Poly[μ₆-benzene-1,2,4,5-tetra­carboxyl­ato-κ⁶O¹:O²:O^2′:O⁴:O⁵:O^5′-bis­[diaqua­zinc(II)]]

The benzene­tetra­carboxyl­ate tetra­anion in the title compound, [Zn₂(C₈H₂O₈)(H₂O)₄]_n, lies on a center of inversion. Two delocalized carboxylate –CO₂ groups are each connected to two different diaqua­zinc units, whereas the other two localized carboxylate –CO₂ are each bonded to one different diaqua­zinc unit. The metal atom is five-coordinate as a consequence of such μ₆-bridging; the water mol­ecules occupy an axial and an equatorial site of the trigonal bipyramid in the three-dimensional network. The architecture is further consolidated by extensive hydrogen bonding in which one water mol­ecule serves as a donor and the other as both a donor and an acceptor.

Key indicators

• Single-crystal X-ray study
• T = 295 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.024
• wR factor = 0.066
• Data-to-parameter ratio = 10.5

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT222_ALERT_3_B Large Non-Solvent    H     Ueq(max)/Ueq(min) ...       5.00 Ratio

Author Response: Al H atoms were freely refined.

PLAT731_ALERT_1_B Bond    Calc     0.85(5), Rep   0.850(10) ......       5.00 su-Ra
              O1W  -H1      1.555   1.555

Alert level C
PLAT041_ALERT_1_C Calc. and Rep. SumFormula Strings    Differ ....          ?
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?
PLAT045_ALERT_1_C Calculated and Reported Z Differ by ............       2.00 Ratio
PLAT062_ALERT_4_C Rescale T(min) & T(max) by .....................       0.91
PLAT152_ALERT_1_C Supplied and Calc Volume s.u. Inconsistent .....          ?
PLAT153_ALERT_1_C The su's on the Cell Axes   are Equal (x 100000)        100 Ang.
PLAT164_ALERT_4_C Nr. of Refined C-H H-Atoms in Heavy-At Struct...          1
PLAT180_ALERT_3_C Check Cell Rounding: # of Values Ending with 0 =          4
PLAT715_ALERT_1_C D-H     Unknown or Inconsistent Label ..........    O1<I>W<
PLAT715_ALERT_1_C D-H     Unknown or Inconsistent Label ..........    O1<I>W<
PLAT715_ALERT_1_C D-H     Unknown or Inconsistent Label ..........    O1<I>W<
PLAT715_ALERT_1_C D-H     Unknown or Inconsistent Label ..........    O2<I>W<
PLAT715_ALERT_1_C D-H     Unknown or Inconsistent Label ..........    O2<I>W<
PLAT731_ALERT_1_C Bond    Calc     0.85(3), Rep   0.850(10) ......       3.00 su-Ra
              O2W  -H4      1.555   1.555

Alert level G
ABSTM02_ALERT_3_G  When printed, the submitted absorption T values will be
            replaced by the scaled T values. Since the ratio of scaled T's
            is identical to the ratio of reported T values, the scaling
            does not imply a change to the absorption corrections used in
            the study.
            Ratio of Tmax expected/reported      0.909
            Tmax scaled      0.477 Tmin scaled      0.389
PLAT794_ALERT_5_G Check Predicted Bond Valency for Zn1         (2)       2.02
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          5

   0 ALERT level A = In general: serious problem
   2 ALERT level B = Potentially serious problem
  14 ALERT level C = Check and explain
   3 ALERT level G = General alerts; check

  12 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   4 ALERT type 3 Indicator that the structure quality may be low
   2 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

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S1. Comment

The are many crystallographic studies of coordination compounds of 1,2,4,5-benzenetetracarboxylic acid (Cambridge Structural Database, Version 5.28, Nov. 2006); a water-coordinated zinc derivative with zinc in both tetrahedral and octahedral geometries has been reported (Robl, 1987; Wei et al., 1991). A slight variation of the synthesis has yielded the title diaquazinc compound, which features a trigonal-bipyramidal zinc coordination environment (Scheme I; Fig. 1).

Related literature

For the structure of catena-poly[µ₅-1,2,4,5-benzenetetracarboxylato-pentaaquadizinc], which has one Zn atom in a tetrahedral and the other in an octahedral coordination geometry, see: Robl (1987); Wei et al. (1991).

S2. Experimental

Benzene-1,2,4,5-tetracarboxylic acid (0.05 g, 0.22 mmol), zinc acetate (0.062 g, 0.20 mmol) and sodium hydroxide (0.08 g, 0.20 mmol) were heated in acetonitrile (25 ml) until the reagents dissolved completely. The solution was filtered; diethyl ether was layered over the solution, which was kept in a closed container. Crystals were obtained after a week.

S3. Refinement

All hydrogen atoms were located in difference Fourier maps, and were refined with distance restraints of C–H 0.95±0.01 Å and O–H 0.85±0.01 Å. Their temperature factors were freely refined.

Computing details

Data collection: SMART (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: X-SEED (Barbour, 2001); software used to prepare material for publication: publCIF (Westrip, 2007).

Figures

Fig. 1. Thermal ellipsoid plot of a portion of the polymeric structure. Displacement ellipsoids are drawn at the 70% probabability level, and H atoms as spheres of arbitrary radii. [Symmetry codes (i): 1/2 + x, 3/2 - y, 1/2 + z; (ii) x - 1/2, 3/2 - y, 1/2 + z.]

Poly[µ₆-benzene-1,2,4,5-tetracarboxylato- κ⁶O¹:O²:O^2':O⁴:O⁵:O^5'-bis[diaquazinc(II)]]

Crystal data

[Zn2(C8H2O8)(H2O)4]	F(000) = 452
Mr = 452.92	Dx = 2.170 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 2515 reflections
a = 5.259 (1) Å	θ = 2.5–26.1°
b = 16.342 (1) Å	µ = 3.53 mm^−1
c = 8.143 (1) Å	T = 295 K
β = 97.939 (1)°	Block, colorless
V = 693.1 (2) Å^3	0.29 × 0.25 × 0.21 mm
Z = 2

Data collection

Bruker APEX area-detector diffractometer	1362 independent reflections
Radiation source: fine-focus sealed tube	1284 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.028
ϕ and ω scans	θmax = 26.1°, θmin = 2.5°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −6→5
Tmin = 0.428, Tmax = 0.524	k = −19→16
3774 measured reflections	l = −9→10

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)] = 0.024	All H-atom parameters refined
wR(F^2) = 0.066	w = 1/[σ^2(Fo^2) + (0.0414P)^2 + 0.1318P] where P = (Fo^2 + 2Fc^2)/3
S = 1.06	(Δ/σ)max = 0.001
1362 reflections	Δρmax = 0.41 e Å^−3
130 parameters	Δρmin = −0.46 e Å^−3
5 restraints	Extinction correction: SHELXL, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.030 (2)

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

	x	y	z	Uiso*/Ueq
Zn1	0.64624 (4)	0.66722 (1)	0.6294 (1)	0.0154 (1)
O1	0.6293 (3)	0.78505 (9)	0.57696 (18)	0.0215 (3)
O2	0.4252 (3)	0.79266 (9)	0.31917 (17)	0.0190 (3)
O3	0.9206 (3)	0.87008 (9)	0.28756 (18)	0.0199 (3)
O4	0.9313 (3)	0.99480 (9)	0.18210 (18)	0.0230 (3)
O1w	0.3378 (3)	0.6354 (1)	0.4158 (2)	0.0230 (3)
O2w	0.8804 (3)	0.5957 (1)	0.5220 (2)	0.0271 (4)
C1	0.5300 (4)	0.8244 (1)	0.4509 (3)	0.0145 (4)
C2	0.5241 (4)	0.9156 (1)	0.4733 (2)	0.0132 (4)
C3	0.6670 (4)	0.9715 (1)	0.3922 (2)	0.0142 (4)
C4	0.8534 (4)	0.9442 (1)	0.2782 (2)	0.0148 (4)
C5	0.6398 (4)	1.0548 (1)	0.4197 (2)	0.0155 (4)
H1	0.308 (11)	0.672 (3)	0.341 (5)	0.15 (3)*
H2	0.372 (5)	0.591 (1)	0.370 (3)	0.04 (1)*
H3	1.008 (4)	0.612 (2)	0.478 (3)	0.04 (1)*
H4	0.795 (5)	0.564 (2)	0.452 (3)	0.04 (1)*
H5	0.748 (4)	1.091 (1)	0.371 (3)	0.03 (1)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Zn1	0.0175 (2)	0.0122 (2)	0.0172 (2)	−0.0011 (1)	0.0051 (1)	0.0004 (1)
O1	0.033 (1)	0.012 (1)	0.018 (1)	−0.001 (1)	−0.004 (1)	0.001 (1)
O2	0.024 (1)	0.014 (1)	0.018 (1)	0.001 (1)	−0.003 (1)	−0.003 (1)
O3	0.024 (1)	0.016 (1)	0.022 (1)	0.006 (1)	0.010 (1)	0.000 (1)
O4	0.028 (1)	0.020 (1)	0.024 (1)	0.001 (1)	0.014 (1)	0.004 (1)
O1w	0.026 (1)	0.019 (1)	0.025 (1)	0.002 (1)	0.006 (1)	0.003 (1)
O2w	0.019 (1)	0.031 (1)	0.033 (1)	−0.004 (1)	0.009 (1)	−0.014 (1)
C1	0.014 (1)	0.014 (1)	0.017 (1)	0.001 (1)	0.004 (1)	0.000 (1)
C2	0.015 (1)	0.012 (1)	0.013 (1)	0.002 (1)	0.000 (1)	0.000 (1)
C3	0.016 (1)	0.013 (1)	0.014 (1)	0.002 (1)	0.003 (1)	0.001 (1)
C4	0.014 (1)	0.016 (1)	0.015 (1)	0.000 (1)	0.001 (1)	−0.002 (1)
C5	0.019 (1)	0.014 (1)	0.015 (1)	−0.001 (1)	0.004 (1)	0.001 (1)

Geometric parameters (Å, º)

Zn1—O1	1.972 (2)	O1w—H2	0.85 (1)
Zn1—O2^i	2.084 (1)	O2w—H3	0.85 (1)
Zn1—O3^ii	1.965 (1)	O2w—H4	0.85 (1)
Zn1—O1w	2.269 (2)	C1—C2	1.502 (3)
Zn1—O2w	1.986 (2)	C2—C5^iii	1.394 (3)
O1—C1	1.262 (3)	C2—C3	1.404 (3)
O2—C1	1.249 (3)	C3—C5	1.390 (3)
O3—C4	1.261 (2)	C3—C4	1.508 (2)
O4—C4	1.246 (2)	C5—C2^iii	1.394 (3)
O1w—H1	0.85 (1)	C5—H5	0.94 (1)
O3^ii—Zn1—O1	115.55 (6)	Zn1—O2w—H4	110 (2)
O3^ii—Zn1—O2w	125.00 (7)	H3—O2w—H4	106 (3)
O1—Zn1—O2w	119.44 (7)	O2—C1—O1	124.8 (2)
O3^ii—Zn1—O2^i	92.21 (6)	O2—C1—C2	120.2 (2)
O1—Zn1—O2^i	81.92 (6)	O1—C1—C2	114.9 (2)
O2w—Zn1—O2^i	95.49 (6)	C5^iii—C2—C3	119.0 (2)
O3^ii—Zn1—O1w	89.93 (6)	C5^iii—C2—C1	116.5 (2)
O1—Zn1—O1w	92.96 (6)	C3—C2—C1	124.5 (2)
O2w—Zn1—O1w	87.07 (6)	C5—C3—C2	119.2 (2)
O2^i—Zn1—O1w	174.88 (6)	C5—C3—C4	118.6 (2)
C1—O1—Zn1	132.5 (1)	C2—C3—C4	122.2 (2)
C1—O2—Zn1^iv	133.5 (1)	O4—C4—O3	124.2 (2)
C4—O3—Zn1^v	116.6 (1)	O4—C4—C3	119.3 (2)
Zn1—O1w—H1	116 (4)	O3—C4—C3	116.5 (2)
Zn1—O1w—H2	111 (2)	C3—C5—C2^iii	121.8 (2)
H1—O1w—H2	109 (4)	C3—C5—H5	118 (2)
Zn1—O2w—H3	126 (2)	C2^iii—C5—H5	120 (2)
O3^ii—Zn1—O1—C1	−105.7 (2)	C5^iii—C2—C3—C5	−0.6 (3)
O2w—Zn1—O1—C1	73.9 (2)	C1—C2—C3—C5	178.2 (2)
O2^i—Zn1—O1—C1	165.7 (2)	C5^iii—C2—C3—C4	178.4 (2)
O1w—Zn1—O1—C1	−14.4 (2)	C1—C2—C3—C4	−2.9 (3)
Zn1^iv—O2—C1—O1	155.2 (2)	Zn1^v—O3—C4—O4	−3.8 (3)
Zn1^iv—O2—C1—C2	−19.4 (3)	Zn1^v—O3—C4—C3	176.3 (1)
Zn1—O1—C1—O2	−4.4 (3)	C5—C3—C4—O4	−16.9 (3)
Zn1—O1—C1—C2	170.4 (1)	C2—C3—C4—O4	164.1 (2)
O2—C1—C2—C5^iii	106.5 (2)	C5—C3—C4—O3	163.0 (2)
O1—C1—C2—C5^iii	−68.6 (2)	C2—C3—C4—O3	−15.9 (3)
O2—C1—C2—C3	−72.3 (3)	C2—C3—C5—C2^iii	0.6 (3)
O1—C1—C2—C3	112.6 (2)	C4—C3—C5—C2^iii	−178.4 (2)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1w—H1···O1^iv	0.85 (1)	2.33 (3)	3.109 (2)	152 (6)
O1w—H1···O2	0.85 (1)	2.08 (4)	2.745 (2)	134 (5)
O1w—H2···O4^vi	0.85 (1)	1.96 (1)	2.767 (2)	159 (3)
O2w—H3···O1w^vii	0.85 (1)	1.91 (1)	2.744 (2)	168 (3)
O2w—H4···O4^vi	0.85 (1)	1.89 (1)	2.724 (2)	172 (3)

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