metal-organic compounds
trans-N,N,N′,N′-Tetrakis(carboxymethyl)cyclohexane-1,2-diammonium tetrachloridocadmium(II) tetrahydrate
aCollege of Chemistry and Life Science, Gannan Normal University, Ganzhou, Jiangxi 341000, People's Republic of China, and bDepartment of Chemistry and Environmental Science, Zhangzhou Normal University, Zhangzhou, Fujian 363000, People's Republic of China
*Correspondence e-mail: ghx919@yahoo.com.cn
In the title compound, (C14H24N2O8)[CdCl4]·4H2O, the Cd atom in the tetrahedral [CdCl4]2− anion lies on a twofold rotation axis, and the diprotonated organic molecule, trans-N,N,N′,N′-tetrakis(carboxymethyl)cyclohexane-1,2-diammonium, has 2 symmetry with the twofold rotation axis running through the mid-point of two C—C bonds in the cyclohexane unit. In the classical intramolecular O—H⋯O and N—H⋯O and intermolecular O—H⋯O, N—H⋯O, O—H⋯Cl and C—H⋯Cl hydrogen bonds are observed.
Related literature
For the structure of 1,2-diaminocyclohexane-N,N′-tetraacetate ferrate(III), see: Seibig & Van Eldik (1998). For related tetraacetate-based Cu(II) dimeric and polymeric complexes, see: Wang et al. (1999); Ben Amor & Jouini (1999). For highly stable chiral three-dimensional cadmium 1,2,4-benzenetricarboxylate structures with NLO and fluorescence properties, see: Wang et al. (2006). For a flexible multicarboxylate ligand used to form homochiral helical Zn and Cd coordination polymers, see: Zang et al. (2006).
Experimental
Crystal data
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Refinement
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Data collection: SMART (Siemens, 1996); cell SAINT (Siemens, 1996); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL/PC (Sheldrick, 2008); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2003).
Supporting information
10.1107/S160053680804110X/si2140sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: 10.1107/S160053680804110X/si2140Isup2.hkl
Trans-1,2-cyclohexanediamine-N,N,N',N' -tetra-acetic acid (0.012 mol, 0.4156 g) and CdCl2 (0.0045 mol, 0.8249 g) were dissolved in dilute HCl (10 ml, 1M) and the resultant solution was evaporated slowly at ca 323 K. The title compound was obtained as block colourless crystals after several days.
The C-bound H atoms were positioned geometrically, with C—H = 0.98 Å and 0.97 Å and refined as riding with Uiso(H) = 1.2Ueq(C) or 1.5Ueq. Atom H1B was positioned geometrically and allowed to ride on N1, with N—H = 0.91Å and Uiso(H)= 1.2Ueq(N). The H atoms bonded to carboxyl O atoms were located in a difference Fourier map and refined with O–H distance restraints of 0.85 (2) Å. Water H atoms were located in a difference map and refined with O—H and H···H distance restraints of 0.85 (1) and 1.39 (2) Å, respectively, and with Uiso(H) = 1.5Ueq(O).
Data collection: SMART (Siemens, 1996); cell
SAINT (Siemens, 1996); data reduction: SAINT (Siemens, 1996); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL/PC (Sheldrick, 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2003).Fig. 1. View of the molecular structure of (I), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 35% probability level. Symmetry related atoms are labeled A (symmetry code: -x, y, -z - 3/2) for the CdCl4 unit and (1 - x,y, -z - 1/2) for the cation. | |
Fig. 2. View of the 3-D network for compound (I) along the b axis. |
(C14H24N2O8)[CdCl4]·4H2O | F(000) = 684 |
Mr = 674.63 | Dx = 1.711 Mg m−3 |
Monoclinic, P2/c | Mo Kα radiation, λ = 0.71070 Å |
Hall symbol: -P 2yc | Cell parameters from 4992 reflections |
a = 11.3772 (14) Å | θ = 3.0–25.4° |
b = 8.5734 (10) Å | µ = 1.30 mm−1 |
c = 16.2189 (16) Å | T = 291 K |
β = 124.119 (6)° | Block, colorless |
V = 1309.7 (3) Å3 | 0.68 × 0.54 × 0.28 mm |
Z = 2 |
Siemens SMART CCD area-detector diffractometer | 2400 independent reflections |
Radiation source: fine-focus sealed tube | 2319 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.021 |
ω scans | θmax = 25.4°, θmin = 3.0° |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | h = −13→13 |
Tmin = 0.472, Tmax = 0.712 | k = −9→10 |
12160 measured reflections | l = −19→17 |
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)] = 0.025 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.069 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.01 | w = 1/[σ2(Fo2) + (0.0429P)2 + 0.6848P] where P = (Fo2 + 2Fc2)/3 |
2400 reflections | (Δ/σ)max = 0.002 |
166 parameters | Δρmax = 0.33 e Å−3 |
9 restraints | Δρmin = −0.59 e Å−3 |
(C14H24N2O8)[CdCl4]·4H2O | V = 1309.7 (3) Å3 |
Mr = 674.63 | Z = 2 |
Monoclinic, P2/c | Mo Kα radiation |
a = 11.3772 (14) Å | µ = 1.30 mm−1 |
b = 8.5734 (10) Å | T = 291 K |
c = 16.2189 (16) Å | 0.68 × 0.54 × 0.28 mm |
β = 124.119 (6)° |
Siemens SMART CCD area-detector diffractometer | 2400 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 2319 reflections with I > 2σ(I) |
Tmin = 0.472, Tmax = 0.712 | Rint = 0.021 |
12160 measured reflections |
R[F2 > 2σ(F2)] = 0.025 | 9 restraints |
wR(F2) = 0.069 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.01 | Δρmax = 0.33 e Å−3 |
2400 reflections | Δρmin = −0.59 e Å−3 |
166 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
Cd1 | 0.0000 | 0.53761 (3) | 0.2500 | 0.03615 (11) | |
Cl1 | 0.02889 (8) | 0.72055 (7) | 0.37802 (5) | 0.04979 (18) | |
Cl2 | 0.21701 (5) | 0.38349 (7) | 0.32009 (4) | 0.03949 (15) | |
O1 | 0.4348 (2) | 0.2419 (2) | 0.94146 (13) | 0.0498 (5) | |
H1C | 0.3671 | 0.1650 | 0.9099 | 0.075* | |
O1W | 0.2453 (3) | 0.0262 (3) | 0.8865 (2) | 0.0679 (6) | |
O2 | 0.40158 (16) | 0.24536 (18) | 0.79129 (11) | 0.0359 (4) | |
O2W | −0.0832 (3) | 0.9342 (3) | 0.8284 (2) | 0.0894 (9) | |
O3 | 0.75562 (17) | 0.18174 (18) | 0.96741 (12) | 0.0415 (4) | |
O4 | 0.96749 (15) | 0.3009 (2) | 1.05918 (12) | 0.0402 (4) | |
H4C | 0.9916 | 0.2307 | 1.1010 | 0.060* | |
N1 | 0.62609 (17) | 0.44661 (18) | 0.85909 (12) | 0.0222 (3) | |
H1B | 0.6007 | 0.3609 | 0.8194 | 0.027* | |
C1 | 0.5801 (2) | 0.5898 (2) | 0.79036 (14) | 0.0247 (4) | |
H1A | 0.6297 | 0.5854 | 0.7568 | 0.030* | |
C2 | 0.6258 (3) | 0.7396 (2) | 0.85186 (17) | 0.0363 (5) | |
H2A | 0.5848 | 0.7420 | 0.8905 | 0.044* | |
H2B | 0.7283 | 0.7402 | 0.8980 | 0.044* | |
C3 | 0.5796 (3) | 0.8841 (3) | 0.78646 (19) | 0.0443 (6) | |
H3A | 0.6088 | 0.9769 | 0.8277 | 0.053* | |
H3B | 0.6248 | 0.8856 | 0.7505 | 0.053* | |
C4 | 0.5549 (2) | 0.4321 (2) | 0.91397 (15) | 0.0270 (4) | |
H4A | 0.6261 | 0.4184 | 0.9846 | 0.032* | |
H4B | 0.5022 | 0.5267 | 0.9052 | 0.032* | |
C5 | 0.4558 (2) | 0.2950 (3) | 0.87470 (16) | 0.0301 (4) | |
C6 | 0.7845 (2) | 0.4427 (2) | 0.92917 (16) | 0.0306 (5) | |
H6A | 0.8157 | 0.5296 | 0.9752 | 0.037* | |
H6B | 0.8270 | 0.4539 | 0.8917 | 0.037* | |
C7 | 0.8335 (2) | 0.2919 (3) | 0.98686 (15) | 0.0306 (5) | |
H2WA | −0.126 (7) | 0.924 (6) | 0.7667 (17) | 0.18 (3)* | |
H2WB | −0.090 (5) | 1.020 (3) | 0.848 (3) | 0.106 (18)* | |
H1WA | 0.271 (5) | −0.061 (4) | 0.915 (4) | 0.15 (2)* | |
H1WB | 0.189 (5) | 0.069 (4) | 0.899 (6) | 0.29 (5)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Cd1 | 0.03114 (15) | 0.04045 (17) | 0.03324 (15) | 0.000 | 0.01584 (12) | 0.000 |
Cl1 | 0.0697 (4) | 0.0412 (3) | 0.0407 (3) | 0.0038 (3) | 0.0323 (3) | −0.0005 (3) |
Cl2 | 0.0280 (3) | 0.0544 (4) | 0.0334 (3) | 0.0020 (2) | 0.0156 (2) | −0.0005 (2) |
O1 | 0.0634 (11) | 0.0554 (11) | 0.0410 (10) | −0.0215 (9) | 0.0357 (9) | −0.0021 (8) |
O1W | 0.0683 (14) | 0.0591 (14) | 0.0808 (16) | −0.0126 (11) | 0.0445 (14) | 0.0116 (12) |
O2 | 0.0398 (8) | 0.0370 (8) | 0.0317 (8) | −0.0104 (7) | 0.0205 (7) | −0.0036 (7) |
O2W | 0.0851 (18) | 0.0461 (13) | 0.0653 (16) | 0.0025 (13) | −0.0017 (14) | 0.0128 (12) |
O3 | 0.0376 (9) | 0.0303 (8) | 0.0397 (9) | −0.0023 (7) | 0.0113 (7) | 0.0016 (7) |
O4 | 0.0262 (8) | 0.0442 (9) | 0.0355 (9) | 0.0021 (7) | 0.0083 (7) | 0.0114 (7) |
N1 | 0.0222 (8) | 0.0239 (8) | 0.0187 (8) | −0.0013 (6) | 0.0103 (7) | −0.0016 (6) |
C1 | 0.0271 (10) | 0.0240 (9) | 0.0206 (9) | −0.0011 (8) | 0.0120 (9) | 0.0022 (8) |
C2 | 0.0394 (12) | 0.0262 (11) | 0.0295 (11) | −0.0050 (9) | 0.0109 (10) | −0.0033 (9) |
C3 | 0.0488 (14) | 0.0257 (11) | 0.0440 (13) | −0.0060 (10) | 0.0174 (12) | −0.0003 (10) |
C4 | 0.0297 (10) | 0.0328 (10) | 0.0213 (10) | 0.0010 (9) | 0.0161 (9) | 0.0015 (8) |
C5 | 0.0303 (11) | 0.0328 (11) | 0.0300 (11) | 0.0018 (9) | 0.0185 (9) | 0.0054 (9) |
C6 | 0.0207 (10) | 0.0348 (11) | 0.0297 (11) | −0.0005 (8) | 0.0101 (9) | 0.0033 (9) |
C7 | 0.0288 (11) | 0.0341 (11) | 0.0241 (10) | 0.0006 (9) | 0.0119 (9) | −0.0013 (9) |
Cd1—Cl2i | 2.4465 (6) | N1—H1B | 0.9105 |
Cd1—Cl2 | 2.4465 (6) | C1—C2 | 1.527 (3) |
Cd1—Cl1 | 2.4725 (7) | C1—C1ii | 1.536 (4) |
Cd1—Cl1i | 2.4725 (7) | C1—H1A | 0.9800 |
O1—C5 | 1.314 (3) | C2—C3 | 1.520 (3) |
O1—H1C | 0.9209 | C2—H2A | 0.9700 |
O1W—H1WA | 0.84 (4) | C2—H2B | 0.9700 |
O1W—H1WB | 0.86 (7) | C3—C3ii | 1.508 (5) |
O2—C5 | 1.207 (3) | C3—H3A | 0.9700 |
O2W—H2WA | 0.84 (3) | C3—H3B | 0.9700 |
O2W—H2WB | 0.82 (3) | C4—C5 | 1.501 (3) |
O3—C7 | 1.209 (3) | C4—H4A | 0.9700 |
O4—C7 | 1.304 (3) | C4—H4B | 0.9700 |
O4—H4C | 0.8305 | C6—C7 | 1.508 (3) |
N1—C6 | 1.497 (3) | C6—H6A | 0.9700 |
N1—C4 | 1.508 (2) | C6—H6B | 0.9700 |
N1—C1 | 1.539 (2) | ||
Cl2i—Cd1—Cl2 | 114.62 (3) | C1—C2—H2B | 109.2 |
Cl2i—Cd1—Cl1 | 110.91 (2) | H2A—C2—H2B | 107.9 |
Cl2—Cd1—Cl1 | 109.16 (2) | C3ii—C3—C2 | 109.91 (19) |
Cl2i—Cd1—Cl1i | 109.16 (2) | C3ii—C3—H3A | 109.7 |
Cl2—Cd1—Cl1i | 110.91 (2) | C2—C3—H3A | 109.7 |
Cl1—Cd1—Cl1i | 101.26 (3) | C3ii—C3—H3B | 109.7 |
C5—O1—H1C | 105.8 | C2—C3—H3B | 109.7 |
H1WA—O1W—H1WB | 110 (3) | H3A—C3—H3B | 108.2 |
H2WA—O2W—H2WB | 116 (3) | C5—C4—N1 | 109.79 (16) |
C7—O4—H4C | 112.1 | C5—C4—H4A | 109.7 |
C6—N1—C4 | 111.50 (15) | N1—C4—H4A | 109.7 |
C6—N1—C1 | 110.05 (15) | C5—C4—H4B | 109.7 |
C4—N1—C1 | 114.62 (15) | N1—C4—H4B | 109.7 |
C6—N1—H1B | 106.8 | H4A—C4—H4B | 108.2 |
C4—N1—H1B | 106.7 | O2—C5—O1 | 125.9 (2) |
C1—N1—H1B | 106.7 | O2—C5—C4 | 122.82 (18) |
C2—C1—C1ii | 111.29 (14) | O1—C5—C4 | 111.22 (18) |
C2—C1—N1 | 110.17 (15) | N1—C6—C7 | 111.04 (17) |
C1ii—C1—N1 | 112.08 (13) | N1—C6—H6A | 109.4 |
C2—C1—H1A | 107.7 | C7—C6—H6A | 109.4 |
C1ii—C1—H1A | 107.7 | N1—C6—H6B | 109.4 |
N1—C1—H1A | 107.7 | C7—C6—H6B | 109.4 |
C3—C2—C1 | 111.84 (18) | H6A—C6—H6B | 108.0 |
C3—C2—H2A | 109.2 | O3—C7—O4 | 126.6 (2) |
C1—C2—H2A | 109.2 | O3—C7—C6 | 123.08 (19) |
C3—C2—H2B | 109.2 | O4—C7—C6 | 110.27 (18) |
C6—N1—C1—C2 | −61.6 (2) | C1—N1—C4—C5 | 111.04 (18) |
C4—N1—C1—C2 | 65.0 (2) | N1—C4—C5—O2 | −26.1 (3) |
C6—N1—C1—C1ii | 173.88 (18) | N1—C4—C5—O1 | 155.57 (17) |
C4—N1—C1—C1ii | −59.5 (2) | C4—N1—C6—C7 | 60.0 (2) |
C1ii—C1—C2—C3 | −53.8 (3) | C1—N1—C6—C7 | −171.67 (16) |
N1—C1—C2—C3 | −178.77 (19) | N1—C6—C7—O3 | 10.0 (3) |
C1—C2—C3—C3ii | 58.3 (3) | N1—C6—C7—O4 | −168.89 (18) |
C6—N1—C4—C5 | −123.10 (18) |
Symmetry codes: (i) −x, y, −z+1/2; (ii) −x+1, y, −z+3/2. |
D—H···A | D—H | H···A | D···A | D—H···A |
O1W—H1WA···O3iii | 0.84 (4) | 2.34 (4) | 2.970 (3) | 132 (5) |
N1—H1B···O2 | 0.91 | 2.27 | 2.750 (3) | 112 |
N1—H1B···O2ii | 0.91 | 2.04 | 2.857 (2) | 149 |
O1—H1C···O1W | 0.92 | 1.70 | 2.590 (4) | 162 |
O2W—H2WA···O1Wiv | 0.84 (3) | 2.24 (3) | 2.993 (4) | 151 (5) |
O2W—H2WB···Cl1v | 0.82 (3) | 2.51 (4) | 3.144 (3) | 136 (4) |
O1W—H1WB···Cl1vi | 0.86 (7) | 2.45 (3) | 3.227 (3) | 152 (6) |
O4—H4C···O2Wvii | 0.83 | 1.75 | 2.535 (3) | 157 |
C1—H1A···Cl2viii | 0.98 | 2.67 | 3.637 (3) | 171 |
C4—H4A···Cl2ii | 0.97 | 2.64 | 3.600 (2) | 170 |
C4—H4B···Cl2vi | 0.97 | 2.83 | 3.610 (3) | 138 |
C6—H6A···Cl1ii | 0.97 | 2.60 | 3.537 (2) | 163 |
Symmetry codes: (ii) −x+1, y, −z+3/2; (iii) −x+1, −y, −z+2; (iv) −x, y+1, −z+3/2; (v) x, −y+2, z+1/2; (vi) x, −y+1, z+1/2; (vii) −x+1, −y+1, −z+2; (viii) −x+1, −y+1, −z+1. |
Experimental details
Crystal data | |
Chemical formula | (C14H24N2O8)[CdCl4]·4H2O |
Mr | 674.63 |
Crystal system, space group | Monoclinic, P2/c |
Temperature (K) | 291 |
a, b, c (Å) | 11.3772 (14), 8.5734 (10), 16.2189 (16) |
β (°) | 124.119 (6) |
V (Å3) | 1309.7 (3) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 1.30 |
Crystal size (mm) | 0.68 × 0.54 × 0.28 |
Data collection | |
Diffractometer | Siemens SMART CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 1996) |
Tmin, Tmax | 0.472, 0.712 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 12160, 2400, 2319 |
Rint | 0.021 |
(sin θ/λ)max (Å−1) | 0.602 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.025, 0.069, 1.01 |
No. of reflections | 2400 |
No. of parameters | 166 |
No. of restraints | 9 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.33, −0.59 |
Computer programs: SMART (Siemens, 1996), SAINT (Siemens, 1996), SHELXS97 (Sheldrick, 2008), SHELXTL/PC (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2003).
D—H···A | D—H | H···A | D···A | D—H···A |
O1W—H1WA···O3i | 0.84 (4) | 2.34 (4) | 2.970 (3) | 132 (5) |
N1—H1B···O2 | 0.91 | 2.27 | 2.750 (3) | 112.3 |
N1—H1B···O2ii | 0.91 | 2.04 | 2.857 (2) | 149.0 |
O1—H1C···O1W | 0.92 | 1.70 | 2.590 (4) | 161.5 |
O2W—H2WA···O1Wiii | 0.84 (3) | 2.24 (3) | 2.993 (4) | 151 (5) |
O2W—H2WB···Cl1iv | 0.82 (3) | 2.51 (4) | 3.144 (3) | 136 (4) |
O1W—H1WB···Cl1v | 0.86 (7) | 2.45 (3) | 3.227 (3) | 152 (6) |
O4—H4C···O2Wvi | 0.83 | 1.75 | 2.535 (3) | 157.4 |
C1—H1A···Cl2vii | 0.98 | 2.67 | 3.637 (3) | 170.9 |
C4—H4A···Cl2ii | 0.97 | 2.64 | 3.600 (2) | 170.2 |
C4—H4B···Cl2v | 0.97 | 2.83 | 3.610 (3) | 138.1 |
C6—H6A···Cl1ii | 0.97 | 2.60 | 3.537 (2) | 163.0 |
Symmetry codes: (i) −x+1, −y, −z+2; (ii) −x+1, y, −z+3/2; (iii) −x, y+1, −z+3/2; (iv) x, −y+2, z+1/2; (v) x, −y+1, z+1/2; (vi) −x+1, −y+1, −z+2; (vii) −x+1, −y+1, −z+1. |
Acknowledgements
This work was supported by Jiangxi Provincial Educational Foundation (No. 20060237), the Natural Science Foundation of Fujian Province (No. 2008 J0172) and the Key Laboratory of Jiangxi University for Functional Materials Chemistry.
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In recent years, one-, two- and three-dimensional infinite supramolecular coordination assemblies of Cd(II) have been the subject of great interest owing to their potential applications in many fields, such as catalysis and optical properties (Wang et al., 2006; Zang et al., 2006). Trans-1,2- cyclohexanediamine-N,N,N',N'-tetra-acetic acid (H4CTA) is a multifunctional ligand that not only can coordinate to metal ions to form coordination complexes, also can act as hydrogen bonding donors in forming supramolecular coordination assemblies (Ben Amor & Jouini, 1999; Seibig & Van Eldik, 1998; Wang et al., 1999). In this work, we report a novel Cd(II) complex accidently obtained by CdCl2 and H4CTA, [CdCl4].H6CTA.4H2O (I).
The molecular structure of the compound (I) is revealed in Fig. 1. The asymmetric unit of the complex consists of 1/2 [CdCl4]2- tetrahedral anion unit, one protonated H6CTA cation plus two interstitial water molecules. The Cd(II) atom in the anion is tetrahedrally coordinated by four chlorine atoms, in which the bond length of Cd—Cl lie in the range from 2.4465 (6) Å to 2.4725 (7) Å, and the bond angles Cl—Cd—Cl vary from 101.26 (3) to 114.62 (3)°. The cadmium atom in the tetrahedral anion unit, [CdCl4]2-, lies on a crystallographic rotation axis (site symmetry 2), and the diprotonated organic molecule, [H6CTA]2+, has a twofold rotation symmetry with the crystallographic twofold axis running through the middle of two C—C bonds of the cyclohexane part.
In the crystal structure of the compound (I), classic inter- and intra- molecular O—H···O, N—H···O, O—H···Cl and C—H···Cl hydrogen bonds are observed (Table 1), which link the ammonium cations, [CdCl4]2- anions and uncoordinated water molecules into a 3-D hydrogen-bonded network and stabilize the crystal packing, as shown in Fig. 2.