A one-dimensional Cd^II coordination polymer: catena-poly[cadmium(II)-bis­(μ-6-methyl­picolinato)]

In the title compound, [Cd(C₇H₆NO₂)₂]_n, the Cd^II ion has a distorted octa­hedral geometry. The 6-methyl­pyridine-2-carboxyl­ate anions are perpendicular to one another and act as bidentate and bridging ligands. Two carboxyl­ate O atoms bridge the Cd^II ions, forming centrosymmetric dinuclear units. These units are further connected via carboxyl­ate O atoms into a one-dimensional polymeric chain which extends in the [100] direction.

S1. Comment

Several metal ions, such as Zn²⁺, Ca²⁺, Cu²⁺, Mn²⁺ and Mg²⁺, are commonly found in living organisms, acting as structure promoters or playing important roles in enzymatic activity. A systematic study of the coordination chemistry of metal ions in bioinorganic complexes is essential for obtaining a clear understanding of the role of these metals in biochemical processes (Lippert, 2000). The cadmium ion, a congener of zinc, has a similar size to both Zn²⁺ and Ca²⁺, and can therefore replace these ions in their complexes. This fact is utilized in using the cadmium ion as an NMR probe for elucidating the structure around the metal centres. It is also of interest in the identification of its preferred coordination sites, due to the improved control of the interactions in Zn, Cd or Hg homeostasis.

Metal complexes of picolinic acid have been widely investigated, as well as metal complexes of its derivatives containing electron-withdrawing substituents, such as 3-hydroxy- or 6-hydroxypicolinic acid. In contrast, less attention has been given to complexes of derivatives of picolinic acid containing electron-donating substituents, such as 6-methylpicolinic acid (6-MepicH). To the best of our knowledge, only a few papers deal with this ligand. Two [Three?] zinc(II) complexes with 6-methyl and 3-methylpicolinic acid (3-MepicH) have been described to date: [Zn(6-Mepic)₂(H₂O)]·H₂O, which exhibits in vitro insulinomimetic activity (Yoshikawa et al., 2002), and Zn(3-Mepic)₂ and Zn(6-Mepic)₂ (Pons et al., 2004). Besides these two [Three?] zinc complexes and the cadmium complex described in this report, the only other complex involving a group 12 element, namely mercury(II), was structurally described by González-Duarte et al. (1998).

Hitherto, only two complexes of 6-MepicH with 3 d block metals have been structurally characterized, namely a mononuclear Co^II complex (March et al., 2003) and a heterobinuclear complex containing Cr^III (Xu et al., 2006). Various silver salts react with 6-MepicH to give different complexes, but the structure of only one of them, Ag[(6-Mepic)(6-MepicH)], has been reported to date (Leiva et al., 1999). The only other complexes of 6-methylpicolinic acid with platinum group metals are two containing ruthenium (Rachford et al., 2006) and palladium (Hoare et al., 1996).

In the title complex, (I), the Cd^II ion is octahedrally coordinated by two 6-methylpyridine-2-carboxylate ligands (Table 1 and Fig. 1) perpendicular to one another. Two carboxylate O atoms from another two symmetry-related ligand molecules are also coordinated to the Cd^II ion, expanding its coordination to a distorted octahedron. Each carboxylate O atom in (I) bridges Cd^II ions, forming centrosymmetric dinuclear units which are further connected via the same O atoms into a one-dimensional chain which extends in the [100] direction (Fig. 2). The bond angles around the Cd centre lie within the ranges 68–117° for the formally cis pairs of ligating atoms and 138–173° for the formally trans pairs, indicating the distortion of the octahedron (Table 1).

There are only three cadmium(II) coordination polymers found in the literature that are similar to (I). These are poly[bis(µ-pyridine-2-carboxylato-N,O)cadmium(II)] (Deloume & Loiseleur, 1974), poly[bis(µ-3-hydroxypyridine-2-carboxylato-N,O)cadmium(II)] (Kukovec et al., 2007) and poly[[[bis[methanolcadmium(II)]-µ₂-aqua]-bis-(µ₃-pyridine-2,6-dicarboxylato-O,N,O)] (Wu et al., 2007). In the Cd^II complex with picolinic acid, the coordination mode of picolinic acid and the type of polymerization are the same as in (I). The bond distances Cd—N [2.35 (1) and 2.34 (2) Å] are comparable with Cd1—N2 in (I) but shorter than Cd1—N1. The Cd—O bond distances [2.35 (2) and 2.36 (2) Å] are slightly larger than in (I), while the other Cd—O bond distances [2.23 (2) and 2.25 (1) Å] (Deloume & Loiseleur, 1974) are shorter than the analogous ones in (I).

The Cd^II ion is seven-coordinate in the complex prepared by Wu and co-workers (Wu et al., 2007). Cadmium(II) ions are bridged by pyridine-2,6-dicarboxylate ligands and water molecules into a one-dimensional chain similar to that in (I). Two cadmium(II) dimers with pyridine-2,6-dicarboxylic acid (Odoko et al., 2002) and its ethyl ester (Yang et al., 2004) have been reported. The coordination of Cd^II ions is pentagonal–bipyramidal in both dimers, while the Cd^II ions are bridged by carboxylic O atoms from the corresponding ligand. The Cd—N bond distances in the Cd^II complex with pyridine-2,6-dicarboxylic acid and its ethyl ester are 2.315 (4) (Odoko et al., 2002) and 2.340 (3) Å (Yang et al., 2004), respectively, which are slightly shorter than the corresponding distances in (I), while the Cd—O bond distances (where O is bridging carboxylate O atom) are 2.396 (4) and 2.376 (3) Å (Odoko et al., 2002) and 2.389 (3) and 2.370 (3) Å (Yang et al., 2004), respectively, which are longer than the analogous values in (I).

The dihedral angle between the least-squares calculated planes through the atoms of the pyridine ring (N1/C1/C2/C3/C4/C5) and the corresponding five-membered chelate ring (Cd1/N1/C1/C6/O1) is 5.0 (1)°, while the analogous angle (between planes defined by atoms N2/C8/C9/C10/C11/C12 and Cd1/N2/C8/C13/O3) is 4.8 (1)°. The O1—C6 and O3—C13 bond distances of the carboxylate group [1.280 (3) and 1.276 (3) Å, respectively] are longer than O2—C6 and O4—C13 [1.216 (3) and 1.221 (3) Å, respectively], due to the coordination of atoms O1 and O3 to Cd^II. This deviation of carboxylate-group geometry was also found for the Pd complex with 6-methylpicolinic acid [1.280 (6) and 1.220 (6) Å; Hoare et al., 1996].

Related literature

For related literature, see: Deloume & Loiseleur (1974); González-Duarte, Leiva, March, Pons, Clegg, Solans, Álvarez-Larena & Piniella (1998); Hoare et al. (1996); Kukovec et al. (2007); Leiva et al. (1999); Lippert (2000); March et al. (2003); Odoko et al. (2002); Pons et al. (2004); Rachford et al. (2006); Wu et al. (2007); Xu et al. (2006); Yang et al. (2004); Yoshikawa et al. (2002).

S2. Experimental

A solution of 6-methylpicolinic acid (0.1 g, 0.7 mmol) in water (15 ml) was added to a solution of cadmium(II) acetate dihydrate (0.1 g, 0.4 mmol) in water (5 ml); the pH of the resulting colourless solution was 5. The solution was left to stand for 5 d until the white product of (I) was formed. This was then filtered off, washed with water and dried in air (yield 0.08 g, 57.1%). Spectroscopic analysis: IR (KBr pellet, ν, cm^-1): 2922 (m), 1657 (s), 1594 (s), 1570 (m), 1457 (m), 1404 (m), 1344 (s), 1244 (m), 791 (m), 779 (m), 679 (m). Colourless crystals of (I) suitable for X-ray analysis were obtained by slow evaporation at room temperature of the mother liquor which remained after filtration of the white product.

S3. Refinement

H atoms bonded to C atoms were introduced in calculated positions and refined using a riding model, with C—H = 0.93 Å and U_iso(H) = 1.2U_eq(C) for aromatic H atoms, and C—H = 0.96 Å and U_iso(H) = 1.5U_eq(C) for methyl H atoms.

Computing details

Data collection: CrysAlis CCD (Oxford Diffraction, 2007); cell refinement: CrysAlis CCD or RED? (Oxford Diffraction, 2007); data reduction: CrysAlis RED (Oxford Diffraction, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997) and Mercury (Version 1.4.2; Macrae et al., 2006); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. A view of the Cd^II coordination environment in the polymeric structure of (I), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii. [Symmetry codes: (i) 1 - x, 2 - y, 1 - z; (ii) -x, 2 - y, 1 - z.]
	Fig. 2. A view of the packing of (I). [Symmetry codes: (i) 1 - x, 2 - y, 1 - z; (iii) 1 + x, y, z.]

catena-poly[cadmium(II)]-bis(µ-6-methylpicolinato)]

Crystal data

[Cd(C7H6NO2)2]	F(000) = 760
Mr = 384.67	Dx = 1.892 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 13135 reflections
a = 6.8284 (1) Å	θ = 3.8–34.9°
b = 10.6888 (2) Å	µ = 1.64 mm^−1
c = 18.5505 (3) Å	T = 296 K
β = 94.305 (1)°	Prism, colourless
V = 1350.13 (4) Å^3	0.13 × 0.10 × 0.02 mm
Z = 4

Data collection

Oxford Diffraction Xcalibur2 diffractometer with Sapphire-3 CCD detector	3929 independent reflections
Radiation source: fine-focus sealed tube	2814 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.038
ω scans	θmax = 30.0°, θmin = 3.8°
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2007)	h = −9→9
Tmin = 0.879, Tmax = 0.968	k = −15→15
33784 measured reflections	l = −26→26

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) = 0.062	H-atom parameters constrained
S = 0.95	w = 1/[σ^2(Fo^2) + (0.0344P)^2] where P = (Fo^2 + 2Fc^2)/3
3929 reflections	(Δ/σ)max = 0.002
192 parameters	Δρmax = 1.44 e Å^−3
0 restraints	Δρmin = −0.44 e Å^−3

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Cd1	0.24929 (2)	0.925426 (15)	0.490873 (8)	0.02877 (6)
N1	0.2634 (3)	0.76358 (18)	0.57874 (9)	0.0306 (4)
N2	0.1995 (3)	0.79286 (18)	0.39066 (9)	0.0309 (4)
O1	0.5605 (2)	0.92104 (15)	0.55186 (8)	0.0332 (4)
O2	0.7106 (3)	0.8831 (2)	0.66004 (10)	0.0562 (5)
O3	−0.0676 (2)	0.95305 (16)	0.43833 (9)	0.0376 (4)
O4	−0.2616 (3)	0.93148 (17)	0.33710 (9)	0.0467 (5)
C1	0.4240 (3)	0.7670 (2)	0.62519 (11)	0.0323 (5)
C2	0.4491 (4)	0.6841 (3)	0.68242 (13)	0.0427 (6)
H2	0.5613	0.6879	0.7140	0.051*
C3	0.3065 (4)	0.5958 (3)	0.69212 (15)	0.0468 (7)
H3	0.3199	0.5401	0.7307	0.056*
C4	0.1441 (4)	0.5918 (2)	0.64373 (15)	0.0447 (6)
H4	0.0478	0.5315	0.6485	0.054*
C5	0.1245 (4)	0.6778 (2)	0.58792 (13)	0.0380 (6)
C6	0.5790 (3)	0.8656 (2)	0.61319 (12)	0.0334 (5)
C7	−0.0529 (4)	0.6769 (3)	0.53546 (16)	0.0517 (7)
H7A	−0.1094	0.7591	0.5325	0.078*
H7B	−0.1476	0.6187	0.5515	0.078*
H7C	−0.0156	0.6521	0.4887	0.078*
C8	0.0291 (3)	0.8111 (2)	0.35011 (11)	0.0300 (5)
C9	−0.0215 (4)	0.7417 (2)	0.28898 (12)	0.0396 (6)
H9	−0.1402	0.7556	0.2622	0.048*
C10	0.1066 (4)	0.6514 (3)	0.26808 (13)	0.0440 (6)
H10	0.0763	0.6039	0.2267	0.053*
C11	0.2782 (4)	0.6326 (3)	0.30893 (14)	0.0426 (6)
H11	0.3654	0.5712	0.2958	0.051*
C12	0.3235 (4)	0.7049 (2)	0.37024 (13)	0.0365 (6)
C13	−0.1141 (3)	0.9074 (2)	0.37584 (12)	0.0302 (5)
C14	0.5098 (4)	0.6864 (3)	0.41708 (15)	0.0547 (8)
H14A	0.5588	0.7662	0.4341	0.082*
H14B	0.6058	0.6467	0.3895	0.082*
H14C	0.4842	0.6347	0.4576	0.082*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cd1	0.02110 (9)	0.03256 (10)	0.03173 (9)	0.00108 (8)	−0.00403 (6)	−0.00091 (7)
N1	0.0271 (10)	0.0322 (11)	0.0323 (9)	0.0022 (9)	0.0009 (8)	0.0018 (8)
N2	0.0275 (10)	0.0348 (11)	0.0300 (9)	−0.0006 (9)	−0.0009 (8)	−0.0021 (8)
O1	0.0243 (8)	0.0412 (10)	0.0329 (8)	−0.0054 (7)	−0.0060 (6)	0.0069 (7)
O2	0.0478 (12)	0.0702 (14)	0.0465 (11)	−0.0092 (10)	−0.0233 (9)	0.0126 (10)
O3	0.0254 (8)	0.0523 (11)	0.0340 (9)	0.0084 (8)	−0.0052 (7)	−0.0100 (7)
O4	0.0378 (10)	0.0599 (13)	0.0399 (9)	0.0101 (9)	−0.0141 (8)	−0.0020 (9)
C1	0.0315 (13)	0.0342 (13)	0.0307 (11)	0.0055 (10)	−0.0009 (9)	0.0023 (10)
C2	0.0404 (15)	0.0491 (16)	0.0378 (13)	0.0079 (13)	−0.0022 (11)	0.0092 (11)
C3	0.0488 (17)	0.0456 (17)	0.0471 (15)	0.0086 (13)	0.0099 (13)	0.0188 (12)
C4	0.0408 (15)	0.0386 (16)	0.0558 (16)	−0.0024 (12)	0.0105 (12)	0.0096 (12)
C5	0.0355 (14)	0.0363 (14)	0.0426 (13)	0.0010 (11)	0.0056 (11)	0.0043 (11)
C6	0.0283 (12)	0.0388 (14)	0.0325 (12)	0.0042 (11)	−0.0019 (10)	0.0047 (10)
C7	0.0340 (15)	0.0538 (18)	0.0659 (19)	−0.0116 (13)	−0.0061 (13)	0.0094 (14)
C8	0.0256 (11)	0.0374 (13)	0.0270 (11)	−0.0044 (10)	0.0011 (9)	0.0009 (9)
C9	0.0387 (14)	0.0488 (16)	0.0303 (12)	−0.0011 (12)	−0.0054 (10)	−0.0056 (11)
C10	0.0499 (17)	0.0466 (16)	0.0354 (13)	−0.0037 (13)	0.0022 (12)	−0.0120 (11)
C11	0.0450 (16)	0.0385 (14)	0.0455 (15)	0.0049 (13)	0.0104 (12)	−0.0081 (12)
C12	0.0320 (13)	0.0373 (14)	0.0406 (13)	0.0009 (11)	0.0060 (10)	−0.0031 (11)
C13	0.0268 (12)	0.0345 (13)	0.0287 (11)	−0.0023 (10)	−0.0025 (9)	0.0018 (9)
C14	0.0326 (15)	0.067 (2)	0.0626 (18)	0.0171 (14)	−0.0066 (13)	−0.0132 (15)

Geometric parameters (Å, º)

Cd1—O1^i	2.2724 (16)	C3—C4	1.374 (4)
Cd1—O3^ii	2.2793 (16)	C3—H3	0.9300
Cd1—O3	2.3247 (16)	C4—C5	1.383 (3)
Cd1—O1	2.3315 (15)	C4—H4	0.9300
Cd1—N2	2.3418 (18)	C5—C7	1.496 (4)
Cd1—N1	2.3739 (18)	C7—H7A	0.9600
N1—C5	1.340 (3)	C7—H7B	0.9600
N1—C1	1.344 (3)	C7—H7C	0.9600
N2—C12	1.339 (3)	C8—C9	1.377 (3)
N2—C8	1.351 (3)	C8—C13	1.520 (3)
O1—C6	1.280 (3)	C9—C10	1.378 (4)
O1—Cd1^i	2.2724 (15)	C9—H9	0.9300
O2—C6	1.216 (3)	C10—C11	1.362 (4)
O3—C13	1.276 (3)	C10—H10	0.9300
O3—Cd1^ii	2.2793 (16)	C11—C12	1.391 (3)
O4—C13	1.221 (3)	C11—H11	0.9300
C1—C2	1.384 (3)	C12—C14	1.499 (3)
C1—C6	1.522 (3)	C14—H14A	0.9600
C2—C3	1.377 (4)	C14—H14B	0.9600
C2—H2	0.9300	C14—H14C	0.9600
O1—Cd1—O3	172.67 (6)	C5—C4—H4	120.1
O1^i—Cd1—N1	140.44 (6)	N1—C5—C4	121.3 (2)
O3^ii—Cd1—N2	138.53 (6)	N1—C5—C7	117.9 (2)
O1^i—Cd1—O3^ii	98.02 (7)	C4—C5—C7	120.7 (2)
O1^i—Cd1—O3	107.49 (6)	O2—C6—O1	125.6 (2)
O3^ii—Cd1—O3	68.87 (6)	O2—C6—C1	119.1 (2)
O1^i—Cd1—O1	70.11 (6)	O1—C6—C1	115.27 (19)
O3^ii—Cd1—O1	104.32 (6)	C5—C7—H7A	109.5
O1^i—Cd1—N2	102.29 (6)	C5—C7—H7B	109.5
O3—Cd1—N2	70.67 (6)	H7A—C7—H7B	109.5
O1—Cd1—N2	116.47 (6)	C5—C7—H7C	109.5
O3^ii—Cd1—N1	90.89 (6)	H7A—C7—H7C	109.5
O3—Cd1—N1	111.65 (6)	H7B—C7—H7C	109.5
O1—Cd1—N1	70.34 (6)	N2—C8—C9	122.2 (2)
N2—Cd1—N1	95.75 (7)	N2—C8—C13	118.04 (19)
C5—N1—C1	119.3 (2)	C9—C8—C13	119.7 (2)
C5—N1—Cd1	126.41 (15)	C8—C9—C10	118.9 (2)
C1—N1—Cd1	114.18 (15)	C8—C9—H9	120.5
C12—N2—C8	118.71 (19)	C10—C9—H9	120.5
C12—N2—Cd1	126.32 (15)	C11—C10—C9	119.0 (2)
C8—N2—Cd1	114.96 (15)	C11—C10—H10	120.5
C6—O1—Cd1^i	128.53 (15)	C9—C10—H10	120.5
C6—O1—Cd1	117.80 (14)	C10—C11—C12	120.2 (2)
Cd1^i—O1—Cd1	109.89 (6)	C10—C11—H11	119.9
C13—O3—Cd1^ii	129.26 (15)	C12—C11—H11	119.9
C13—O3—Cd1	119.49 (14)	N2—C12—C11	121.0 (2)
Cd1^ii—O3—Cd1	111.13 (6)	N2—C12—C14	117.1 (2)
N1—C1—C2	121.5 (2)	C11—C12—C14	121.9 (2)
N1—C1—C6	117.92 (19)	O4—C13—O3	126.3 (2)
C2—C1—C6	120.6 (2)	O4—C13—C8	118.7 (2)
C3—C2—C1	119.4 (2)	O3—C13—C8	114.99 (19)
C3—C2—H2	120.3	C12—C14—H14A	109.5
C1—C2—H2	120.3	C12—C14—H14B	109.5
C4—C3—C2	118.7 (2)	H14A—C14—H14B	109.5
C4—C3—H3	120.7	C12—C14—H14C	109.5
C2—C3—H3	120.7	H14A—C14—H14C	109.5
C3—C4—C5	119.8 (3)	H14B—C14—H14C	109.5
C3—C4—H4	120.1
O1^i—Cd1—N1—C5	−174.35 (17)	C1—C2—C3—C4	0.9 (4)
O3^ii—Cd1—N1—C5	81.89 (19)	C2—C3—C4—C5	−1.8 (4)
O3—Cd1—N1—C5	14.3 (2)	C1—N1—C5—C4	−0.8 (4)
O1—Cd1—N1—C5	−173.2 (2)	Cd1—N1—C5—C4	−176.35 (18)
N2—Cd1—N1—C5	−57.11 (19)	C1—N1—C5—C7	179.7 (2)
O1^i—Cd1—N1—C1	9.9 (2)	Cd1—N1—C5—C7	4.1 (3)
O3^ii—Cd1—N1—C1	−93.90 (16)	C3—C4—C5—N1	1.7 (4)
O3—Cd1—N1—C1	−161.45 (14)	C3—C4—C5—C7	−178.8 (3)
O1—Cd1—N1—C1	11.01 (14)	Cd1^i—O1—C6—O2	−2.8 (4)
N2—Cd1—N1—C1	127.10 (16)	Cd1—O1—C6—O2	−158.5 (2)
O1^i—Cd1—N2—C12	82.13 (19)	Cd1^i—O1—C6—C1	179.40 (14)
O3^ii—Cd1—N2—C12	−160.35 (17)	Cd1—O1—C6—C1	23.7 (3)
O3—Cd1—N2—C12	−173.4 (2)	N1—C1—C6—O2	169.1 (2)
O1—Cd1—N2—C12	8.4 (2)	C2—C1—C6—O2	−10.8 (4)
N1—Cd1—N2—C12	−62.46 (19)	N1—C1—C6—O1	−12.9 (3)
O1^i—Cd1—N2—C8	−96.63 (16)	C2—C1—C6—O1	167.2 (2)
O3^ii—Cd1—N2—C8	20.9 (2)	C12—N2—C8—C9	0.5 (3)
O3—Cd1—N2—C8	7.82 (15)	Cd1—N2—C8—C9	179.38 (18)
O1—Cd1—N2—C8	−170.34 (14)	C12—N2—C8—C13	177.3 (2)
N1—Cd1—N2—C8	118.78 (16)	Cd1—N2—C8—C13	−3.8 (2)
O1^i—Cd1—O1—C6	160.0 (2)	N2—C8—C9—C10	−0.6 (4)
N2—Cd1—O1—C6	−105.84 (17)	C13—C8—C9—C10	−177.4 (2)
N1—Cd1—O1—C6	−19.23 (16)	C8—C9—C10—C11	0.7 (4)
O1^i—Cd1—O1—Cd1^i	0.0	C9—C10—C11—C12	−0.8 (4)
N2—Cd1—O1—Cd1^i	94.16 (8)	C8—N2—C12—C11	−0.6 (3)
N1—Cd1—O1—Cd1^i	−179.23 (9)	Cd1—N2—C12—C11	−179.29 (18)
O1^i—Cd1—O3—C13	84.54 (17)	C8—N2—C12—C14	−179.3 (2)
O3^ii—Cd1—O3—C13	176.5 (2)	Cd1—N2—C12—C14	2.0 (3)
N2—Cd1—O3—C13	−12.69 (16)	C10—C11—C12—N2	0.7 (4)
N1—Cd1—O3—C13	−101.25 (17)	C10—C11—C12—C14	179.4 (3)
O3^ii—Cd1—O3—Cd1^ii	0.0	Cd1^ii—O3—C13—O4	8.8 (4)
N2—Cd1—O3—Cd1^ii	170.76 (9)	Cd1—O3—C13—O4	−167.08 (19)
N1—Cd1—O3—Cd1^ii	82.21 (8)	Cd1^ii—O3—C13—C8	−169.34 (14)
C5—N1—C1—C2	−0.1 (3)	Cd1—O3—C13—C8	14.8 (3)
Cd1—N1—C1—C2	175.98 (19)	N2—C8—C13—O4	174.6 (2)
C5—N1—C1—C6	180.0 (2)	C9—C8—C13—O4	−8.4 (3)
Cd1—N1—C1—C6	−3.9 (3)	N2—C8—C13—O3	−7.1 (3)
N1—C1—C2—C3	0.0 (4)	C9—C8—C13—O3	169.8 (2)
C6—C1—C2—C3	179.9 (2)

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