The title compound, {[Cd
3(C
6H
13N
2)
2Cl
8]·2H
2O}
n, consists of pendant protonated cationic diamine ligands bonded to an anionic one-dimensional coordination polymer chloridocadmate scaffold. Each coordination chain features two kinds of Cd
II centre, each with distorted octahedral coordination geometry. One Cd
II cation lies on a centre of inversion and is coordinated by six bridging chloride ligands, while the other is coordinated by four bridging chloride ligands, one terminal chloride ligand and a 1-aza-4-azoniabicyclo[2.2.2]octane aza N atom. This gives a reversible corner-sharing half-cubic linear polymer that lies along the crystallographic
a direction. The chains interact through hydrogen bonding with solvent water, with each water molecule accepting one N—H
O interaction from a cation and donating to two O—H
Cl interactions with anionic chains, thus linking three separate chains and completing the packing structure.
Supporting information
CCDC reference: 934556
(HDABCO)Cl (10 mmol, 1.48 g) was dissolved in water (20 ml) and a solution of
CdCl2.2.5H2O (10 mmol, 2.28 g) in water (30 ml) was added. The resulting
mixture was stirred and filtered. After a few days of slow evaporation at room
temperature, a large quantity of colourless crystals of (I) were obtained.
H atoms bonded to O and N atoms were found by difference synthesis and refined
isotropically, with water O—H and H···H distances restrained to 0.88 (1) and
1.33 (2) Å, respectively. Methylene H atoms were placed geometrically in
idealised positions and were allowed to ride on their parent C atoms, with
C—H = 0.97 Å and Uiso(H) = 1.2Ueq(C).
Data collection: CrystalClear (Rigaku, 2005); cell refinement: CrystalClear (Rigaku, 2005); data reduction: CrystalClear (Rigaku, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).
Poly[[bis(1-aza-4-azoniabicyclo[2.2.2]octane)di-µ
3-chlorido-tetra-µ
2-chlorido-dichloridotricadmium(II)] dihydrate]
top
Crystal data top
[Cd3(C6H13N2)2Cl8]·2H2O | F(000) = 852 |
Mr = 883.23 | Dx = 2.253 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 5904 reflections |
a = 6.8035 (14) Å | θ = 3.0–27.5° |
b = 21.209 (4) Å | µ = 3.27 mm−1 |
c = 9.0101 (18) Å | T = 293 K |
β = 92.64 (3)° | Block, colourless |
V = 1298.8 (5) Å3 | 0.20 × 0.20 × 0.20 mm |
Z = 2 | |
Data collection top
Rigaku SCXmini diffractometer | 2947 independent reflections |
Radiation source: fine-focus sealed tube | 2688 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.041 |
CCD profile–fitting scans | θmax = 27.5°, θmin = 3.0° |
Absorption correction: multi-scan (CrystalClear; Rigaku, 2005) | h = −8→8 |
Tmin = 0.520, Tmax = 0.525 | k = −27→27 |
12961 measured reflections | l = −11→11 |
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)] = 0.029 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.064 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.14 | w = 1/[σ2(Fo2) + (0.0213P)2 + 1.2063P] where P = (Fo2 + 2Fc2)/3 |
2947 reflections | (Δ/σ)max = 0.001 |
142 parameters | Δρmax = 0.49 e Å−3 |
3 restraints | Δρmin = −0.70 e Å−3 |
Crystal data top
[Cd3(C6H13N2)2Cl8]·2H2O | V = 1298.8 (5) Å3 |
Mr = 883.23 | Z = 2 |
Monoclinic, P21/c | Mo Kα radiation |
a = 6.8035 (14) Å | µ = 3.27 mm−1 |
b = 21.209 (4) Å | T = 293 K |
c = 9.0101 (18) Å | 0.20 × 0.20 × 0.20 mm |
β = 92.64 (3)° | |
Data collection top
Rigaku SCXmini diffractometer | 2947 independent reflections |
Absorption correction: multi-scan (CrystalClear; Rigaku, 2005) | 2688 reflections with I > 2σ(I) |
Tmin = 0.520, Tmax = 0.525 | Rint = 0.041 |
12961 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.029 | 3 restraints |
wR(F2) = 0.064 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.14 | Δρmax = 0.49 e Å−3 |
2947 reflections | Δρmin = −0.70 e Å−3 |
142 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 | Uiso*/Ueq | |
C1 | 0.7176 (6) | 0.67393 (19) | 0.1686 (4) | 0.0398 (10) | |
H1A | 0.7901 | 0.7046 | 0.2292 | 0.048* | |
H1B | 0.6041 | 0.6607 | 0.2221 | 0.048* | |
Cd1 | 0.99124 (3) | 0.584555 (11) | 0.38677 (2) | 0.02223 (8) | |
Cl3 | 0.67275 (12) | 0.60967 (4) | 0.52426 (9) | 0.02722 (18) | |
Cl4 | 1.17901 (11) | 0.53525 (4) | 0.64079 (8) | 0.02392 (17) | |
Cl5 | 1.29096 (12) | 0.53942 (4) | 0.25900 (9) | 0.0310 (2) | |
Cl6 | 1.12874 (14) | 0.69575 (4) | 0.42916 (10) | 0.0383 (2) | |
N1 | 0.8456 (4) | 0.61834 (13) | 0.1428 (3) | 0.0225 (6) | |
C4 | 0.7220 (5) | 0.56807 (17) | 0.0717 (4) | 0.0317 (8) | |
H4A | 0.6393 | 0.5494 | 0.1448 | 0.038* | |
H4B | 0.8057 | 0.5352 | 0.0343 | 0.038* | |
C5 | 0.9936 (5) | 0.6366 (2) | 0.0345 (4) | 0.0347 (9) | |
H5A | 1.0901 | 0.6032 | 0.0274 | 0.042* | |
H5B | 1.0617 | 0.6744 | 0.0689 | 0.042* | |
C3 | 0.5919 (6) | 0.59557 (17) | −0.0572 (4) | 0.0337 (8) | |
H3A | 0.5877 | 0.5668 | −0.1411 | 0.040* | |
H3B | 0.4587 | 0.6018 | −0.0260 | 0.040* | |
C2 | 0.6483 (7) | 0.70448 (19) | 0.0203 (4) | 0.0427 (10) | |
H2A | 0.5103 | 0.7158 | 0.0224 | 0.051* | |
H2B | 0.7237 | 0.7423 | 0.0028 | 0.051* | |
N2 | 0.6788 (4) | 0.65695 (13) | −0.1002 (3) | 0.0262 (6) | |
Cd2 | 0.5000 | 0.5000 | 0.5000 | 0.02356 (9) | |
O1 | 0.3815 (5) | 0.71058 (16) | 0.7324 (3) | 0.0527 (8) | |
C6 | 0.8938 (5) | 0.6489 (2) | −0.1206 (4) | 0.0368 (9) | |
H6A | 0.9476 | 0.6866 | −0.1642 | 0.044* | |
H6B | 0.9161 | 0.6135 | −0.1861 | 0.044* | |
H2 | 0.315 (5) | 0.7038 (19) | 0.649 (3) | 0.053* | |
H3 | 0.308 (5) | 0.7397 (16) | 0.771 (4) | 0.058* | |
H1 | 0.623 (5) | 0.6717 (17) | −0.177 (4) | 0.022* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
C1 | 0.054 (2) | 0.040 (2) | 0.0239 (17) | 0.0255 (19) | −0.0132 (17) | −0.0070 (15) |
Cd1 | 0.02099 (13) | 0.02288 (14) | 0.02276 (13) | 0.00287 (9) | 0.00043 (9) | 0.00148 (9) |
Cl3 | 0.0269 (4) | 0.0262 (4) | 0.0288 (4) | 0.0015 (3) | 0.0040 (3) | −0.0017 (3) |
Cl4 | 0.0232 (4) | 0.0258 (4) | 0.0227 (4) | 0.0034 (3) | 0.0004 (3) | 0.0011 (3) |
Cl5 | 0.0260 (4) | 0.0437 (5) | 0.0235 (4) | 0.0115 (4) | 0.0025 (3) | 0.0051 (3) |
Cl6 | 0.0437 (5) | 0.0277 (5) | 0.0419 (5) | −0.0060 (4) | −0.0142 (4) | 0.0026 (4) |
N1 | 0.0242 (14) | 0.0236 (15) | 0.0193 (13) | 0.0032 (11) | −0.0025 (11) | 0.0032 (10) |
C4 | 0.036 (2) | 0.0274 (19) | 0.0310 (18) | −0.0064 (15) | −0.0062 (15) | 0.0052 (14) |
C5 | 0.0275 (19) | 0.045 (2) | 0.0311 (18) | −0.0056 (16) | −0.0032 (15) | 0.0140 (16) |
C3 | 0.037 (2) | 0.032 (2) | 0.0319 (18) | −0.0077 (16) | −0.0059 (16) | 0.0017 (15) |
C2 | 0.065 (3) | 0.031 (2) | 0.0306 (19) | 0.0227 (19) | −0.0146 (18) | −0.0099 (16) |
N2 | 0.0328 (16) | 0.0264 (16) | 0.0187 (13) | 0.0038 (12) | −0.0062 (12) | 0.0022 (11) |
Cd2 | 0.01766 (17) | 0.02753 (19) | 0.02530 (17) | 0.00030 (13) | −0.00089 (13) | 0.00338 (13) |
O1 | 0.0486 (18) | 0.070 (2) | 0.0375 (16) | 0.0231 (16) | −0.0182 (14) | −0.0111 (14) |
C6 | 0.032 (2) | 0.050 (2) | 0.0288 (18) | −0.0021 (17) | 0.0006 (15) | 0.0111 (16) |
Geometric parameters (Å, º) top
C1—N1 | 1.490 (4) | C4—H4B | 0.9700 |
C1—C2 | 1.539 (5) | C5—C6 | 1.547 (5) |
C1—H1A | 0.9700 | C5—H5A | 0.9700 |
C1—H1B | 0.9700 | C5—H5B | 0.9700 |
Cd1—N1 | 2.475 (2) | C3—N2 | 1.488 (4) |
Cl3—Cd2 | 2.6108 (9) | C3—H3A | 0.9700 |
Cd1—Cl6 | 2.5592 (10) | C3—H3B | 0.9700 |
Cd2—Cl4i | 2.6818 (10) | C2—N2 | 1.503 (4) |
Cd1—Cl5 | 2.5721 (10) | C2—H2A | 0.9700 |
Cd2—Cl5i | 2.6745 (11) | C2—H2B | 0.9700 |
Cd1—Cl3 | 2.6001 (11) | N2—C6 | 1.492 (5) |
Cd1—Cd2 | 3.9674 (8) | N2—H1 | 0.83 (3) |
Cd1—Cl4 | 2.7740 (10) | Cd2—Cl3iii | 2.6108 (9) |
Cd1—Cd2ii | 3.9891 (8) | Cd2—Cl5i | 2.6745 (11) |
Cd1—Cl4i | 2.7988 (10) | Cd2—Cl5iv | 2.6745 (11) |
Cl4—Cd2ii | 2.6818 (10) | Cd2—Cl4iv | 2.6818 (10) |
Cl4—Cd1i | 2.7988 (10) | Cd2—Cl4i | 2.6818 (10) |
Cl5—Cd2ii | 2.6745 (11) | O1—H2 | 0.871 (10) |
N1—C4 | 1.485 (4) | O1—H3 | 0.875 (10) |
N1—C5 | 1.486 (4) | C6—H6A | 0.9700 |
C4—C3 | 1.542 (5) | C6—H6B | 0.9700 |
C4—H4A | 0.9700 | | |
| | | |
N1—C1—C2 | 110.8 (3) | N1—C5—H5B | 109.5 |
N1—C1—H1A | 109.5 | C6—C5—H5B | 109.5 |
C2—C1—H1A | 109.5 | H5A—C5—H5B | 108.1 |
N1—C1—H1B | 109.5 | N2—C3—C4 | 107.8 (3) |
C2—C1—H1B | 109.5 | N2—C3—H3A | 110.1 |
H1A—C1—H1B | 108.1 | C4—C3—H3A | 110.1 |
N1—Cd1—Cl6 | 89.68 (7) | N2—C3—H3B | 110.1 |
N1—Cd1—Cl5 | 90.20 (7) | C4—C3—H3B | 110.1 |
Cl6—Cd1—Cl5 | 96.77 (3) | H3A—C3—H3B | 108.5 |
N1—Cd1—Cl3 | 93.18 (7) | N2—C2—C1 | 107.3 (3) |
Cl6—Cd1—Cl3 | 92.69 (3) | N2—C2—H2A | 110.2 |
Cl5—Cd1—Cl3 | 169.97 (3) | C1—C2—H2A | 110.2 |
N1—Cd1—Cl4 | 172.84 (7) | N2—C2—H2B | 110.2 |
Cl6—Cd1—Cl4 | 94.18 (3) | C1—C2—H2B | 110.2 |
Cl5—Cd1—Cl4 | 83.37 (3) | H2A—C2—H2B | 108.5 |
Cl3—Cd1—Cl4 | 92.66 (3) | C3—N2—C6 | 109.6 (3) |
N1—Cd1—Cl4i | 92.11 (7) | C3—N2—C2 | 109.2 (3) |
Cl6—Cd1—Cl4i | 175.40 (3) | C6—N2—C2 | 109.6 (3) |
Cl5—Cd1—Cl4i | 87.47 (3) | C3—N2—H1 | 112 (2) |
Cl3—Cd1—Cl4i | 82.98 (3) | C6—N2—H1 | 111 (2) |
Cl4—Cd1—Cl4i | 84.49 (3) | C2—N2—H1 | 106 (2) |
Cd1—Cl3—Cd2 | 99.17 (3) | Cl3iii—Cd2—Cl3 | 180.0 |
Cd1—Cl4—Cd1i | 95.51 (3) | Cl3iii—Cd2—Cl5i | 90.57 (3) |
Cd2ii—Cl4—Cd1 | 93.95 (3) | Cl3—Cd2—Cl5i | 89.43 (3) |
Cd1—Cl5—Cd2ii | 98.97 (3) | Cl3iii—Cd2—Cl5iv | 89.43 (3) |
Cd2ii—Cl4—Cd1i | 92.73 (3) | Cl3—Cd2—Cl5iv | 90.57 (3) |
Cd1—Cl4—Cd1i | 95.51 (3) | Cl5i—Cd2—Cl5iv | 180.0 |
Cd1—Cl5—Cd2ii | 98.97 (3) | Cl3iii—Cd2—Cl4iv | 85.11 (3) |
C4—N1—C5 | 107.0 (3) | Cl3—Cd2—Cl4iv | 94.89 (3) |
C4—N1—C1 | 108.2 (3) | Cl5i—Cd2—Cl4iv | 96.74 (3) |
C5—N1—C1 | 108.3 (3) | Cl5iv—Cd2—Cl4iv | 83.26 (3) |
C4—N1—Cd1 | 111.77 (19) | Cl3iii—Cd2—Cl4i | 94.89 (3) |
C5—N1—Cd1 | 113.78 (19) | Cl3—Cd2—Cl4i | 85.11 (3) |
C1—N1—Cd1 | 107.67 (18) | Cl5i—Cd2—Cl4i | 83.26 (3) |
N1—C4—C3 | 110.3 (3) | Cl5iv—Cd2—Cl4i | 96.74 (3) |
N1—C4—H4A | 109.6 | Cl4iv—Cd2—Cl4i | 180.0 |
C3—C4—H4A | 109.6 | H2—O1—H3 | 100 (2) |
N1—C4—H4B | 109.6 | N2—C6—C5 | 107.5 (3) |
C3—C4—H4B | 109.6 | N2—C6—H6A | 110.2 |
H4A—C4—H4B | 108.1 | C5—C6—H6A | 110.2 |
N1—C5—C6 | 110.7 (3) | N2—C6—H6B | 110.2 |
N1—C5—H5A | 109.5 | C5—C6—H6B | 110.2 |
C6—C5—H5A | 109.5 | H6A—C6—H6B | 108.5 |
| | | |
N1—Cd1—Cl3—Cd2 | 90.84 (7) | Cl5—Cd1—N1—C5 | −32.3 (2) |
Cl6—Cd1—Cl3—Cd2 | −179.33 (3) | Cl3—Cd1—N1—C5 | 157.2 (2) |
Cl5—Cd1—Cl3—Cd2 | −18.67 (17) | Cl4—Cd1—N1—C5 | −58.3 (6) |
Cl4—Cd1—Cl3—Cd2 | −85.01 (3) | Cl4i—Cd1—N1—C5 | −119.8 (2) |
Cl4i—Cd1—Cl3—Cd2 | −0.90 (2) | Cl6—Cd1—N1—C1 | −55.6 (2) |
N1—Cd1—Cl4—Cd2ii | 31.2 (5) | Cl5—Cd1—N1—C1 | −152.4 (2) |
Cl6—Cd1—Cl4—Cd2ii | −91.29 (3) | Cl3—Cd1—N1—C1 | 37.1 (2) |
Cl5—Cd1—Cl4—Cd2ii | 5.05 (3) | Cl4—Cd1—N1—C1 | −178.3 (4) |
Cl3—Cd1—Cl4—Cd2ii | 175.81 (3) | Cl4i—Cd1—N1—C1 | 120.2 (2) |
Cl4i—Cd1—Cl4—Cd2ii | 93.13 (3) | C5—N1—C4—C3 | −69.6 (4) |
N1—Cd1—Cl4—Cd1i | −61.9 (5) | C1—N1—C4—C3 | 46.9 (4) |
Cl6—Cd1—Cl4—Cd1i | 175.58 (3) | Cd1—N1—C4—C3 | 165.2 (2) |
Cl5—Cd1—Cl4—Cd1i | −88.08 (3) | C4—N1—C5—C6 | 48.8 (4) |
Cl3—Cd1—Cl4—Cd1i | 82.68 (3) | C1—N1—C5—C6 | −67.6 (4) |
Cl4i—Cd1—Cl4—Cd1i | 0.0 | Cd1—N1—C5—C6 | 172.7 (3) |
N1—Cd1—Cl5—Cd2ii | 178.03 (7) | N1—C4—C3—N2 | 18.6 (4) |
Cl6—Cd1—Cl5—Cd2ii | 88.33 (4) | N1—C1—C2—N2 | 17.6 (5) |
Cl3—Cd1—Cl5—Cd2ii | −72.21 (16) | C4—C3—N2—C6 | 49.3 (4) |
Cl4—Cd1—Cl5—Cd2ii | −5.12 (3) | C4—C3—N2—C2 | −70.7 (4) |
Cl4i—Cd1—Cl5—Cd2ii | −89.86 (3) | C1—C2—N2—C3 | 49.8 (4) |
C2—C1—N1—C4 | −68.3 (4) | C1—C2—N2—C6 | −70.2 (4) |
C2—C1—N1—C5 | 47.3 (4) | Cd1—Cl3—Cd2—Cl3iii | −36 (100) |
C2—C1—N1—Cd1 | 170.7 (3) | Cd1—Cl3—Cd2—Cl5i | 84.22 (3) |
Cl6—Cd1—N1—C4 | −174.3 (2) | Cd1—Cl3—Cd2—Cl5iv | −95.78 (3) |
Cl5—Cd1—N1—C4 | 89.0 (2) | Cd1—Cl3—Cd2—Cl4iv | −179.06 (3) |
Cl3—Cd1—N1—C4 | −81.6 (2) | Cd1—Cl3—Cd2—Cl4i | 0.94 (3) |
Cl4—Cd1—N1—C4 | 63.0 (6) | C3—N2—C6—C5 | −69.2 (4) |
Cl4i—Cd1—N1—C4 | 1.5 (2) | C2—N2—C6—C5 | 50.6 (4) |
Cl6—Cd1—N1—C5 | 64.5 (2) | N1—C5—C6—N2 | 16.6 (4) |
Symmetry codes: (i) −x+2, −y+1, −z+1; (ii) x+1, y, z; (iii) −x+1, −y+1, −z+1; (iv) x−1, y, z. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
C5—H5A···Cl5 | 0.97 | 2.79 | 3.472 (4) | 128 |
C4—H4A···Cl5iv | 0.97 | 2.64 | 3.503 (4) | 149 |
C3—H3A···Cl5v | 0.97 | 2.64 | 3.503 (4) | 148 |
O1—H3···Cl6vi | 0.88 (1) | 2.36 (1) | 3.214 (3) | 166 (4) |
O1—H2···Cl6iv | 0.87 (1) | 2.31 (1) | 3.177 (3) | 175 (4) |
N2—H1···O1vii | 0.83 (3) | 1.98 (4) | 2.716 (4) | 147 (3) |
Symmetry codes: (iv) x−1, y, z; (v) −x+2, −y+1, −z; (vi) x−1, −y+3/2, z+1/2; (vii) x, y, z−1. |
Experimental details
Crystal data |
Chemical formula | [Cd3(C6H13N2)2Cl8]·2H2O |
Mr | 883.23 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 293 |
a, b, c (Å) | 6.8035 (14), 21.209 (4), 9.0101 (18) |
β (°) | 92.64 (3) |
V (Å3) | 1298.8 (5) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 3.27 |
Crystal size (mm) | 0.20 × 0.20 × 0.20 |
|
Data collection |
Diffractometer | Rigaku SCXmini diffractometer |
Absorption correction | Multi-scan (CrystalClear; Rigaku, 2005) |
Tmin, Tmax | 0.520, 0.525 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 12961, 2947, 2688 |
Rint | 0.041 |
(sin θ/λ)max (Å−1) | 0.649 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.029, 0.064, 1.14 |
No. of reflections | 2947 |
No. of parameters | 142 |
No. of restraints | 3 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.49, −0.70 |
Selected geometric parameters (Å, º) topCd1—N1 | 2.475 (2) | Cd1—Cl3 | 2.6001 (11) |
Cl3—Cd2 | 2.6108 (9) | Cd1—Cd2 | 3.9674 (8) |
Cd1—Cl6 | 2.5592 (10) | Cd1—Cl4 | 2.7740 (10) |
Cd2—Cl4i | 2.6818 (10) | Cd1—Cd2ii | 3.9891 (8) |
Cd1—Cl5 | 2.5721 (10) | Cd1—Cl4i | 2.7988 (10) |
Cd2—Cl5i | 2.6745 (11) | | |
| | | |
Cd1—Cl3—Cd2 | 99.17 (3) | Cd1—Cl5—Cd2ii | 98.97 (3) |
Cd1—Cl4—Cd1i | 95.51 (3) | Cd2ii—Cl4—Cd1i | 92.73 (3) |
Cd2ii—Cl4—Cd1 | 93.95 (3) | | |
Symmetry codes: (i) −x+2, −y+1, −z+1; (ii) x+1, y, z. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
C5—H5A···Cl5 | 0.97 | 2.79 | 3.472 (4) | 127.9 |
C4—H4A···Cl5iii | 0.97 | 2.64 | 3.503 (4) | 149.1 |
C3—H3A···Cl5iv | 0.97 | 2.64 | 3.503 (4) | 148.3 |
O1—H3···Cl6v | 0.875 (10) | 2.358 (14) | 3.214 (3) | 166 (4) |
O1—H2···Cl6iii | 0.871 (10) | 2.308 (11) | 3.177 (3) | 175 (4) |
N2—H1···O1vi | 0.83 (3) | 1.98 (4) | 2.716 (4) | 147 (3) |
Symmetry codes: (iii) x−1, y, z; (iv) −x+2, −y+1, −z; (v) x−1, −y+3/2, z+1/2; (vi) x, y, z−1. |
With the discovery of dielectric–ferroelectric systems and their wide range of applications, for instance as filter, capacitor, resonator or solid-state transducer components in microwave communication systems, much attention has been concentrated on studies of new dielectric and ferroelectric materials (Fu et al., 2008; Vanderah, 2002; Ye et al., 2009; Zhang et al., 2010). In the search for potential ferroelectric materials, molecular-based one-, two- and three-dimensional chloridocadmate(II) organic–inorganic compounds have been of interest as they often display solid–solid phase transitions induced by a variation in temperature (Kind et al., 1979; Ma et al., 2006; Peral et al., 2000). A second strand of interest is the potentially bidentate ligand DABCO (1,4-diazoniabicyclo[2.2.2]octane or triethylenediamine), which is well known to bridge metal centres (Fronczek et al., 1990). Our laboratory recently reported a new DABCO compound, Cu(HDABCO)(H2O)Cl3, and its ferroelectric properties. This compound was especially interesting as its ferroelectric properties varied with the different twist angles of the protonated DABCO ligands at different temperatures (Zhang et al., 2012). Combining these themes, some chloridocadmate compounds containg cationic DABCO derivatives are known, such as the one-dimensional compound based on inorganic chains, {[Cd3Cl10]4-}∞, reported by Xiao (2010), and the dimeric chloride-bridged cadmium compound reported by Sampanthar & Vittal (2001). Against this background, the title compound, (I), was prepared and characterised.
Compound (I) consists of one-dimensional organic–inorganic neutral [Cd3(HDABCO)2Cl8]∞ chains that propagate along the crystallographic a direction. The neutrality of the chain comes about from having positively charged HDABCO+ ligands pendant on an anionic Cd/Cl core. Note that here HDABCO+ does not bond to Cd in a bridging mode. The water molecules interact with the chains only through hydrogen bonding (Figs. 1 and 2). The CdII centres are all six-coordinate with distorted octahedral geometries, but there are two kinds of CdII coordination environment in each chain. The Cd1 centre is coordinated by one N atom from a protonated and terminal HDABCO+ ligand, one terminal chloride ligand and four bridging Cl atoms [Cl3, Cl4, Cl4i and Cl5; symmetry code: (i) -x + 2, -y + 1, -z + 1], and Cd2 is situated on an inversion centre and surrounded by six bridging chloride ligands (Table 1). The Cd1 and Cd1i centres are linked together by bridging atoms Cl4 and Cl4i, and the Cd1 and Cd2 cations are linked by atoms Cl4i and Cl3. Meanwhile, the Cd1 and Cd2ii [symmetry code: (ii) x + 1, y, z] cations are linked by atoms Cl4 and Cl5.
Viewing the four-membered Cd2Cl2 rings and their symmetry equivalents as plane faces allows the coordination in (I) to be described as formed from reversible half-cubic cages (Zhang et al., 2007). The Cd···Cd distances are in agreement with those reported for other one-dimensional cadmium polymers bridged by chloride ligands (Huang et al., 1998; Hu et al., 2003; Laskar et al., 2002).
There are several interesting features of structural detail in the [Cd3(HDABCO)2Cl8]∞ structure of (I). From the above description of Cd—Cl bonding, it can be seen that there are three distinct kinds of Cl bonding mode present. Thus, the chloride ligands may be terminal (Cl6), bridge two metal atoms (Cl3 and Cl5) or bridge three metal centres (Cl4). The terminal Cd—Cl distance is 2.559 (4) Å, while the Cd—µ2-Cl distances range from 2.572 (1) to 2.674 (1) Å and the Cd—Cl distances of the three-coordinate Cl ligands range from 2.682 (1) to 2.774 (1) Å. Thus, the order of the Cd—Cl distances is clearly differentiated as: µ3-Cl > µ2-Cl > terminal Cl.
The one-dimensional chain of (I) is a new coordination architecture compared with the related structures {[C7H15N2Cl]2[Cd3Cl10].4H2O}∞, (II), and [{Cl2Cd(DABCO-CH2Cl)}2(µ-Cl)2], (III). In (II) (Xiao, 2010), there is a inorganic zigzag anionic chain. As with (I), this features two six-coordinate but non-equivalent CdII centre types, one of which is coordinated by six bridging chloride ligands. However, the second type of CdII centre is bound to one terminal and five bridging chloride anions, so there is no coordination bond to the HDABCO+ ligand. Coordinatively similar Cd—Cl bonds in (I) and (II) have lengths in agreement with each other. Compound (III) does feature Cd-to-HDABCO+ ligand bonding but is not polymeric (Sampanthar & Vittal, 2001). Instead, its structure is dimeric and centrosymmetric and its two halves are linked together by two Cd—Cl—Cd bridges. Each CdII cation is further bonded to two terminal chloride ligands and a DABCO–CH2Cl ligand (through the tertiary amine N atom) to give a trigonal–bipyramidal coordination geometry. It is noted that the terminal Cd—Cl bond of the three available compounds is always appreciably shorter than the bridging Cd—Cl bonds.
As well as the coordination chains, (I) also contains uncoordinated solvent water molecules. These are connected to the coordination polymer by means of two O—H···Cl hydrogen bonds (Fig. 3 and Table 2). The water molecules thus act as hydrogen-bond donors, but only to the terminal chloride ligands. The packing structure is further stabilised by the formally charged R3NH+ group of the singly protonated HDABCO+ ligand, acting as a hydrogen-bond donor to water. Thus, each water molecule takes part in three hydrogen bonds, with the shortest and strongest hydrogen bond linking water to HDABCO+ (Table 2). These interactions link three polymeric chains together.
The hydrogen-bonding patterns formed by polar organic donors with halometallate anions and water molecules have been described previously, an example being the 4,4'-bipyrazolium system described by Boldog et al. (2009). The HDABCO+ ligands in the chain of (I) are twisted, with the N—C—C—N torsion angles ranging from 16.6 (4) to 18.6 (4)°. Such twisted conformations can also be found in other DABCO compounds (Wei & Willett, 2002; Zhang et al., 2012). Both the C—N and C—C bond lengths are unexceptional compared with those observed previously for other DABCO compounds (Kubiak et al., 1983; Xiao, 2010).
Our original interest in (I) lay mainly in its potential as a molecular ferroelectric material. However, measurement of its dielectric properties with varying temperature did not find a dielectric anomaly within the temperature range 93–293 K. This implies that there is no structural phase transition within this temperature range and so (I) is not a ferroelectric material like those reported earlier (Ye et al., 2009; Fu et al., 2008). Other related materials are currently being investigated for ferroelectric activity.