Poly[[μ₄-4-(carb­oxylato­meth­yl)benzoato]zinc(II)]

In the title compound, [Zn(C₉H₆O₄)]_n, the Zn^II cations are coordinated in a tetra­hedral fashion by carboxyl­ate O-atom donors belonging to four 4-(carb­oxy­meth­yl) benzoate (4-cmb) ligands. Each 4-cmb ligand binds to four Zn^II cations in an exo­tetra­dentate fashion to create a non-inter­penetrated [Zn(4-cmb)]_n three-dimensional coordination polymer network with a new non-diamondoid 6⁶ topology. The crystal studied was refined as an inversion twin.

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Chemical scheme

Structure description

The title compound was isolated during an exploratory synthetic effort aiming to produce a zinc coordination polymer containing both 4-(carb­oxy­meth­yl)benzoate (4-cmb) and bis­(4-pyrid­yl)urea (bpu) ligands. The bpu ligand has seldom been used in coordination polymer chemistry to date (Kumar et al., 2007).

The asymmetric unit of the title compound contains a single Zn^II cation and a single deprotonated 4-cmb ligand. The divalent Zn atom is coordinated in a distorted tetra­hedral fashion, with single carboxyl­ate O-atom donors from four different 4-cmb ligands comprising the coordination environment (Fig. 1).

Figure 1 The distorted tetrahedral coordination environment of zinc(II) in the title compound. Displacement ellipsoids are drawn at the 50% probability level. H-atom positions are shown as sticks.

The 4-cmb ligands in the title compound adopt an exo­tetra­dentate μ₄-κ⁴-O:O′:O′′:O′′′ bridging mode (Fig. 2). The shorter carboxyl­ate arms of the 4-cmb ligands construct [Zn(OCO)]_n chain motifs parallel to the a axis, with an anti–syn bridging mode and a Zn⋯Zn inter­nuclear distance of 4.875 (1) Å. Meanwhile, the longer carboxyl­ate arms of the 4-cmb ligands construct [Zn(OCO)]_n chain motifs parallel to the b axis, also with an anti–syn bridging mode. The Zn⋯Zn distance in this case measures 4.861 (1) Å, which matches the b lattice parameter. The full span of the 4-cmb ligands constructs a non-inter­penetrated three-dimensional [Zn(4-cmb)]_n coordination polymer network (Fig. 3). The topology of the title complex can be simplified by considering both the Zn atoms and the exo­tetra­dentate 4-cmb ligands as 4-connected nodes. A topological analysis performed with TOPOS software (Blatov et al., 2014) reveals the presence of a new underlying non-diamondoid 6⁶ topology (Fig. 4). While the full vertex symbol of the 6⁶ diamondoid net is 6(2).6(2).6(2).6(2).6(2).6(2), the full vertex symbol of the topology in the title compound is 6.6 (2).6.6 (2).6.6 (2).

Figure 2 The exo­tetra­dentate μ4-κ^4-O:O′:O′′:O′′′ bridging mode of the 4-cmb ligand in the title compound. Color code: Zn, gray, O, red; C, black.

Figure 3 A rendering of the three-dimensional [Zn(4-cmb)]n coordination polymer network in the title compound, viewed down and slightly offset from the b-axis direction.

Figure 4 A schematic perspective of the 4,4-connected non-diamondoid 6^6 topology net in the title compound. The Zn atoms are shown in gray, and the centroids of the phenyl rings of the 4-cmb ligands are shown in teal.

Non classical C—H⋯O inter­actions between phenyl C—H bonds (C6—H6) and longer arm carboxyl­ate O atoms (O3) of the 4-cmb ligands provide some ancillary structural stabilization for the three-dimensional coordination polymer network. The C⋯O distance across these inter­actions measures 3.163 (1) Å.

Synthesis and crystallization

Zn(NO₃)₂^.6H₂O (110 mg, 0.37 mmol), 4-(carb­oxy­meth­yl)benzoic acid (67 mg, 0.37 mmol), bis­(4-pyrid­yl)urea (79 mg, 0.37 mmol) and 0.75 mL of a 1.0 M NaOH solution were placed into 10 mL of distilled H₂O in a Teflon-lined acid digestion bomb. The bomb was sealed and heated in an oven at 393 K for 2 d, and then cooled slowly to 273 K. Colorless crystals of the title complex (35 mg, 39% yield based on Zn) were isolated after washing with distilled water and acetone, and drying in air.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1. The crystal of the title compound was an inversion twin, and the structure could not be solved or refined in centrosymmetric space groups.

Table 1
Experimental details

Crystal data
Chemical formula	[Zn(C9H6O4)]
Mr	243.51
Crystal system, space group	Orthorhombic, Pca21
Temperature (K)	173
a, b, c (Å)	9.6314 (11), 4.8612 (6), 17.269 (2)
V (Å^3)	808.54 (17)
Z	4
Radiation type	Mo Kα
μ (mm^−1)	3.02
Crystal size (mm)	0.11 × 0.07 × 0.05
Data collection
Diffractometer	Bruker APEXII CCD
Absorption correction	Multi-scan (SADABS; Bruker, 2013)
Tmin, Tmax	0.608, 0.745
No. of measured, independent and observed [I > 2σ(I)] reflections	5902, 1474, 1441
Rint	0.026
Refinement
R[F^2 > 2σ(F^2)], wR(F^2), S	0.019, 0.049, 1.07
No. of reflections	1474
No. of parameters	128
No. of restraints	1
H-atom treatment	H-atom parameters constrained
Δρmax, Δρmin (e Å^−3)	0.41, −0.26
Absolute structure	Refined as an inversion twin
Absolute structure parameter	0.440 (19)
Computer programs: COSMO and SAINT (Bruker, 2013), SHELXT (Sheldrick, 2015a), SHELXL (Sheldrick, 2015) and OLEX2 (Dolomanov et al., 2009).

Structural data

Computing details

Data collection: COSMO (Bruker, 2013); cell refinement: SAINT (Bruker, 2013); data reduction: SAINT (Bruker, 2013); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL (Sheldrick, 2015); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).

Poly[[µ₄-4-(carboxylatomethyl)benzoato]zinc(II)]

Crystal data

[Zn(C9H6O4)]	Dx = 2.000 Mg m^−3
Mr = 243.51	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pca21	Cell parameters from 4707 reflections
a = 9.6314 (11) Å	θ = 2.4–25.4°
b = 4.8612 (6) Å	µ = 3.02 mm^−1
c = 17.269 (2) Å	T = 173 K
V = 808.54 (17) Å^3	Block, colorless
Z = 4	0.11 × 0.07 × 0.05 mm
F(000) = 488

Data collection

Bruker APEXII CCD diffractometer	1474 independent reflections
Radiation source: sealed tube	1441 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.026
Detector resolution: 8.36 pixels mm^-1	θmax = 25.4°, θmin = 2.4°
ω scans	h = −11→11
Absorption correction: multi-scan (SADABS; Bruker, 2013)	k = −5→5
Tmin = 0.608, Tmax = 0.745	l = −20→20
5902 measured reflections

Refinement

Refinement on F^2	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H-atom parameters constrained
R[F^2 > 2σ(F^2)] = 0.019	w = 1/[σ^2(Fo^2) + (0.0274P)^2 + 0.2338P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.049	(Δ/σ)max < 0.001
S = 1.07	Δρmax = 0.41 e Å^−3
1474 reflections	Δρmin = −0.26 e Å^−3
128 parameters	Absolute structure: Refined as an inversion twin
1 restraint	Absolute structure parameter: 0.440 (19)
Primary atom site location: dual

Special details

Experimental. Data was collected using a BRUKER CCD (charge coupled device) based diffractometer equipped with an Oxford low-temperature apparatus operating at 173 K. A suitable crystal was chosen and mounted on a nylon loop using Paratone oil. Data were measured using omega scans of 0.5° per frame for 30 s. The total number of images were based on results from the program COSMO where redundancy was expected to be 4 and completeness to 0.83Å to 100%. Cell parameters were retrieved using APEX II software and refined using SAINT on all observed reflections.Data reduction was performed using the SAINT software which corrects for Lp. Scaling and absorption corrections were applied using SADABS6 multi-scan technique, supplied by George Sheldrick. The structure was solved by the direct method using the SHELXT program and refined by least squares method on F2, SHELXL, incorporated in OLEX2.

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 structure was refined by Least Squares using version 2018/3 of XL (Sheldrick, 2015) incorporated in Olex2 (Dolomanov et al., 2009). All non-hydrogen atoms were refined anisotropically. Hydrogen atom positions were calculated geometrically and refined using the riding model.

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

	x	y	z	Uiso*/Ueq
Zn1	0.56331 (4)	0.57814 (7)	0.73682 (2)	0.01480 (14)
O3	−0.0109 (3)	0.3545 (6)	0.32739 (16)	0.0183 (6)
O2	0.2616 (3)	0.4478 (5)	0.71219 (15)	0.0190 (7)
O4	−0.0524 (3)	−0.0286 (6)	0.26387 (17)	0.0209 (7)
O1	0.4561 (3)	0.4858 (7)	0.64554 (17)	0.0198 (6)
C2	0.2647 (4)	0.3138 (8)	0.5782 (2)	0.0171 (8)
C5	0.1557 (4)	0.0862 (7)	0.4423 (2)	0.0170 (8)
C1	0.3286 (4)	0.4242 (7)	0.6498 (2)	0.0145 (8)
C6	0.2485 (4)	0.3057 (8)	0.4389 (3)	0.0191 (8)
H6	0.2738	0.3798	0.3900	0.023*
C8	0.1057 (5)	−0.0552 (8)	0.3698 (3)	0.0203 (9)
H8A	0.0600	−0.2290	0.3853	0.024*
H8B	0.1883	−0.1051	0.3387	0.024*
C7	0.3041 (4)	0.4171 (7)	0.5055 (2)	0.0167 (8)
H7	0.3691	0.5638	0.5022	0.020*
C4	0.1169 (4)	−0.0147 (8)	0.5143 (3)	0.0190 (8)
H4	0.0531	−0.1634	0.5173	0.023*
C9	0.0067 (4)	0.0996 (8)	0.3177 (2)	0.0161 (8)
C3	0.1700 (4)	0.0985 (7)	0.5818 (2)	0.0171 (8)
H3	0.1415	0.0287	0.6307	0.021*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Zn1	0.0149 (2)	0.0164 (2)	0.0131 (2)	−0.00133 (14)	0.0010 (2)	−0.0021 (2)
O3	0.0217 (16)	0.0151 (13)	0.0181 (14)	0.0020 (12)	−0.0014 (13)	0.0002 (11)
O2	0.0129 (13)	0.0284 (15)	0.0156 (15)	0.0007 (10)	0.0007 (10)	−0.0013 (11)
O4	0.0286 (17)	0.0157 (13)	0.0185 (15)	0.0017 (11)	−0.0095 (11)	−0.0052 (11)
O1	0.0168 (15)	0.0291 (15)	0.0136 (15)	−0.0051 (13)	−0.0003 (12)	−0.0045 (14)
C2	0.015 (2)	0.0170 (19)	0.020 (2)	0.0027 (15)	0.0009 (16)	−0.0022 (17)
C5	0.0162 (19)	0.0146 (19)	0.020 (2)	0.0057 (14)	−0.0049 (18)	−0.0007 (16)
C1	0.013 (2)	0.0136 (19)	0.016 (2)	−0.0007 (14)	−0.0022 (16)	0.0023 (15)
C6	0.023 (2)	0.018 (2)	0.016 (2)	−0.0001 (18)	0.0031 (18)	0.0010 (17)
C8	0.025 (2)	0.016 (2)	0.020 (2)	0.0022 (16)	−0.0039 (19)	−0.0017 (17)
C7	0.016 (2)	0.0153 (19)	0.019 (2)	−0.0009 (14)	0.0013 (15)	−0.0004 (16)
C4	0.016 (2)	0.0178 (18)	0.023 (2)	−0.0030 (16)	−0.0008 (17)	−0.0028 (17)
C9	0.016 (2)	0.019 (2)	0.0134 (19)	−0.0016 (15)	0.0025 (16)	−0.0009 (15)
C3	0.017 (2)	0.0184 (19)	0.016 (2)	−0.0002 (15)	0.0021 (16)	0.0020 (16)

Geometric parameters (Å, º)

Zn1—O3^i	1.971 (3)	C2—C3	1.390 (6)
Zn1—O2^ii	1.961 (3)	C5—C6	1.393 (5)
Zn1—O4^iii	1.971 (3)	C5—C8	1.507 (6)
Zn1—O1	1.937 (3)	C5—C4	1.387 (6)
O3—Zn1^iv	1.971 (3)	C6—H6	0.9500
O3—C9	1.261 (5)	C6—C7	1.379 (6)
O2—Zn1^v	1.961 (3)	C8—H8A	0.9900
O2—C1	1.262 (5)	C8—H8B	0.9900
O4—Zn1^vi	1.971 (3)	C8—C9	1.511 (6)
O4—C9	1.256 (5)	C7—H7	0.9500
O1—C1	1.266 (5)	C4—H4	0.9500
C2—C1	1.482 (6)	C4—C3	1.388 (6)
C2—C7	1.404 (6)	C3—H3	0.9500
O3^i—Zn1—O4^iii	109.47 (12)	C7—C6—C5	121.0 (4)
O2^ii—Zn1—O3^i	112.72 (12)	C7—C6—H6	119.5
O2^ii—Zn1—O4^iii	99.55 (11)	C5—C8—H8A	107.8
O1—Zn1—O3^i	112.43 (12)	C5—C8—H8B	107.8
O1—Zn1—O2^ii	109.13 (11)	C5—C8—C9	117.9 (3)
O1—Zn1—O4^iii	112.90 (14)	H8A—C8—H8B	107.2
C9—O3—Zn1^iv	118.1 (3)	C9—C8—H8A	107.8
C1—O2—Zn1^v	132.7 (3)	C9—C8—H8B	107.8
C9—O4—Zn1^vi	132.9 (3)	C2—C7—H7	120.0
C1—O1—Zn1	121.7 (3)	C6—C7—C2	120.0 (4)
C7—C2—C1	120.3 (3)	C6—C7—H7	120.0
C3—C2—C1	120.5 (4)	C5—C4—H4	119.5
C3—C2—C7	119.2 (4)	C5—C4—C3	120.9 (4)
C6—C5—C8	121.3 (4)	C3—C4—H4	119.5
C4—C5—C6	118.8 (4)	O3—C9—C8	119.7 (4)
C4—C5—C8	119.8 (3)	O4—C9—O3	121.6 (4)
O2—C1—O1	121.6 (4)	O4—C9—C8	118.6 (3)
O2—C1—C2	122.2 (3)	C2—C3—H3	119.9
O1—C1—C2	116.1 (4)	C4—C3—C2	120.1 (4)
C5—C6—H6	119.5	C4—C3—H3	119.9
Zn1^iv—O3—C9—O4	−25.6 (5)	C1—C2—C3—C4	−176.1 (4)
Zn1^iv—O3—C9—C8	151.8 (3)	C6—C5—C8—C9	−71.1 (5)
Zn1^v—O2—C1—O1	170.3 (3)	C6—C5—C4—C3	−0.5 (6)
Zn1^v—O2—C1—C2	−12.0 (5)	C8—C5—C6—C7	−173.7 (4)
Zn1^vi—O4—C9—O3	−173.7 (3)	C8—C5—C4—C3	175.0 (4)
Zn1^vi—O4—C9—C8	8.9 (6)	C7—C2—C1—O2	145.3 (4)
Zn1—O1—C1—O2	7.6 (5)	C7—C2—C1—O1	−36.9 (5)
Zn1—O1—C1—C2	−170.3 (3)	C7—C2—C3—C4	1.0 (6)
C5—C6—C7—C2	−1.6 (6)	C4—C5—C6—C7	1.7 (6)
C5—C8—C9—O3	13.3 (6)	C4—C5—C8—C9	113.6 (4)
C5—C8—C9—O4	−169.2 (4)	C3—C2—C1—O2	−37.7 (5)
C5—C4—C3—C2	−0.8 (6)	C3—C2—C1—O1	140.2 (4)
C1—C2—C7—C6	177.3 (4)	C3—C2—C7—C6	0.2 (6)

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