Two cadmium coordination polymers with bridging acetate and phenyl-enedi-amine ligands that exhibit two-dimensional layered structures.

Poly[tetra-μ2-acetato-κ8O:O'-bis-(μ2-benzene-1,2-di-amine-κ2N:N')dicadmium], [Cd2(CH3COO)4(C6H8N2)2] n , (I), and poly[[(μ2-acetato-κ2O:O')(acetato-κ2O,O')(μ2-benzene-1,3-di-amine-κ2N:N')cadmium] hemihydrate], {[Cd(CH3COO)2(C6H8N2)]·0.5H2O} n , (II), have two-dimensional polymeric structures in which monomeric units are joined by bridging acetate and benzenedi-amine ligands. Each of the CdII ions has an O4N2 coordination environment. The coordination geometries of the symmetry-independent CdII ions are distorted octa-hedral and distorted trigonal anti-prismatic in (I) and distorted anti-prismatic in (II). Both compounds exhibit an intra-layer hydrogen-bonding network. In addition, the water of hydration in (II) is involved in inter-layer hydrogen bonding.

Chemical context

CdII is able to substitute for ZnII in the active sites of zinc-containing enzymes and to inter­fere with the metabolism of CaII, which are the primary reasons for its toxicity (Borsari, 2014 ▸). In addition, the substitution of CdII for spectroscopically silent ZnII provides a means of exploring zinc-containing biomolecules using 111Cd and 113Cd NMR spectroscopies (Kimblin & Parkin, 1996 ▸; Henehan et al., 1993 ▸; Jalilehvand et al., 2009 ▸, 2012 ▸). Thus, the coordination chemistry of cadmium is of inter­est.

Metal–organic frameworks (MOFs) have received much attention because of their many potential applications including gas storage, catalysis, chemical sensors and mol­ecular separation (Dey et al., 2014 ▸; Kreno et al., 2012 ▸; Farha & Hupp, 2010 ▸). Our previous efforts in the area of coordination polymers have focused on compounds based on phenyl­enedi­amine and acetate ligands incorporating ZnII (Geiger & Parsons, 2014 ▸) and PbII (Geiger et al., 2014 ▸). We have extended this work to include Cd and report the structural analyses of two Cd compounds herein. Although acetate ligands adopt a myriad of different metal-binding modes, only the μ2-acetato-κ2 O:O′ mode is observed in (I). Both acetato-κ2 O,O′ and μ2-acetato-κ2 O:O′ modes are found in (II).

Numerous examples of structures with benzene-1,2-di­amines exhibiting monodentate and/or bidentate coordination modes have been reported (Narayanan & Bhadbhade, 1996 ▸; Ovalle-Marroquín et al., 2002 ▸; Ariyananda & Norman, 2005 ▸; Chen et al., 2006 ▸; Maxcy et al., 2000 ▸; Qian et al., 2007 ▸; Dickman, 2000 ▸; Mei et al., 2009 ▸; Djebli et al., 2012 ▸; Zick & Geiger, 2016 ▸; Geiger et al., 2014 ▸; Geiger & Parsons, 2014 ▸; Geiger, 2012 ▸). Examples of benzene-1,4-di­amine metal-complex structures have also been reported (Batten et al., 2001 ▸; Faizi & Prisyazhnaya, 2015 ▸). Few examples of bridging benzene-1,2-di­amine-κ2 N:N′ (Liang & Qu, 2008 ▸; Duff, 1968 ▸), 1,3-di­amine-κ2 N:N′ (Chemli et al., 2013 ▸), or benzene-1,4-di­amine-κ2 N:N′ (Liu et al., 2012 ▸) ligands have been reported. Compounds (I) and (II) are two new examples of coordination polymers in which benzenedi­amine ligands bridge two metal atoms.

Structural commentary

As shown in Fig. 1 ▸, (I) has two symmetry-independent CdII ions. Cd1 sits on a crystallographically imposed inversion center and Cd2 resides on a crystallographically imposed twofold rotation axis. Each of the CdII ions exhibits an O4N2 coordination sphere composed of four bridging κ2 O:O′ acetate ligands and two bridging κ2 N:N′ benzene-1,2-di­amine ligands. For the coordination sphere of Cd1, the twist angles (Muetterties & Guggenberger, 1974 ▸; Dymock & Palenik, 1975 ▸) defined employing the triangular face centroids N1O1O3 and N1iiiO3iiiO1iii (see Fig. 2 ▸) are 52.26 (12), 66.27 (15) and 56.47 (9)°, giving an average value of 60 (5)°. Perfect Oh or D3d trigonal anti­prismatic structures have a twist angle of 60°, whereas a D3h trigonal prismatic structure has a twist angle of 0°. The coordination sphere of Cd2 exhibits twist angles of 35.49 (8), 45.92 (17) and 45.92 (17)° [average 42 (6)°] using opposite triangular faces O2O4iN2iv and N2iiO4ivO2vii (see Fig. 2 ▸). The coordination geometry is best described as distorted octa­hedral with the two nitro­gen donor atoms trans for Cd1 and distorted trigonal anti­prismatic for Cd2 with O2N trigonal faces. Selected geometrical parameters are given in Table 1 ▸.

Figure 1

The atom-labeling scheme for (I). Anisotropic displacement parameters for non-H atoms are drawn at the 30% probability level. [Symmetry codes: (i) −x + 1, −y + 3, −z + 2; (ii) x, y + 1, z; (iii) −x + 1, −y + 2, −z + 2; (iv) x, −y + 3, z − ; (v) x, y − 1, z; (vi) −x + 1, y + 1, −z + ; (vii) −x + 1, y, −z + .]

Figure 2

Representations of the CdII coordination environments observed in (I) and (II). Symmetry identifiers are those used in Figs. 1 ▸ and 3 ▸.

Table 1

Selected geometric parameters (Å, °) for (I)

Cd1—O3	2.323 (3)	Cd2—O4i	2.365 (3)
Cd1—O1	2.332 (3)	Cd2—O2	2.260 (3)
Cd1—N1	2.325 (4)	Cd2—N2ii	2.416 (4)
O3—Cd1—N1	84.79 (12)	O4i—Cd2—O4iv	80.73 (15)
O3—Cd1—O1	82.98 (11)	O2iii—Cd2—N2ii	79.40 (12)
N1—Cd1—O1	84.38 (12)	O2—Cd2—N2ii	115.81 (12)
O2iii—Cd2—O2	99.65 (17)	O4i—Cd2—N2ii	76.91 (12)
O2iii—Cd2—O4i	156.01 (10)	O4iv—Cd2—N2ii	85.97 (11)
O2—Cd2—O4i	93.98 (12)	N2ii—Cd2—N2v	157.5 (2)

Symmetry codes: (i) ; (ii) ; (iii) ; (iv) ; (v) .

The N2O4 coordination geometry of (II) can be described as severely distorted trigonal anti­prismatic with bidentate acetate oxygen atoms and a κ2 N:N′ benzene-1,3-di­amine nitro­gen atom (O1O2N2i) forming one of the trigonal faces and two κ2 O:O′ acetate ligand oxygen atoms and a nitro­gen atom from a κ2 N:N′ benzene-1,3-di­amine (O3O4iiN1) forming the other trigonal face (see Fig. 2 ▸). The atom-labeling scheme is shown in Fig. 3 ▸. The twist angles are 53.71 (11), 22.56 (8) and 45.38 (13)° [average = 41 (16)°]. As seen in Table 2 ▸, the Cd—O bond lengths associated with the bidentate acetate ligand are shorter than those of the bridging, monodentate acetate ligands, as has been observed in other cadmium complexes (Wang et al., 2011 ▸, 2013 ▸).

Figure 3

The atom-labeling scheme for (II). Anisotropic displacement parameters for non-H atoms are drawn at the 30% probability level. [Symmetry codes: (i) x, −y + 1, z + ; (ii) −x + , y − , −z + ; (iii) −x + , y + , −z + .]

Table 2

Selected geometric parameters (Å, °) for (II)

Cd1—O3	2.275 (3)	Cd1—O1	2.374 (4)
Cd1—O4i	2.301 (3)	Cd1—N2ii	2.388 (4)
Cd1—N1	2.324 (4)	Cd1—O2	2.443 (4)
O3—Cd1—O4i	79.37 (11)	N1—Cd1—N2ii	101.86 (14)
O3—Cd1—N1	107.45 (13)	O1—Cd1—N2ii	84.00 (13)
O4i—Cd1—N1	99.25 (13)	O3—Cd1—O2	168.71 (11)
O3—Cd1—O1	114.63 (11)	O4i—Cd1—O2	98.78 (12)
O4i—Cd1—O1	85.82 (12)	N1—Cd1—O2	83.83 (13)
N1—Cd1—O1	137.80 (13)	O1—Cd1—O2	54.09 (11)
O3—Cd1—N2ii	86.63 (14)	N2ii—Cd1—O2	91.49 (13)
O4i—Cd1—N2ii	157.39 (13)

Symmetry codes: (i) ; (ii) .

Supra­molecular features

As seen in Fig. 4 ▸, the supra­molecular architecture of (I) exhibits independent layers in the bc plane, which are repeated in the [100] direction. Extensive N—H⋯O hydrogen-bonding inter­actions exist (see Table 3 ▸), but none of them extend between the layers. Based on an analysis of the extended structure using the SOLV routine of PLATON (Spek, 2009 ▸), the unit cell contains no solvent-accessible voids.

Figure 4

Packing diagram for (I) showing the two-dimensional network parallel to (100). All H atoms have been omitted for clarity.

Table 3

Hydrogen-bond geometry (Å, °) for (I)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1A⋯O2iii	0.86 (2)	2.34 (2)	3.175 (5)	163 (4)
N1—H1B⋯O4vi	0.91 (2)	2.21 (3)	3.003 (5)	146 (4)
N1—H1B⋯O4vii	0.91 (2)	2.38 (4)	3.029 (5)	128 (4)
N2—H2A⋯O3viii	0.86 (2)	2.30 (2)	3.111 (5)	158 (4)
N2—H2B⋯O3vi	0.86 (2)	2.64 (2)	3.458 (5)	161 (4)
N2—H2B⋯O4vi	0.86 (2)	2.55 (4)	2.973 (5)	111 (3)

Symmetry codes: (iii) ; (vi) ; (vii) ; (viii) .

Compound (II) also exhibits a two-dimensional extended structure. Layers parallel to the bc plane and repeated in the [100] direction are observed as seen in Fig. 5 ▸. N—H⋯O(acetate) hydrogen bonds (Table 4 ▸) are present within the layers. The water of hydration sits on a crystallographically imposed twofold rotation axis and, as seen in Fig. 6 ▸, is involved in O—H⋯O and N—H⋯O hydrogen-bonding inter­actions (Table 4 ▸) that link adjacent layers.

Figure 5

Packing diagram for (II) showing the layers parallel to (100). H atoms have been omitted for clarity.

Table 4

Hydrogen-bond geometry (Å, °) for (II)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O5—H5⋯O2	0.81 (2)	2.06 (4)	2.788 (5)	149 (7)
N1—HN1A⋯O5	0.86 (2)	2.34 (2)	3.183 (4)	166 (4)
N1—HN1B⋯O3iii	0.89 (2)	2.12 (2)	2.991 (5)	166 (5)
N2—HN2A⋯O4iv	0.87 (2)	2.32 (4)	3.012 (6)	137 (4)
N2—HN2B⋯O1iii	0.88 (2)	2.17 (3)	2.994 (5)	156 (5)

Symmetry codes: (iii) ; (iv) .

Figure 6

Partial packing diagram for (II) showing the hydrogen-bonded network. Only H atoms involved in the hydrogen-bonded network are shown. [Symmetry codes: (i) −x + 1, y, −z + ; (ii) −x + , y + , −z + ; (iii)x, −y + 1, z − .]

Database survey

Examples of cadmium coordination polymers with carboxyl­ate ligands and that exhibit two-dimensional sheet structures have been reported (Li et al., 2014 ▸; Gao et al., 2004 ▸; Chen & Zhang, 2014 ▸; Zhang et al., 2007 ▸; Liu & Xu, 2005 ▸; Song et al., 2006 ▸; Kong et al., 2008a ▸,b ▸; Xu et al., 2013 ▸; Zhuo et al., 2006 ▸). Cadmium is commonly observed with a trigonal–prismatic or trigonal–anti­prismatic coordination geometry, often with one or two capping ligands (Bygott et al., 2007 ▸; Cherni et al., 2012 ▸; Uçar et al., 2004 ▸; Banerjee et al., 2005 ▸; Keypour et al., 2000 ▸). Coordination polymers with bridging benzene-1,2-di­amine ligands (Liang & Qu, 2008 ▸; Duff, 1968 ▸), bridging benzene-1,3-di­amine ligands (Chemli et al., 2013 ▸), and bridging benzene-1,4-di­amine ligands (Liu et al., 2012 ▸) have been reported

Synthesis and crystallization

Preparation of (I)

213 mg (0.924 mmole) cadmium acetate hydrate were dissolved in 10 mL of ethanol. With stirring, 204 mg (1.89 mmol) of benzene-1,2-di­amine were added and the resulting solution was refluxed for 2 h. A white precipitate formed, which was isolated by filtration and dried under vacuum. The yield was qu­anti­tative (310 mg). Selected IR bands (diamond anvil, cm−1): 3278 (w), 1532 (s), 1504 (s), 1405 (s). 1H NMR (400 MHz, dmso-d 6, p.p.m.): 1.87 (s, 6H), 6.35 (m, 2H), 6.35 (m, 2H).

Single crystals were obtained by heating some of the product in N,N′-di­methyl­formamide and allowing the solution to slowly cool to room temperature. The crystal used for data collection was obtained by cutting a piece from a larger plate.

Preparation of (II)

230 mg (1.00 mmol) cadmium acetate hydrate were dissolved in 10 mL of ethanol. 217 mg (2.01 mmol) benzene-1,3-di­amine were added with stirring. The solution was gently refluxed for 2 h. After chilling the reaction mixture in an ice bath, the precipitate was filtered and dried under vacuum. A yield of 248 mg (71%) was obtained. Selected IR bands (diamond anvil, cm−1): 3425 (b), 3329 (s) 3328 (b), 3137 (m), 1520 (s), 1505 (s), 1400 (s). 1H NMR (400 MHz, dmso-d 6, p.p.m.): 1.83 (s, 6H), 5.78 (m, 3H), 6.64 (t, 1H). 13C NMR (dmso-d 6, p.p.m.): 22.1, 100.5, 103.6, 129.6, 149.5, 178.0.

Clear, brown needles suitable for X-ray analysis were obtained upon slow evaporation of an ethano­lic solution of the product. The crystals exhibit a melting range of 441–443 K with decomposition.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 5 ▸. For both (I) and (II), all hydrogen atoms were located in difference Fourier maps. The hydrogen atoms were refined using a riding model with a C—H distance of 0.98 Å for the methyl groups and 0.95 Å for the phenyl carbon atoms. The methyl hydrogen atom isotropic displacement parameters were set using the approximation U iso(H) = 1.5U eq(C). All other C—H hydrogen atom isotropic displacement parameters were set using the approximation U iso(H) = 1.2U eq(C). The N—H bond lengths were restrained to 0.88 Å in (I) and (II). The O—H bond length of the water of hydration in (II) was restrained to 0.84 Å and the H—O—H angle was restrained to 105°. U iso(H) was refined freely for the amine and water hydrogen atoms, except that for (II) the isotropic displacement parameters of the hydrogen atoms associated with N2 were restrained to be the same.

Table 5

Experimental details

	(I)	(II)
Crystal data
Chemical formula	[Cd2(C2H3O2)4(C6H8N2)2]	[Cd(C2H3O2)2(C6H8N2)]·0.5H2O
M r	338.63	695.28
Crystal system, space group	Monoclinic, C2/c	Monoclinic, C2/c
Temperature (K)	200	200
a, b, c (Å)	23.283 (3), 7.2399 (9), 14.2744 (16)	20.777 (6), 8.2374 (18), 15.002 (4)
β (°)	96.887 (4)	102.583 (9)
V (Å3)	2388.8 (5)	2505.9 (11)
Z	8	4
Radiation type	Mo Kα	Mo Kα
μ (mm−1)	1.83	1.75
Crystal size (mm)	0.40 × 0.40 × 0.05	0.40 × 0.08 × 0.08
Data collection
Diffractometer	Bruker SMART X2S benchtop	Bruker SMART X2S benchtop
Absorption correction	Multi-scan (SADABS; Bruker, 2013 ▸)	Multi-scan (SADABS; Bruker, 2013 ▸)
T min, T max	0.53, 0.91	0.69, 0.87
No. of measured, independent and observed [I > 2σ(I)] reflections	14588, 2263, 1633	8942, 2443, 1859
R int	0.089	0.057
(sin θ/λ)max (Å−1)	0.610	0.617
Refinement
R[F 2 > 2σ(F 2)], wR(F 2), S	0.038, 0.109, 1.05	0.037, 0.095, 0.99
No. of reflections	2263	2443
No. of parameters	174	180
No. of restraints	4	6
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement	H atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å−3)	1.14, −1.17	0.86, −1.02

Computer programs: APEX2 and SAINT (Bruker, 2013 ▸), SHELXS97 (Sheldrick, 2008 ▸), SHELXL2014 (Sheldrick, 2015 ▸), PLATON (Spek, 2009 ▸), Mercury (Macrae et al., 2006 ▸) and publCIF (Westrip, 2010 ▸).

Crystal structure: contains datablock(s) global, I, II. DOI: 10.1107/S2056989016017382/pj2037sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S2056989016017382/pj2037Isup2.hkl

Click here for additional data file.

Supporting information file. DOI: 10.1107/S2056989016017382/pj2037Isup4.mol

Structure factors: contains datablock(s) II. DOI: 10.1107/S2056989016017382/pj2037IIsup3.hkl

Click here for additional data file.

Supporting information file. DOI: 10.1107/S2056989016017382/pj2037IIsup5.mol

CCDC references: 1512964, 1512963

Additional supporting information: crystallographic information; 3D view; checkCIF report

[Cd2(C2H3O2)4(C6H8N2)2]	F(000) = 1344
Mr = 338.63	Dx = 1.883 Mg m−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
a = 23.283 (3) Å	Cell parameters from 120 reflections
b = 7.2399 (9) Å	θ = 3.5–24.0°
c = 14.2744 (16) Å	µ = 1.83 mm−1
β = 96.887 (4)°	T = 200 K
V = 2388.8 (5) Å3	Plate, clear colourless
Z = 8	0.40 × 0.40 × 0.05 mm

Bruker SMART X2S benchtop diffractometer	2263 independent reflections
Radiation source: sealed microfocus tube	1633 reflections with I > 2σ(I)
Doubly curved silicon crystal monochromator	Rint = 0.089
Detector resolution: 8.3330 pixels mm-1	θmax = 25.7°, θmin = 2.9°
ω scans	h = −28→27
Absorption correction: multi-scan (SADABS; Bruker, 2013)	k = −8→8
Tmin = 0.53, Tmax = 0.91	l = −17→16
14588 measured reflections

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)] = 0.038	Hydrogen site location: mixed
wR(F2) = 0.109	H atoms treated by a mixture of independent and constrained refinement
S = 1.05	w = 1/[σ2(Fo2) + (0.0496P)2 + 0.5909P] where P = (Fo2 + 2Fc2)/3
2263 reflections	(Δ/σ)max < 0.001
174 parameters	Δρmax = 1.14 e Å−3
4 restraints	Δρmin = −1.17 e Å−3

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

	x	y	z	Uiso*/Ueq
Cd1	0.5	1.0	1.0	0.02022 (18)
Cd2	0.5	1.48311 (6)	0.75	0.02246 (18)
O1	0.53894 (13)	1.2329 (4)	0.91404 (19)	0.0280 (7)
O2	0.57421 (14)	1.2817 (4)	0.7785 (2)	0.0341 (8)
O3	0.43034 (13)	1.2226 (4)	1.01819 (19)	0.0287 (8)
O4	0.44787 (12)	1.2680 (4)	1.17354 (18)	0.0275 (7)
N1	0.44368 (16)	0.9351 (5)	0.8581 (2)	0.0220 (8)
H1A	0.4354 (19)	1.040 (4)	0.831 (3)	0.033 (14)*
H1B	0.4683 (16)	0.875 (6)	0.824 (3)	0.045 (15)*
N2	0.44711 (17)	0.5481 (6)	0.8818 (2)	0.0226 (8)
H2A	0.438 (2)	0.445 (4)	0.905 (3)	0.040 (15)*
H2B	0.4719 (16)	0.612 (6)	0.917 (3)	0.044 (15)*
C1	0.39101 (18)	0.8316 (6)	0.8544 (3)	0.0232 (10)
C2	0.39284 (18)	0.6415 (6)	0.8678 (3)	0.0213 (10)
C3	0.3425 (2)	0.5424 (7)	0.8632 (3)	0.0315 (12)
H3	0.344	0.4118	0.8697	0.038*
C4	0.2890 (2)	0.6318 (8)	0.8489 (3)	0.0409 (13)
H4	0.2541	0.5629	0.8467	0.049*
C5	0.2872 (2)	0.8209 (8)	0.8380 (3)	0.0403 (13)
H5	0.251	0.8824	0.829	0.048*
C6	0.3376 (2)	0.9219 (7)	0.8400 (3)	0.0326 (11)
H6	0.336	1.052	0.8316	0.039*
C7	0.57788 (19)	1.2169 (6)	0.8615 (3)	0.0267 (11)
C8	0.6357 (3)	1.1326 (10)	0.8978 (4)	0.0650 (18)
H8A	0.6648	1.2304	0.9089	0.098*
H8B	0.6473	1.0454	0.8511	0.098*
H8C	0.6324	1.0673	0.9571	0.098*
C9	0.41522 (19)	1.2753 (6)	1.0965 (3)	0.0248 (10)
C10	0.3540 (2)	1.3437 (8)	1.0964 (3)	0.0450 (14)
H10A	0.3441	1.3462	1.1612	0.067*
H10B	0.3274	1.2609	1.0581	0.067*
H10C	0.3507	1.4686	1.0697	0.067*

	U11	U22	U33	U12	U13	U23
Cd1	0.0250 (3)	0.0215 (3)	0.0140 (3)	−0.00045 (16)	0.0019 (2)	−0.00028 (16)
Cd2	0.0275 (3)	0.0228 (3)	0.0180 (3)	0	0.0066 (2)	0
O1	0.0330 (18)	0.0259 (18)	0.0270 (16)	0.0015 (14)	0.0107 (14)	0.0053 (14)
O2	0.047 (2)	0.034 (2)	0.0226 (18)	0.0065 (16)	0.0110 (14)	0.0081 (15)
O3	0.0396 (18)	0.0311 (19)	0.0166 (16)	0.0122 (15)	0.0083 (13)	0.0014 (14)
O4	0.0324 (18)	0.0324 (19)	0.0173 (16)	−0.0035 (15)	0.0010 (14)	−0.0029 (14)
N1	0.030 (2)	0.018 (2)	0.017 (2)	0.0000 (18)	0.0014 (16)	0.0001 (17)
N2	0.032 (2)	0.021 (2)	0.016 (2)	−0.0048 (19)	0.0047 (17)	0.0002 (18)
C1	0.032 (3)	0.028 (3)	0.010 (2)	−0.001 (2)	0.0050 (18)	−0.0021 (18)
C2	0.028 (2)	0.023 (2)	0.012 (2)	0.0015 (19)	0.0038 (18)	−0.0012 (18)
C3	0.039 (3)	0.030 (3)	0.026 (3)	−0.008 (2)	0.007 (2)	−0.004 (2)
C4	0.033 (3)	0.051 (4)	0.038 (3)	−0.006 (3)	0.004 (2)	−0.001 (3)
C5	0.030 (3)	0.049 (4)	0.041 (3)	0.011 (3)	0.004 (2)	0.003 (3)
C6	0.032 (3)	0.035 (3)	0.029 (3)	0.006 (2)	0.000 (2)	−0.002 (2)
C7	0.029 (3)	0.023 (3)	0.028 (3)	0.003 (2)	0.004 (2)	0.001 (2)
C8	0.065 (4)	0.066 (5)	0.065 (4)	0.004 (4)	0.013 (3)	0.002 (4)
C9	0.030 (2)	0.017 (2)	0.028 (3)	−0.0014 (19)	0.009 (2)	0.000 (2)
C10	0.036 (3)	0.063 (4)	0.036 (3)	0.016 (3)	0.006 (2)	−0.004 (3)

C1—C6	1.398 (6)	Cd1—O1i	2.332 (3)
C1—C2	1.390 (6)	Cd1—N1	2.325 (4)
C10—H10C	0.98	Cd1—N1i	2.325 (4)
C10—H10B	0.98	Cd2—O4ii	2.365 (3)
C10—H10A	0.98	Cd2—O4iii	2.365 (3)
C2—C3	1.369 (6)	Cd2—O2iv	2.260 (3)
C3—H3	0.95	Cd2—O2	2.260 (3)
C3—C4	1.398 (7)	Cd2—N2v	2.416 (4)
C4—H4	0.95	Cd2—N2vi	2.416 (4)
C4—C5	1.378 (7)	N1—H1B	0.907 (19)
C5—H5	0.95	N1—H1A	0.864 (19)
C5—C6	1.378 (7)	N1—C1	1.432 (5)
C6—H6	0.95	N2—H2B	0.857 (19)
C7—C8	1.512 (7)	N2—H2A	0.86 (2)
C8—H8C	0.98	N2—Cd2vii	2.415 (4)
C8—H8B	0.98	N2—C2	1.426 (6)
C8—H8A	0.98	O1—C7	1.250 (5)
C9—C10	1.509 (6)	O2—C7	1.267 (5)
Cd1—O3i	2.323 (3)	O3—C9	1.270 (5)
Cd1—O3	2.323 (3)	O4—Cd2ii	2.365 (3)
Cd1—O1	2.332 (3)	O4—C9	1.261 (5)
O3i—Cd1—O3	180.00 (13)	C2—N2—H2A	102 (3)
O3i—Cd1—N1	95.21 (12)	Cd2vii—N2—H2A	108 (3)
O3—Cd1—N1	84.79 (12)	C2—N2—H2B	110 (4)
O3i—Cd1—N1i	84.79 (12)	Cd2vii—N2—H2B	101 (3)
O3—Cd1—N1i	95.21 (12)	H2A—N2—H2B	115 (4)
N1—Cd1—N1i	180.0	C2—C1—C6	119.7 (4)
O3i—Cd1—O1	97.02 (11)	C2—C1—N1	120.1 (4)
O3—Cd1—O1	82.98 (11)	C6—C1—N1	120.2 (4)
N1—Cd1—O1	84.38 (12)	C3—C2—C1	120.1 (4)
N1i—Cd1—O1	95.62 (12)	C3—C2—N2	119.8 (4)
O3i—Cd1—O1i	82.98 (11)	C1—C2—N2	120.1 (4)
O3—Cd1—O1i	97.02 (11)	C2—C3—C4	120.5 (5)
N1—Cd1—O1i	95.62 (12)	C2—C3—H3	119.8
N1i—Cd1—O1i	84.38 (12)	C4—C3—H3	119.8
O1—Cd1—O1i	180.0	C5—C4—C3	119.4 (5)
O2iv—Cd2—O2	99.65 (17)	C5—C4—H4	120.3
O2iv—Cd2—O4ii	156.01 (10)	C3—C4—H4	120.3
O2—Cd2—O4ii	93.98 (12)	C4—C5—C6	120.7 (5)
O2iv—Cd2—O4iii	93.98 (11)	C4—C5—H5	119.6
O2—Cd2—O4iii	156.01 (10)	C6—C5—H5	119.6
O4ii—Cd2—O4iii	80.73 (15)	C5—C6—C1	119.6 (5)
O2iv—Cd2—N2v	79.40 (12)	C5—C6—H6	120.2
O2—Cd2—N2v	115.81 (12)	C1—C6—H6	120.2
O4ii—Cd2—N2v	76.91 (12)	O1—C7—O2	123.6 (4)
O4iii—Cd2—N2v	85.97 (11)	O1—C7—C8	120.8 (4)
O2iv—Cd2—N2vi	115.81 (12)	O2—C7—C8	115.3 (4)
O2—Cd2—N2vi	79.40 (12)	C7—C8—H8A	109.5
O4ii—Cd2—N2vi	85.97 (12)	C7—C8—H8B	109.5
O4iii—Cd2—N2vi	76.91 (12)	H8A—C8—H8B	109.5
N2v—Cd2—N2vi	157.5 (2)	C7—C8—H8C	109.5
C7—O1—Cd1	127.2 (3)	H8A—C8—H8C	109.5
C7—O2—Cd2	111.8 (3)	H8B—C8—H8C	109.5
C9—O3—Cd1	125.3 (3)	O4—C9—O3	123.6 (4)
C9—O4—Cd2ii	126.4 (3)	O4—C9—C10	119.1 (4)
C1—N1—Cd1	121.9 (2)	O3—C9—C10	117.3 (4)
C1—N1—H1A	107 (3)	C9—C10—H10A	109.5
Cd1—N1—H1A	107 (3)	C9—C10—H10B	109.5
C1—N1—H1B	109 (3)	H10A—C10—H10B	109.5
Cd1—N1—H1B	104 (3)	C9—C10—H10C	109.5
H1A—N1—H1B	107 (4)	H10A—C10—H10C	109.5
C2—N2—Cd2vii	120.6 (2)	H10B—C10—H10C	109.5
Cd1—N1—C1—C2	−75.0 (4)	C4—C5—C6—C1	−0.8 (7)
Cd1—N1—C1—C6	103.1 (4)	C2—C1—C6—C5	−0.9 (6)
C6—C1—C2—C3	2.6 (6)	N1—C1—C6—C5	−179.0 (4)
N1—C1—C2—C3	−179.3 (4)	Cd1—O1—C7—O2	131.3 (4)
C6—C1—C2—N2	179.5 (4)	Cd1—O1—C7—C8	−54.7 (6)
N1—C1—C2—N2	−2.4 (6)	Cd2—O2—C7—O1	13.3 (6)
Cd2vii—N2—C2—C3	99.3 (4)	Cd2—O2—C7—C8	−160.9 (4)
Cd2vii—N2—C2—C1	−77.6 (5)	Cd2ii—O4—C9—O3	100.8 (5)
C1—C2—C3—C4	−2.7 (6)	Cd2ii—O4—C9—C10	−81.4 (5)
N2—C2—C3—C4	−179.6 (4)	Cd1—O3—C9—O4	26.7 (6)
C2—C3—C4—C5	1.0 (7)	Cd1—O3—C9—C10	−151.1 (4)
C3—C4—C5—C6	0.8 (7)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···O2iv	0.86 (2)	2.34 (2)	3.175 (5)	163 (4)
N1—H1B···O4i	0.91 (2)	2.21 (3)	3.003 (5)	146 (4)
N1—H1B···O4viii	0.91 (2)	2.38 (4)	3.029 (5)	128 (4)
N2—H2A···O3vii	0.86 (2)	2.30 (2)	3.111 (5)	158 (4)
N2—H2B···O3i	0.86 (2)	2.64 (2)	3.458 (5)	161 (4)
N2—H2B···O4i	0.86 (2)	2.55 (4)	2.973 (5)	111 (3)
C8—H8C···O3i	0.98	2.61	3.295 (7)	127

[Cd(C2H3O2)2(C6H8N2)]·0.5H2O	F(000) = 1384
Mr = 695.28	Dx = 1.843 Mg m−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
a = 20.777 (6) Å	Cell parameters from 2588 reflections
b = 8.2374 (18) Å	θ = 2.7–23.5°
c = 15.002 (4) Å	µ = 1.75 mm−1
β = 102.583 (9)°	T = 200 K
V = 2505.9 (11) Å3	Needle, clear brown
Z = 4	0.40 × 0.08 × 0.08 mm

Bruker SMART X2S benchtop diffractometer	2443 independent reflections
Radiation source: sealed microfocus tube	1859 reflections with I > 2σ(I)
Doubly curved silicon crystal monochromator	Rint = 0.057
Detector resolution: 8.3330 pixels mm-1	θmax = 26.0°, θmin = 2.7°
ω scans	h = −25→25
Absorption correction: multi-scan (SADABS; Bruker, 2013)	k = −9→10
Tmin = 0.69, Tmax = 0.87	l = −18→11
8942 measured reflections

Refinement on F2	6 restraints
Least-squares matrix: full	Hydrogen site location: mixed
R[F2 > 2σ(F2)] = 0.037	H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.095	w = 1/[σ2(Fo2) + (0.0489P)2] where P = (Fo2 + 2Fc2)/3
S = 0.99	(Δ/σ)max = 0.001
2443 reflections	Δρmax = 0.86 e Å−3
180 parameters	Δρmin = −1.02 e Å−3

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

	x	y	z	Uiso*/Ueq
Cd1	0.69991 (2)	0.34064 (4)	0.80989 (2)	0.02831 (14)
O1	0.68026 (16)	0.1764 (4)	0.9313 (2)	0.0381 (9)
O2	0.59435 (17)	0.3087 (4)	0.8546 (2)	0.0436 (9)
O3	0.80578 (15)	0.3370 (3)	0.7917 (3)	0.0357 (8)
O4	0.79978 (15)	0.6013 (4)	0.7691 (2)	0.0375 (8)
O5	0.5	0.5121 (7)	0.75	0.0581 (16)
H5	0.517 (3)	0.455 (4)	0.792 (2)	0.09 (2)*
N1	0.63907 (19)	0.5002 (5)	0.6938 (3)	0.0281 (9)
HN1A	0.6021 (14)	0.522 (5)	0.708 (3)	0.039 (15)*
HN1B	0.649 (2)	0.605 (3)	0.701 (3)	0.039 (14)*
N2	0.7361 (2)	0.4639 (5)	0.4277 (3)	0.0328 (9)
HN2A	0.750 (2)	0.394 (5)	0.393 (3)	0.044 (11)*
HN2B	0.7682 (17)	0.526 (5)	0.457 (3)	0.044 (11)*
C1	0.6204 (2)	0.2190 (6)	0.9196 (3)	0.0316 (11)
C2	0.5810 (3)	0.1613 (6)	0.9855 (4)	0.0553 (16)
H2A	0.5764	0.2496	1.0275	0.083*
H2B	0.6034	0.0692	1.0204	0.083*
H2C	0.5372	0.1272	0.952	0.083*
C3	0.8315 (2)	0.4712 (5)	0.7778 (3)	0.0283 (10)
C4	0.9037 (2)	0.4701 (6)	0.7760 (4)	0.0423 (13)
H4A	0.9093	0.5044	0.7156	0.064*
H4B	0.9213	0.3602	0.7888	0.064*
H4C	0.9275	0.5451	0.8224	0.064*
C5	0.6364 (2)	0.4410 (5)	0.6031 (3)	0.0276 (10)
C6	0.6875 (2)	0.4739 (5)	0.5613 (3)	0.0292 (11)
H6	0.7238	0.5375	0.5921	0.035*
C7	0.6866 (2)	0.4152 (5)	0.4748 (3)	0.0314 (11)
C8	0.6335 (3)	0.3195 (6)	0.4305 (4)	0.0463 (14)
H8	0.6327	0.2769	0.3714	0.056*
C9	0.5833 (3)	0.2881 (7)	0.4720 (4)	0.0573 (17)
H9	0.5473	0.2237	0.4413	0.069*
C10	0.5832 (3)	0.3481 (5)	0.5588 (4)	0.0436 (14)
H10	0.5475	0.3258	0.5871	0.052*

	U11	U22	U33	U12	U13	U23
Cd1	0.0331 (2)	0.0280 (2)	0.0254 (2)	0.00293 (14)	0.00988 (14)	−0.00140 (14)
O1	0.0347 (19)	0.045 (2)	0.036 (2)	0.0083 (15)	0.0105 (16)	0.0041 (15)
O2	0.043 (2)	0.049 (2)	0.038 (2)	0.0063 (16)	0.0066 (17)	0.0087 (16)
O3	0.0333 (17)	0.0217 (17)	0.056 (2)	−0.0019 (13)	0.0175 (17)	0.0015 (15)
O4	0.0414 (19)	0.0292 (17)	0.047 (2)	0.0059 (15)	0.0204 (17)	0.0114 (15)
O5	0.044 (3)	0.065 (4)	0.058 (4)	0	−0.004 (3)	0
N1	0.032 (2)	0.029 (2)	0.026 (2)	−0.0001 (19)	0.0113 (17)	0.0008 (17)
N2	0.041 (2)	0.036 (2)	0.024 (2)	−0.0003 (19)	0.0143 (18)	−0.0007 (18)
C1	0.033 (3)	0.035 (3)	0.028 (3)	−0.006 (2)	0.011 (2)	−0.005 (2)
C2	0.041 (3)	0.073 (4)	0.054 (4)	0.004 (3)	0.014 (3)	0.014 (3)
C3	0.033 (2)	0.033 (3)	0.021 (2)	−0.001 (2)	0.0095 (19)	−0.0018 (18)
C4	0.036 (3)	0.045 (3)	0.045 (3)	−0.006 (2)	0.007 (2)	0.004 (2)
C5	0.034 (2)	0.025 (2)	0.022 (2)	0.0006 (19)	0.002 (2)	0.0044 (17)
C6	0.029 (2)	0.030 (2)	0.027 (2)	−0.0059 (19)	0.002 (2)	0.0020 (19)
C7	0.041 (3)	0.025 (2)	0.029 (3)	0.004 (2)	0.011 (2)	0.0054 (19)
C8	0.070 (4)	0.043 (3)	0.027 (3)	−0.020 (3)	0.013 (3)	−0.008 (2)
C9	0.070 (4)	0.064 (4)	0.037 (3)	−0.041 (3)	0.009 (3)	−0.014 (3)
C10	0.044 (3)	0.052 (3)	0.035 (3)	−0.025 (2)	0.012 (2)	−0.001 (2)

Cd1—O3	2.275 (3)	C1—C2	1.492 (8)
Cd1—O4i	2.301 (3)	C2—H2A	0.98
Cd1—N1	2.324 (4)	C2—H2B	0.98
Cd1—O1	2.374 (4)	C2—H2C	0.98
Cd1—N2ii	2.388 (4)	C3—C4	1.506 (6)
Cd1—O2	2.443 (4)	C4—H4A	0.98
O1—C1	1.268 (5)	C4—H4B	0.98
O2—C1	1.249 (5)	C4—H4C	0.98
O3—C3	1.265 (5)	C5—C6	1.374 (6)
O4—C3	1.250 (5)	C5—C10	1.388 (6)
O4—Cd1iii	2.301 (3)	C6—C7	1.381 (6)
O5—H5	0.808 (18)	C6—H6	0.95
N1—C5	1.435 (6)	C7—C8	1.401 (6)
N1—HN1A	0.859 (19)	C8—C9	1.350 (8)
N1—HN1B	0.886 (19)	C8—H8	0.95
N2—C7	1.425 (6)	C9—C10	1.394 (8)
N2—Cd1iv	2.388 (4)	C9—H9	0.95
N2—HN2A	0.870 (19)	C10—H10	0.95
N2—HN2B	0.877 (19)
O3—Cd1—O4i	79.37 (11)	C1—C2—H2A	109.5
O3—Cd1—N1	107.45 (13)	C1—C2—H2B	109.5
O4i—Cd1—N1	99.25 (13)	H2A—C2—H2B	109.5
O3—Cd1—O1	114.63 (11)	C1—C2—H2C	109.5
O4i—Cd1—O1	85.82 (12)	H2A—C2—H2C	109.5
N1—Cd1—O1	137.80 (13)	H2B—C2—H2C	109.5
O3—Cd1—N2ii	86.63 (14)	O4—C3—O3	122.3 (4)
O4i—Cd1—N2ii	157.39 (13)	O4—C3—C4	120.5 (4)
N1—Cd1—N2ii	101.86 (14)	O3—C3—C4	117.1 (4)
O1—Cd1—N2ii	84.00 (13)	C3—C4—H4A	109.5
O3—Cd1—O2	168.71 (11)	C3—C4—H4B	109.5
O4i—Cd1—O2	98.78 (12)	H4A—C4—H4B	109.5
N1—Cd1—O2	83.83 (13)	C3—C4—H4C	109.5
O1—Cd1—O2	54.09 (11)	H4A—C4—H4C	109.5
N2ii—Cd1—O2	91.49 (13)	H4B—C4—H4C	109.5
C1—O1—Cd1	93.7 (3)	C6—C5—C10	120.3 (5)
C1—O2—Cd1	91.0 (3)	C6—C5—N1	119.4 (4)
C3—O3—Cd1	117.6 (3)	C10—C5—N1	120.3 (5)
C3—O4—Cd1iii	136.7 (3)	C5—C6—C7	120.4 (4)
C5—N1—Cd1	114.9 (3)	C5—C6—H6	119.8
C5—N1—HN1A	117 (3)	C7—C6—H6	119.8
Cd1—N1—HN1A	108 (3)	C6—C7—C8	119.4 (5)
C5—N1—HN1B	114 (3)	C6—C7—N2	120.2 (4)
Cd1—N1—HN1B	113 (3)	C8—C7—N2	120.1 (5)
HN1A—N1—HN1B	88 (4)	C9—C8—C7	119.8 (5)
C7—N2—Cd1iv	114.3 (3)	C9—C8—H8	120.1
C7—N2—HN2A	119 (3)	C7—C8—H8	120.1
Cd1iv—N2—HN2A	96 (3)	C8—C9—C10	121.4 (5)
C7—N2—HN2B	118 (4)	C8—C9—H9	119.3
Cd1iv—N2—HN2B	94 (3)	C10—C9—H9	119.3
HN2A—N2—HN2B	111 (5)	C5—C10—C9	118.7 (5)
O2—C1—O1	121.0 (5)	C5—C10—H10	120.6
O2—C1—C2	120.0 (4)	C9—C10—H10	120.6
O1—C1—C2	119.0 (4)
Cd1—O2—C1—O1	−4.6 (4)	N1—C5—C6—C7	178.6 (4)
Cd1—O2—C1—C2	174.9 (4)	C5—C6—C7—C8	−1.0 (7)
Cd1—O1—C1—O2	4.8 (5)	C5—C6—C7—N2	173.2 (4)
Cd1—O1—C1—C2	−174.8 (4)	Cd1iv—N2—C7—C6	−103.9 (4)
Cd1iii—O4—C3—O3	−148.4 (4)	Cd1iv—N2—C7—C8	70.2 (5)
Cd1iii—O4—C3—C4	34.3 (6)	C6—C7—C8—C9	1.1 (8)
Cd1—O3—C3—O4	−3.8 (6)	N2—C7—C8—C9	−173.1 (5)
Cd1—O3—C3—C4	173.5 (3)	C7—C8—C9—C10	−0.4 (9)
Cd1—N1—C5—C6	−82.6 (4)	C6—C5—C10—C9	0.6 (7)
Cd1—N1—C5—C10	95.9 (4)	N1—C5—C10—C9	−177.9 (5)
C10—C5—C6—C7	0.1 (6)	C8—C9—C10—C5	−0.5 (9)

D—H···A	D—H	H···A	D···A	D—H···A
O5—H5···O2	0.81 (2)	2.06 (4)	2.788 (5)	149 (7)
N1—HN1A···O5	0.86 (2)	2.34 (2)	3.183 (4)	166 (4)
N1—HN1B···O3iii	0.89 (2)	2.12 (2)	2.991 (5)	166 (5)
N2—HN2A···O4iv	0.87 (2)	2.32 (4)	3.012 (6)	137 (4)
N2—HN2B···O1iii	0.88 (2)	2.17 (3)	2.994 (5)	156 (5)
C6—H6···O1iii	0.95	2.39	3.195 (5)	142