catena-Poly[[diaqua­cobalt(II)]-μ₂-7-oxa­bicyclo­[2.2.1]heptane-2,3-dicarboxyl­ato-κ⁴O²,O³,O⁷:O^2′]

The polymeric title complex, [Co(C₈H₈O₅)(H₂O)₂]_n was synthesized by reaction of cobalt acetate with 7-oxabicyclo­[2,2,1]heptane-2,3-dicarb­oxy­lic anhydride. The Co^II ion is six-coordinated in a distorted octa­hedral environment, binding to two water O atoms, to the ether O atom of the bicyclo­heptane unit, to two carboxyl­ate O atoms from two different carboxyl­ate groups of the same anion and to one carboxyl­ate O atom from a symmetry-related anion. The bridging character of the dianion leads to the formation of ribbons along [001]. The ribbons are linked into a layered network parallel to (010) by several O—H...O hydrogen-bonding inter­actions involving the coordinating water mol­ecules as donors and the carboxyl­ate O atoms of neighbouring ribbons as acceptors. The crystal under investigation was an inversion twin.

Key indicators

• Single-crystal X-ray study
• T = 296 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.029
• wR factor = 0.088
• Data-to-parameter ratio = 12.6

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT934_ALERT_3_B Number of (Iobs-Icalc)/SigmaW .gt. 10 Outliers .          1

Alert level C
PLAT232_ALERT_2_C Hirshfeld Test Diff (M-X)  Co1    --  O1      ..        6.0 su
PLAT232_ALERT_2_C Hirshfeld Test Diff (M-X)  Co1    --  O5      ..        7.8 su
PLAT232_ALERT_2_C Hirshfeld Test Diff (M-X)  Co1    --  O2_a    ..        5.1 su
PLAT314_ALERT_2_C Check Small Angle for H2O: Metal-O1W    -H1WA         87.21 Deg.

Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           25.00
           From the CIF: _reflns_number_total               1837
           Count of symmetry unique reflns          977
           Completeness (_total/calc)            188.02%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured       860
           Fraction of Friedel pairs measured     0.880
           Are heavy atom types Z>Si present        yes
PLAT002_ALERT_2_G Number of Distance or Angle Restraints on AtSite          6
PLAT004_ALERT_5_G Info: Polymeric Structure Found with Dimension .          1
PLAT005_ALERT_5_G No _iucr_refine_instructions_details in CIF ....          ?
PLAT007_ALERT_5_G Note: Number of Unrefined D-H Atoms ............          4
PLAT033_ALERT_4_G Flack x Parameter Value Deviates from Zero .....      0.120
PLAT158_ALERT_4_G The Input Unitcell is NOT Standard/Reduced .....          ?
PLAT720_ALERT_4_G Number of Unusual/Non-Standard Labels ..........          4
PLAT792_ALERT_1_G Note: The Model has Chirality at C1     (Verify)          R
PLAT792_ALERT_1_G Note: The Model has Chirality at C2     (Verify)          S
PLAT792_ALERT_1_G Note: The Model has Chirality at C3     (Verify)          R
PLAT792_ALERT_1_G Note: The Model has Chirality at C4     (Verify)          S
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          7
PLAT909_ALERT_3_G Percentage of Observed Data at Theta(Max) still          98 Perc.
PLAT961_ALERT_5_G Dataset Contains no Negative Intensities .......          !

   0 ALERT level A = Most likely a serious problem - resolve or explain
   1 ALERT level B = A potentially serious problem, consider carefully
   4 ALERT level C = Check. Ensure it is not caused by an omission or oversight
  15 ALERT level G = General information/check it is not something unexpected

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

---

S1. Comment

7-oxabicyclo[2,2,1]heptane-2,3-dicarboxylic anhydride (norcantharidin), a traditional Chinese drug, has great anti-cancer activity. The coordination chemistry of cobalt has been important in biology mainly because of coenzyme B₁₂ (Yang et al., 2002). Therefore studying the combination of norcantharidin and cobalt seemed interesting. In this communication, the polymeric title complex, [Co(C₈H₈O₅)(H₂O)₂]_n is reported.

The isostructural cooper complex (Wang et al., 2009a) and a similar nickel complex with monoclinic symmetry (Wang et al., 2009b) of demethylcantharate have been reported previously. The coordination of the Co²⁺ ion in the title complex is shown in Fig. 1. The Co²⁺ ion is six-coordinated in a distorted octahedral coordination mode, binding to two water O atoms, to the bridging O atom of the bicycloheptane unit, to two carboxylate O atoms from different carboxylate groups and to one carboxylate O atom from a symmetry-related bridging anion. This leads to the formation of ribbons extending along [001] (Fig. 2).

As also shown in Fig. 2, the ribbons are linked into a two-dimensional network parallel to (010) by several O—H···O hydrogen-bonding interactions involving the coordinating water molecules as donors and the carboxylate O atoms of neighbouring ribbons as acceptors.

Related literature

For background to the applications of norcantharidin [systematic name: 7-oxabicyclo(2.2.1)heptane-2,3-dicarboxylic anhydride], see: Yang et al. (2002). For the isotypic Cu analogue, see: Wang et al. (2009a), and for a related Ni complex with monoclinic symmetry, see: Wang et al. (2009b).

S2. Experimental

A mixture of 0.5 mmol norcantharidin, 0.5 mmol cobalt acetate and 15 mL distilled water was sealed in a 25 mL Teflon-lined stainless vessel and heated at 443 K for 3 d, then cooled slowly to room temperature. The solution was filtered and block red crystals were obtained.

S3. Refinement

H atoms bonded to C atoms were positioned geometrically and refined using a riding model [aliphatic tertiary carbon C—H = 0.98 Å, aliphatic secondary carbon C—H = 0.97 Å, both with U_iso(H) = 1.2U_eq(C)]. The H atoms bonded to the O atoms were located in a difference Fourier map and refined with O—H distance restraints of 0.85 (1) Å and U_iso(H) = 1.5U_eq(O). The crystal under investigation was an inversion twin with a ratio of 0.88 (3):0.12 (3).

Computing details

Data collection: APEX2 (Bruker, 2006); cell refinement: SAINT (Bruker, 2006); data reduction: SAINT (Bruker, 2006); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2006); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures

	Fig. 1. The coordination of the Co^2+ ion with atom-labelling scheme and displacement ellipsoids drawn at the 30% probability level. [[Symmetry code (A) x, -y+2, z-1/2].
	Fig. 2. The one-dimensional polymeric structure of the title complex along [001] with hydrogen bonding interactions (dotted lines).

catena-Poly[[diaquacobalt(II)]-µ₂-7-oxabicyclo[2.2.1]heptane-2,3- dicarboxylato-κ⁴O²,O³,O⁷:O^2']

Crystal data

[Co(C8H8O5)(H2O)2]	F(000) = 1144
Mr = 279.11	Dx = 1.792 Mg m^−3
Orthorhombic, Iba2	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: I 2 -2c	Cell parameters from 9954 reflections
a = 10.3794 (10) Å	θ = 2.2–25.0°
b = 18.983 (3) Å	µ = 1.68 mm^−1
c = 10.5021 (12) Å	T = 296 K
V = 2069.3 (5) Å^3	Block, red
Z = 8	0.22 × 0.15 × 0.10 mm

Data collection

Bruker APEXII area-detector diffractometer	1837 independent reflections
Radiation source: fine-focus sealed tube	1821 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.025
ω scans	θmax = 25.0°, θmin = 2.2°
Absorption correction: multi-scan (SADABS; Bruker, 2006)	h = −12→9
Tmin = 0.742, Tmax = 0.851	k = −22→22
13174 measured reflections	l = −12→12

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)] = 0.029	H-atom parameters constrained
wR(F^2) = 0.088	w = 1/[σ^2(Fo^2) + (0.0734P)^2 + 1.6545P] where P = (Fo^2 + 2Fc^2)/3
S = 1.00	(Δ/σ)max = 0.001
1837 reflections	Δρmax = 0.32 e Å^−3
146 parameters	Δρmin = −0.77 e Å^−3
7 restraints	Absolute structure: Flack (1983), 860 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.12 (3)

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
Co1	0.23966 (4)	0.966647 (19)	0.74932 (8)	0.02813 (16)
O1W	0.1588 (3)	0.91672 (15)	0.5806 (2)	0.0429 (6)
H1WA	0.2080	0.9431	0.5369	0.064*
H1WB	0.0843	0.8987	0.5727	0.064*
O1	0.3221 (2)	0.99510 (11)	0.9348 (2)	0.0248 (4)
O2W	0.1226 (2)	1.06142 (12)	0.7759 (2)	0.0374 (6)
H2WA	0.0483	1.0731	0.8026	0.056*
H2WB	0.1121	1.0858	0.7089	0.056*
O2	0.3530 (2)	0.96635 (11)	1.1378 (2)	0.0257 (5)
O3	0.1138 (2)	0.90091 (11)	0.8609 (2)	0.0303 (5)
O4	0.0868 (2)	0.85747 (12)	1.0548 (2)	0.0309 (5)
O5	0.37724 (17)	0.87420 (9)	0.76172 (19)	0.0215 (4)
C1	0.4783 (3)	0.87921 (15)	0.8584 (3)	0.0242 (6)
H1	0.5346	0.9202	0.8480	0.029*
C2	0.4010 (3)	0.87971 (14)	0.9824 (3)	0.0201 (6)
H2	0.4522	0.8587	1.0510	0.024*
C3	0.2838 (3)	0.82969 (15)	0.9480 (3)	0.0217 (6)
H3	0.2852	0.7878	1.0023	0.026*
C4	0.3196 (3)	0.80965 (14)	0.8104 (3)	0.0258 (6)
H4	0.2465	0.7927	0.7597	0.031*
C5	0.4367 (4)	0.75899 (17)	0.8103 (4)	0.0389 (8)
H5A	0.4272	0.7223	0.8738	0.047*
H5B	0.4492	0.7376	0.7273	0.047*
C6	0.5475 (3)	0.80918 (18)	0.8437 (3)	0.0351 (7)
H6A	0.5895	0.7953	0.9224	0.042*
H6B	0.6110	0.8110	0.7760	0.042*
C7	0.3557 (2)	0.95301 (15)	1.0216 (3)	0.0179 (6)
C8	0.1514 (3)	0.86588 (14)	0.9561 (3)	0.0211 (6)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Co1	0.0293 (2)	0.0306 (3)	0.0245 (2)	−0.00025 (14)	0.0007 (2)	0.0048 (2)
O1W	0.0397 (14)	0.0645 (17)	0.0247 (11)	−0.0249 (12)	−0.0039 (11)	0.0043 (12)
O1	0.0329 (11)	0.0223 (10)	0.0191 (9)	0.0030 (8)	0.0000 (9)	0.0004 (8)
O2W	0.0309 (12)	0.0419 (12)	0.0394 (14)	0.0150 (10)	0.0098 (10)	0.0125 (10)
O2	0.0236 (12)	0.0331 (10)	0.0203 (10)	0.0057 (8)	−0.0002 (9)	−0.0052 (7)
O3	0.0186 (10)	0.0394 (12)	0.0329 (12)	0.0013 (9)	0.0023 (9)	0.0144 (10)
O4	0.0272 (11)	0.0399 (12)	0.0257 (11)	0.0020 (9)	0.0057 (9)	0.0035 (9)
O5	0.0231 (9)	0.0226 (9)	0.0187 (10)	0.0008 (7)	0.0006 (8)	−0.0003 (8)
C1	0.0195 (13)	0.0282 (14)	0.0249 (15)	0.0029 (11)	0.0012 (12)	−0.0046 (11)
C2	0.0196 (13)	0.0224 (14)	0.0183 (13)	0.0023 (11)	−0.0012 (11)	−0.0008 (11)
C3	0.0240 (13)	0.0184 (13)	0.0227 (14)	−0.0009 (12)	−0.0005 (12)	0.0036 (11)
C4	0.0310 (16)	0.0205 (13)	0.0259 (14)	−0.0007 (11)	−0.0011 (13)	−0.0034 (11)
C5	0.051 (2)	0.0250 (15)	0.0408 (18)	0.0140 (14)	0.0077 (17)	−0.0045 (13)
C6	0.0303 (16)	0.0438 (17)	0.0312 (17)	0.0170 (14)	0.0038 (15)	−0.0048 (14)
C7	0.0125 (12)	0.0237 (13)	0.0174 (14)	−0.0020 (10)	−0.0001 (11)	−0.0046 (11)
C8	0.0200 (14)	0.0196 (13)	0.0238 (14)	−0.0038 (10)	−0.0011 (12)	−0.0001 (11)

Geometric parameters (Å, º)

Co1—O2^i	2.091 (2)	C1—C6	1.519 (4)
Co1—O3	2.154 (2)	C1—C2	1.529 (4)
Co1—O1W	2.178 (3)	C1—H1	0.9800
Co1—O2W	2.188 (2)	C2—C7	1.525 (4)
Co1—O1	2.194 (2)	C2—C3	1.585 (4)
Co1—O5	2.2664 (18)	C2—H2	0.9800
O1W—H1WA	0.8500	C3—C8	1.539 (4)
O1W—H1WB	0.8500	C3—C4	1.540 (4)
O1—C7	1.262 (4)	C3—H3	0.9800
O2W—H2WA	0.8501	C4—C5	1.550 (4)
O2W—H2WB	0.8499	C4—H4	0.9800
O2—C7	1.246 (4)	C5—C6	1.534 (5)
O2—Co1^ii	2.091 (2)	C5—H5A	0.9700
O3—C8	1.262 (4)	C5—H5B	0.9700
O4—C8	1.244 (4)	C6—H6A	0.9700
O5—C4	1.456 (3)	C6—H6B	0.9700
O5—C1	1.462 (4)
O2^i—Co1—O3	176.84 (9)	C1—C2—C3	101.8 (2)
O2^i—Co1—O1W	91.46 (10)	C7—C2—H2	109.9
O3—Co1—O1W	87.54 (10)	C1—C2—H2	109.9
O2^i—Co1—O2W	83.31 (9)	C3—C2—H2	109.9
O3—Co1—O2W	94.03 (8)	C8—C3—C4	112.2 (2)
O1W—Co1—O2W	104.34 (11)	C8—C3—C2	113.9 (2)
O2^i—Co1—O1	97.37 (9)	C4—C3—C2	100.2 (2)
O3—Co1—O1	84.03 (9)	C8—C3—H3	110.0
O1W—Co1—O1	168.35 (9)	C4—C3—H3	110.0
O2W—Co1—O1	84.31 (9)	C2—C3—H3	110.0
O2^i—Co1—O5	98.56 (8)	O5—C4—C3	102.7 (2)
O3—Co1—O5	84.39 (7)	O5—C4—C5	101.5 (2)
O1W—Co1—O5	87.28 (10)	C3—C4—C5	110.1 (2)
O2W—Co1—O5	168.22 (10)	O5—C4—H4	113.8
O1—Co1—O5	83.92 (8)	C3—C4—H4	113.8
Co1—O1W—H1WA	87.2	C5—C4—H4	113.8
Co1—O1W—H1WB	127.2	C6—C5—C4	101.7 (2)
H1WA—O1W—H1WB	137.0	C6—C5—H5A	111.4
C7—O1—Co1	126.40 (17)	C4—C5—H5A	111.4
Co1—O2W—H2WA	139.4	C6—C5—H5B	111.4
Co1—O2W—H2WB	114.5	C4—C5—H5B	111.4
H2WA—O2W—H2WB	90.8	H5A—C5—H5B	109.3
C7—O2—Co1^ii	133.2 (2)	C1—C6—C5	102.2 (3)
C8—O3—Co1	123.30 (19)	C1—C6—H6A	111.3
C4—O5—C1	96.1 (2)	C5—C6—H6A	111.3
C4—O5—Co1	114.38 (16)	C1—C6—H6B	111.3
C1—O5—Co1	116.19 (14)	C5—C6—H6B	111.3
O5—C1—C6	102.2 (2)	H6A—C6—H6B	109.2
O5—C1—C2	102.4 (2)	O2—C7—O1	124.9 (3)
C6—C1—C2	109.8 (2)	O2—C7—C2	117.2 (2)
O5—C1—H1	113.7	O1—C7—C2	117.9 (2)
C6—C1—H1	113.7	O4—C8—O3	124.1 (3)
C2—C1—H1	113.7	O4—C8—C3	118.0 (3)
C7—C2—C1	113.4 (2)	O3—C8—C3	117.8 (3)
C7—C2—C3	111.8 (2)
O2^i—Co1—O1—C7	−134.4 (2)	C7—C2—C3—C4	122.2 (2)
O3—Co1—O1—C7	48.5 (2)	C1—C2—C3—C4	0.9 (3)
O1W—Co1—O1—C7	4.6 (6)	C1—O5—C4—C3	57.7 (2)
O2W—Co1—O1—C7	143.1 (2)	Co1—O5—C4—C3	−64.7 (2)
O5—Co1—O1—C7	−36.5 (2)	C1—O5—C4—C5	−56.1 (2)
O1W—Co1—O3—C8	131.9 (2)	Co1—O5—C4—C5	−178.54 (17)
O2W—Co1—O3—C8	−123.9 (2)	C8—C3—C4—O5	85.4 (3)
O1—Co1—O3—C8	−40.0 (2)	C2—C3—C4—O5	−35.8 (3)
O5—Co1—O3—C8	44.4 (2)	C8—C3—C4—C5	−167.1 (2)
O2^i—Co1—O5—C4	−167.10 (18)	C2—C3—C4—C5	71.7 (3)
O3—Co1—O5—C4	11.75 (19)	O5—C4—C5—C6	34.5 (3)
O1W—Co1—O5—C4	−76.03 (19)	C3—C4—C5—C6	−73.8 (3)
O2W—Co1—O5—C4	94.6 (4)	O5—C1—C6—C5	−35.0 (3)
O1—Co1—O5—C4	96.32 (19)	C2—C1—C6—C5	73.2 (3)
O2^i—Co1—O5—C1	82.24 (18)	C4—C5—C6—C1	0.3 (3)
O3—Co1—O5—C1	−98.90 (18)	Co1^ii—O2—C7—O1	27.9 (4)
O1W—Co1—O5—C1	173.31 (19)	Co1^ii—O2—C7—C2	−151.0 (2)
O2W—Co1—O5—C1	−16.1 (5)	Co1—O1—C7—O2	−149.7 (2)
O1—Co1—O5—C1	−14.33 (18)	Co1—O1—C7—C2	29.1 (3)
C4—O5—C1—C6	57.0 (3)	C1—C2—C7—O2	−144.6 (3)
Co1—O5—C1—C6	178.01 (18)	C3—C2—C7—O2	101.0 (3)
C4—O5—C1—C2	−56.8 (2)	C1—C2—C7—O1	36.5 (3)
Co1—O5—C1—C2	64.2 (2)	C3—C2—C7—O1	−77.9 (3)
O5—C1—C2—C7	−86.2 (3)	Co1—O3—C8—O4	142.1 (2)
C6—C1—C2—C7	165.7 (2)	Co1—O3—C8—C3	−39.6 (3)
O5—C1—C2—C3	34.1 (3)	C4—C3—C8—O4	149.2 (3)
C6—C1—C2—C3	−74.0 (3)	C2—C3—C8—O4	−97.8 (3)
C7—C2—C3—C8	2.2 (3)	C4—C3—C8—O3	−29.2 (3)
C1—C2—C3—C8	−119.1 (2)	C2—C3—C8—O3	83.8 (3)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1WA···O1^i	0.85	1.98	2.832 (3)	180
O2W—H2WB···O4^i	0.85	1.96	2.811 (3)	180
O1W—H1WB···O4^iii	0.85	1.95	2.800 (3)	180
O2W—H2WA···O3^iv	0.85	1.86	2.708 (3)	180

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