The coordination polymer poly[[aqua(μ-oxalato)[1H-1,2,4-triazole-5(4H)-thione]cadmium(II)] monohydrate]

The title complex, {[Cd(C₂O₄)(C₂H₃N₃S)(H₂O)]·H₂O}_n, has a two-dimensional metal–organic framework, with the Cd^II cation coordinated by three oxalate ligands, a 1H-1,2,4-tri­az­ole-5(4H)-thione (H₂trzS) ligand and a water mol­ecule. The CdO₆S and oxalate units form an extended two-dimen­sional layered structure, with the terminal H₂trzS ligands bonded to the Cd^II sites through the thione S atoms. Hydrogen-bond inter­actions exist between adjacent layers.

S1. Introduction

In recent decades, the study of metal coordination polymers has witnessed tremendous growth as an attractive inter­face between synthetic chemistry and materials science. These studies have significantly boosted the understanding of the relationship between molecular structure and material function (Zhang et al., 2009, Wang, Zhang et al., 2010). Polyaza heterocyclic compounds have attracted considerable attention as ligands for producing coordination polymers with useful functional properties, such as gas storage (Zhang & Chen, 2008; Cha et al., 2010), magnetism (Ma et al., 2010; Wang, Liu et al., 2010) and catalysis (Wu et al., 2005; Jurss et al., 2010). As a ligand with multiple coordination sites, 1H-1,2,4-triazole-5(4H)-thione (H₂trzS) has gained much attention, since it can bridge different metal centres to afford coordination polymers that exhibit extraordinary structural diversity (Cheng et al., 2009). Oxalate is unique due to its function as a bis-bidentate ligand, and a number of its coordination complexes have been obtained with rigid framework structures (García-Terán et al., 2004; Prasad et al., 2002). In some metal–organic frameworks (MOFs), more than one type of ligand has been used to expand their structural diversity, as well as to enhance their physical properties (García-Couceiro et al., 2005; Yang et al., 2013). In this work, we use both 1H-1,2,4-triazole-5(4H)-thione (H₂trzS) and oxalate (ox) as mixed ligands to construct a new framework and report the structure of the title two-dimensional coordination polymer {[Cd(ox)(H₂trzS)(H₂O)].H₂O}_n, (I). To the best of our knowledge, (I) is the first example adopting the oxalate ligand as the second ligand among the H₂trzS-based coordination polymers.

S2. Experimental

S2.1. Synthesis and crystallization

The title compound was prepared under mild hydro­thermal conditions. 3CdSO₄.8H₂O (0.133 mmol, 0.103 g), 1H-1,2,4-triazole-3-thiol (0.4 mmol, 0.0404 g), H₂C₂O₄.2H₂O (0.4 mmol, 0.0504 g) and water (5 ml) were placed in a Teflon-lined autoclave (23 ml) and the pH of the mixture was adjusted to 5.0 by slow addition of an NaOH (1.0 M) solution. The mixture was heated to 403 K for 4 [Time unit missing], and then cooled to room temperature at a rate of 5 K h^-1. Colourless crystals of (I) suitable for X-ray analysis were obtained.

S2.2. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1. H atoms bonded to C and N atoms were refined in idealized positions using the riding-model approximation, with C—H = 0.93 Å, N—H = 0.86 Å and U_iso(H) = 1.2U_eq(C,N). H atoms bonded to water O atoms were located in difference maps and treated as riding atoms [refined freely according to CIF data tables - please clarify], with a restraint of O—H = 0.840 (2) Å.

S3. Comment

Complex (I) is a two-dimensional coordination polymer. There is one Cd^II cation, one 1H-1,2,4-triazole-5(4H)-thione (H₂trzS) group, two half-oxalate groups and two water molecules in the asymmetric unit (Fig. 1). Atom Cd1 is coordinated by six O atoms and a thione S atom from the monodentate H₂trzS ligand. Water atom O5 is a terminal linkage. The Cd—O bond lengths are in the range 2.296 (2)–2.440 (2) Å and the Cd—S bond distance is 2.5637 (10) Å (Table 2). The C—O and C—N bond lengths are as expected.

In this structure, the CdO₆S and oxalate units form an extended two-dimensional layered structure, with the η¹-H₂trzS ligands directly bonded to the Cd^II sites through the thione S atoms. The connectivity between the Cd^II cations and the oxalate units forms a unique layered architecture along the ab plane, with eight-membered re­cta­ngular apertures (four Cd^II cations and four oxalate ligands) within the layers, as shown in Fig. 2. The oxalate ligands link to the Cd1 sites of an adjacent aperture, forming the layered structure. It is noted that both µ₂- and µ₄-oxalate ligands are incorporated in this compound. In addition, the structure contains solvent water molecules, which extend the layers into a three-dimensional supra­molecular structure via hydrogen-bonding inter­actions (Fig. 3). Geometric details are given in Table 3.

Compared with the previously reported Cd analogue [CdCl₂(H₂trzS)₂] (Zhang et al., 2008), the differences in the ancillary ligand and the diverse coordination modes of the H₂trzS group lead to a different network. In (I), the µ₂- and µ₄-oxalate ligands connect the Cd^II sites into a layered structure. H₂trzS in (I) adopts a monodentate η¹-H₂trzS coordination mode. By contrast, in [CdCl₂(H₂trzS)₂], the Cd^II sites are linked through µ₂-H₂trzS and µ₂-chloride ligands, affording a one-dimensional chain. Both monodentate η¹-H₂trzS and bidentate µ₂-H₂trzS are incorporated in this compound [Not clear - (I) or [CdCl₂(H₂trzS)₂]?].

Powder X-ray diffraction (PXRD) experiments were carried out on (I) in order to establish the crystalline phase purity. As shown in Fig. 4, the major peak positions of the PXRD pattern of the bulk solid of (I) match well with those of the simulated pattern obtained from the single-crystal data, indicating the presence of mainly one crystalline phase in the coordination polymer.

The IR spectrum of complex (I) (Fig. 5) shows a medium–strong intensity band at 3469 cm^-1, which can be assigned to the ν(OH) characteristic stretching frequency of the water molecules. The bands in the range of 2650–3000 cm^-1 may be attributable to the ν(NH) and ν(CH) stretching frequency of the H₂trzS ring. The band at 1316 cm^-1 may be attributable to the symmetric vibration of the carboxyl­ate groups and that at 1597 cm^-1 may be attributable to the asymmetric vibration of the carboxyl­ate groups. In the range 788–960 cm^-1, many deformation vibrations and combinations of the H₂trzS ring can be found (Liu et al., 2009).

In summary, a new cadmium coordination polymer has been prepared using the mixed ligands 1H-1,2,4-triazole-5(4H)-thione and oxalate under hydro­thermal conditions. This result reveals that the mixed-ligand synthetic approach is viable for obtaining unusual MOFs in H₂trzS-based systems.

Related literature

For related literature, see: Cha et al. (2010); Cheng et al. (2009); García-Couceiro, Olea, Castillo, Luque, Román, de Pablo, Gómez-Herrero, Zamora & l (2005); García-Terán, Castillo, Luque, García-Couceiro, Román & Lezama (2004); Jurss et al. (2010); Liu et al. (2009); Ma et al. (2010); Prasad et al. (2002); Wang, Liu, Huang, Sui, Huang, Chen & You (2010); Wang, Zhang, Liu, Shan, Cao, Wang, Luo & Yang (2010); Wu et al. (2005); Yang et al. (2013); Zhang & Chen (2008); Zhang et al. (2009); Zhang, Li, Cheng, Qin, Zhang & Yao (2008).

Computing details

Data collection: CrystalClear (Rigaku, 2002); cell refinement: CrystalClear (Rigaku, 2002); data reduction: CrystalClear (Rigaku, 2002); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures

Fig. 1. The structure of (I), showing the atom-numbering scheme and 30% probability displacement ellipsoids. H atoms have been omitted for clarity. [Symmetry codes: (i) -x, -y + 2, -z + 1; (ii) -x - 1, -y + 1, -z + 1; (iii) ?, ?, ? [Please provide missing details]]

Fig. 2. A view of the two-dimensional layer in (I). All H atoms have been omitted for clarity.

Fig. 3. A packing diagram for (I), showing the hydrogen bonds (dashed lines). All H atoms, except for those involved in the weak interactions, have been omitted. All atoms are shown as wires or sticks.

Fig. 4. Simulated (bottom) and experimental (top) powder X-ray diffraction patterns of (I).

Fig. 5. The IR spectrum of (I).

Poly[[aqua(µ-oxalato)[1H-1,2,4-triazole-5(4H)-thione]cadmium(II)] monohydrate]

Crystal data

[Cd(C2O4)(C2H3N3S)(H2O)]·H2O	Z = 2
Mr = 337.61	F(000) = 328
Triclinic, P1	Dx = 2.340 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 6.1241 (12) Å	Cell parameters from 1807 reflections
b = 8.4939 (17) Å	θ = 3.4–27.5°
c = 10.224 (2) Å	µ = 2.51 mm^−1
α = 67.94 (3)°	T = 298 K
β = 80.46 (3)°	Parallelepiped, colourless
γ = 77.48 (3)°	0.18 × 0.13 × 0.11 mm
V = 479.08 (16) Å^3

Data collection

Rigaku Saturn 724 CCD area-detector diffractometer	2096 independent reflections
Radiation source: fine-focus sealed tube	2063 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.029
scintillation counter scans	θmax = 27.5°, θmin = 3.4°
Absorption correction: multi-scan (CrystalClear; Rigaku, 2002)	h = −7→7
Tmin = 0.566, Tmax = 0.655	k = −8→11
3967 measured reflections	l = −13→13

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)] = 0.023	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.061	H atoms treated by a mixture of independent and constrained refinement
S = 1.08	w = 1/[σ^2(Fo^2) + (0.0243P)^2 + 0.645P] where P = (Fo^2 + 2Fc^2)/3
2096 reflections	(Δ/σ)max = 0.008
152 parameters	Δρmax = 0.50 e Å^−3
6 restraints	Δρmin = −0.58 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	0.06101 (3)	0.72697 (2)	0.36944 (2)	0.02138 (8)
S1	0.16890 (14)	0.67263 (11)	0.13487 (8)	0.03012 (18)
O1	−0.0964 (4)	0.8018 (3)	0.5624 (2)	0.0281 (5)
O2	−0.1294 (4)	0.9938 (3)	0.6672 (2)	0.0287 (5)
O5	−0.2415 (4)	0.9201 (3)	0.2340 (3)	0.0376 (6)
OW1	0.2909 (6)	0.1351 (4)	0.0417 (3)	0.0519 (7)
N1	0.6216 (4)	0.5468 (3)	0.1247 (3)	0.0283 (5)
H1	0.6641	0.6415	0.0684	0.034*
N2	0.6448 (5)	0.2761 (4)	0.2602 (3)	0.0333 (6)
N3	0.4260 (4)	0.3591 (3)	0.2547 (3)	0.0285 (5)
H3	0.3130	0.3096	0.2989	0.034*
C1	0.4083 (5)	0.5249 (4)	0.1733 (3)	0.0243 (6)
C2	0.7569 (6)	0.3954 (5)	0.1792 (4)	0.0335 (7)
H2	0.9124	0.3785	0.1609	0.040*
C3	−0.0652 (5)	0.9420 (3)	0.5665 (3)	0.0205 (5)
O3	0.2238 (3)	0.4587 (3)	0.5331 (2)	0.0244 (4)
C4	0.4311 (5)	0.4276 (4)	0.5450 (3)	0.0203 (5)
O4	0.5387 (4)	0.2902 (3)	0.6223 (3)	0.0324 (5)
H4	−0.257 (7)	1.023 (2)	0.229 (6)	0.082 (19)*
H5	−0.364 (4)	0.887 (5)	0.273 (6)	0.086 (19)*
HW2	0.237 (8)	0.089 (6)	0.1253 (18)	0.072 (17)*
HW1	0.270 (12)	0.076 (7)	−0.004 (5)	0.13 (3)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cd1	0.01985 (12)	0.01948 (14)	0.02487 (12)	−0.00268 (8)	−0.00135 (8)	−0.00853 (9)
S1	0.0284 (4)	0.0344 (4)	0.0263 (4)	0.0008 (3)	−0.0035 (3)	−0.0123 (3)
O1	0.0336 (12)	0.0221 (11)	0.0300 (11)	−0.0121 (9)	0.0076 (9)	−0.0110 (9)
O2	0.0361 (12)	0.0230 (11)	0.0267 (10)	−0.0103 (9)	0.0074 (9)	−0.0098 (9)
O5	0.0302 (13)	0.0231 (13)	0.0542 (16)	−0.0053 (10)	−0.0046 (11)	−0.0071 (11)
OW1	0.068 (2)	0.0374 (16)	0.0416 (15)	−0.0230 (14)	0.0027 (14)	0.0008 (13)
N1	0.0274 (13)	0.0267 (14)	0.0303 (13)	−0.0090 (11)	0.0038 (10)	−0.0098 (11)
N2	0.0287 (14)	0.0284 (15)	0.0386 (15)	−0.0002 (11)	−0.0011 (11)	−0.0105 (12)
N3	0.0262 (13)	0.0237 (13)	0.0332 (13)	−0.0071 (10)	0.0028 (10)	−0.0081 (11)
C1	0.0286 (15)	0.0253 (15)	0.0216 (13)	−0.0066 (12)	0.0019 (11)	−0.0119 (12)
C2	0.0258 (16)	0.042 (2)	0.0345 (16)	−0.0056 (14)	0.0025 (13)	−0.0173 (15)
C3	0.0205 (13)	0.0159 (14)	0.0225 (13)	−0.0045 (10)	−0.0010 (10)	−0.0035 (11)
O3	0.0170 (9)	0.0214 (10)	0.0323 (11)	−0.0053 (8)	−0.0028 (8)	−0.0052 (9)
C4	0.0207 (13)	0.0187 (14)	0.0223 (13)	−0.0043 (11)	−0.0013 (10)	−0.0080 (11)
O4	0.0217 (11)	0.0267 (12)	0.0420 (13)	−0.0027 (9)	−0.0099 (9)	−0.0024 (10)

Geometric parameters (Å, º)

Cd1—O1	2.296 (2)	N1—C2	1.343 (5)
Cd1—O2^i	2.377 (2)	N1—C1	1.345 (4)
Cd1—O3	2.386 (2)	N1—H1	0.8600
Cd1—O5	2.422 (3)	N2—C2	1.290 (4)
Cd1—O4^ii	2.438 (2)	N2—N3	1.371 (4)
Cd1—O3^iii	2.441 (2)	N3—C1	1.331 (4)
Cd1—S1	2.5643 (10)	N3—H3	0.8600
S1—C1	1.704 (3)	C2—H2	0.9300
O1—C3	1.263 (3)	C3—C3^i	1.559 (5)
O2—C3	1.241 (3)	O3—C4	1.256 (3)
O2—Cd1^i	2.377 (2)	O3—Cd1^iii	2.441 (2)
O5—H4	0.840 (2)	C4—O4	1.252 (4)
O5—H5	0.840 (2)	C4—C4^ii	1.553 (5)
OW1—HW2	0.840 (2)	O4—Cd1^ii	2.438 (2)
OW1—HW1	0.840 (2)
O1—Cd1—O2^i	70.83 (8)	H4—O5—H5	105.8 (5)
O1—Cd1—O3	87.12 (8)	HW2—OW1—HW1	105.9 (5)
O2^i—Cd1—O3	127.38 (8)	C2—N1—C1	108.3 (3)
O1—Cd1—O5	90.01 (9)	C2—N1—H1	125.9
O2^i—Cd1—O5	76.08 (9)	C1—N1—H1	125.9
O3—Cd1—O5	153.24 (8)	C2—N2—N3	103.5 (3)
O1—Cd1—O4^ii	102.59 (9)	C1—N3—N2	112.4 (3)
O2^i—Cd1—O4^ii	71.42 (8)	C1—N3—H3	123.8
O3—Cd1—O4^ii	67.73 (8)	N2—N3—H3	123.8
O5—Cd1—O4^ii	138.57 (8)	N3—C1—N1	104.1 (3)
O1—Cd1—O3^iii	78.97 (8)	N3—C1—S1	127.7 (2)
O2^i—Cd1—O3^iii	142.39 (8)	N1—C1—S1	128.2 (2)
O3—Cd1—O3^iii	71.16 (8)	N2—C2—N1	111.8 (3)
O5—Cd1—O3^iii	82.17 (8)	N2—C2—H2	124.1
O4^ii—Cd1—O3^iii	138.69 (8)	N1—C2—H2	124.1
O1—Cd1—S1	169.54 (6)	O2—C3—O1	125.3 (3)
O2^i—Cd1—S1	108.16 (6)	O2—C3—C3^i	118.0 (3)
O3—Cd1—S1	101.12 (6)	O1—C3—C3^i	116.7 (3)
O5—Cd1—S1	79.73 (7)	C4—O3—Cd1	119.76 (18)
O4^ii—Cd1—S1	86.61 (7)	C4—O3—Cd1^iii	130.91 (19)
O3^iii—Cd1—S1	97.48 (6)	Cd1—O3—Cd1^iii	108.84 (8)
C1—S1—Cd1	100.58 (10)	O4—C4—O3	126.2 (3)
C3—O1—Cd1	118.45 (18)	O4—C4—C4^ii	116.4 (3)
C3—O2—Cd1^i	115.75 (18)	O3—C4—C4^ii	117.4 (3)
Cd1—O5—H4	115 (4)	C4—O4—Cd1^ii	118.60 (19)
Cd1—O5—H5	109 (4)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···OW1^iv	0.86	1.86	2.712 (4)	170
OW1—HW2···O2^iii	0.84 (1)	2.01 (1)	2.842 (4)	170 (5)
N3—H3···O1^iii	0.86	1.89	2.733 (3)	165
O5—H5···O4^iii	0.84 (1)	1.92 (2)	2.686 (3)	152 (4)

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