0021 (14)0.0097 (14)
C70.0454 (17)0.0208 (13)0.0458 (15)0.0011 (11)0.0106 (13)0.0029 (11)
N10.0278 (11)0.0226 (10)0.0336 (11)0.0015 (9)0.0092 (9)0.0011 (9)
N20.0331 (13)0.0363 (13)0.0476 (13)0.0022 (10)0.0011 (11)0.0110 (10)
N30.0330 (12)0.0218 (11)0.0330 (11)0.0011 (9)0.0102 (10)0.0021 (9)
N40.0339 (13)0.0634 (17)0.0408 (13)0.0025 (12)0.0144 (11)0.0077 (12)
O10.0487 (13)0.0509 (14)0.0815 (16)0.0081 (11)0.0169 (12)0.0172 (12)
O20.0453 (11)0.0378 (10)0.0453 (10)0.0033 (9)0.0226 (9)0.0051 (9)
O30.118 (2)0.125 (2)0.100 (2)0.0031 (19)0.090 (2)0.0153 (17)
O40.0714 (15)0.0405 (12)0.0721 (15)0.0098 (11)0.0319 (12)0.0052 (11)
O50.126 (4)0.113 (3)0.068 (2)0.0000.047 (2)0.000
Geometric parameters (Å, º) top
Ni1—N32.0183 (19)C5—C61.488 (3)
Ni1—N12.0855 (19)C6—H6A0.9600
Ni1—O22.1032 (17)C6—H6B0.9600
C1—N11.334 (3)C6—H6C0.9600
C1—C21.368 (3)C7—N31.468 (3)
C1—H10.9300C7—C7i1.521 (5)
C2—N21.355 (3)C7—H7A0.9700
C2—H20.9300C7—H7B0.9700
C3—N21.358 (3)N2—O11.283 (3)
C3—C41.371 (3)N4—O31.224 (3)
C3—H3A0.9300N4—O41.230 (3)
C4—N11.351 (3)N4—O21.275 (3)
C4—C51.506 (3)O5—H1W0.780 (5)
C5—N31.274 (3)
N3—Ni1—N3i81.53 (11)N3—C5—C4113.8 (2)
N3—Ni1—N1i160.01 (8)C6—C5—C4120.1 (2)
N3i—Ni1—N1i78.71 (8)C5—C6—H6A109.5
N3—Ni1—N178.71 (8)C5—C6—H6B109.5
N3i—Ni1—N1160.01 (8)H6A—C6—H6B109.5
N1i—Ni1—N1121.17 (11)C5—C6—H6C109.5
N3—Ni1—O2i90.67 (7)H6A—C6—H6C109.5
N3i—Ni1—O2i87.44 (7)H6B—C6—H6C109.5
N1i—Ni1—O2i91.42 (7)N3—C7—C7i109.44 (14)
N1—Ni1—O2i89.81 (7)N3—C7—H7A109.8
N3—Ni1—O287.44 (7)C7i—C7—H7A109.8
N3i—Ni1—O290.67 (7)N3—C7—H7B109.8
N1i—Ni1—O289.81 (7)C7i—C7—H7B109.8
N1—Ni1—O291.42 (7)H7A—C7—H7B108.2
O2i—Ni1—O2177.50 (10)C1—N1—C4116.2 (2)
N1—C1—C2123.2 (2)C1—N1—Ni1130.95 (16)
N1—C1—H1118.4C4—N1—Ni1112.79 (15)
C2—C1—H1118.4O1—N2—C2121.5 (2)
N2—C2—C1119.9 (2)O1—N2—C3120.2 (2)
N2—C2—H2120.1C2—N2—C3118.3 (2)
C1—C2—H2120.1C5—N3—C7125.5 (2)
N2—C3—C4119.7 (2)C5—N3—Ni1118.92 (16)
N2—C3—H3A120.2C7—N3—Ni1114.52 (15)
C4—C3—H3A120.2O3—N4—O4121.7 (3)
N1—C4—C3122.7 (2)O3—N4—O2117.7 (3)
N1—C4—C5115.32 (19)O4—N4—O2120.6 (2)
C3—C4—C5122.0 (2)N4—O2—Ni1121.09 (16)
N3—C5—C6126.1 (2)
N1—C1—C2—N20.4 (4)C4—C3—N2—O1178.2 (2)
N2—C3—C4—N11.4 (4)C4—C3—N2—C20.8 (4)
N2—C3—C4—C5177.5 (2)C6—C5—N3—C73.4 (4)
N1—C4—C5—N37.4 (3)C4—C5—N3—C7174.4 (2)
C3—C4—C5—N3173.6 (2)C6—C5—N3—Ni1170.6 (2)
N1—C4—C5—C6170.5 (2)C4—C5—N3—Ni17.1 (3)
C3—C4—C5—C68.5 (3)C7i—C7—N3—C5164.2 (3)
C2—C1—N1—C41.0 (4)C7i—C7—N3—Ni128.1 (3)
C2—C1—N1—Ni1176.96 (19)N3i—Ni1—N3—C5179.1 (2)
C3—C4—N1—C11.4 (3)N1i—Ni1—N3—C5170.39 (19)
C5—C4—N1—C1177.5 (2)N1—Ni1—N3—C53.94 (17)
C3—C4—N1—Ni1176.86 (18)O2i—Ni1—N3—C593.61 (18)
C5—C4—N1—Ni14.2 (2)O2—Ni1—N3—C588.02 (18)
N3—Ni1—N1—C1178.5 (2)N3i—Ni1—N3—C710.46 (13)
N3i—Ni1—N1—C1169.8 (2)N1i—Ni1—N3—C71.8 (3)
N1i—Ni1—N1—C13.71 (19)N1—Ni1—N3—C7172.56 (17)
O2i—Ni1—N1—C187.8 (2)O2i—Ni1—N3—C797.77 (17)
O2—Ni1—N1—C194.4 (2)O2—Ni1—N3—C780.60 (17)
N3—Ni1—N1—C40.56 (15)O3—N4—O2—Ni1178.3 (2)
N3i—Ni1—N1—C48.2 (3)O4—N4—O2—Ni14.6 (3)
N1i—Ni1—N1—C4178.30 (17)N3—Ni1—O2—N4134.41 (18)
O2i—Ni1—N1—C490.16 (15)N3i—Ni1—O2—N4144.10 (18)
O2—Ni1—N1—C487.66 (15)N1i—Ni1—O2—N465.39 (18)
C1—C2—N2—O1178.7 (3)N1—Ni1—O2—N455.78 (18)
C1—C2—N2—C30.3 (4)
Symmetry code: (i) x, y, z+1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O5—H1W···O2ii0.78 (12)2.46 (14)3.086 (4)139 (14)
C3—H3A···O2iii0.932.583.389 (3)146
C6—H6A···O1iv0.962.563.453 (4)156
Symmetry codes: (ii) x+1, y, z; (iii) x+1/2, y+1/2, z+1/2; (iv) x+1/2, y+1/2, z+3/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O5—H1W···O2i0.78 (12)2.46 (14)3.086 (4)139 (14)
C3—H3A···O2ii0.932.583.389 (3)146
C6—H6A···O1iii0.962.563.453 (4)156
Symmetry codes: (i) x+1, y, z; (ii) x+1/2, y+1/2, z+1/2; (iii) x+1/2, y+1/2, z+3/2.
Acknowledgements top

We are thankful for support of this study by the National Natural Science Foundation of China (No. 20871099) and the Gansu Provincial Natural Science Foundation of China (No. 0710RJZA113).

references
References top

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