The title compound, [Ni(C
3H
4N
2)
5(H
2O)](C
4H
2Br
2O
4), consists of Ni
II complex cations and dibromosuccinate anions. The Ni atom, water O atom and one imidazole N atom of the complex cation lie on a twofold axis. The anion lies on an inversion centre. The crystal packing is reinforced by O—H
O and N—H
O hydrogen bonds, but there are no π–π stacking interactions even though the complex contains five aromatic imidazole rings. The compound is isostructural with its cobalt analogue.
Supporting information
CCDC reference: 287700
Key indicators
- Single-crystal X-ray study
- T = 298 K
- Mean (C-C) = 0.008 Å
- Disorder in main residue
- R factor = 0.050
- wR factor = 0.155
- Data-to-parameter ratio = 17.1
checkCIF/PLATON results
No syntax errors found
Alert level B
PLAT242_ALERT_2_B Check Low Ueq as Compared to Neighbors for C7
Alert level C
PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical . ?
PLAT301_ALERT_3_C Main Residue Disorder ......................... 4.00 Perc.
PLAT341_ALERT_3_C Low Bond Precision on C-C bonds (x 1000) Ang ... 8
0 ALERT level A = In general: serious problem
1 ALERT level B = Potentially serious problem
3 ALERT level C = Check and explain
0 ALERT level G = General alerts; check
1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
1 ALERT type 2 Indicator that the structure model may be wrong or deficient
2 ALERT type 3 Indicator that the structure quality may be low
0 ALERT type 4 Improvement, methodology, query or suggestion
An ethanol–water solution (5 ml, 1:1) of NiCl2·6H2O (0.24 g, 1 mmol) was mixed with an aqueous solution (4 ml) containing DBrSH2 (0.55 g, 2 mmol) and Na2CO3 (0.21 g, 2 mmol). The mixture was refluxed for 4 h and filtered. After cooling to room temperature, imidazole (0.20 g, 3 mmol) was added to the filtrate and green single crystals of (I) were obtained after 4 d.
The water H atoms were located in a difference Fourier map and included in the final cycles of refinement with fixed positional and displacement parameters, with Uiso(H) = 0.05 Å2. Other H atoms were placed in calculated positions, with C—H = 0.93 Å (aromatic) or 0.98 Å (methine), and included in the final cycles of refinement in the riding model, with Uiso(H) = 1.2Ueq or 1.5Ueq of the carrier atoms.
Data collection: SMART (Bruker, 1999); cell refinement: SAINT (Bruker, 1999); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).
Aquapentakis(1
H-imidazole-
κN3)nickel(II) dibromosuccinate
top
Crystal data top
[Ni(C3H4N2)5(H2O)](C4H2Br2O4) | F(000) = 1384 |
Mr = 690.97 | Dx = 1.702 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -C 2yc | Cell parameters from 175 reflections |
a = 15.8702 (11) Å | θ = 2.5–24.5° |
b = 12.9262 (11) Å | µ = 3.73 mm−1 |
c = 13.9436 (11) Å | T = 298 K |
β = 109.468 (3)° | Prism, green |
V = 2696.9 (4) Å3 | 0.36 × 0.24 × 0.22 mm |
Z = 4 | |
Data collection top
Bruker SMART CCD area-detector diffractometer | 3000 independent reflections |
Radiation source: fine-focus sealed tube | 2048 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.020 |
ϕ and ω scans | θmax = 27.2°, θmin = 2.1° |
Absorption correction: multi-scan (SADABS; Bruker, 1999) | h = −20→20 |
Tmin = 0.355, Tmax = 0.440 | k = −16→16 |
5513 measured reflections | l = −17→17 |
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)] = 0.050 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.156 | H-atom parameters constrained |
S = 1.05 | w = 1/[σ2(Fo2) + (0.0964P)2] where P = (Fo2 + 2Fc2)/3 |
3000 reflections | (Δ/σ)max < 0.001 |
175 parameters | Δρmax = 0.67 e Å−3 |
0 restraints | Δρmin = −0.66 e Å−3 |
Crystal data top
[Ni(C3H4N2)5(H2O)](C4H2Br2O4) | V = 2696.9 (4) Å3 |
Mr = 690.97 | Z = 4 |
Monoclinic, C2/c | Mo Kα radiation |
a = 15.8702 (11) Å | µ = 3.73 mm−1 |
b = 12.9262 (11) Å | T = 298 K |
c = 13.9436 (11) Å | 0.36 × 0.24 × 0.22 mm |
β = 109.468 (3)° | |
Data collection top
Bruker SMART CCD area-detector diffractometer | 3000 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 1999) | 2048 reflections with I > 2σ(I) |
Tmin = 0.355, Tmax = 0.440 | Rint = 0.020 |
5513 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.050 | 0 restraints |
wR(F2) = 0.156 | H-atom parameters constrained |
S = 1.05 | Δρmax = 0.67 e Å−3 |
3000 reflections | Δρmin = −0.66 e Å−3 |
175 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. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | Occ. (<1) |
Br | 0.40093 (4) | 0.44731 (4) | 0.34294 (4) | 0.0676 (2) | |
O2 | 0.6046 (2) | 0.5643 (3) | 0.4011 (3) | 0.0715 (10) | |
C8 | 0.5087 (4) | 0.4605 (5) | 0.4681 (4) | 0.0739 (15) | |
H9 | 0.5170 | 0.3947 | 0.5050 | 0.089* | |
C7 | 0.5897 (3) | 0.4772 (5) | 0.4322 (4) | 0.0761 (14) | |
O1 | 0.6357 (5) | 0.3984 (5) | 0.4389 (5) | 0.156 (3) | |
Ni | 0.5000 | 0.85930 (5) | 0.2500 | 0.0443 (2) | |
N1 | 0.6115 (2) | 0.8477 (3) | 0.1917 (3) | 0.0486 (8) | |
N3 | 0.5938 (2) | 0.8538 (2) | 0.4021 (3) | 0.0454 (8) | |
N4 | 0.7211 (3) | 0.8630 (3) | 0.5330 (3) | 0.0576 (10) | |
H7 | 0.7762 | 0.8754 | 0.5671 | 0.069* | |
O3 | 0.5000 | 0.6904 (3) | 0.2500 | 0.0551 (11) | |
C4 | 0.5809 (3) | 0.8174 (3) | 0.4908 (3) | 0.0498 (10) | |
H5 | 0.5269 | 0.7934 | 0.4946 | 0.060* | |
C6 | 0.6804 (3) | 0.8796 (4) | 0.4338 (4) | 0.0537 (11) | |
H8 | 0.7092 | 0.9064 | 0.3911 | 0.064* | |
C1 | 0.6512 (3) | 0.7563 (4) | 0.1787 (4) | 0.0635 (13) | |
H1 | 0.6360 | 0.6909 | 0.1957 | 0.076* | |
C5 | 0.6584 (3) | 0.8222 (4) | 0.5704 (4) | 0.0595 (12) | |
H6 | 0.6673 | 0.8019 | 0.6370 | 0.071* | |
N2 | 0.7169 (3) | 0.8790 (4) | 0.1244 (3) | 0.0706 (12) | |
H3 | 0.7511 | 0.9124 | 0.0987 | 0.085* | |
C3 | 0.6544 (4) | 0.9210 (4) | 0.1590 (4) | 0.0686 (14) | |
H4 | 0.6429 | 0.9915 | 0.1598 | 0.082* | |
C2 | 0.7163 (3) | 0.7765 (5) | 0.1373 (4) | 0.0735 (15) | |
H2 | 0.7529 | 0.7283 | 0.1211 | 0.088* | |
N5 | 0.5000 | 1.0308 (4) | 0.2500 | 0.0509 (12) | |
C9 | 0.5437 (3) | 1.0948 (4) | 0.3265 (4) | 0.0614 (12) | |
C10 | 0.5281 (3) | 1.1952 (3) | 0.2999 (4) | 0.065 (15) | 0.50 |
N6 | 0.5281 (3) | 1.1952 (3) | 0.2999 (4) | 0.066 (12) | 0.50 |
H12 | 0.5260 | 0.6414 | 0.2986 | 0.050* | |
H10 | 0.5720 | 1.0730 | 0.3975 | 0.050* | |
H11 | 0.5508 | 1.2421 | 0.3417 | 0.050* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Br | 0.0756 (4) | 0.0682 (4) | 0.0577 (4) | −0.0106 (2) | 0.0205 (3) | 0.0019 (2) |
O2 | 0.0562 (19) | 0.086 (3) | 0.065 (2) | −0.0171 (17) | 0.0102 (17) | 0.0161 (18) |
C8 | 0.069 (3) | 0.096 (4) | 0.068 (4) | 0.006 (3) | 0.037 (3) | −0.004 (3) |
C7 | 0.068 (3) | 0.087 (4) | 0.061 (3) | 0.027 (3) | 0.046 (3) | 0.019 (3) |
O1 | 0.210 (6) | 0.152 (5) | 0.169 (5) | 0.130 (5) | 0.147 (5) | 0.098 (4) |
Ni | 0.0462 (4) | 0.0377 (4) | 0.0537 (5) | 0.000 | 0.0227 (4) | 0.000 |
N1 | 0.0452 (18) | 0.052 (2) | 0.054 (2) | 0.0021 (15) | 0.0223 (16) | 0.0002 (17) |
N3 | 0.0457 (18) | 0.0410 (18) | 0.052 (2) | −0.0021 (14) | 0.0198 (16) | −0.0029 (15) |
N4 | 0.0483 (19) | 0.056 (2) | 0.064 (3) | 0.0006 (17) | 0.0119 (19) | −0.0079 (19) |
O3 | 0.061 (2) | 0.034 (2) | 0.066 (3) | 0.000 | 0.016 (2) | 0.000 |
C4 | 0.051 (2) | 0.047 (2) | 0.053 (3) | −0.0112 (19) | 0.020 (2) | −0.0035 (19) |
C6 | 0.049 (2) | 0.056 (3) | 0.061 (3) | −0.0015 (19) | 0.024 (2) | −0.003 (2) |
C1 | 0.057 (3) | 0.052 (3) | 0.087 (4) | 0.002 (2) | 0.032 (3) | −0.010 (3) |
C5 | 0.073 (3) | 0.056 (3) | 0.048 (3) | −0.007 (2) | 0.017 (2) | −0.006 (2) |
N2 | 0.062 (2) | 0.097 (4) | 0.068 (3) | 0.004 (2) | 0.042 (2) | 0.012 (3) |
C3 | 0.071 (3) | 0.063 (3) | 0.086 (4) | 0.007 (2) | 0.045 (3) | 0.015 (3) |
C2 | 0.062 (3) | 0.087 (4) | 0.078 (4) | 0.015 (3) | 0.033 (3) | −0.012 (3) |
N5 | 0.059 (3) | 0.034 (2) | 0.068 (3) | 0.000 | 0.032 (3) | 0.000 |
C9 | 0.075 (3) | 0.043 (2) | 0.069 (3) | 0.002 (2) | 0.028 (3) | −0.006 (2) |
C10 | 0.10 (3) | 0.030 (13) | 0.09 (3) | −0.014 (14) | 0.07 (2) | −0.002 (13) |
N6 | 0.066 (16) | 0.066 (17) | 0.07 (2) | 0.000 (12) | 0.022 (13) | 0.000 (13) |
Geometric parameters (Å, º) top
Br—C8 | 2.002 (6) | O3—H12 | 0.9200 |
O2—C7 | 1.257 (6) | C4—C5 | 1.355 (7) |
C8—C8i | 1.440 (10) | C4—H5 | 0.9300 |
C8—C7 | 1.543 (7) | C6—H8 | 0.9300 |
C8—H9 | 0.9800 | C1—C2 | 1.367 (7) |
C7—O1 | 1.239 (6) | C1—H1 | 0.9300 |
Ni—N3 | 2.147 (3) | C5—H6 | 0.9300 |
Ni—N3ii | 2.147 (3) | N2—C2 | 1.338 (7) |
Ni—O3 | 2.183 (4) | N2—C3 | 1.352 (7) |
Ni—N1ii | 2.185 (3) | N2—H3 | 0.8600 |
Ni—N1 | 2.185 (3) | C3—H4 | 0.9300 |
Ni—N5 | 2.217 (5) | C2—H2 | 0.9300 |
N1—C3 | 1.333 (6) | N5—C9 | 1.346 (6) |
N1—C1 | 1.379 (5) | N5—C9ii | 1.346 (6) |
N3—C6 | 1.338 (5) | C9—C10 | 1.350 (7) |
N3—C4 | 1.402 (5) | C9—H10 | 0.9800 |
N4—C6 | 1.335 (6) | C10—N6ii | 1.379 (10) |
N4—C5 | 1.373 (6) | C10—C10ii | 1.379 (10) |
N4—H7 | 0.8600 | C10—H11 | 0.835 (5) |
| | | |
C8i—C8—C7 | 116.9 (6) | Ni—O3—H12 | 134.00 |
C8i—C8—Br | 108.4 (5) | C5—C4—N3 | 110.4 (4) |
C7—C8—Br | 107.0 (4) | C5—C4—H5 | 124.8 |
C8i—C8—H9 | 108.1 | N3—C4—H5 | 124.8 |
C7—C8—H9 | 108.1 | N4—C6—N3 | 113.0 (4) |
Br—C8—H9 | 108.1 | N4—C6—H8 | 123.5 |
O1—C7—O2 | 126.1 (5) | N3—C6—H8 | 123.5 |
O1—C7—C8 | 113.2 (6) | C2—C1—N1 | 109.5 (5) |
O2—C7—C8 | 120.7 (5) | C2—C1—H1 | 125.2 |
N3—Ni—N3ii | 176.24 (17) | N1—C1—H1 | 125.2 |
N3—Ni—O3 | 88.12 (9) | C4—C5—N4 | 106.3 (4) |
N3ii—Ni—O3 | 88.12 (9) | C4—C5—H6 | 126.8 |
N3—Ni—N1ii | 90.61 (14) | N4—C5—H6 | 126.8 |
N3ii—Ni—N1ii | 89.13 (14) | C2—N2—C3 | 108.1 (4) |
O3—Ni—N1ii | 86.07 (10) | C2—N2—H3 | 125.9 |
N3—Ni—N1 | 89.13 (14) | C3—N2—H3 | 125.9 |
N3ii—Ni—N1 | 90.61 (14) | N1—C3—N2 | 110.9 (5) |
O3—Ni—N1 | 86.07 (10) | N1—C3—H4 | 124.6 |
N1ii—Ni—N1 | 172.14 (19) | N2—C3—H4 | 124.6 |
N3—Ni—N5 | 91.88 (9) | N2—C2—C1 | 106.6 (4) |
N3ii—Ni—N5 | 91.88 (9) | N2—C2—H2 | 126.7 |
O3—Ni—N5 | 180.000 (1) | C1—C2—H2 | 126.7 |
N1ii—Ni—N5 | 93.93 (10) | C9—N5—C9ii | 104.1 (6) |
N1—Ni—N5 | 93.93 (9) | C9—N5—Ni | 127.9 (3) |
C3—N1—C1 | 104.9 (4) | C9ii—N5—Ni | 127.9 (3) |
C3—N1—Ni | 130.4 (3) | N5—C9—C10 | 112.0 (5) |
C1—N1—Ni | 124.7 (3) | N5—C9—H10 | 124.00 |
C6—N3—C4 | 103.2 (4) | C10—C9—H10 | 122.3 (5) |
C6—N3—Ni | 128.0 (3) | C9—C10—N6ii | 106.0 (3) |
C4—N3—Ni | 128.8 (3) | C9—C10—C10ii | 106.0 (3) |
C6—N4—C5 | 107.1 (4) | C9—C10—H11 | 120.6 (5) |
C6—N4—H7 | 126.5 | N6ii—C10—H11 | 133.5 (3) |
C5—N4—H7 | 126.5 | C10ii—C10—H11 | 133.5 (3) |
| | | |
C8i—C8—C7—O1 | 135.7 (8) | C4—N3—C6—N4 | −0.4 (5) |
Br—C8—C7—O1 | −102.6 (6) | Ni—N3—C6—N4 | −177.2 (3) |
C8i—C8—C7—O2 | −43.6 (9) | C3—N1—C1—C2 | −0.8 (6) |
Br—C8—C7—O2 | 78.1 (6) | Ni—N1—C1—C2 | 177.7 (4) |
N3—Ni—N1—C3 | −98.0 (5) | N3—C4—C5—N4 | 0.7 (5) |
N3ii—Ni—N1—C3 | 85.8 (5) | C6—N4—C5—C4 | −0.9 (5) |
O3—Ni—N1—C3 | 173.8 (5) | C1—N1—C3—N2 | 1.5 (6) |
N5—Ni—N1—C3 | −6.2 (5) | Ni—N1—C3—N2 | −176.9 (3) |
N3—Ni—N1—C1 | 83.9 (4) | C2—N2—C3—N1 | −1.6 (6) |
N3ii—Ni—N1—C1 | −92.3 (4) | C3—N2—C2—C1 | 1.0 (6) |
O3—Ni—N1—C1 | −4.2 (4) | N1—C1—C2—N2 | −0.1 (6) |
N5—Ni—N1—C1 | 175.8 (4) | N3—Ni—N5—C9 | −2.8 (3) |
O3—Ni—N3—C6 | 110.0 (3) | N3ii—Ni—N5—C9 | 177.2 (3) |
N1ii—Ni—N3—C6 | −164.0 (4) | N1ii—Ni—N5—C9 | 88.0 (3) |
N1—Ni—N3—C6 | 23.9 (4) | N1—Ni—N5—C9 | −92.0 (3) |
N5—Ni—N3—C6 | −70.0 (3) | N3—Ni—N5—C9ii | 177.2 (3) |
O3—Ni—N3—C4 | −66.1 (3) | N3ii—Ni—N5—C9ii | −2.8 (3) |
N1ii—Ni—N3—C4 | 19.9 (3) | N1ii—Ni—N5—C9ii | −92.0 (3) |
N1—Ni—N3—C4 | −152.2 (4) | N1—Ni—N5—C9ii | 88.0 (3) |
N5—Ni—N3—C4 | 113.9 (3) | C9ii—N5—C9—C10 | 0.2 (3) |
C6—N3—C4—C5 | −0.2 (5) | Ni—N5—C9—C10 | −179.8 (3) |
Ni—N3—C4—C5 | 176.6 (3) | N5—C9—C10—N6ii | −0.6 (6) |
C5—N4—C6—N3 | 0.8 (5) | N5—C9—C10—C10ii | −0.6 (6) |
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) −x+1, y, −z+1/2. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H12···O2 | 0.92 | 1.85 | 2.743 (5) | 165 |
N2—H3···O1iii | 0.86 | 2.04 | 2.773 (9) | 143 |
N4—H7···O2iv | 0.86 | 1.95 | 2.771 (6) | 158 |
N6—H11···O1v | 0.84 | 2.55 | 3.372 (8) | 167 |
C10—H11···O1v | 0.84 | 2.55 | 3.372 (8) | 167 |
Symmetry codes: (iii) −x+3/2, y+1/2, −z+1/2; (iv) −x+3/2, −y+3/2, −z+1; (v) x, y+1, z. |
Experimental details
Crystal data |
Chemical formula | [Ni(C3H4N2)5(H2O)](C4H2Br2O4) |
Mr | 690.97 |
Crystal system, space group | Monoclinic, C2/c |
Temperature (K) | 298 |
a, b, c (Å) | 15.8702 (11), 12.9262 (11), 13.9436 (11) |
β (°) | 109.468 (3) |
V (Å3) | 2696.9 (4) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 3.73 |
Crystal size (mm) | 0.36 × 0.24 × 0.22 |
|
Data collection |
Diffractometer | Bruker SMART CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Bruker, 1999) |
Tmin, Tmax | 0.355, 0.440 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 5513, 3000, 2048 |
Rint | 0.020 |
(sin θ/λ)max (Å−1) | 0.643 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.050, 0.156, 1.05 |
No. of reflections | 3000 |
No. of parameters | 175 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.67, −0.66 |
Selected geometric parameters (Å, º) topNi—N3 | 2.147 (3) | Ni—N1 | 2.185 (3) |
Ni—O3 | 2.183 (4) | Ni—N5 | 2.217 (5) |
| | | |
N3—Ni—N3i | 176.24 (17) | N1i—Ni—N1 | 172.14 (19) |
N3—Ni—O3 | 88.12 (9) | N3—Ni—N5 | 91.88 (9) |
N3—Ni—N1 | 89.13 (14) | O3—Ni—N5 | 180.000 (1) |
N3i—Ni—N1 | 90.61 (14) | N1i—Ni—N5 | 93.93 (10) |
O3—Ni—N1 | 86.07 (10) | | |
Symmetry code: (i) −x+1, y, −z+1/2. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H12···O2 | 0.92 | 1.85 | 2.743 (5) | 165 |
N2—H3···O1ii | 0.86 | 2.04 | 2.773 (9) | 143 |
N4—H7···O2iii | 0.86 | 1.95 | 2.771 (6) | 158 |
N6—H11···O1iv | 0.84 | 2.55 | 3.372 (8) | 167 |
C10—H11···O1iv | 0.84 | 2.55 | 3.372 (8) | 167 |
Symmetry codes: (ii) −x+3/2, y+1/2, −z+1/2; (iii) −x+3/2, −y+3/2, −z+1; (iv) x, y+1, z. |
As π–π stacking plays an important role in some biological processes (Deisenhofer & Michel, 1989), the nature of these stacking interactions has attracted our attention. A series of metal complexes incorporating different aromatic ligands has been prepared and their structures determined to compare the effect of the size of the aromatic ring on π–π stacking. The research results show that not all complexes containing aromatic rings display π–π stacking interactions. The title NiII complex, (I), with imidazole ligands and dibromosuccinate anions, has been prepared, but its crystal structure shows no π–π stacking.
The crystal structure of (I) consists of NiII complex cations and dibromosuccinate anions (DBrS), as shown in Fig. 1. The compound is isostructural with the corresponding CoII complex (Li et al., 2004). The NiII atom, located on a twofold axis, is coordinated by five imidazole ligands and one water molecule in an octahedral geometry. The coordinated water O atom and the N5-containing imidazole ligand are also located on the twofold axis. Thus, the N5-imidazole is disordered, with atoms N6 and C10 occupying the same site with 0.5 occupancy each. The N5-imidazole is linked to the carboxyl group of DBrS via a disordered N6—H11···O1i or C10—H11···O1i hydrogen bond [Table 2; symmetry code: (i) x, 1 + y, z].
The complete DBrS anion lies on an inversion centre. Each carboxyl group participates in similar hydrogen-bond linkages with the N2ii-imidazole, the N4iii-imidazole and the O3 water molecule [symmetry codes: (ii) 3/2 − x, 1/2 + y, 1/2 − z; (iii) 3/2 − x, 3/2 − y, 1 − z], as shown in Fig. 2. No π–π stacking is observed in (I). The nearest distance between imidazole rings of neighbouring complex cations is 3.284 (6) Å (N4···N4iii; Fig.3).