The two dimensional coordination polymer tetra­aqua­mesaconatobarium(II), [Ba(C5H4O4)(OH2)4]n

metal-organic papers

m602

Alexander BricenÄoet al. [Ba(C₅H₄O₄)(H₂O)₄] DOI: 10.1107/S1600536802017099 Acta Cryst.(2002). E58, m602±m605 Acta Crystallographica Section E

Structure Reports Online

ISSN 1600-5368

The two-dimensional coordination

polymer tetraaquamesaconatobarium(II),

[Ba(C

5

H

4

O

4

)(OH

2

)

4

]

n

Alexander BricenÄo,a_{Jose Miguel}

Delgadob_{and Graciela DõÂaz de}

Delgadob_*

a_{Centro de QuõÂmica, Instituto Venezolano de}

Investigaciones CientõÂficas (IVIC), Apartado 21827, Caracas 1020-A, Venezuela, and b_{Facultad de Ciencias, Departamento de}

QuõÂmica, Universidad de Los Andes, Apartado 40 La Hechicera, MeÂrida 5201, Venezuela

Correspondence e-mail: diaz@ciens.ula.ve

Key indicators

Single-crystal X-ray study

T= 293 K

Mean(C±C) = 0.007 AÊ H-atom completeness 34%

Rfactor = 0.046

wRfactor = 0.132

Data-to-parameter ratio = 19.0

For details of how these key indicators were automatically derived from the article, see http://journals.iucr.org/e.

#2002 International Union of Crystallography Printed in Great Britain ± all rights reserved

The structure of [Ba(C5H4O4)(OH2)4]n consists of

two-dimensional rectangular grid layers, built up from the self-assembly of zigzag chains of edge-sharing {BaO9} polyhedra

linked by bridging bidendate mesaconate anions (C5H4O42ÿ)

through different coordination modes of the carboxylate groups. The polymer layers form a three-dimensional network via OÐH O hydrogen-bond interactions between the coordinated water molecules and the O atoms of the carboxylate groups.

Comment

Unsaturated carboxylic acids and their derivatives display interesting reactivity patterns when they are heated and/or irradiated in the solid state (DõÂaz de Delgadoet al., 1991; Case & Foxman, 1994; Velaet al., 2000; Xiaoet al., 2000; Odaniet al., 2001). The nature of the reactions in the solid state is deter-mined by the control that the crystalline lattice exerts. In general, the preorganization of molecules and the orientation of double bonds in the crystal determine the nature of the reaction products. For example, we have reported that, when barium hydrogen itaconate monohydrate is heated to about 473 K, an unusual isomerization to barium citraconate occurs in the solid state as a consequence of the arrangement of the molecules in the starting material (BricenÄoet al., 1999).

In this work, we report the X-ray diffraction study of barium mesaconate tetrahydrate, (I), and its thermal behavior. This study is part of a systematic investigation of the struc-ture±reactivity relationships in the solid state of metal complexes of,-unsaturated carboxylic acids. In spite of the simplicity of mesaconic acid (methylmaleic acid), and its similarity to maleic and fumaric acids (cis- and

dioic acids, respectively), the structural chemistry of its salts and complexes is unknown. Only the structure of potassium mesaconate (Gupta & Yadav, 1975) has been reported, as indicated by a search in the Cambridge Structural Database (Version 5.23; Allen & Kennard, 1993).

In the structure of (I), the Ba atoms are coordinated by nine O atoms, as shown in Fig. 1. Five of these O atoms come from four different mesaconate anions and four O atoms come from water molecules. The BaÐO distances range from 2.683 (3) to 2.967 (4) AÊ. The disposition of the O atoms around the Ba atom can be described as a distorted monocapped rectangular antiprism. Edge-sharing polyhedra form unidimensional zigzag chains along the b axis, which are linked through bridging bidendate mesaconate anions (Fig. 2). The carboxylate groups display different coordination modes. The

O1/C1/O2 carboxylate acts as monodentate group through the O2 atom, while O3/C4/O4 displays a combination of sym-metrical chelating and monoatomicanti±antibridging modes, allowing the coordination to three different Ba atoms. The dihedral angle between the planes containing the carboxylate groups is approximately 89.8 (1)_{. These coordination modes}

induce self-assembly of the chains of barium polyhedra with the mesaconate anions, as well as their arrangement in a parallel and alternate head-to-tail fashion, and produce two-dimensional rectangular grid layers parallel to the bc plane (Fig. 3). The polymer layers interact through extensive hydrogen bonds between water molecules and carboxylate O atoms: O1W O3Wi _{2.836 (3), O1W O2W}ii _{2.833 (2) and}

O2W O1iii _{2.807 (3) AÊ [symmetry codes: (i)} 1

2ÿx, 12+y, 1

2ÿz; (ii)12ÿx,ÿ21+y,12ÿz; (iii)ÿ1 +x, y, z], among others,

along thecaxis.

The disposition of the double bonds in neighboring mol-ecules is parallel, and a series of in®nite contacts along theb axis is observed. An analysis of the distances for such contacts indicates that there are contacts C2 C2iv _{[symmetry code:}

Acta Cryst.(2002). E58, m602±m605 Alexander BricenÄoet al. [Ba(C₅H₄O₄)(H₂O)₄]

m603

metal-organic papers

Figure 1

Coordination environment of the Ba atom in [Ba(C5H4O4)(OH2)4]n.

Displacement ellipsoids are shown at the 50% probability level.

Figure 2

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m604

Alexander BricenÄoet al. [Ba(C₅H₄O₄)(H₂O)₄] Acta Cryst.(2002). E58, m602±m605

(iv)ÿx+ 1,ÿy+ 1,ÿz+ 1] along this direction at a distance of 4.168 (2) AÊ. In spite of these favorable structural char-acteristics for reactivity in the solid state, thermal analysis (TGA and DSC) and FT±IR spectra indicate that the material does not react upon heating. It is stable between 473 and 613 K, which corresponds to the temperature range between dehydration and decomposition of the organic ligand.

It is worth noting that the analysis of the results using PLATON(Spek, 1990) suggested the existence of a unit cell (2) with half of the volume of the experimentally determined cell, (1). They are related by the following transformation matrix: [a,b,c]2 = [1₂,0,1₂/0,1,0/1,0,0][a,b,c]1. The dimensions of

the proposed smaller cell are:a= 8.323 (1),b= 7.478 (1),c= 8.893 (1) AÊ, = 105.92 (1)_{, space group P2}

1/m. PLATON

also indicated pseudo-B centering and the possibility of maintaining cell 1 but in space group P21/m. Solution and

re®nement of the structure in cell 1 using space groupsP21/m

andP2/mwere not successful.

A careful examination of the data set collected showed that 1125 out the 2446 unique re¯ections can only be accounted for using the larger cell. Even though the majority of the super-structure re¯ections are rather weak, 376 of those re¯ections haveFo> 4(Fo). It may be noticed that the majority of the

atoms haveycoordinates equal or close to1

4, and that only a

few of the O atoms are clearly removed from such a position. After the reduction of the unit cell proposed byPLATON, the atoms withycoordinates equal or close to1

4are assigned to

special positions withy= 1

4. In the case of the Ba atom, the

value obtained for itsy-coordinate in the structure re®nement carried out in the larger cell [y = 0.24927 (2)] is statistically different from 1

4. Also, after the reduction, in order to

accommodate the number of O atoms in the small unit cell in general positions, they should have half of the occupancy factors indicated by the multiplicity of their positions.

Because of the substructure±superstructure relationship that exists between cells 1 and 2, we believe that the experi-mentally determined unit cell (cell 1) should used in order to properly describe the structure of the compound under study. Sub-superstructure relationships have been observed in other metal dicarboxylates, for example lithium hydrogen maleate dihydrate (DõÂaz de Delgadoet al., 1993).

Experimental

The title compound was prepared by reaction of mesaconic acid (C5H6O4) and BaCO3 in a 1:1 ratio in water. The mixture was maintained under continuous stirring for 24 h. The resulting solution was ®ltered and allowed to evaporate slowly at ambient temperature. After 2±3 weeks, colorless crystals suitable for X-ray analysis formed. The IR spectra were recorded from KBr discs, using a PE-1725X FT± IR spectrometer. IR (cmÿ1_{):(br, OÐH) 3495,(w, C C) 1627,(s,} C Oasym) 1501, (s, C Osym) 1389±1335. In order to study the reactivity in the solid state, samples of approximately 80 mg of the material were placed in a reactor connected to a vacuum line and heated at 473, 543, 613 and 823 K. In each case, once the desired temperature was reached, the temperature was kept constant for 10 min. Thermogravimetric analyses (TG and DTG) and differential scanning calorimetry measurements (DSC) were performed in a Dupont 951 Thermal Analyzer and a Dupont 990 cell, under a dynamic dry nitrogen atmosphere at a ¯ow rate of 50 ml sÿ1_{and a} heating rate of 20 K minÿ1_{. The temperature range was 298±873 K.} TGA and DSC data: weight loss to step 1: 21.29% (calculated 21.34%), 343±443 K,endo; step 2: 20.20% (calculated 20.16%), 673± 783 K,endo.

Crystal data

[Ba(C5H4O4)(H2O)4]

Mr= 337.49 Monoclinic,P21=n a= 8.893 (1) AÊ

b= 7.478 (1) AÊ

c= 16.582 (2) AÊ = 105.13 (1)

V= 1064.5 (2) AÊ3

Z= 4

Dx= 2.106 Mg mÿ3

Dm= 2.07 (2) Mg mÿ3

Dmmeasured by neutral buoyancy in CHCl3/CH3I

MoKradiation Cell parameters from 25

re¯ections = 20.0±35.0 = 3.75 mmÿ1

T= 293 (2) K Prism, colorless 0.600.350.28 mm

Data collection

NicoletP3/F(Crystal Logic) diffractometer

±2scans

Absorption correction: scan (Northet al., 1968)

Tmin= 0.220,Tmax= 0.350 4858 measured re¯ections 2446 independent re¯ections 1478 re¯ections withI> 2(I)

Rint= 0.026 max= 27.5

h=ÿ11!11

k=ÿ9!9

l= 0!21

3 standard re¯ections every 97 re¯ections intensity decay: <0.5%

Re®nement

Re®nement onF2

R[F2_{> 2(F}2_{)] = 0.046}

wR(F2_{) = 0.133}

S= 1.18 2446 re¯ections 129 parameters

H-atom parameters constrained

w= 1/[2_(F

o2) + (0.0728P)2 + 0.0708P]

whereP= (Fo2+ 2Fc2)/3 (/)max= 0.001

max= 2.06 e AÊÿ3 min=ÿ2.88 e AÊÿ3

Extinction correction:SHELXL97 Extinction coef®cient: 0.045 (2)

Figure 3

Table 1

Selected geometric parameters (AÊ,_).

Ba1ÐO3i _{2.683 (3)}

Ba1ÐO4ii _{2.685 (3)}

Ba1ÐO2 2.796 (4)

Ba1ÐO1W 2.838 (4)

Ba1ÐO3iii _{2.853 (3)}

Ba1ÐO4iii _{2.855 (3)}

Ba1ÐO2W 2.861 (3)

Ba1ÐO3W 2.862 (3)

Ba1ÐO4W 2.967 (4)

C1ÐO2 1.250 (6)

C1ÐO1 1.278 (6)

C1ÐC2 1.495 (7)

C2ÐC3 1.352 (6)

C2ÐC5 1.523 (6)

C3ÐC4 1.492 (5)

C4ÐO4 1.248 (4)

C4ÐO3 1.253 (4)

O2ÐC1ÐO1 122.8 (4)

O2ÐC1ÐC2 117.1 (4)

O1ÐC1ÐC2 120.1 (4)

C3ÐC2ÐC1 121.1 (4)

C3ÐC2ÐC5 120.6 (5)

C1ÐC2ÐC5 118.2 (5)

C2ÐC3ÐC4 121.6 (4)

O4ÐC4ÐO3 122.4 (4)

O4ÐC4ÐC3 119.0 (3)

O3ÐC4ÐC3 118.6 (3)

Symmetry codes: (i) 1ÿx;ÿy;ÿz; (ii) 1ÿx;1ÿy;ÿz; (iii)xÿ1

2;12ÿy;12‡z.

Two unassigned extremes of residual density, positive 2.06 e AÊÿ3 (0.17, 0.25, 0.20) and negativeÿ2.88 e AÊÿ3_{(0.13, 0.25, 0.12), were} observed approximately 0.7 and 0.9 AÊ from atom Ba1. The water H atoms were not located; all other H atoms were re®ned as riding.

Data collection:COLLECTinUCLA Crystallographic Package (Strouse, 1988); cell re®nement:LEASTin UCLA Crystallographic Package; data reduction: REDUCE in UCLA Crystallographic Package; program(s) used to solve structure:SHELXS97 (Sheldrick, 1997); program(s) used to re®ne structure:SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND(Brandenburg, 1996±1998); software used to prepare material for publication:SHELXL97 and PLATON(Spek, 1990).

This work was possible thanks to grants LAB-98000821 and S1-95000398 from FONACIT-Venezuela. AB is grateful for support from the Instituto Venezolano de Investigaciones Cienti®cas (IVIC) and FONACIT.

References

Allen, F. H. & Kennard, O. (1993).Chem. Des. Autom. News,8, 1, 31±37. Brandenburg, K. (1996±1998). DIAMOND. Version 2.0h. Crystal Impact

GbR, Bonn, Germany.

BricenÄo, A., DõÂaz de Delgado, G., RamõÂrez, B., VelaÂzquez, W. O. & Bahsas, A. (1999).J. Chem. Crystallogr.29, 785±791.

Case, C. B. & Foxman, B. M. (1994).Inorg. Chim. Acta,222, 239±343. DõÂaz de Delgado, G., Wheeler, K. A., Snider, B. B. & Foxman, B. M. (1991).

Angew. Chem. Int. Ed. Engl.30, 420±422.

DõÂaz de Delgado, G., Mora, A. J. & Delgado, J. M. (1993).Acta Cryst.A49 (Suppl.), 233.

Gupta, M. P. & Yadav, S. R. P. (1975).Z. Kristallogr.141, 151.

North, A. C. T., Phillips, D. C. & Mathews, F. S. (1968).Acta Cryst.A24, 351± 359.

Odani, T., Matsumoto, A., Sada, K. & Miyata, M. (2001).Chem. Commun.pp. 2004±2005.

Sheldrick, G. M. (1997). SHELXL97 and SHELXS97. University of GoÈttingen, Germany.

Spek, A. L. (1990).Acta Cryst.A46, C-34.

Strouse, C. E. (1988). UCLA Crystallographic Package. University of California, Los Angeles, USA.

Vela, M. J., Buchholz, V., Enkelmann, V., Snider, B. B. & Foxman, B. M. (2000).

Chem. Commun.pp. 2225±2226.

Xiao, J., Yang, M., Lauher, J. W. & Fowler, F. W. (2000).Angew. Chem. Int. Ed. Engl.39, 2132±2135.

Acta Cryst.(2002). E58, m602±m605 Alexander BricenÄoet al. [Ba(C₅H₄O₄)(H₂O)₄]

m605

supporting information

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Acta Cryst. (2002). E58, m602–m605

supporting information

Acta Cryst. (2002). E58, m602–m605 [doi:10.1107/S1600536802017099]

The two-dimensional coordination polymer tetraaquamesaconatobarium(II),

[Ba(C

5

H

4

O

4

)(OH

2

)

4

]

n

Alexander Briceño, José Miguel Delgado and Graciela Díaz de Delgado

S1. Comment

Unsaturated carboxylic acids and their derivatives display interesting reactivity patterns when they are heated and/or

irradiated in the solid state (Díaz de Delgado et al., 1991; Case et al., 1994; Vela et al., 2000; Xiao et al., 2000; Odani et

al., 2001). The nature of the reactions in the solid state is determined by the control that the crystalline lattice exerts. In general, the preorganization of molecules and the orientation of double bonds in the crystal determine the nature of the

reaction products. For example, we have reported that when heating barium hydrogen itaconate monohydrate at about

473 K, an unusual isomerization to barium citraconate in the solid state occurs as a consequence of the arrangement of

the molecules in the starting material (Briceño et al., 1999).

In this work, we report the X-ray diffraction study of barium mesaconate tetrahydrate, (I), and its thermal behavior. This

study is part of a systematic investigation on the structure–reactivity relationships in the solid state of metal complexes of

α,β-unsaturated carboxylic acids. In spite of the simplicity of mesaconic acid (methylmaleic acid), and of its similarity with maleic and fumaric acids (cis and trans butenedioic acids, respectively), the structural chemistry of its salts and

complexes is unknown. Only the structure of potassium mesaconate (Gupta & Yadav, 1975) has been reported, as

indicated by a search in the Cambridge Structural Database (Allen & Kennard, 1993).

In the structure of (I), the Ba atoms are coordinated to nine O atoms, as shown in Fig. 1. Five of these O atoms come

from four different mesaconate anions and four O atoms come from water molecules. The Ba—O distances range from

2.683 (3) to 2.967 (4) Å. The disposition of the O atoms around the Ba atom can be described as a distorted monocapped

rectangular antiprism. Edge-sharing polyhedra form unidimensional zigzag chains along the b axis, which are linked

through bridging bidendate mesaconate anions (Fig. 2). The carboxylate groups display different coordination modes.

The O1/C1/O2 carboxylate acts as monodentade group through the O2 atom, while O3/C4/O4 displays a combination of

symmetrical chelating and monoatomic anti–anti bridging modes, allowing the coordination to three different Ba atoms.

The dihedral angle between the planes containing the carboxylate groups is approximately 89.8 (1)°. These coordination

modes induce self-assembly of the chains of barium polyhedra with the mesaconate anions, as well as their arrangement

in a parallel and alternate head-to-tail fashion, and produce two-dimensional rectangular grid layers parallel to the bc

plane (Fig. 3). The polymer layers interact through extensive hydrogen bonds between water molecules and carboxylate

O atoms: O1W···O3Wi _{2.836 (3) Å, O1W···O2W}ii _{2.833 (2) Å and O2W···O1}iii _{2.807 (3) Å [symmetry codes: (i) 1/2 − x,}

1/2 + y, 1/2 − z; (ii) 1/2 − x, −1/2 + y, 1/2 − z; (iii) −1 + x, y, z], among others, along the c direction.

The disposition of the double bonds in neighboring molecules is parallel, and a series of infinite contacts along the b

direction is observed. An analysis of the distances among such contacts indicates that there exist a group of infinite

contacts between the atoms C2···C2iv _{[symmetry code: (iv) −x + 1, −y + 1, −z + 1] along this direction at a distance of}

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Acta Cryst. (2002). E58, m602–m605

DSC) and FT–IR spectra indicate that the material does not react upon heating. It is stable between 473 and 613 K, which

corresponds to the temperature range between dehydration and decomposition of the organic ligand.

It is worth noting that the analysis of the results using PLATON (Spek, 1990) suggested the existence of a unit cell (2)

with half of the volume of the experimentally determined cell, (1). They are related by the following transformation

matrix: [a,b,c]2 = [1/2,0,1/2/0,1,0/-1,0,0][a,b,c]1. The dimensions of the proposed smaller cell are: a = 8.323 (1), b =

7.478 (1), c = 8.893 (1) Å, β = 105.92 (1)°, space group P21/m. PLATON also indicated pseudo-B centering and the

possibility of maintaining cell 1 but in space group P21/m. Solution and refinement of the structure in cell 1 using space

groups P21/m and P2/m were not successful.

A careful examination of the data set collected showed that 1125 out the 2446 unique reflections, can only be accounted

for using the larger cell. Even though the majority of the superstructure reflections are rather weak, 376 of those

reflections have Fo > 4σFo. It may be noticed that the majority of the atoms have y coordinates equal or close to 1/4, and

that only a few of the O atoms are clearly distant from such a position. After the reduction of the unit cell proposed by

PLATON, the atoms with y coordinates equal or close to 1/4 are assigned to special positions with y = 1/4. In the ase of the Ba atom, the value obtained for its y-coordinate in the structure refinement carried out in the larger cell [y =

0.24927 (2)] is statistically different from 1/4. Also, after the reduction, in order to accomodate the number of O atoms in

the small unit cell in general positions, they should have half of the occupancy factors indicated by the multiplicity of

their positions.

Because of the substructure–superstructure relationship that exists between cells 1 and 2, we believe that the

experimentally determined unit cell (cell 1) should used in order to properly describe the structure of the compound

under study. Sub-superstructure relationships have been observed in other metal dicarboxylates, for example lithium

hydrogen maleate dihydrate (Díaz de Delgado et al., 1993).

S2. Experimental

The title compound was prepared by reaction of mesaconic acid (C5H6O4) and BaCO3 in a 1:1 ratio in water. The mixture

was maintained under continuous stirring for 24 h. The resulting solution was filtered and allowed to evaporate slowly at

ambient temperature. After 2–3 weeks, colorless crystals suitable for X-ray analysis formed. The IR spectra were

recorded from KBr discs, using a PE-1725X FT—IR spectrometer. IR (cm−1_{): υ(br, O—H) 3495, υ(w, C═C) 1627, υ(s,}

C═Oasym) 1501, υ(s, C═Osym) 1389–1335. In order to study the reactivity in solid state, samples of approximately 80 mg

of the material were placed in a reactor connected to a vacuum line an heated at 473, 543, 613 and 823 K. In each case,

once the desired temperature was reached, the temperature was kept constant for 10 min. Thermogravimetric analyses

(TG and DTG) and differential scanning calorimetry measurements (DSC) were perfomed in a Dupont 951 Thermal

Analyzer and a Dupont 990 cell, under a dynamic dry nitrogen atmosphere at a flow rate of 50 ml seg−1 _{and a heating rate}

of 20 K min−1_{. The temperatue range was 298–873 K. TGA and DSC data: weight loss to step 1: 21.29% (calculated}

21.34%), 343–443 K, endo; step 2: 20.20% (calculated 20.16%), 673–783 K, endo.

S3. Refinement

Two unassigned extremes of residual density, positive 2.06 e/A3 _{(0.17, 1/4, 1/5) and negative −2.88 e/A}3 _{(0.13, 1/4, 0.12),}

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Acta Cryst. (2002). E58, m602–m605

Figure 1

Coordination enviroment of the Ba atom in [Ba(C5H4O4)(OH2)4]n. Displacement ellipsoids are shown at the 50%

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[image:8.610.163.453.68.518.2]

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Figure 2

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[image:9.610.127.485.69.394.2]

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Acta Cryst. (2002). E58, m602–m605

Figure 3

Projection of the structure of [Ba(C5H4O4)(OH2)4]n onto the bc plane.

tetraaquomesaconatebarium(II)

Crystal data

[Ba(C5H4O4)(H2O)4]

Mr = 337.49 Monoclinic, P21/n

Hall symbol: -P 2yn

a = 8.893 (1) Å

b = 7.478 (1) Å

c = 16.582 (2) Å

β = 105.13 (1)°

V = 1064.5 (2) Å3

Z = 4

F(000) = 648

Dx = 2.106 Mg m−3

Dm = 2.07 (2) Mg m−3

Dm measured by Neutral buoyancy in

CHCl3/CH3I

Mo Kα radiation, λ = 0.71070 Å Cell parameters from 25 reflections

θ = 20.0–35.0°

µ = 3.75 mm−1

T = 293 K Prism, colorless 0.60 × 0.35 × 0.28 mm

Data collection

Nicolet P3/F (Crystal Logic) diffractometer

Radiation source: normal-focus sealed tube Graphite monochromator

τ–2τ scans

Absorption correction: ψ scan (North et al., 1968)

Tmin = 0.220, Tmax = 0.350

4858 measured reflections 2446 independent reflections 1478 reflections with I > 2σ(I)

Rint = 0.026

θmax = 27.5°, θmin = 2.4°

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Acta Cryst. (2002). E58, m602–m605

k = −9→9

l = 0→21

3 standard reflections every 97 reflections intensity decay: <0.5

Refinement

Refinement on F2

Least-squares matrix: full

R[F2 _{> 2σ(F}2_{)] = 0.046}

wR(F2_{) = 0.133}

S = 1.18 2446 reflections 129 parameters 0 restraints

Primary atom site location: structure-invariant direct methods

Secondary atom site location: difference Fourier map

Hydrogen site location: inferred from neighbouring sites

H atoms treated by a mixture of independent and constrained refinement

w = 1/[σ2_(F

o2) + (0.0728P)2 + 0.0708P]

where P = (Fo2 + 2Fc2)/3

(Δ/σ)max = 0.001

Δρmax = 2.06 e Å−3

Δρmin = −2.88 e Å−3

Extinction correction: SHELXL97, Fc*_{=kFc[1+0.001xFc}2_λ3_/sin(2θ)]-1/4

Extinction coefficient: 0.045 (2)

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 F}2_,

conventional R-factors R are based on F, with F set to zero for negative F2_{. The threshold expression of F}2 _{> σ(F}2_{) 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 (Å2₎

x y z Uiso*/Ueq

Ba1 0.21293 (2) 0.249273 (16) 0.166617 (10) 0.0224 (2)

C1 0.5437 (5) 0.2496 (3) 0.0509 (3) 0.0286 (8)

C2 0.5626 (6) 0.2498 (3) −0.0361 (3) 0.0321 (9)

C3 0.7056 (5) 0.2502 (3) −0.0504 (3) 0.0286 (8)

H3 0.7933 0.2500 −0.0052 0.034*

C4 0.7258 (5) 0.2509 (3) −0.1369 (2) 0.0268 (8)

C5 0.4164 (7) 0.2510 (5) −0.1085 (4) 0.057 (2)

H5A 0.4454 0.2471 −0.1604 0.074*

H5B 0.3581 0.3581 −0.1063 0.074*

H5C 0.3537 0.1486 −0.1046 0.074*

O1 0.6636 (5) 0.2501 (2) 0.1134 (3) 0.0380 (10)

O2 0.4076 (5) 0.2492 (2) 0.0587 (3) 0.0384 (10)

O3 0.7329 (4) 0.1041 (4) −0.17209 (17) 0.0386 (7)

O4 0.7329 (4) 0.3971 (4) −0.17193 (17) 0.0391 (7)

O1W 0.5357 (4) 0.2496 (2) 0.2489 (2) 0.0351 (7)

O2W −0.0654 (3) 0.4583 (5) 0.1388 (2) 0.0471 (8)

O3W −0.0659 (3) 0.0409 (4) 0.1385 (2) 0.0446 (8)

supporting information

sup-7

Acta Cryst. (2002). E58, m602–m605

Atomic displacement parameters (Å2₎

U11 _U22 _U33 _U12 _U13 _U23

Ba1 0.0237 (3) 0.0231 (3) 0.0207 (3) 0.00033 (7) 0.00595 (14) 0.00038 (6)

C1 0.0261 (18) 0.035 (2) 0.026 (2) −0.0022 (12) 0.0098 (15) −0.0018 (11)

C2 0.027 (2) 0.043 (2) 0.027 (2) −0.0024 (13) 0.0090 (17) −0.0008 (12)

C3 0.033 (2) 0.030 (2) 0.0236 (17) 0.0010 (12) 0.0095 (15) 0.0001 (10)

C4 0.0279 (19) 0.0275 (19) 0.0262 (18) 0.0001 (11) 0.0089 (15) −0.0006 (10)

C5 0.031 (3) 0.109 (6) 0.029 (3) −0.0013 (19) 0.006 (2) −0.0004 (17)

O1 0.0252 (19) 0.059 (3) 0.0308 (19) 0.0013 (10) 0.0098 (15) −0.0009 (9)

O2 0.0265 (19) 0.063 (3) 0.0277 (19) −0.0013 (10) 0.0106 (16) 0.0015 (9)

O3 0.064 (2) 0.0233 (13) 0.0357 (14) 0.0038 (13) 0.0254 (13) −0.0012 (10)

O4 0.064 (2) 0.0234 (13) 0.0376 (14) −0.0031 (13) 0.0259 (14) 0.0012 (10)

O1W 0.0333 (17) 0.0457 (19) 0.0266 (16) 0.0013 (9) 0.0084 (13) 0.0015 (8)

O2W 0.0363 (16) 0.0426 (17) 0.059 (2) −0.0006 (13) 0.0071 (14) −0.0077 (14)

O3W 0.0240 (14) 0.0429 (17) 0.064 (2) 0.0004 (12) 0.0069 (13) 0.0095 (14)

O4W 0.0342 (18) 0.077 (3) 0.0333 (17) 0.0012 (11) 0.0089 (14) 0.0005 (10)

Geometric parameters (Å, º)

Ba1—O3i _{2.683 (3) C2—C3 1.352 (6)}

Ba1—O4ii _{2.685 (3) C2—C5 1.523 (6)}

Ba1—O2 2.796 (4) C3—C4 1.492 (5)

Ba1—O1W 2.838 (4) C3—H3 0.9300

Ba1—O3iii _{2.853 (3) C4—O4 1.248 (4)}

Ba1—O4iii _{2.855 (3) C4—O3 1.253 (4)}

Ba1—O2W 2.861 (3) C4—Ba1vi _{3.231 (4)}

Ba1—O3W 2.862 (3) C5—H5A 0.9600

Ba1—O4W 2.967 (4) C5—H5B 0.9600

Ba1—C4iii _{3.231 (4) C5—H5C 0.9600}

Ba1—Ba1iv _{4.5946 (5) O3—Ba1}i _{2.683 (3)}

Ba1—Ba1v _{4.5946 (5) O3—Ba1}vi _{2.853 (3)}

C1—O2 1.250 (6) O4—Ba1ii _{2.685 (3)}

C1—O1 1.278 (6) O4—Ba1vi _{2.855 (3)}

C1—C2 1.495 (7)

O3i_—Ba1—O4ii _{160.00 (15) O2—Ba1—Ba1}iv _{111.71 (6)}

O3i_{—Ba1—O2 83.44 (8) O1W—Ba1—Ba1}iv _{75.03 (5)}

O4ii_{—Ba1—O2 83.43 (8) O3}iii_—Ba1—Ba1iv _{32.75 (5)}

O3i_{—Ba1—O1W 80.48 (9) O4}iii_—Ba1—Ba1iv _{77.50 (6)}

O4ii_{—Ba1—O1W 80.40 (9) O2W—Ba1—Ba1}iv _{68.57 (6)}

O2—Ba1—O1W 65.80 (11) O3W—Ba1—Ba1iv _{121.55 (7)}

O3i_—Ba1—O3iii _{112.34 (6) O4W—Ba1—Ba1}iv _{125.23 (4)}

O4ii_—Ba1—O3iii _{67.91 (8) C4}iii_—Ba1—Ba1iv _{55.35 (4)}

O2—Ba1—O3iii _{134.64 (11) O3}i_—Ba1—Ba1v _{35.11 (5)}

O1W—Ba1—O3iii _{75.00 (10) O4}ii_—Ba1—Ba1v _{141.75 (6)}

O3i_—Ba1—O4iii _{67.91 (8) O2—Ba1—Ba1}v _{111.68 (6)}

supporting information

sup-8

Acta Cryst. (2002). E58, m602–m605

O2—Ba1—O4iii _{134.64 (11) O3}iii_—Ba1—Ba1v _{77.55 (6)}

O1W—Ba1—O4iii _{75.04 (10) O4}iii_—Ba1—Ba1v _{32.80 (5)}

O3iii_—Ba1—O4iii _{45.15 (10) O2W—Ba1—Ba1}v _{121.58 (7)}

O3i_{—Ba1—O2W 133.12 (11) O3W—Ba1—Ba1}v _{68.73 (6)}

O4ii_{—Ba1—O2W 66.89 (10) O4W—Ba1—Ba1}v _{125.61 (4)}

O2—Ba1—O2W 123.45 (10) C4iii_—Ba1—Ba1v _{55.31 (4)}

O1W—Ba1—O2W 143.20 (8) Ba1iv_—Ba1—Ba1v _{108.935 (12)}

O3iii_{—Ba1—O2W 77.34 (10) O2—C1—O1 122.8 (4)}

O4iii_{—Ba1—O2W 101.55 (10) O2—C1—C2 117.1 (4)}

O3i_{—Ba1—O3W 67.03 (10) O1—C1—C2 120.1 (4)}

O4ii_{—Ba1—O3W 132.98 (11) C3—C2—C1 121.1 (4)}

O2—Ba1—O3W 123.41 (10) C3—C2—C5 120.6 (5)

O1W—Ba1—O3W 143.46 (8) C1—C2—C5 118.2 (5)

O3iii_{—Ba1—O3W 101.61 (10) C2—C3—C4 121.6 (4)}

O4iii_{—Ba1—O3W 77.49 (10) C2—C3—H3 119.2}

O2W—Ba1—O3W 66.09 (12) C4—C3—H3 119.2

O3i_{—Ba1—O4W 92.55 (7) O4—C4—O3 122.4 (4)}

O4ii_{—Ba1—O4W 92.12 (7) O4—C4—C3 119.0 (3)}

O2—Ba1—O4W 54.75 (12) O3—C4—C3 118.6 (3)

O1W—Ba1—O4W 120.54 (10) O4—C4—Ba1vi _{61.5 (2)}

O3iii_{—Ba1—O4W 153.30 (8) O3—C4—Ba1}vi _{61.5 (2)}

O4iii_{—Ba1—O4W 153.67 (8) C3—C4—Ba1}vi _{171.4 (3)}

O2W—Ba1—O4W 78.53 (9) C2—C5—H5A 109.5

O3W—Ba1—O4W 78.64 (9) C2—C5—H5B 109.5

O3i_—Ba1—C4iii _{90.39 (7) H5A—C5—H5B 109.5}

O4ii_—Ba1—C4iii _{90.48 (7) C2—C5—H5C 109.5}

O2—Ba1—C4iii _{141.32 (13) H5A—C5—H5C 109.5}

O1W—Ba1—C4iii _{75.52 (10) H5B—C5—H5C 109.5}

O3iii_—Ba1—C4iii _{22.69 (6) C1—O2—Ba1 147.6 (4)}

O4iii_—Ba1—C4iii _{22.60 (6) C4—O3—Ba1}i _{151.4 (2)}

O2W—Ba1—C4iii _{87.95 (10) C4—O3—Ba1}vi _{95.9 (2)}

O3W—Ba1—C4iii _{88.01 (10) Ba1}i_—O3—Ba1vi _{112.14 (9)}

O4W—Ba1—C4iii _{163.93 (12) C4—O4—Ba1}ii _{151.4 (2)}

O3i_—Ba1—Ba1iv _{141.70 (6) C4—O4—Ba1}vi _{95.9 (2)}

O4ii_—Ba1—Ba1iv _{35.16 (6) Ba1}ii_—O4—Ba1vi _{112.03 (9)}