Poly[di(μ2-2-hy­droxy­propano­ato)cadmium]

Chen, A.-W.; Shi, R.; Wang, C.; Shi, B.-B.; Yin, Z.

doi:10.1107/S2414314619012550

metal-organic compounds

IUCrDATA

ISSN: 2414-3146

Volume 4| Part 9| September 2019| x191255

https://doi.org/10.1107/S2414314619012550

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Poly[di(μ₂-2-hydroxypropanoato)cadmium]

Ao-Wei Chen,^a Rong Shi,^a Ce Wang,^a Bi-Bo Shi ^a and Zheng Yin ^a ^*

^aCollege of Chemistry and Chemical Engineering, Shaanxi University of Science and Technology, Xi'an 710021, People's Republic of China
^*Correspondence e-mail: yinzheng@sust.edu.cn

Edited by M. Weil, Vienna University of Technology, Austria (Received 10 June 2019; accepted 9 September 2019; online 10 September 2019)

The asymmetric unit of the title inorganic–organic salt, poly[di(μ₂-2-hydroxypropanoato)cadmium], [Cd(C₃H₅O₃)₂]_n or [Cd(Hlac)₂]_n (H₂lac = 2-hydroxypropanoic acid), comprises of a cadmium cation and two 2-hydroxypropanoate anions. The cadmium cation exhibits a distorted pentagonal–bipyramidal coordination environment defined by the hydroxy and carbonyl O atoms of the 2-hydroxypropanoate anions. The coordination mode leads to the formation of layers extending parallel to (010). O—H⋯O hydrogen bonding between the hydroxy and carbonyl groups stabilizes the structure packing.

Keywords: crystal structure; inorganic–organic hybrid compound; cadmium; hydrogen bonding.

CCDC reference: 1921720

Structure description

Compounds with metal–organic framework (MOF) structures with accessible open space have rapidly grown into a major area of chemical research because of their structural diversity and wide applications (Furukawa et al., 2013 ). Crystal engineering of MOFs has been dominated by single organic units like polycarboxylates, polypyridines, azolate or their derivatives. Recently, mixed-ligand MOFs (Yin et al., 2015 ), were found to be successful in the rational construction of materials with targeted functionalities. One of the interesting candidates for the construction of mixed-ligand MOFs is 2-hydroxypropanoic acid (H₂lac). Working with the corresponding anion has several advantages: (i) multiple coordination modes by using the hydroxyl and carboxyl groups are possible; (ii) the anion is flexible and a chelating ligand, and thus can facilitate the formation of key building units such as chains or layers; (iii) the terminal methyl group can be replaced by –H, –C₂H₅, –Ph and other groups for structural regulation and expansion. As a typical example, the combination of H₂lac and linear pyridine carboxylate generates highly stable rod-spacer MOFs with double π-wall and square nano-channels (Zeng et al., 2010 ), achieving high-efficiency iodine capture.

During exploration of the coordination chemistry of H₂lac with different metals and co-ligands, the title compound was obtained as a single-ligand cadmium compound, notwithstanding the presence of the linear pyrazine co-ligand under the given solvothermal conditions. The asymmetric unit of the title compound comprises of one cadmium cation and two 2-hydroxypropanoate anions (Fig. 1). The Cd1 cation is sevenfold-coordinated by oxygen and adopts a distorted pentagonal–bipyramidal coordination environment. Four oxygen atoms stem from carboxyl groups and three from hydroxyl groups from four different Hlac⁻ ligands whereby three ligands are chelating and one is monodentate. This coordination mode leads to the formation of layers extending parallel to (010) (Fig. 2, left). Under consideration of the Cd as nodes, the cations are extended to tapes parallel to [001] consisting of a (4,4) grid (Fig. 2, right). The tapes are stacked along [100] and are linked into a three-dimensional network by more distant nodes [Cd⋯Cd distances of 6.4014 (14) Å] parallel to [210]. The crystal packing is consolidated by O—H⋯O hydrogen-bonding interactions of medium strength between hydroxy and carbonyl functions, and additional weak C—H⋯O interactions (Table 1).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O3—H3⋯O2ⁱ	0.87 (1)	1.81 (2)	2.657 (6)	163 (5)
C5—H5⋯O4ⁱⁱ	0.98	2.22	3.021 (8)	139
O6—H6⋯O5ⁱⁱ	0.85 (1)	2.11 (9)	2.747 (7)	132 (11)
Symmetry codes: (i) $[x, -y+1, z+{\script{1\over 2}}]$ ; (ii) $[-x+{\script{3\over 2}}, -y+{\script{1\over 2}}, z+{\script{1\over 2}}]$ .

Figure 1
The asymmetric unit of the title compound showing the atom numbering with displacement ellipsoids drawn at the 50% probability level.

Figure 2
Left: formation of polymeric layers extending parallel to (010); right: bands of (4,4) grids between Cd nodes extending parallel to [001]. H atoms have been omitted for clarity.

Synthesis and crystallization

A mixture of H₂lac (0.125 mmol), pyrazine (0.1 mmol) and Cd(NO₃)₂·4H₂O (0.2 mmol) in C₂H₅OH (15 ml) was stirred in air with a magnetic stirrer, generating a colourless clear solution after 10 min. The reaction solution was then transferred to a solvothermal PTFE reaction vessel with 25 ml capacity, followed by heating at 393 K for 72 h. The reaction vessel was then cooled to room temperature at a rate of 10 K h⁻¹. The formed crystalline material was filtered to obtain colourless rod-like crystals with a yield of about 52% (based on Cd). The obtained crystals are insoluble in common organic solvents such as DMF, CH₃OH, C₂H₅OH, CH₂Cl₂, and acetone. IR (KBr pellets, cm⁻¹): 3044 (m), 1626 (s), 1563 (s), 1451 (s), 1370 (s), 1092 (m). Elemental analysis (%), calculated: C, 24.80; H, 3.47; found: C, 24.71; H, 3.55. The compound is thermally stable up to 533 K under an N₂ atmosphere.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2.

Table 2
Experimental details

Crystal data
Chemical formula	[Cd(C₃H₅O₃)₂]
M_r	290.54
Crystal system, space group	Orthorhombic, Iba2
Temperature (K)	298
a, b, c (Å)	10.238 (2), 19.104 (4), 9.463 (2)
V (Å³)	1850.8 (7)
Z	8
Radiation type	Mo Kα
μ (mm⁻¹)	2.36
Crystal size (mm)	0.3 × 0.2 × 0.2

Data collection
Diffractometer	Bruker APEXII CCD
Absorption correction	Multi-scan (SADABS; Bruker, 2016 )
T_min, T_max	0.547, 0.746
No. of measured, independent and observed [I > 2σ(I)] reflections	9606, 2230, 2032
R_int	0.031
(sin θ/λ)_max (Å⁻¹)	0.672

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.025, 0.065, 1.05
No. of reflections	2230
No. of parameters	127
No. of restraints	18
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.88, −0.36
Absolute structure	Flack x determined using 836 quotients [(I⁺)−(I⁻)]/[(I⁺)+(I⁻)] (Parsons et al., 2013 )
Absolute structure parameter	0.02 (2)
Computer programs: APEX2 and SAINT (Bruker, 2016), SHELXT (Sheldrick, 2015a ), SHELXL (Sheldrick, 2015b ), OLEX2 (Dolomanov et al., 2009 ) and PLATON (Spek, 2009 ).

Structural data

CCDC reference: 1921720

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2414314619012550/wm4107sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314619012550/wm4107Isup2.hkl

checkCIF report

Computing details top

Data collection: SAINT (Bruker, 2016); cell refinement: APEX2(Bruker, 2016); data reduction: SAINT (Bruker, 2016); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL (Sheldrick, 2015b); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009) and PLATON (Spek, 2009).

Poly[di(µ₂-2-hydroxypropanoato)cadmium] top

Crystal data top

[Cd(C₃H₅O₃)₂]	D_x = 2.085 Mg m⁻³
M_r = 290.54	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Iba2	Cell parameters from 9045 reflections
a = 10.238 (2) Å	θ = 3.1–28.5°
b = 19.104 (4) Å	µ = 2.36 mm⁻¹
c = 9.463 (2) Å	T = 298 K
V = 1850.8 (7) Å³	Block, clear light colourless
Z = 8	0.3 × 0.2 × 0.2 mm
F(000) = 1136

Data collection top

Bruker APEXII CCD diffractometer	2032 reflections with I > 2σ(I)
φ and ω scans	R_int = 0.031
Absorption correction: multi-scan (SADABS; Bruker, 2016)	θ_max = 28.5°, θ_min = 3.6°
T_min = 0.547, T_max = 0.746	h = −13→13
9606 measured reflections	k = −20→25
2230 independent reflections	l = −10→12

Refinement top

Refinement on F²	Hydrogen site location: mixed
Least-squares matrix: full	H atoms treated by a mixture of independent and constrained refinement
R[F² > 2σ(F²)] = 0.025	w = 1/[σ²(F_o²) + (0.0315P)² + 2.8326P] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.065	(Δ/σ)_max < 0.001
S = 1.05	Δρ_max = 0.88 e Å⁻³
2230 reflections	Δρ_min = −0.36 e Å⁻³
127 parameters	Absolute structure: Flack x determined using 836 quotients [(I⁺)-(I^-)]/[(I⁺)+(I^-)] (Parsons et al., 2013)
18 restraints	Absolute structure parameter: 0.02 (2)

Special details top

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.

Refinement. The H atoms (H3 and H6) bound to the O3 and O6 atoms were located from a difference-Fourier map. The O—H bond lengths were restrained by DFIX command to be 0.85 Å. The DANG command was used for H3 and H6 to restrain their orientation. Due to unresolved disorder of the methyl groups involving C3 and C6, the latter atoms were treated with ISOR commands.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Cd1	0.45111 (3)	0.35060 (2)	0.51898 (10)	0.03129 (11)
O1	0.4657 (3)	0.3771 (3)	0.2739 (5)	0.0439 (10)
O2	0.3965 (5)	0.4340 (2)	0.0914 (5)	0.0512 (11)
O3	0.3247 (5)	0.4498 (2)	0.4582 (5)	0.0458 (10)
H3	0.332 (5)	0.4896 (11)	0.502 (3)	0.069*
O4	0.8064 (5)	0.2269 (3)	0.4374 (6)	0.0697 (18)
O5	0.6209 (4)	0.2835 (2)	0.4492 (5)	0.0461 (10)
O6	0.7918 (5)	0.1741 (3)	0.6884 (5)	0.0573 (13)
C1	0.3958 (5)	0.4223 (3)	0.2229 (6)	0.0344 (11)
C2	0.3081 (7)	0.4690 (4)	0.3124 (7)	0.0514 (16)
H2	0.3376	0.5174	0.3010	0.062*
C3	0.1765 (9)	0.4651 (6)	0.2688 (12)	0.086 (3)
H3A	0.1440	0.4186	0.2847	0.129*
H3B	0.1706	0.4761	0.1700	0.129*
H3C	0.1254	0.4980	0.3220	0.129*
C4	0.7044 (5)	0.2430 (3)	0.5010 (10)	0.0370 (17)
C5	0.6793 (7)	0.2125 (4)	0.6430 (6)	0.0497 (16)
H5	0.6663	0.2513	0.7093	0.060*
C6	0.5661 (9)	0.1679 (6)	0.6511 (14)	0.086 (3)
H6A	0.5790	0.1275	0.5923	0.129*
H6B	0.4906	0.1932	0.6193	0.129*
H6C	0.5532	0.1532	0.7472	0.129*
H6	0.843 (6)	0.202 (2)	0.732 (11)	0.12 (5)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cd1	0.03011 (16)	0.03302 (16)	0.03074 (17)	−0.00204 (12)	−0.0024 (2)	−0.0012 (2)
O1	0.039 (2)	0.049 (2)	0.043 (2)	0.0177 (17)	0.004 (2)	0.004 (2)
O2	0.073 (3)	0.043 (2)	0.037 (2)	0.015 (2)	0.012 (2)	0.0042 (18)
O3	0.061 (3)	0.044 (2)	0.0328 (18)	0.011 (2)	−0.0017 (18)	−0.0084 (18)
O4	0.052 (3)	0.096 (4)	0.061 (3)	0.036 (3)	0.021 (2)	0.046 (3)
O5	0.045 (2)	0.053 (2)	0.040 (2)	0.0210 (19)	0.0023 (18)	0.0086 (19)
O6	0.059 (3)	0.084 (3)	0.029 (2)	0.036 (3)	−0.004 (2)	−0.002 (2)
C1	0.035 (3)	0.030 (2)	0.039 (3)	0.001 (2)	0.002 (2)	0.000 (2)
C2	0.060 (4)	0.058 (4)	0.037 (3)	0.021 (3)	0.002 (3)	−0.003 (3)
C3	0.070 (4)	0.111 (5)	0.078 (5)	0.025 (4)	−0.001 (4)	0.001 (4)
C4	0.033 (2)	0.037 (2)	0.041 (5)	0.0039 (18)	−0.002 (2)	−0.001 (2)
C5	0.052 (4)	0.069 (4)	0.028 (3)	0.029 (3)	0.002 (2)	0.007 (3)
C6	0.072 (4)	0.092 (4)	0.094 (5)	0.002 (4)	0.013 (4)	0.028 (4)

Geometric parameters (Å, º) top

Cd1—O1ⁱ	2.607 (5)	O6—Cd1^iv	2.335 (5)
Cd1—O1	2.379 (5)	O6—C5	1.432 (7)
Cd1—O2ⁱ	2.333 (5)	O6—H6	0.848 (14)
Cd1—O3	2.366 (4)	C1—C2	1.523 (8)
Cd1—O4ⁱⁱ	2.232 (5)	C2—H2	0.9800
Cd1—O5	2.259 (4)	C2—C3	1.411 (11)
Cd1—O6ⁱⁱ	2.335 (5)	C3—H3A	0.9600
O1—Cd1ⁱⁱⁱ	2.607 (5)	C3—H3B	0.9600
O1—C1	1.221 (7)	C3—H3C	0.9600
O2—Cd1ⁱⁱⁱ	2.333 (5)	C4—C5	1.488 (10)
O2—C1	1.264 (7)	C5—H5	0.9800
O3—H3	0.868 (13)	C5—C6	1.440 (12)
O3—C2	1.438 (8)	C6—H6A	0.9600
O4—Cd1^iv	2.232 (5)	C6—H6B	0.9600
O4—C4	1.244 (8)	C6—H6C	0.9600
O5—C4	1.252 (7)

O1—Cd1—O1ⁱ	147.17 (16)	C5—O6—H6	109 (3)
O2ⁱ—Cd1—O1ⁱ	51.48 (14)	O1—C1—O2	120.7 (5)
O2ⁱ—Cd1—O1	95.71 (16)	O1—C1—C2	122.7 (5)
O2ⁱ—Cd1—O3	83.72 (18)	O2—C1—C2	116.6 (5)
O2ⁱ—Cd1—O6ⁱⁱ	113.78 (18)	O3—C2—C1	108.4 (5)
O3—Cd1—O1ⁱ	104.37 (15)	O3—C2—H2	108.1
O3—Cd1—O1	68.10 (14)	C1—C2—H2	108.1
O4ⁱⁱ—Cd1—O1	81.1 (2)	C3—C2—O3	112.3 (7)
O4ⁱⁱ—Cd1—O1ⁱ	131.71 (18)	C3—C2—C1	111.7 (7)
O4ⁱⁱ—Cd1—O2ⁱ	176.8 (2)	C3—C2—H2	108.1
O4ⁱⁱ—Cd1—O3	94.8 (2)	C2—C3—H3A	109.5
O4ⁱⁱ—Cd1—O5	91.90 (19)	C2—C3—H3B	109.5
O4ⁱⁱ—Cd1—O6ⁱⁱ	68.90 (17)	C2—C3—H3C	109.5
O5—Cd1—O1	77.72 (15)	H3A—C3—H3B	109.5
O5—Cd1—O1ⁱ	97.42 (15)	H3A—C3—H3C	109.5
O5—Cd1—O2ⁱ	87.63 (19)	H3B—C3—H3C	109.5
O5—Cd1—O3	143.58 (16)	O4—C4—O5	122.5 (8)
O5—Cd1—O6ⁱⁱ	128.6 (2)	O4—C4—C5	119.0 (6)
O6ⁱⁱ—Cd1—O1	139.13 (16)	O5—C4—C5	118.5 (6)
O6ⁱⁱ—Cd1—O1ⁱ	68.43 (15)	O6—C5—C4	109.5 (5)
O6ⁱⁱ—Cd1—O3	86.9 (2)	O6—C5—H5	107.7
Cd1—O1—Cd1ⁱⁱⁱ	151.79 (19)	O6—C5—C6	109.2 (7)
C1—O1—Cd1ⁱⁱⁱ	87.9 (4)	C4—C5—H5	107.7
C1—O1—Cd1	119.9 (4)	C6—C5—C4	114.8 (7)
C1—O2—Cd1ⁱⁱⁱ	99.9 (4)	C6—C5—H5	107.7
Cd1—O3—H3	123 (2)	C5—C6—H6A	109.5
C2—O3—Cd1	120.1 (4)	C5—C6—H6B	109.5
C2—O3—H3	104 (2)	C5—C6—H6C	109.5
C4—O4—Cd1^iv	123.7 (5)	H6A—C6—H6B	109.5
C4—O5—Cd1	139.6 (5)	H6A—C6—H6C	109.5
Cd1^iv—O6—H6	92 (8)	H6B—C6—H6C	109.5
C5—O6—Cd1^iv	117.4 (3)

Cd1—O1—C1—O2	−175.5 (4)	Cd1—O5—C4—C5	19.2 (10)
Cd1ⁱⁱⁱ—O1—C1—O2	−0.4 (6)	Cd1^iv—O6—C5—C4	−13.4 (8)
Cd1ⁱⁱⁱ—O1—C1—C2	−178.1 (5)	Cd1^iv—O6—C5—C6	113.0 (7)
Cd1—O1—C1—C2	6.7 (8)	O1—C1—C2—O3	0.2 (9)
Cd1ⁱⁱⁱ—O2—C1—O1	0.5 (6)	O1—C1—C2—C3	−124.1 (8)
Cd1ⁱⁱⁱ—O2—C1—C2	178.3 (5)	O2—C1—C2—O3	−177.6 (6)
Cd1—O3—C2—C1	−7.1 (7)	O2—C1—C2—C3	58.1 (9)
Cd1—O3—C2—C3	116.8 (7)	O4—C4—C5—O6	6.9 (9)
Cd1^iv—O4—C4—O5	−175.6 (5)	O4—C4—C5—C6	−116.2 (8)
Cd1^iv—O4—C4—C5	3.4 (9)	O5—C4—C5—O6	−174.0 (6)
Cd1—O5—C4—O4	−161.7 (6)	O5—C4—C5—C6	62.8 (9)

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O3—H3···O2^v	0.87 (1)	1.81 (2)	2.657 (6)	163 (5)
C5—H5···O4^vi	0.98	2.22	3.021 (8)	139
O6—H6···O5^vi	0.85 (1)	2.11 (9)	2.747 (7)	132 (11)

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

Acknowledgements

The authors thank Shaanxi University of Science and Technology for supporting this work.

Funding information

Funding for this research was provided by: the National Science Foundation of China (No. 21601116), the NSF of Shaanxi Province (Nos. 2017JQ2008, 17JK0113), the China Postdoctoral Science Foundation (2016M592736), and the College students' innovation and entrepreneurship training program (No. 201710708017).

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