catena-Poly[[bis­­(N,N-di­methyl­formamide-κO)zinc]-μ₂-oxalato-κ⁴O¹,O²:O^1′,O^2′]

In the crystal structure of the title compound, [Zn(C₂O₄)(C₃H₇NO)₂]_n, the Zn^II ion is situated on a twofold rotation axis and has a distorted octa­hedral coordination geometry defined by the O atoms of two dimethyl­formamide mol­ecules and four O atoms of two bidentate oxalate ligands. The oxalate anion is located on an inversion centre and bridges two metal ions, resulting in a polymeric structure with infinite zigzag chains extending parallel to [010].

Related literature

For related structures, see: Yao et al. (2007); van Albada et al. (2004); Ghosh et al. (2004); Evans & Lin (2001). For a general review on compounds with metal-organic framework structures, see: Czaja et al. (2009). For the synthesis of the ligand, see: Yoneda et al. (1978).

Experimental

Crystal data

• [Zn(C₂O₄)(C₃H₇NO)₂]

• M_r = 299.58

• Orthorhombic, P b n a

• a = 7.795 (1) Å

• b = 9.809 (1) Å

• c = 15.421 (1) Å

• V = 1179.1 (2) ų

• Z = 4

• Synchrotron radiation

• λ = 0.90000 Å

• μ = 2.10 mm⁻¹

• T = 298 K

• 0.14 × 0.10 × 0.09 mm

Data collection

• ADSC Quantum210 diffractometer

• Absorption correction: multi-scan (HKL-2000 SCALEPACK; Otwinowski & Minor, 1997) T_min = 0.757, T_max = 0.833

• 839 measured reflections

• 839 independent reflections

• 778 reflections with I > 2σ(I)

• θ_max = 30.4°

Refinement

• R[F² > 2σ(F²)] = 0.058

• wR(F²) = 0.169

• S = 1.09

• 839 reflections

• 81 parameters

• H-atom parameters constrained

• Δρ_max = 0.80 e Å⁻³

• Δρ_min = −0.82 e Å⁻³

Table 1
Selected bond lengths (Å)

Zn1—O2	2.101 (2)
Zn1—O1	2.104 (2)
Zn1—O3	2.134 (2)

Data collection: ADSC Quantum-210 ADX (Arvai & Nielsen, 1983); cell refinement: HKL-2000 (Otwinowski & Minor, 1997); data reduction: HKL-2000; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: CrystalMaker (CrystalMaker, 2007); software used to prepare material for publication: publCIF (Westrip, 2010).

Supporting information

S1. Comment

Metal-organic frameworks (MOFs) have been widely investigated for their potential and/or practical applications in catalysis, gas storage, and many others fields (Czaja et al., 2009). We aimed at constructing a new functional MOF material using a conducting organic molecule, viz tetrathiafulvalene (TTF) functionalized with carboxylate groups, by the hydro(solvo)thermal method. During synthesis, we unexpectedly discovered a Zn^II-oxalate coordination polymer, (I), forming an infinite one-dimensional zigzag chain. We are currently studying the detailed formation mechanism of the compound.

In the structure of compound (I), the Zn^II ion lies on a 2-fold axis and is coordinated by four oxygen atoms of the two bridging oxalate groups and two oxygen atoms of DMF solvent molecules, resulting in a distorted octahedral geometry (Fig. 1). The Zn—O_ox bond lengths are in the range of 2.101 (2) - 2.104 (2) Å and the Zn—O_DMF bond length is 2.134 (2) Å. The bond angles about the Zn^II ion range between 78.62 (8) and 98.81 (9)° for cis and between 163.08 (9) and 176.23 (11)° for the trans ligands (Table 1). The bond angle of O_ox—Zn—O_ox (78.62 (8)°) is smaller than that of O_DMF—Zn—O_DMF (86.53 (13)°) due to the five-membered chelate ring strain. The Zn—O bond lengths and the bond angles about Zn^II are comparable to those of other reported Zn-oxalate coordination polymers (Yao et al., 2007; van Albada et al., 2004; Ghosh et al., 2004; Evans & Lin, 2001). The Zn-oxalate backbone has a zigzag shape with a Zn—Zn—Zn angle of 126.47 (2)° and a Zn—Zn distance of 5.493 (1) Å. The resulting one-dimensional zigzag chains run parallel to [010] and pack effectively through the inter-wedges of the coordinated DMF ligands (Fig. 2).

Related literature

For related structures, see: Yao et al. (2007); van Albada et al. (2004); Ghosh et al. (2004); Evans & Lin (2001). For a general review on compounds with metal-organic framework structures, see: Czaja et al. (2009). For the synthesis of the ligand, see: Yoneda et al. (1978).

S2. Experimental

This experiment was originally intended for synthesis of compounds with metal-organic frameworks, consisting of Zn^II ions and tetrathiafulvalene (TTF) functionalized with carboxylate groups [= bis(4-carboxy-1,3-dithiolidene) = 2COOH-TTF]. Bis(4-carboxy-1,3-dithiolidene) was prepared according to literature (Yoneda et al. 1978). 2COOH-TTF (0.050 g, 0.17 mmol) and 4,4-bipyridine (0.013 g, 0.098 mmol) were added to 12 ml DMF:H₂O (5:1, v/v) solution of [Zn(NO₃)₂]^.6H₂O (0.051 g, 0.17 mmol) to be stirred for 10 min. The mixture was sealed in a Pyrex test tube and stored at 358 K for 3 days. After cooled down to room temperature, the mixture was filtered and washed with ethanol. Colorless crystals suitable for X-ray analysis were obtained and were dried in air.

S3. Refinement

All C-bound H atoms were placed in geometrically idealized positions and refined using a riding model with U_iso = 1.5U_eq and C–H = 0.96 Å for CH₃, and U_iso = 1.2U_eq and C–H = 0.93 Å for CH.

Computing details

Data collection: ADSC Quantum-210 ADX (Arvai & Nielsen, 1983); cell refinement: HKL-2000 (Otwinowski & Minor, 1997); data reduction: HKL-2000 (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: CrystalMaker (CrystalMaker Software, 2007); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures

	Fig. 1. Partial structure of the title compound showing 30% probability displacement ellipsoids and the atom-numbering scheme. All H atoms are omitted for clarity. Symmetry codes: (i) x, -y + 3/2, -z. (ii) -x, -y + 1, -z.
	Fig. 2. two-dimensional packing structure of the one-dimensional zigzag chains of the title compound viewing along the crystal z-direction (gray, Zn; black, C; red, O; blue, N) Dotted box represents the xy-plane of the unit cell and x-, y- directions are denoted by arrows at upper right corner.

catena-Poly[[bis(N,N-dimethylformamide-κO)zinc]- µ₂-oxalato-κ⁴O¹,O²:O^1',O^2']

Crystal data

[Zn(C2O4)(C3H7NO)2]	F(000) = 616
Mr = 299.58	Dx = 1.688 Mg m^−3
Orthorhombic, Pbna	Synchrotron radiation, λ = 0.90000 Å
Hall symbol: -P 2ac 2b	Cell parameters from 839 reflections
a = 7.795 (1) Å	θ = 5.4–30.4°
b = 9.809 (1) Å	µ = 2.10 mm^−1
c = 15.421 (1) Å	T = 298 K
V = 1179.1 (2) Å^3	Block, colourless
Z = 4	0.14 × 0.10 × 0.09 mm

Data collection

ADSC Quantum210 diffractometer	839 independent reflections
Radiation source: 6BIMX-I synchroton beamlin PLS, KOREA	778 reflections with I > 2σ(I)
Si111 double crystal monochromator	Rint = 0.000
ϕ scans	θmax = 30.4°, θmin = 5.4°
Absorption correction: multi-scan (HKL-2000 SCALEPACK; Otwinowski & Minor, 1997)	h = 0→8
Tmin = 0.757, Tmax = 0.833	k = 0→10
839 measured reflections	l = 0→16

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.058	H-atom parameters constrained
wR(F^2) = 0.169	w = 1/[σ^2(Fo^2) + (0.1443P)^2 + 0.1456P] where P = (Fo^2 + 2Fc^2)/3
S = 1.09	(Δ/σ)max < 0.001
839 reflections	Δρmax = 0.80 e Å^−3
81 parameters	Δρmin = −0.82 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.034 (9)

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	0.15869 (6)	0.7500	0.0000	0.0503 (6)
O1	0.1498 (3)	0.5678 (2)	0.07184 (15)	0.0600 (8)
O2	−0.0220 (3)	0.6367 (2)	−0.07091 (14)	0.0592 (8)
O3	0.3580 (3)	0.6927 (3)	−0.08757 (15)	0.0599 (8)
N1	0.5920 (4)	0.7617 (2)	−0.1613 (2)	0.0541 (9)
C1	−0.0497 (4)	0.5204 (3)	−0.0417 (2)	0.0498 (9)
C2	0.4708 (5)	0.7774 (4)	−0.1043 (3)	0.0559 (10)
H2	0.4686	0.8590	−0.0737	0.067*
C3	0.6058 (5)	0.6357 (4)	−0.2119 (2)	0.0687 (11)
H3A	0.6896	0.5769	−0.1858	0.103*
H3B	0.6403	0.6571	−0.2701	0.103*
H3C	0.4966	0.5905	−0.2130	0.103*
C4	0.7261 (5)	0.8631 (4)	−0.1751 (3)	0.0741 (11)
H4A	0.7063	0.9400	−0.1379	0.111*
H4B	0.7244	0.8924	−0.2345	0.111*
H4C	0.8358	0.8237	−0.1620	0.111*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Zn1	0.0436 (8)	0.0500 (8)	0.0573 (8)	0.000	0.000	0.00088 (15)
O1	0.0572 (14)	0.0566 (14)	0.0661 (16)	−0.0077 (9)	−0.0120 (9)	0.0045 (10)
O2	0.0611 (15)	0.0539 (14)	0.0626 (15)	−0.0058 (9)	−0.0082 (9)	0.0082 (9)
O3	0.0538 (16)	0.0587 (17)	0.0672 (16)	−0.0041 (10)	0.0109 (9)	−0.0060 (12)
N1	0.0432 (19)	0.0546 (18)	0.065 (2)	0.0040 (10)	0.0055 (18)	0.0000 (10)
C1	0.0438 (14)	0.0507 (17)	0.055 (2)	0.0013 (12)	0.0012 (15)	0.0008 (13)
C2	0.051 (2)	0.0531 (17)	0.063 (2)	0.0038 (16)	−0.0031 (17)	−0.0021 (16)
C3	0.060 (2)	0.074 (2)	0.072 (2)	0.0038 (16)	0.0104 (18)	−0.0101 (17)
C4	0.057 (2)	0.065 (2)	0.101 (3)	−0.0029 (15)	0.014 (2)	0.0077 (18)

Geometric parameters (Å, º)

Zn1—O2	2.101 (2)	N1—C3	1.466 (4)
Zn1—O2^i	2.101 (2)	C1—O1^ii	1.254 (4)
Zn1—O1	2.104 (2)	C1—C1^ii	1.554 (6)
Zn1—O1^i	2.104 (2)	C2—H2	0.9300
Zn1—O3^i	2.134 (2)	C3—H3A	0.9600
Zn1—O3	2.134 (2)	C3—H3B	0.9600
O1—C1^ii	1.254 (4)	C3—H3C	0.9600
O2—C1	1.246 (3)	C4—H4A	0.9600
O3—C2	1.237 (5)	C4—H4B	0.9600
N1—C2	1.299 (5)	C4—H4C	0.9600
N1—C4	1.458 (5)
O2—Zn1—O2^i	95.82 (14)	C4—N1—C3	116.4 (3)
O2—Zn1—O1	78.62 (8)	O2—C1—O1^ii	127.3 (3)
O2^i—Zn1—O1	98.81 (9)	O2—C1—C1^ii	116.7 (3)
O2—Zn1—O1^i	98.81 (9)	O1^ii—C1—C1^ii	116.1 (3)
O2^i—Zn1—O1^i	78.62 (8)	O3—C2—N1	125.3 (4)
O1—Zn1—O1^i	176.23 (11)	O3—C2—H2	117.3
O2—Zn1—O3^i	163.08 (9)	N1—C2—H2	117.3
O2^i—Zn1—O3^i	91.12 (9)	N1—C3—H3A	109.5
O1—Zn1—O3^i	85.09 (9)	N1—C3—H3B	109.5
O1^i—Zn1—O3^i	97.67 (9)	H3A—C3—H3B	109.5
O2—Zn1—O3	91.12 (9)	N1—C3—H3C	109.5
O2^i—Zn1—O3	163.08 (9)	H3A—C3—H3C	109.5
O1—Zn1—O3	97.67 (9)	H3B—C3—H3C	109.5
O1^i—Zn1—O3	85.09 (9)	N1—C4—H4A	109.5
O3^i—Zn1—O3	86.53 (13)	N1—C4—H4B	109.5
C1^ii—O1—Zn1	114.3 (2)	H4A—C4—H4B	109.5
C1—O2—Zn1	114.36 (19)	N1—C4—H4C	109.5
C2—O3—Zn1	118.2 (2)	H4A—C4—H4C	109.5
C2—N1—C4	122.6 (3)	H4B—C4—H4C	109.5
C2—N1—C3	120.9 (3)
O2—Zn1—O1—C1^ii	0.7 (2)	O2^i—Zn1—O3—C2	29.7 (5)
O2^i—Zn1—O1—C1^ii	94.9 (2)	O1—Zn1—O3—C2	−137.2 (3)
O3^i—Zn1—O1—C1^ii	−174.7 (2)	O1^i—Zn1—O3—C2	45.3 (3)
O3—Zn1—O1—C1^ii	−88.9 (2)	O3^i—Zn1—O3—C2	−52.7 (2)
O2^i—Zn1—O2—C1	−98.8 (2)	Zn1—O2—C1—O1^ii	−179.4 (3)
O1—Zn1—O2—C1	−0.9 (2)	Zn1—O2—C1—C1^ii	0.9 (4)
O1^i—Zn1—O2—C1	−178.1 (2)	Zn1—O3—C2—N1	−174.2 (3)
O3^i—Zn1—O2—C1	15.0 (4)	C4—N1—C2—O3	−177.0 (4)
O3—Zn1—O2—C1	96.7 (2)	C3—N1—C2—O3	−0.6 (6)
O2—Zn1—O3—C2	144.1 (3)

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