Zinc(II) and cadmium(II) chloride complexes with 4,4′-bi-1,2,4-triazole

New coordination compounds with the 4,4′-bi-1,2,4-triazole ligand (btr), namely tetra­aqua-2κ⁴O-di-μ₂-4,4′-bi-1,2,4-tri­azole-1:2κ²N¹:N^1′;2:3κ²N¹:N^1′-hexa­chlorido-1κ³Cl,3κ³Cl-tri­zinc(II), [Zn₃Cl₆(C₄H₄N₆)₂(H₂O)₄], (I), and poly[cadmium(II)-μ₂-4,4′-bi-1,2,4-triazole-κ²N¹:N²-di-μ₂-chlorido], [CdCl₂(C₄H₄N₆)]_n, (II), reveal an unprecedented mol­ecular zwitterionic structure for (I) and a polymeric two-dimensional layer structure for (II). Differences between these products, which involve the formation of either charge-separated chloro­metallate/aqua­metal fragments or complementary organic and inorganic bridges, are attributable to the hardness–softness characters of the metal cations. In (I), two N¹,N^1′-bidentate btr mol­ecules connect one [Zn(H₂O)₄]²⁺ cation and two [ZnCl₃]⁻ anions into a linear trizinc motif (the Zn atom of the cation occupies a centre of inversion in an N₂O₄ coordination octa­hedron, whereas the Zn atom of the anion possesses a distorted tetra­hedral Cl₃N environment). In (II), the distorted vertex-sharing CdCl₄N₂ octa­hedra are linked into binuclear [Cd₂(μ₂-Cl)(μ₂-btr)₂]³⁺ fragments by unprecedented N¹:N²-bidentate btr double bridges and bridging chloride ligands, while the additional chloride anions are also bridging, providing further propagation of the fragments into a two-dimensional network [Cd—Cl = 2.5869 (2)–2.6248 (7) Å].

S1. Comment

The cooperative assembly of small inorganic bridging anions (e.g. halogenides), short organic chelating N-donor bridges (e.g. 1,2,4-triazole derivatives, trz) and transition metal cations provides many possibilities for the development of organic–inorganic frameworks. In a series of Cd^II- and Zn^II-1,2,4-triazolates, the combined role of the anionic components is to connect the metal clusters and to participate in the framework connectivity (Ouellette et al., 2007), while utilization of halogenide anions in ZnF₂-trz (Su et al., 2004) and CdCl₂-trz (Yi et al., 2004) leads to hollow tubular architectures and materials with luminescent properties. The use of the bitopic 4,4'-bi-(1,2,4-triazole) (btr) instead of simple monofunctional triazole ligands involves the rational propagation of the characteristic nodal units into the lattice by means of the doubled triazole functionalities. In particular, such a combination of bitopic triazole and chloride bridges contributes to the formation of eight-connected coordination frameworks involving linear tricopper(II) secondary building blocks (Lysenko et al., 2007). The combined behaviour of the btr molecule and Cl^-, as a co-ligand pair, is still unexplored. We wished to correlate this behaviour with the hardness–softness character of the metal cation. To this end, we have examined Zn^II/Cd^II-btr-Cl^- systems and we report here the structures of two new complexes, [Zn(H₂O)₄(µ₂-btr)₂(ZnCl₃)₂], (I), and [Cd(µ₂-Cl)₂(µ₂-btr)]_n, (II).

The molecular trinuclear coordination compound, (I) (Fig. 1), is realised by consecutive interconnection of the Zn ions by two N1,N1'-bitriazole bridges [Zn2—N4 = 2.0545 (18) Å and Zn1—N1 = 2.0930 (17) Å], and involves a cationic part (Zn1) and two outer anionic centres (Zn2). The central Zn1 atom of the cationic fragment lies on an inversion centre and possesses an octahedral N₂O₄ environment involving two N atoms from btr molecules in trans positions and four aqua ligands in the basal plane [Zn1—O = 2.136 (2) and 2.1091 (17) Å], as has been observed for zwitterionic Zn-pyridine complexes, e.g. Zn(H₂O)₄(pyridine-3-sulfonate-N)₂ (Walsh & Hathaway, 1980). The terminal Zn2 atoms of the anionic fragments display a distorted tetrahedral Cl₃N environment [Zn2—Cl = 2.2305 (7)–2.2658 (7) Å], which is similar to that observed for the anion in [LH][Zn(L)Cl₃] (L = quinoline; Wang et al., 2001). A few examples of charge-separated aquazinc(II)/trichlorozincate(II) arrays have been provided by organic N-donors such as urotropine (Mak & Huang, 1987) and 3,7-dihydro-1,3,7-trimethyl-1H-purine-2,6-dione (Jin et al., 2005), but the zwitterionic trinuclear molecule of (I) has no counterpart in the chemistry of zinc(II) chloride and non-chelating nitrogen ligands.

The noncoordinated N atoms of the btr molecules of (I) participate in intermolecular O—H···N hydrogen bonds, one type of which, H4W···N2^v (see Table 2 for details), connects the molecular complexes into chains. In terms of the graph-set formalism (Etter et al., 1990), pairs of such intermolecular interactions lead to ten-membered R₂²(10) rings translated parallel to the a axis (Fig. 1), while pairs of somewhat stronger H3W···N5^iv interactions link the molecules into layers parallel to the bc plane. Thus, the set of O—H···N bonds leads to a three-dimensional array. The role of O—H···Cl hydrogen bonds is also important. These intermolecular interactions generate a two-dimensional packing pattern, parallel to (102) (Fig. 2), employing four of the six available Cl atoms as hydrogen-bond acceptors. Pairs of weaker C—H···Cl hydrogen bonds (Desiraju & Steiner, 1999) are observed between molecules related by inversion and, in total, the terminal ZnCl₃^- units are involved in four hydrogen bonds.

The less polarizing Cd²⁺ cation, as a weaker Lewis acid, forces the Cl^- anions to behave as co-bridging linkers, resulting in the formation of the more complicated polymeric architecture in the structure of (II). The N₂Cl₄ coordination environment of the Cd1 ion is realised as a distorted octahedron comprising four bonds with Cl^- anions [Cd1—Cl = 2.5869 (2)–2.6248 (7) Å], the lengths of which are typical of compounds with the same coordination environment (Villa et al., 1971). The coordination is completed by N atoms of the organic ligand located in cis positions [Cd1—N = 2.386 (2) and 2.382 (2) Å]. Such a configuration of a CdN₂Cl₄ octahedron is uncommon among complexes with non-chelating N-donor ligands [e.g. Cd(piperazine)Cl₂ (Vaidhyanathan et al., 2003)] (Fig. 3).

Both organic and inorganic ligands bridge the metal ions of (II) and they contribute to the overall connectivity as complementary linkers. Thus, pairs of Cd ions are bridged by Cl2 [Cd1—Cl2—Cd1ⁱ = 98.25 (1)°; symmetry code: (i) -x + 1, y, -z + 3/2] and two N1,N2-bidentate triazoles, similar to the pattern observed in [{Cd₃(µ₂-L)₄(µ₂-Cl)₂}(µ₂-NCS)₂(NCS)₂](H₂O)₂ [L = 4-amino-3,5-dimethyltriazole (Yi et al., 2004)], yielding the primary dinuclear unit of the structure. This coordination mode of the bitriazole ligand is unprecedented; it behaves as a monofunctional triazole, leaving the second available trz ring non-coordinated. Interconnection of the dinuclear units occurs entirely via the Cl^- ligands, which function as either single or double bridges between the Cd ions. Two Cl3 atoms act as µ₂ double bridges between the [Cd₂(µ₂-btr)₂(µ₂-Cl2)]³⁺ binuclear fragments [Cd1—Cl3—Cd1ⁱⁱ = 87.59 (2)°; symmetry code: (ii) -x + 1, -y, -z + 2] and assemble them into zigzag [Cd₂(µ₂-btr)₂(µ₂-Cl2)(µ₂-Cl3)₂]_nⁿ⁺ chains running parallel to the c axis with a Cd1···Cd1ⁱⁱ separation of 3.6210 (4) Å. The chains are connected into a two-dimensional coordination network parallel to the bc plane by means of Cl1 anions, which lie on inversion centres and supply unusual linear interlinks between the Cd ions [Cd1···Cd1^vi = 5.1737 (5) Å; symmetry code: (vi) -x + 1, -y + 1, -z + 2]. This geometry at a bridging Cl^- is rare; it has been observed for a few anionic complexes such as (MeNH₃)₂[CdCl₄] (Chapuis et al., 1975). The successive coordination sheets are separated by 10.39 Å and their non-coordinated trz termini are interdigitated, supporting very weak interlayer C—H···N hydrogen bonding (Table 4, Fig. 5).

In conclusion, we have demonstrated how the structure of MCl₂–btr coordination compounds depends upon the Lewis nature of the dication (Zn²⁺ or Cd²⁺). Cooperation of the bitriazole and Cl^- bridges is relevant for the polymeric array adopted by soft Cd²⁺ ions and this provides a paradigm for hybrid organic–inorganic structures of polyfunctional triazoles, whereas for strongly polarizing Zn²⁺, the ligands are not complementary and produce two distinct coordination geometries within a zwitterionic molecular complex.

S2. Experimental

All materials were of reagent grade and were used as received. The btr ligand was prepared according to the reported procedure of Bartlett & Humphrey (1967). The title coordination compounds, (I) and (II), were synthesized in a similar manner. Evaporation of mixed aqueous solutions (3 ml) of CdCl₂.H₂O (0.0402 g, 0.2 mmol) and btr (0.0136 g, 0.1 mmol) in a desiccator over H₂SO₄ for a few days afforded colourless prisms of (II) (yield 84%). Analogously, compound (I) was prepared in 65% yield.

S3. Refinement

For (I), O-bound H atoms were found in intermediate Fourier maps and were refined fully with isotropic displacement parameters and with restraints for the O—H bond lengths [O—H = 0.79 (2)–0.81 (2) Å]. For both structures, C-bound H atoms were treated as riding in geometrically idealized positions, with C—H = 0.94 Å and U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: IPDS Software (Stoe & Cie, 2000) for (I); SMART-NT (Bruker, 1998) for (II). Cell refinement: IPDS Software (Stoe & Cie, 2000) for (I); SAINT-NT (Bruker, 1999) for (II). Data reduction: IPDS Software (Stoe & Cie, 2000) for (I); SAINT-NT (Bruker, 1999) for (II). For both compounds, 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: WinGX (Version 1.70.01; Farrugia, 1999).

Figures

	Fig. 1. The structure of (I), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii. Dashed lines indicate hydrogen bonds. [Symmetry codes: (i) -x, -y, -z; (v) x - 1, y, z.]
	Fig. 2. A fragment of the structure of (I), showing the packing mode of the long metal–organic molecules and their interconnection by O—H···Cl hydrogen bonds. O—H···N hydrogen bonding expands the structure in the [Which?] direction, which is orthogonal to the plane of the drawing. [Symmetry codes: (ii) -x, -y + 1, -z; (vii) x + 1, -y + 1/2, z + 1/2].
	Fig. 3. The structure of (II), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 40% probability level and H atoms are shown as small spheres of arbitrary radii. [Symmetry codes: (i) 1 - x, y, 1.5 - z; (ii) 1 - x, -y, 2 - z].
	Fig. 4. The two-dimensional network in the structure of (II), which is supported by a combination of inorganic (bold lines) and organic bridges. H atoms and part of the non-coordinated triazole groups have been omitted for clarity. N atoms are shaded grey. [Symmetry codes: (i) 1 - x, y, 3/2 - z; (ii) 1 - x, -y, 2 - z; (vi) -x + 1, -y + 1, -z + 2].
	Fig. 5. The packing of successive coordination layers in the structure of (II), showing interdigitation of the non-coordinated trz groups (projection on the ac plane). Dashed lines indicate weak C—H···N hydrogen bonds. [Symmetry codes: (iii) -x + 3/2, -y + 3/2, -z + 2; (iv) -x + 3/2, y - 1/2, -z + 3/2].

(I) tetraaqua-2κ⁴O-di-µ₂-4,4'-bi-1,2,4-triazole- 1:2κ²N¹:N^1',2:3κ²N¹:N^1'-hexachlorido-1κ³Cl,3κ³Cl- trizinc(II)

Crystal data

[Zn3Cl6(C4H4N6)2(H2O)4]	F(000) = 744
Mr = 753.14	Dx = 2.060 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 6.8300 (5) Å	Cell parameters from 8000 reflections
b = 14.6428 (14) Å	θ = 2.8–27.9°
c = 12.5650 (9) Å	µ = 3.64 mm^−1
β = 104.903 (9)°	T = 213 K
V = 1214.36 (17) Å^3	Prism, colourless
Z = 2	0.23 × 0.18 × 0.17 mm

Data collection

Stoe IPDS diffractometer	2849 independent reflections
Radiation source: fine-focus sealed tube	2157 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.040
ϕ oscillation scans	θmax = 27.9°, θmin = 2.8°
Absorption correction: part of the refinement model (ΔF) (DIFABS; Walker & Stuart, 1983)	h = −8→8
Tmin = 0.424, Tmax = 0.536	k = −19→19
10447 measured reflections	l = −15→15

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.024	Hydrogen site location: difference Fourier map
wR(F^2) = 0.056	H atoms treated by a mixture of independent and constrained refinement
S = 0.89	w = 1/[σ^2(Fo^2) + (0.0334P)^2] where P = (Fo^2 + 2Fc^2)/3
2849 reflections	(Δ/σ)max = 0.002
167 parameters	Δρmax = 0.76 e Å^−3
6 restraints	Δρmin = −0.63 e Å^−3

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
Zn1	0.0000	0.0000	0.0000	0.01572 (9)
Zn2	0.32992 (4)	0.623118 (16)	0.11676 (2)	0.01810 (8)
Cl1	0.17784 (11)	0.73159 (4)	0.19116 (6)	0.03413 (16)
Cl2	0.67080 (8)	0.63170 (4)	0.17691 (5)	0.02477 (13)
Cl3	0.23367 (9)	0.61617 (4)	−0.06960 (5)	0.02266 (13)
O1	−0.1708 (3)	0.04515 (13)	−0.15837 (18)	0.0300 (4)
O2	−0.2235 (3)	0.05848 (11)	0.06747 (16)	0.0192 (4)
N1	0.1568 (3)	0.12394 (12)	0.03174 (17)	0.0161 (4)
N2	0.3584 (3)	0.13284 (12)	0.02816 (18)	0.0212 (4)
N3	0.2590 (3)	0.25767 (11)	0.09273 (17)	0.0152 (4)
N4	0.2683 (3)	0.49051 (12)	0.15066 (17)	0.0181 (4)
N5	0.2734 (3)	0.45433 (13)	0.25361 (19)	0.0243 (5)
N6	0.2638 (3)	0.34413 (12)	0.13739 (16)	0.0152 (4)
C1	0.1006 (3)	0.19870 (14)	0.0708 (2)	0.0173 (5)
H1	−0.0281	0.2100	0.0821	0.021*
C2	0.4159 (3)	0.21386 (15)	0.0661 (2)	0.0212 (5)
H2	0.5460	0.2385	0.0739	0.025*
C3	0.2602 (3)	0.42346 (14)	0.0815 (2)	0.0182 (5)
H3	0.2531	0.4291	0.0061	0.022*
C4	0.2713 (4)	0.36578 (15)	0.2431 (2)	0.0229 (5)
H4	0.2745	0.3236	0.3000	0.027*
H1W	−0.172 (5)	0.0974 (14)	−0.177 (3)	0.035 (9)*
H2W	−0.213 (5)	0.0116 (19)	−0.208 (2)	0.040 (10)*
H3W	−0.234 (5)	0.032 (2)	0.122 (2)	0.047 (10)*
H4W	−0.335 (4)	0.065 (3)	0.030 (3)	0.063 (13)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Zn1	0.01852 (18)	0.01153 (16)	0.0180 (2)	−0.00277 (13)	0.00624 (14)	−0.00248 (14)
Zn2	0.02179 (14)	0.01289 (12)	0.01948 (16)	−0.00184 (10)	0.00504 (10)	−0.00071 (10)
Cl1	0.0443 (4)	0.0229 (3)	0.0372 (4)	0.0094 (3)	0.0142 (3)	−0.0043 (3)
Cl2	0.0216 (3)	0.0287 (3)	0.0220 (3)	−0.0029 (2)	0.0021 (2)	−0.0051 (2)
Cl3	0.0241 (3)	0.0238 (3)	0.0183 (3)	−0.0041 (2)	0.0023 (2)	0.0008 (2)
O1	0.0403 (11)	0.0236 (10)	0.0213 (12)	−0.0032 (8)	−0.0010 (8)	0.0026 (8)
O2	0.0206 (9)	0.0186 (8)	0.0204 (11)	0.0001 (6)	0.0090 (7)	−0.0007 (7)
N1	0.0148 (9)	0.0142 (9)	0.0194 (11)	−0.0016 (7)	0.0045 (7)	−0.0008 (7)
N2	0.0175 (9)	0.0184 (9)	0.0301 (13)	−0.0025 (7)	0.0107 (8)	−0.0038 (8)
N3	0.0160 (8)	0.0102 (8)	0.0193 (11)	−0.0023 (7)	0.0044 (7)	−0.0024 (7)
N4	0.0231 (10)	0.0136 (8)	0.0201 (12)	−0.0018 (7)	0.0100 (8)	−0.0012 (7)
N5	0.0358 (12)	0.0184 (10)	0.0206 (13)	−0.0041 (8)	0.0110 (9)	−0.0024 (8)
N6	0.0189 (9)	0.0116 (8)	0.0161 (11)	−0.0031 (7)	0.0062 (7)	−0.0029 (7)
C1	0.0136 (10)	0.0145 (10)	0.0227 (14)	−0.0017 (8)	0.0025 (9)	−0.0017 (9)
C2	0.0162 (11)	0.0199 (11)	0.0302 (16)	−0.0011 (8)	0.0107 (10)	−0.0049 (9)
C3	0.0238 (11)	0.0145 (10)	0.0173 (13)	−0.0016 (9)	0.0068 (9)	−0.0001 (8)
C4	0.0339 (13)	0.0190 (11)	0.0170 (14)	−0.0030 (9)	0.0087 (10)	0.0007 (9)

Geometric parameters (Å, º)

Zn1—N1^i	2.0930 (17)	N1—N2	1.395 (3)
Zn1—N1	2.0930 (17)	N2—C2	1.301 (3)
Zn1—O2^i	2.1091 (17)	N3—C1	1.356 (3)
Zn1—O2	2.1091 (17)	N3—C2	1.363 (3)
Zn1—O1^i	2.136 (2)	N3—N6	1.382 (2)
Zn1—O1	2.136 (2)	N4—C3	1.303 (3)
Zn2—N4	2.0545 (18)	N4—N5	1.390 (3)
Zn2—Cl1	2.2305 (7)	N5—C4	1.303 (3)
Zn2—Cl2	2.2589 (7)	N6—C4	1.354 (3)
Zn2—Cl3	2.2658 (7)	N6—C3	1.354 (3)
O1—H1W	0.80 (2)	C1—H1	0.9400
O1—H2W	0.79 (2)	C2—H2	0.9400
O2—H3W	0.81 (2)	C3—H3	0.9400
O2—H4W	0.80 (2)	C4—H4	0.9400
N1—C1	1.298 (3)
N1^i—Zn1—N1	180.0	C1—N1—N2	108.91 (17)
N1^i—Zn1—O2^i	87.67 (7)	C1—N1—Zn1	128.07 (15)
N1—Zn1—O2^i	92.33 (7)	N2—N1—Zn1	122.40 (13)
N1^i—Zn1—O2	92.33 (7)	C2—N2—N1	106.31 (18)
N1—Zn1—O2	87.67 (7)	C1—N3—C2	106.70 (18)
O2^i—Zn1—O2	180.0	C1—N3—N6	126.88 (18)
N1^i—Zn1—O1^i	92.25 (7)	C2—N3—N6	126.38 (18)
N1—Zn1—O1^i	87.75 (7)	C3—N4—N5	108.67 (18)
O2^i—Zn1—O1^i	88.31 (8)	C3—N4—Zn2	123.35 (17)
O2—Zn1—O1^i	91.69 (8)	N5—N4—Zn2	126.56 (14)
N1^i—Zn1—O1	87.75 (7)	C4—N5—N4	106.8 (2)
N1—Zn1—O1	92.25 (7)	C4—N6—C3	107.40 (18)
O2^i—Zn1—O1	91.69 (8)	C4—N6—N3	127.16 (19)
O2—Zn1—O1	88.31 (8)	C3—N6—N3	125.4 (2)
O1^i—Zn1—O1	180.0	N1—C1—N3	108.39 (19)
N4—Zn2—Cl1	116.35 (6)	N1—C1—H1	125.8
N4—Zn2—Cl2	103.40 (6)	N3—C1—H1	125.8
Cl1—Zn2—Cl2	111.79 (3)	N2—C2—N3	109.69 (19)
N4—Zn2—Cl3	98.71 (6)	N2—C2—H2	125.2
Cl1—Zn2—Cl3	114.99 (3)	N3—C2—H2	125.2
Cl2—Zn2—Cl3	110.39 (3)	N4—C3—N6	108.0 (2)
Zn1—O1—H1W	122 (2)	N4—C3—H3	126.0
Zn1—O1—H2W	123 (3)	N6—C3—H3	126.0
H1W—O1—H2W	113 (4)	N5—C4—N6	109.2 (2)
Zn1—O2—H3W	112 (2)	N5—C4—H4	125.4
Zn1—O2—H4W	119 (3)	N6—C4—H4	125.4
H3W—O2—H4W	106 (4)
O2^i—Zn1—N1—C1	176.2 (2)	C1—N3—N6—C4	72.9 (3)
O2—Zn1—N1—C1	−3.8 (2)	C2—N3—N6—C4	−104.4 (3)
O1^i—Zn1—N1—C1	−95.6 (2)	C1—N3—N6—C3	−106.6 (3)
O1—Zn1—N1—C1	84.4 (2)	C2—N3—N6—C3	76.1 (3)
O2^i—Zn1—N1—N2	−13.82 (18)	N2—N1—C1—N3	0.5 (3)
O2—Zn1—N1—N2	166.18 (18)	Zn1—N1—C1—N3	171.52 (15)
O1^i—Zn1—N1—N2	74.39 (18)	C2—N3—C1—N1	−0.8 (3)
O1—Zn1—N1—N2	−105.61 (18)	N6—N3—C1—N1	−178.6 (2)
C1—N1—N2—C2	0.1 (3)	N1—N2—C2—N3	−0.6 (3)
Zn1—N1—N2—C2	−171.56 (17)	C1—N3—C2—N2	0.9 (3)
Cl1—Zn2—N4—C3	146.99 (17)	N6—N3—C2—N2	178.7 (2)
Cl2—Zn2—N4—C3	−90.08 (19)	N5—N4—C3—N6	−1.2 (3)
Cl3—Zn2—N4—C3	23.43 (19)	Zn2—N4—C3—N6	166.06 (14)
Cl1—Zn2—N4—N5	−48.14 (19)	C4—N6—C3—N4	0.9 (3)
Cl2—Zn2—N4—N5	74.79 (18)	N3—N6—C3—N4	−179.52 (19)
Cl3—Zn2—N4—N5	−171.70 (17)	N4—N5—C4—N6	−0.4 (3)
C3—N4—N5—C4	1.0 (3)	C3—N6—C4—N5	−0.3 (3)
Zn2—N4—N5—C4	−165.72 (16)	N3—N6—C4—N5	−179.9 (2)

Symmetry code: (i) −x, −y, −z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1W···Cl1^ii	0.80 (2)	2.51 (2)	3.294 (2)	167 (3)
O1—H2W···Cl2^iii	0.79 (2)	2.55 (2)	3.318 (2)	163 (3)
O2—H3W···N5^iv	0.81 (2)	2.00 (2)	2.809 (3)	174 (3)
O2—H4W···N2^v	0.80 (2)	2.31 (3)	2.976 (3)	142 (4)
C2—H2···Cl3^vi	0.94	2.62	3.445 (2)	147
C3—H3···Cl2^vi	0.94	2.64	3.493 (3)	151

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

(II) poly[cadmium(II)-µ₂-4,4'-bi-1,2,4-triazole-κ²N¹:N²-di-µ₂-chlorido]

Crystal data

[CdCl2(C4H4N6)]	F(000) = 1216
Mr = 319.43	Dx = 2.316 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
a = 21.789 (2) Å	Cell parameters from 6891 reflections
b = 6.3833 (4) Å	θ = 3.1–28.0°
c = 13.8073 (13) Å	µ = 2.93 mm^−1
β = 107.468 (11)°	T = 213 K
V = 1831.8 (3) Å^3	Prism, colourless
Z = 8	0.21 × 0.20 × 0.17 mm

Data collection

Siemens SMART CCD area-detector diffractometer	2179 independent reflections
Radiation source: fine-focus sealed tube	1863 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.034
ω scans	θmax = 28.0°, θmin = 3.1°
Absorption correction: empirical (using intensity measurements) (SADABS; Sheldrick, 1996)	h = −28→28
Tmin = 0.529, Tmax = 0.610	k = −8→7
6891 measured reflections	l = −18→18

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.027	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.069	H-atom parameters constrained
S = 0.99	w = 1/[σ^2(Fo^2) + (0.0507P)^2] where P = (Fo^2 + 2Fc^2)/3
2179 reflections	(Δ/σ)max = 0.003
120 parameters	Δρmax = 2.76 e Å^−3
0 restraints	Δρmin = −0.67 e Å^−3

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
Cd1	0.500023 (9)	0.16621 (3)	0.893760 (14)	0.01578 (9)
Cl1	0.5000	0.5000	1.0000	0.0334 (3)
Cl2	0.5000	−0.10287 (16)	0.7500	0.01628 (19)
Cl3	0.59084 (3)	0.00467 (13)	1.04472 (5)	0.02184 (16)
N1	0.57722 (12)	0.3547 (4)	0.83723 (19)	0.0193 (5)
N2	0.57513 (12)	0.3622 (4)	0.73589 (18)	0.0179 (5)
N3	0.64474 (11)	0.5896 (5)	0.81943 (18)	0.0182 (5)
N4	0.73062 (17)	1.0614 (6)	0.8613 (3)	0.0503 (10)
N5	0.78008 (14)	0.9138 (7)	0.8890 (3)	0.0404 (8)
N6	0.68965 (12)	0.7476 (5)	0.8409 (2)	0.0216 (5)
C1	0.61885 (15)	0.4937 (6)	0.8863 (2)	0.0228 (6)
H1	0.6293	0.5229	0.9561	0.027*
C2	0.61582 (14)	0.5062 (5)	0.7263 (2)	0.0205 (6)
H2	0.6237	0.5451	0.6655	0.025*
C3	0.67754 (19)	0.9566 (6)	0.8332 (4)	0.0447 (11)
H3	0.6363	1.0166	0.8106	0.054*
C4	0.75511 (15)	0.7283 (7)	0.8765 (3)	0.0338 (8)
H4	0.7781	0.6015	0.8896	0.041*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cd1	0.02063 (13)	0.01550 (14)	0.01164 (12)	−0.00003 (8)	0.00548 (8)	0.00231 (7)
Cl1	0.0455 (7)	0.0291 (7)	0.0248 (6)	0.0029 (6)	0.0095 (5)	−0.0130 (5)
Cl2	0.0222 (4)	0.0120 (5)	0.0150 (4)	0.000	0.0062 (3)	0.000
Cl3	0.0136 (3)	0.0300 (4)	0.0211 (3)	0.0014 (3)	0.0041 (2)	0.0139 (3)
N1	0.0240 (12)	0.0207 (14)	0.0135 (11)	−0.0043 (10)	0.0059 (9)	0.0001 (9)
N2	0.0223 (11)	0.0189 (14)	0.0128 (11)	−0.0028 (10)	0.0055 (9)	−0.0021 (9)
N3	0.0173 (11)	0.0196 (14)	0.0177 (11)	−0.0045 (10)	0.0050 (9)	−0.0015 (10)
N4	0.0409 (19)	0.037 (2)	0.064 (2)	−0.0188 (17)	0.0018 (17)	0.0009 (18)
N5	0.0254 (14)	0.059 (2)	0.0360 (17)	−0.0188 (16)	0.0086 (13)	−0.0087 (17)
N6	0.0152 (11)	0.0237 (15)	0.0250 (13)	−0.0054 (11)	0.0046 (9)	−0.0017 (11)
C1	0.0266 (15)	0.0268 (17)	0.0139 (13)	−0.0076 (13)	0.0045 (11)	−0.0018 (12)
C2	0.0235 (14)	0.0228 (16)	0.0164 (14)	−0.0057 (13)	0.0079 (11)	−0.0029 (11)
C3	0.0282 (18)	0.026 (2)	0.070 (3)	−0.0031 (16)	0.0001 (18)	0.0048 (19)
C4	0.0179 (15)	0.044 (2)	0.0377 (18)	−0.0049 (16)	0.0062 (13)	−0.0072 (18)

Geometric parameters (Å, º)

Cd1—N1	2.382 (2)	N3—N6	1.374 (4)
Cd1—N2^i	2.386 (2)	N4—C3	1.291 (5)
Cd1—Cl1	2.5869 (2)	N4—N5	1.396 (5)
Cd1—Cl3^ii	2.6154 (7)	N5—C4	1.293 (6)
Cd1—Cl3	2.6168 (8)	N6—C3	1.358 (5)
Cd1—Cl2	2.6248 (7)	N6—C4	1.368 (4)
N1—C1	1.304 (4)	C1—H1	0.9400
N1—N2	1.387 (3)	C2—H2	0.9400
N2—C2	1.311 (4)	C3—H3	0.9400
N3—C2	1.359 (4)	C4—H4	0.9400
N3—C1	1.364 (4)
N1—Cd1—N2^i	83.24 (9)	N1—N2—Cd1^i	123.10 (18)
N1—Cd1—Cl1	83.69 (6)	C2—N3—C1	107.2 (3)
N2^i—Cd1—Cl1	82.91 (6)	C2—N3—N6	126.1 (2)
N1—Cd1—Cl3^ii	174.19 (7)	C1—N3—N6	126.6 (2)
N2^i—Cd1—Cl3^ii	92.66 (6)	C3—N4—N5	106.3 (3)
Cl1—Cd1—Cl3^ii	91.74 (2)	C4—N5—N4	108.8 (3)
N1—Cd1—Cl3	91.18 (6)	C3—N6—C4	105.9 (3)
N2^i—Cd1—Cl3	171.48 (7)	C3—N6—N3	126.5 (3)
Cl1—Cd1—Cl3	90.10 (2)	C4—N6—N3	127.6 (3)
Cl3^ii—Cd1—Cl3	92.41 (2)	N1—C1—N3	108.5 (3)
N1—Cd1—Cl2	85.56 (6)	N1—C1—H1	125.7
N2^i—Cd1—Cl2	86.07 (6)	N3—C1—H1	125.7
Cl1—Cd1—Cl2	165.422 (19)	N2—C2—N3	108.4 (3)
Cl3^ii—Cd1—Cl2	98.30 (2)	N2—C2—H2	125.8
Cl3—Cd1—Cl2	99.96 (2)	N3—C2—H2	125.8
Cd1—Cl2—Cd1^i	98.25 (4)	N4—C3—N6	110.5 (4)
Cd1^ii—Cl3—Cd1	87.59 (2)	N4—C3—H3	124.8
C1—N1—N2	107.9 (2)	N6—C3—H3	124.8
C1—N1—Cd1	128.5 (2)	N5—C4—N6	108.5 (4)
N2—N1—Cd1	122.38 (18)	N5—C4—H4	125.8
C2—N2—N1	107.9 (2)	N6—C4—H4	125.8
C2—N2—Cd1^i	128.7 (2)
N1—Cd1—Cl2—Cd1^i	−42.51 (6)	Cd1—N1—N2—Cd1^i	−5.2 (3)
N2^i—Cd1—Cl2—Cd1^i	41.01 (6)	C3—N4—N5—C4	0.0 (5)
Cl1—Cd1—Cl2—Cd1^i	0.07 (3)	C2—N3—N6—C3	84.3 (5)
Cl3^ii—Cd1—Cl2—Cd1^i	133.127 (18)	C1—N3—N6—C3	−92.6 (5)
Cl3—Cd1—Cl2—Cd1^i	−132.927 (17)	C2—N3—N6—C4	−97.4 (4)
N1—Cd1—Cl3—Cd1^ii	175.44 (7)	C1—N3—N6—C4	85.7 (4)
Cl1—Cd1—Cl3—Cd1^ii	91.74 (2)	N2—N1—C1—N3	−0.9 (4)
Cl3^ii—Cd1—Cl3—Cd1^ii	0.0	Cd1—N1—C1—N3	−168.6 (2)
Cl2—Cd1—Cl3—Cd1^ii	−98.86 (2)	C2—N3—C1—N1	1.4 (4)
N2^i—Cd1—N1—C1	114.3 (3)	N6—N3—C1—N1	178.9 (3)
Cl1—Cd1—N1—C1	30.8 (3)	N1—N2—C2—N3	0.8 (3)
Cl3—Cd1—N1—C1	−59.2 (3)	Cd1^i—N2—C2—N3	174.3 (2)
Cl2—Cd1—N1—C1	−159.1 (3)	C1—N3—C2—N2	−1.4 (4)
N2^i—Cd1—N1—N2	−51.7 (2)	N6—N3—C2—N2	−178.8 (3)
Cl1—Cd1—N1—N2	−135.3 (2)	N5—N4—C3—N6	0.0 (5)
Cl3—Cd1—N1—N2	134.7 (2)	C4—N6—C3—N4	0.0 (5)
Cl2—Cd1—N1—N2	34.8 (2)	N3—N6—C3—N4	178.6 (3)
C1—N1—N2—C2	0.1 (3)	N4—N5—C4—N6	0.0 (4)
Cd1—N1—N2—C2	168.7 (2)	C3—N6—C4—N5	0.0 (4)
C1—N1—N2—Cd1^i	−173.8 (2)	N3—N6—C4—N5	−178.6 (3)

Symmetry codes: (i) −x+1, y, −z+3/2; (ii) −x+1, −y, −z+2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C1—H1···N5^iii	0.94	2.47	3.274 (4)	144
C2—H2···N5^iv	0.94	2.57	3.193 (4)	124
C4—H4···Cl3^v	0.94	2.81	3.531 (4)	135

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