Bis(2-pyridinio­methyl­ene­amino­guanidinium) trans-tetra­aqua­di­chloro­nickel(II) dichloride tetrahydrate

Valdés-Martínez, J.; Alstrum-Acevedo, J.H.; Toscano, R.A.; Espinosa-Pérez, G.; Helfrich, B.A.; West, D.X.

doi:10.1107/S1600536801003725

Bis(2-pyridiniomethyleneaminoguanidinium) trans-tetraaquadichloronickel(II) dichloride tetrahydrate

J. Valdés-Martínez, J. H. Alstrum-Acevedo, R. A. Toscano, G. Espinosa-Pérez, B. A. Helfrich and D. X. West

In the title compound, (C₇H₁₁N₄)₂[Ni(H₂O)₄Cl₂]Cl₂·4H₂O, the Ni complex occupies a special position on the twofold axis; both cation and anions, as well as the water molecules, are in general positions. The multiple crystallographically independent hydrogen bonds form an infinite three-dimensional network in the crystal.

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Supporting information

	Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536801003725/ya6010sup1.cif Contains datablocks I, global
	Structure factor file (CIF format) https://doi.org/10.1107/S1600536801003725/ya6010Isup2.hkl Contains datablock I

CCDC reference: 162795

checkCIF report

Key indicators

Single-crystal X-ray study
T = 293 K
Mean (C-C) = 0.008 Å
R factor = 0.044
wR factor = 0.142
Data-to-parameter ratio = 16.7

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level C:



PLAT_745  Alert C D-H     Calc     0.84(4), Rep     0.84000 ....    Missing s.u.
                     O1   -H1A     1.555   1.555

PLAT_745  Alert C D-H     Calc     0.84(4), Rep     0.84000 ....    Missing s.u.
                     O1   -H1B     1.555   1.555

PLAT_745  Alert C D-H     Calc     0.86(5), Rep     0.85000 ....    Missing s.u.
                     O2   -H2A     1.555   1.555

PLAT_745  Alert C D-H     Calc     0.84(5), Rep     0.84000 ....    Missing s.u.
                     O2   -H2B     1.555   1.555

PLAT_745  Alert C D-H     Calc     0.82(6), Rep     0.82000 ....    Missing s.u.
                     O3   -H3A     1.555   1.555

PLAT_745  Alert C D-H     Calc     0.85(6), Rep     0.85000 ....    Missing s.u.
                     O3   -H3B     1.555   1.555

PLAT_745  Alert C D-H     Calc     0.86(3), Rep     0.86000 ....    Missing s.u.
                     O4   -H4A     1.555   1.555

PLAT_745  Alert C D-H     Calc     0.83(4), Rep     0.83000 ....    Missing s.u.
                     O4   -H4B     1.555   1.555

PLAT_745  Alert C D-H     Calc     0.85(4), Rep     0.85000 ....    Missing s.u.
                     N1   -H1      1.555   1.555

PLAT_745  Alert C D-H     Calc     0.85(4), Rep     0.85000 ....    Missing s.u.
                     N1   -H1      1.555   1.555

PLAT_745  Alert C D-H     Calc     0.82(4), Rep     0.82000 ....    Missing s.u.
                     N3   -H3C     1.555   1.555

PLAT_745  Alert C D-H     Calc     0.84(4), Rep     0.84000 ....    Missing s.u.
                     N4   -H4C     1.555   1.555

PLAT_745  Alert C D-H     Calc     0.84(4), Rep     0.84000 ....    Missing s.u.
                     N4   -H4C     1.555   1.555

PLAT_745  Alert C D-H     Calc     0.84(4), Rep     0.84000 ....    Missing s.u.
                     N4   -H4D     1.555   1.555

PLAT_745  Alert C D-H     Calc     0.86(3), Rep     0.86000 ....    Missing s.u.
                     N5   -H5A     1.555   1.555

PLAT_745  Alert C D-H     Calc     0.86(3), Rep     0.86000 ....    Missing s.u.
                     N5   -H5A     1.555   1.555

PLAT_745  Alert C D-H     Calc     0.84(4), Rep     0.84000 ....    Missing s.u.
                     N5   -H5B     1.555   1.555

PLAT_746  Alert C H...A   Calc     1.99(5), Rep     1.99000 ....    Missing s.u.
                     H1A  -O4      1.555   5.556

PLAT_746  Alert C H...A   Calc     2.31(5), Rep     2.30000 ....    Missing s.u.
                     H1B  -CL2     1.555   1.555

PLAT_746  Alert C H...A   Calc     1.96(5), Rep     1.97000 ....    Missing s.u.
                     H2A  -O4      1.555   6.566

PLAT_746  Alert C H...A   Calc     2.31(5), Rep     2.30000 ....    Missing s.u.
                     H2B  -CL2     1.555   2.566

PLAT_746  Alert C H...A   Calc     2.35(6), Rep     2.35000 ....    Missing s.u.
                     H3A  -CL1     1.555   1.555

PLAT_746  Alert C H...A   Calc     2.42(7), Rep     2.42000 ....    Missing s.u.
                     H3B  -CL3     1.555   6.566

PLAT_746  Alert C H...A   Calc     2.26(4), Rep     2.26000 ....    Missing s.u.
                     H4A  -CL3     1.555   1.555

PLAT_746  Alert C H...A   Calc     2.30(4), Rep     2.31000 ....    Missing s.u.
                     H4B  -CL2     1.555   6.555

PLAT_746  Alert C H...A   Calc     2.42(5), Rep     2.42000 ....    Missing s.u.
                     H1   -N2      1.555   1.555

PLAT_746  Alert C H...A   Calc     2.29(4), Rep     2.29000 ....    Missing s.u.
                     H1   -CL3     1.555   1.555

PLAT_746  Alert C H...A   Calc     2.48(5), Rep     2.48000 ....    Missing s.u.
                     H3C  -CL1     1.555   4.556

PLAT_746  Alert C H...A   Calc     2.42(6), Rep     2.43000 ....    Missing s.u.
                     H4C  -O2      1.555   7.556

PLAT_746  Alert C H...A   Calc     2.49(6), Rep     2.49000 ....    Missing s.u.
                     H4C  -O1      1.555   8.555

PLAT_746  Alert C H...A   Calc     2.36(4), Rep     2.35000 ....    Missing s.u.
                     H4D  -CL2     1.555   4.556

PLAT_746  Alert C H...A   Calc     2.37(5), Rep     2.37000 ....    Missing s.u.
                     H5A  -N2      1.555   1.555

PLAT_746  Alert C H...A   Calc     2.39(3), Rep     2.39000 ....    Missing s.u.
                     H5A  -CL3     1.555   1.555

PLAT_746  Alert C H...A   Calc     1.98(4), Rep     1.98000 ....    Missing s.u.
                     H5B  -O3      1.555   7.556

PLAT_748  Alert C D-H..A  Calc      169(4), Rep      169.00 ....    Missing s.u.
                     O1   -H1B  -CL2     1.555   1.555   1.555

PLAT_748  Alert C D-H..A  Calc      172(6), Rep      172.00 ....    Missing s.u.
                     O3   -H3A  -CL1     1.555   1.555   1.555

PLAT_748  Alert C D-H..A  Calc      166(6), Rep      167.00 ....    Missing s.u.
                     O4   -H4A  -CL3     1.555   1.555   1.555

PLAT_748  Alert C D-H..A  Calc      102(3), Rep      101.00 ....    Missing s.u.
                     N1   -H1   -N2      1.555   1.555   1.555

PLAT_748  Alert C D-H..A  Calc      160(4), Rep      160.00 ....    Missing s.u.
                     N1   -H1   -CL3     1.555   1.555   1.555

PLAT_748  Alert C D-H..A  Calc       98(4), Rep       98.00 ....    Missing s.u.
                     N5   -H5A  -N2      1.555   1.555   1.555

PLAT_748  Alert C D-H..A  Calc      163(6), Rep      162.00 ....    Missing s.u.
                     N5   -H5A  -CL3     1.555   1.555   1.555

General Notes



FORMU_01  There is a discrepancy between the atom counts in the
          _chemical_formula_sum and _chemical_formula_moiety. This is
          usually due to the moiety formula being in the wrong format.
          Atom count from _chemical_formula_sum:   C14 H38 Cl6 N10 Ni1 O8
          Atom count from _chemical_formula_moiety:C14 H38 Cl4 N8 Ni1 O8

ABSTM_02  When printed, the submitted absorption T values will be replaced
          by the scaled T values. Since the ratio of scaled T's is
          identical to the ratio of reported T values, the scaling does
          not imply a change to the absorption corrections used in the
          study.
          Ratio of Tmax expected/reported      2.426
          Tmax scaled      0.890 Tmin scaled      0.789


 0 Alert Level A = Potentially serious problem

 0 Alert Level B = Potential problem

 41 Alert Level C = Please check

Comment top

In an attempt to obtain the tetrachloronickelate(II) analogues of tetrachlorocuprate(II) aminoguanidinium compounds (Alstrum-Acevedo et al., 2001), the title compound, (I), was obtained (Fig. 1).

Both pyridyl and guanyl N atoms in (I) are protonated, thus giving rise to a dicationic species. Due to the protonation of the guanyl nitrogen, two NH₂ groups are attached to the C atom of the guanidine moiety. The C—N bond distances involving the two NH₂ groups, viz. C8—N4 and C8—N5, as well as the N4—C8—N5 angle (Table 1), indicate considerable π-character in the bonding. Delocalization and the intramolecular N1—H1···N2 and N5—H5A···N2 hydrogen bonds (Table 2) are responsible for the planarity of the molecule.

Experimental top

1.0 mmol of aminoguanidine bicarbonate was neutralized by the dropwise addition of concentrated H₂SO₄ until the evolution of CO₂ ceased and then added to a solution of 1.0 mmol of 2-formylpyridine in ethanol, followed by 2–3 drops of H₂SO₄ to catalyze the reaction. The mixture was refluxed for 5 h and slowly evaporated at ca 308 K to give a yellow solid, m.p. 463–465 K. Compound (I) was prepared by dissolving 1 mmol of the aminoguanidone in approximately 50 ml of a 3:1 EtOH–HCl (12 N) by volume, adding an equimolar amount of NiCl₂^.6H₂O, and subsequent heating of the reaction mixture under reflux for 1 h. The solution was then filtered and the filtrate left until crystals formed.

Computing details top

Data collection: P4 Software (Siemens, 1995); cell refinement: P4 Software; data reduction: P4 Software; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997).

Figures top

Fig. 1. A view of (I) with the atom-numbering scheme. Displacement ellipsoids are drawn at the 40% probability level.

Bis(2-pyridiniomethyleneaminoguanidinium) trans-tetraaquadichloronickel(II) dichloride tetrahydrate top

Crystal data top

(C₇H₁₁N₄)₂[Ni(H₂O)₄Cl₂]Cl₂·4H₂O	F(000) = 1544
M_r = 745.95	D_x = 1.544 Mg m⁻³
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
a = 24.698 (4) Å	Cell parameters from 33 reflections
b = 7.106 (1) Å	θ = 2.5–12.5°
c = 18.538 (2) Å	µ = 1.16 mm⁻¹
β = 99.59 (1)°	T = 293 K
V = 3208.0 (8) Å³	Prism, yellow
Z = 4	0.30 × 0.16 × 0.10 mm

Data collection top

Siemens P4/PC diffractometer	2222 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.046
Graphite monochromator	θ_max = 27.5°, θ_min = 1.7°
θ/2θ scans	h = −1→32
Absorption correction: ψ scan (North et al., 1968)	k = −1→9
T_min = 0.325, T_max = 0.367	l = −24→23
4547 measured reflections	3 standard reflections every 97 reflections
3656 independent reflections	intensity decay: 3%

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)] = 0.044	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.142	H-atom parameters constrained
S = 1.02	w = 1/[σ²(F_o²) + (0.0678P)²] where P = (F_o² + 2F_c²)/3
3656 reflections	(Δ/σ)_max = 0.007
219 parameters	Δρ_max = 0.45 e Å⁻³
14 restraints	Δρ_min = −0.46 e Å⁻³

Crystal data top

(C₇H₁₁N₄)₂[Ni(H₂O)₄Cl₂]Cl₂·4H₂O	V = 3208.0 (8) Å³
M_r = 745.95	Z = 4
Monoclinic, C2/c	Mo Kα radiation
a = 24.698 (4) Å	µ = 1.16 mm⁻¹
b = 7.106 (1) Å	T = 293 K
c = 18.538 (2) Å	0.30 × 0.16 × 0.10 mm
β = 99.59 (1)°

Data collection top

Siemens P4/PC diffractometer	2222 reflections with I > 2σ(I)
Absorption correction: ψ scan (North et al., 1968)	R_int = 0.046
T_min = 0.325, T_max = 0.367	3 standard reflections every 97 reflections
4547 measured reflections	intensity decay: 3%
3656 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.044	14 restraints
wR(F²) = 0.142	H-atom parameters constrained
S = 1.02	Δρ_max = 0.45 e Å⁻³
3656 reflections	Δρ_min = −0.46 e Å⁻³
219 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
Ni1	0.0000	0.15359 (14)	0.7500	0.02568 (18)
Cl1	0.06641 (4)	0.1543 (2)	0.85984 (5)	0.0369 (3)
Cl2	0.01733 (5)	−0.3392 (2)	0.90767 (6)	0.0416 (3)
Cl3	0.21325 (5)	0.4441 (3)	0.34324 (7)	0.0571 (4)
O1	−0.04439 (13)	−0.0467 (5)	0.79698 (16)	0.0329 (7)
H1A	−0.0665 (18)	−0.115 (7)	0.769 (2)	0.040*
H1B	−0.028 (2)	−0.113 (7)	0.831 (2)	0.040*
O2	0.04223 (12)	0.3594 (6)	0.70079 (16)	0.0348 (7)
H2A	0.061 (2)	0.431 (7)	0.733 (2)	0.042*
H2B	0.023 (2)	0.439 (7)	0.675 (3)	0.042*
O3	0.16180 (17)	0.1824 (9)	0.7657 (2)	0.0638 (14)
H3A	0.137 (2)	0.164 (12)	0.789 (4)	0.077*
H3B	0.187 (2)	0.263 (9)	0.780 (4)	0.077*
O4	0.09134 (14)	0.3454 (7)	0.28761 (19)	0.0452 (8)
H4A	0.1262 (9)	0.354 (11)	0.300 (3)	0.054*
H4B	0.078 (2)	0.354 (10)	0.326 (2)	0.054*
N1	0.20203 (16)	0.5269 (7)	0.5040 (2)	0.0378 (9)
H1	0.213 (2)	0.492 (9)	0.4651 (19)	0.045*
C2	0.23711 (18)	0.5220 (7)	0.5686 (2)	0.0357 (10)
C3	0.2159 (2)	0.5567 (10)	0.6320 (3)	0.0503 (13)
H3	0.2417	0.5589	0.6790	0.060*
C4	0.1603 (2)	0.5944 (10)	0.6271 (4)	0.0587 (16)
H4	0.1449	0.6267	0.6714	0.070*
C5	0.1265 (2)	0.5990 (9)	0.5606 (4)	0.0526 (14)
H5	0.0925	0.6147	0.5563	0.063*
C6	0.1485 (2)	0.5638 (9)	0.4985 (3)	0.0475 (12)
H6	0.1275	0.5750	0.4478	0.057*
C7	0.29455 (18)	0.4806 (8)	0.5687 (2)	0.0369 (10)
H7	0.3187	0.4549	0.6124	0.044*
C8	0.38095 (18)	0.3966 (7)	0.4410 (2)	0.0337 (10)
N2	0.31041 (14)	0.4551 (6)	0.50681 (18)	0.0331 (8)
N3	0.36439 (14)	0.4160 (7)	0.50747 (19)	0.0347 (9)
H3C	0.3840 (19)	0.438 (9)	0.5469 (17)	0.042*
N4	0.43360 (17)	0.3601 (9)	0.4416 (2)	0.0472 (11)
H4C	0.439 (3)	0.338 (11)	0.3988 (17)	0.057*
H4D	0.451 (2)	0.318 (9)	0.481 (2)	0.057*
N5	0.34519 (17)	0.4116 (8)	0.3810 (2)	0.0442 (11)
H5A	0.3109 (11)	0.437 (10)	0.379 (3)	0.053*
H5B	0.352 (2)	0.375 (9)	0.3404 (19)	0.053*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Ni1	0.0262 (3)	0.0259 (4)	0.0236 (3)	0.000	0.0003 (2)	0.000
Cl1	0.0366 (5)	0.0395 (6)	0.0302 (4)	−0.0008 (5)	−0.0070 (4)	0.0024 (5)
Cl2	0.0472 (6)	0.0406 (6)	0.0347 (5)	−0.0040 (6)	0.0001 (4)	−0.0031 (5)
Cl3	0.0395 (6)	0.0873 (11)	0.0408 (6)	0.0026 (7)	−0.0046 (4)	0.0023 (7)
O1	0.0364 (15)	0.0297 (17)	0.0313 (14)	−0.0070 (15)	0.0014 (11)	0.0011 (14)
O2	0.0368 (15)	0.0319 (17)	0.0336 (14)	−0.0012 (16)	−0.0006 (11)	0.0035 (15)
O3	0.049 (2)	0.102 (4)	0.0419 (18)	−0.005 (3)	0.0096 (16)	−0.006 (2)
O4	0.0436 (17)	0.048 (2)	0.0422 (16)	−0.004 (2)	0.0019 (14)	−0.0055 (19)
N1	0.0360 (18)	0.039 (2)	0.0379 (18)	−0.0005 (18)	0.0032 (15)	−0.0047 (18)
C2	0.035 (2)	0.036 (3)	0.036 (2)	−0.007 (2)	0.0080 (16)	−0.0049 (19)
C3	0.051 (3)	0.061 (4)	0.041 (2)	−0.010 (3)	0.013 (2)	−0.003 (3)
C4	0.054 (3)	0.060 (4)	0.069 (4)	−0.004 (3)	0.031 (3)	−0.006 (3)
C5	0.034 (2)	0.047 (3)	0.079 (4)	0.004 (2)	0.016 (2)	0.000 (3)
C6	0.037 (2)	0.039 (3)	0.064 (3)	0.001 (2)	0.000 (2)	0.008 (3)
C7	0.033 (2)	0.044 (3)	0.0325 (19)	−0.005 (2)	0.0008 (16)	0.000 (2)
C8	0.036 (2)	0.033 (2)	0.0315 (18)	−0.0010 (19)	0.0051 (16)	0.0018 (17)
N2	0.0301 (16)	0.038 (2)	0.0292 (16)	−0.0012 (17)	0.0004 (13)	−0.0035 (17)
N3	0.0280 (16)	0.049 (2)	0.0254 (15)	−0.0001 (17)	−0.0003 (12)	−0.0026 (16)
N4	0.0396 (19)	0.067 (3)	0.0372 (18)	0.009 (2)	0.0120 (16)	0.013 (2)
N5	0.043 (2)	0.061 (3)	0.0263 (16)	0.007 (2)	−0.0020 (15)	−0.0007 (19)

Geometric parameters (Å, º) top

Ni1—O1ⁱ	2.075 (3)	C2—C7	1.449 (6)
Ni1—O1	2.075 (3)	C3—C4	1.386 (8)
Ni1—O2	2.092 (4)	C4—C5	1.369 (9)
Ni1—O2ⁱ	2.092 (4)	C5—C6	1.376 (8)
Ni1—Cl1	2.3923 (9)	C7—N2	1.286 (6)
Ni1—Cl1ⁱ	2.3924 (9)	C8—N3	1.368 (5)
N1—C6	1.334 (6)	C8—N4	1.324 (6)
N1—C2	1.356 (6)	C8—N5	1.304 (6)
C2—C3	1.386 (7)	N2—N3	1.360 (5)

O1ⁱ—Ni1—O1	93.4 (2)	C6—N1—C2	123.5 (4)
O1ⁱ—Ni1—O2	87.70 (13)	N1—C2—C3	117.9 (4)
O1—Ni1—O2	178.04 (13)	N1—C2—C7	119.2 (4)
O1ⁱ—Ni1—O2ⁱ	178.05 (13)	C3—C2—C7	122.9 (4)
O1—Ni1—O2ⁱ	87.71 (13)	C2—C3—C4	119.2 (5)
O2—Ni1—O2ⁱ	91.3 (2)	C5—C4—C3	120.9 (5)
O1ⁱ—Ni1—Cl1	91.35 (9)	C4—C5—C6	118.7 (5)
O1—Ni1—Cl1	88.83 (9)	N1—C6—C5	119.8 (5)
O2—Ni1—Cl1	92.79 (9)	N2—C7—C2	118.1 (4)
O2ⁱ—Ni1—Cl1	87.03 (9)	N5—C8—N4	123.2 (4)
O1ⁱ—Ni1—Cl1ⁱ	88.82 (9)	N5—C8—N3	119.9 (4)
O1—Ni1—Cl1ⁱ	91.34 (9)	N4—C8—N3	116.9 (4)
O2—Ni1—Cl1ⁱ	87.03 (9)	C7—N2—N3	117.7 (4)
O2ⁱ—Ni1—Cl1ⁱ	92.79 (9)	N2—N3—C8	116.9 (3)
Cl1—Ni1—Cl1ⁱ	179.75 (9)

Symmetry code: (i) −x, y, −z+3/2.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1A···O4ⁱⁱ	0.84	1.99	2.775 (5)	156
O1—H1B···Cl2	0.84	2.30	3.132 (4)	169
O2—H2A···O4ⁱⁱⁱ	0.85	1.97	2.795 (6)	163
O2—H2B···Cl2^iv	0.84	2.30	3.131 (4)	169
O3—H3A···Cl1	0.82	2.35	3.163 (4)	172
O3—H3B···Cl3ⁱⁱⁱ	0.85	2.42	3.180 (6)	147
O4—H4A···Cl3	0.86	2.26	3.096 (4)	167
O4—H4B···Cl2^v	0.83	2.31	3.107 (4)	161
N1—H1···N2	0.85	2.42	2.717 (5)	101
N1—H1···Cl3	0.85	2.29	3.096 (4)	160
N3—H3C···Cl1^vi	0.82	2.48	3.231 (4)	153
N4—H4C···O2^vii	0.84	2.43	3.207 (6)	155
N4—H4C···O1^viii	0.84	2.49	3.119 (5)	132
N4—H4D···Cl2^vi	0.84	2.35	3.187 (4)	168
N5—H5A···N2	0.86	2.37	2.634 (5)	98
N5—H5A···Cl3	0.86	2.39	3.225 (4)	162
N5—H5B···O3^vii	0.84	1.98	2.778 (6)	157

Symmetry codes: (ii) −x, −y, −z+1; (iii) x, −y+1, z+1/2; (iv) −x, y+1, −z+3/2; (v) x, −y, z−1/2; (vi) −x+1/2, y+1/2, −z+3/2; (vii) −x+1/2, −y+1/2, −z+1; (viii) x+1/2, −y+1/2, z−1/2.

Experimental details

Crystal data
Chemical formula	(C₇H₁₁N₄)₂[Ni(H₂O)₄Cl₂]Cl₂·4H₂O
M_r	745.95
Crystal system, space group	Monoclinic, C2/c
Temperature (K)	293
a, b, c (Å)	24.698 (4), 7.106 (1), 18.538 (2)
β (°)	99.59 (1)
V (Å³)	3208.0 (8)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	1.16
Crystal size (mm)	0.30 × 0.16 × 0.10

Data collection
Diffractometer	Siemens P4/PC diffractometer
Absorption correction	ψ scan (North et al., 1968)
T_min, T_max	0.325, 0.367
No. of measured, independent and observed [I > 2σ(I)] reflections	4547, 3656, 2222
R_int	0.046
(sin θ/λ)_max (Å⁻¹)	0.650

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.044, 0.142, 1.02
No. of reflections	3656
No. of parameters	219
No. of restraints	14
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.45, −0.46

Computer programs: P4 Software (Siemens, 1995), P4 Software, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997).

Selected geometric parameters (Å, º) top

Ni1—O1	2.075 (3)	C4—C5	1.369 (9)
Ni1—O2	2.092 (4)	C5—C6	1.376 (8)
Ni1—Cl1	2.3923 (9)	C7—N2	1.286 (6)
N1—C6	1.334 (6)	C8—N3	1.368 (5)
N1—C2	1.356 (6)	C8—N4	1.324 (6)
C2—C3	1.386 (7)	C8—N5	1.304 (6)
C2—C7	1.449 (6)	N2—N3	1.360 (5)
C3—C4	1.386 (8)

O1—Ni1—O2	178.04 (13)	N5—C8—N4	123.2 (4)
O1—Ni1—Cl1	88.83 (9)	N5—C8—N3	119.9 (4)
O2—Ni1—Cl1	92.79 (9)	N4—C8—N3	116.9 (4)
N1—C2—C7	119.2 (4)	C7—N2—N3	117.7 (4)
N2—C7—C2	118.1 (4)	N2—N3—C8	116.9 (3)