PMCCPMCCPMCC

Search tips
Search criteria 

Advanced

 
Logo of actaeInternational Union of Crystallographysearchopen accessarticle submissionjournal home pagethis article
 
Acta Crystallogr Sect E Struct Rep Online. 2008 April 1; 64(Pt 4): m590.
Published online 2008 March 29. doi:  10.1107/S1600536808008118
PMCID: PMC2961059

Aqua­dicrotonato(di-2-pyridyl­amine)cobalt(II)

Abstract

The Co atom in the title complex, [Co(CH3CHCHCOO)2(C10H9N3)(H2O)], has a distorted recta­ngular–pyramidal geometry formed by the chelating dipyridylamine ligand, and two O atoms of monodentate carboxyl­ate groups of two different crotonate anions and a water molecule. The complex forms a three-dimensional supra­molecular network via inter­molecular O—H(...)O, N—H(...)O and C—H(...)O hydrogen-bonding contacts.

Related literature

For related literature, see: Addison et al. (1984 [triangle]); Chang et al. (1999 [triangle]); Peng et al. (2000 [triangle]); Wu (2007 [triangle]); Xu et al. (2004 [triangle]); Zhang (2007 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-64-0m590-scheme1.jpg

Experimental

Crystal data

  • [Co(C4H5O2)2(C10H9N3)(H2O)]
  • M r = 418.31
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-64-0m590-efi1.jpg
  • a = 7.1113 (7) Å
  • b = 16.8303 (15) Å
  • c = 15.9850 (14) Å
  • β = 91.291 (2)°
  • V = 1912.7 (3) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.93 mm−1
  • T = 298 (2) K
  • 0.28 × 0.22 × 0.19 mm

Data collection

  • Bruker APEXII area-detector diffractometer
  • Absorption correction: multi-scan (SADABS; Sheldrick, 2004 [triangle]) T min = 0.781, T max = 0.843
  • 9697 measured reflections
  • 3448 independent reflections
  • 2714 reflections with I > 2σ(I)
  • R int = 0.064

Refinement

  • R[F 2 > 2σ(F 2)] = 0.041
  • wR(F 2) = 0.107
  • S = 0.96
  • 3448 reflections
  • 252 parameters
  • 2 restraints
  • H atoms treated by a mixture of independent and constrained refinement
  • Δρmax = 0.34 e Å−3
  • Δρmin = −0.36 e Å−3

Data collection: APEX2 (Bruker, 2004 [triangle]); cell refinement: SAINT (Bruker, 2004 [triangle]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: SHELXTL (Sheldrick, 2008 [triangle]); software used to prepare material for publication: SHELXTL.

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks I. DOI: 10.1107/S1600536808008118/si2078sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808008118/si2078Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

The author is grateful to the Guangxi University for Nationalities for financial support.

supplementary crystallographic information

Comment

Transition metal complexes with polypyridylamine ligands, possessing diverse structures and special optical and electromagnetic properties (Peng et al., 2000), have aroused great interest among researchers. The pyridyldiamine ligand usually exhibits donor as well as acceptor properties and can be used as a popular chelating ligand (Chang et al., 1999; Xu et al., 2004).

As shown in the Scheme and Fig. 1, the Co atom in the title complex has a contorted rectangular pyramidal coordination geometry formed by the chelating dipyridine-2-ylamine (tpdaH2) ligand and two oxygen atoms of monodenate carboxylate groups of two different crotonic acid anions. The tpdaH2 ligand and the crotonic acid ligand consist of the basal plane. The coordinated water molecule hold the vertex location. The O1–Co1–N3 and O3–Co1–N1 angles are α = 156.63 (9)° and β = 175.67 (10)°, respectively. These angles were used to calculate a parameter τ, which is defined as τ = (β - α)/60 (Addison et al., 1984). In the case of a perfectly tetragonal symmetry, this value is equal to zero, and for a perfectly trigonal symmetry it is 1.0. In the presented structure this value is 0.317, indicating that the polyhedron is about 70% rectangular pyramidal. The dihedral angle between the pyridine ring planes is 12.74 (8)°, which is much larger than that of our reported similar organic ligand (6.10 (15)°) (Wu, 2007). The average bond lengths with Co–N is 2.01 Å, and the Co–O bond lengths range from 1.943 (2) to 2.215 (3) Å. The bond lengths with Co–N are shorter than those of a nickel complex with 2,3'-dipyridylamine (Zhang, 2007).

In the title complex the H atoms of two NH groups of tpdaH2 act as donors to form intermolecular classical hydrogen bonds with O2 as acceptor atoms. Synchronously, the coordinated water molecule takes as donor and binds to the uncoordinated oxygen atom O2 of one of the carboxylate groups, and to the intramolecular acceptor atom O4. A weak intermolecular C—H···O contact completes the three-dimensional supramolecular network (Table 1 and Fig. 2).

Experimental

CoSO4(0.022 g, 0.011 mmol), L(0.035 g, 0.023 mmol), tpdaH2 (0.028 mg, 0.013 mmol) and NaOH(0.048 mmol,0.12 mmol), were added in a mixed solvent of benzene and methanol, the mixture was heated for six hours under reflux. During the process stirring and influx were required. The resultant was then filtered to give a pure solution which was infiltrated by diethyl ether freely in a closed vessel. Two weeks later some single crystals of the size suitable for X-ray diffraction analysis were obtained.

Refinement

All H atoms (except the water H atoms) were placed in calculated positions [Csp2—H and N—H = 0.93 Å and 0.86 Å, respectively, and Csp3—H = 0.96 Å] and they were refined using a riding model, with Uiso(H) = 1.2Ueq(C,N) and 1.5Ueq for the CH3 groups. The methyl H atoms were allowed to rotate (AFIX 137) to optimal positions. The water H atoms were found in a difference electron density map, they were refined using distance restraints (O—H = 0.900(0.015) Å), with Uiso(H) = 1.5Ueq(O).

Figures

Fig. 1.
The molecular structure of the title complex, showing 30% probability displacement ellipsoids and the atomic numbering scheme. H atoms are shown as spheres of arbitrary radii.
Fig. 2.
A view of the title complex, showing O—H···O and C—H···O hydrogen bonds that contribute to the construction of a three-dimensional network, with hydrogen bonds shown as dashed lines.

Crystal data

[Co(C4H5O2)2(C10H9N3)(H2O)]F000 = 868
Mr = 418.31Dx = 1.453 Mg m3
Monoclinic, P21/nMo Kα radiation λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 3448 reflections
a = 7.1113 (7) Åθ = 1.8–25.2º
b = 16.8303 (15) ŵ = 0.93 mm1
c = 15.9850 (14) ÅT = 298 (2) K
β = 91.291 (2)ºBlock, green
V = 1912.7 (3) Å30.28 × 0.22 × 0.19 mm
Z = 4

Data collection

Bruker APEXII area-detector diffractometer3448 independent reflections
Radiation source: fine-focus sealed tube2714 reflections with I > 2σ(I)
Monochromator: graphiteRint = 0.064
T = 298(2) Kθmax = 25.2º
[var phi] and ω scanθmin = 1.8º
Absorption correction: multi-scan(SADABS; Sheldrick, 2004)h = −7→8
Tmin = 0.781, Tmax = 0.843k = −20→20
9697 measured reflectionsl = −17→19

Refinement

Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.041H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.107  w = 1/[σ2(Fo2) + (0.0594P)2] where P = (Fo2 + 2Fc2)/3
S = 0.96(Δ/σ)max = 0.001
3448 reflectionsΔρmax = 0.34 e Å3
252 parametersΔρmin = −0.36 e Å3
2 restraintsExtinction correction: none
Primary atom site location: structure-invariant direct methods

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 (Å2)

xyzUiso*/Ueq
Co10.19268 (5)0.572818 (19)0.66967 (2)0.04151 (15)
O10.0960 (3)0.68420 (11)0.66984 (13)0.0643 (6)
O2−0.1802 (3)0.62901 (12)0.64366 (13)0.0706 (6)
O30.0968 (4)0.56293 (13)0.78204 (14)0.0757 (7)
O40.3464 (4)0.59240 (16)0.86323 (16)0.0932 (8)
O50.4820 (4)0.6001 (3)0.71532 (17)0.1196 (12)
H5B0.600 (3)0.605 (3)0.699 (3)0.179*
H5A0.468 (9)0.598 (3)0.7706 (11)0.179*
N10.2756 (3)0.58881 (12)0.55228 (14)0.0464 (5)
N210.2027 (3)0.45990 (12)0.50412 (13)0.0478 (5)
H210.17780.43340.45930.057*
N30.1831 (3)0.45414 (14)0.65122 (14)0.0491 (6)
C10.3429 (4)0.66182 (15)0.53387 (18)0.0544 (7)
H10.35670.69830.57730.065*
C20.3914 (4)0.68510 (16)0.45638 (19)0.0584 (8)
H20.43760.73590.44680.070*
C30.3700 (4)0.63086 (17)0.39168 (19)0.0594 (8)
H30.39860.64550.33730.071*
C40.3073 (4)0.55626 (16)0.40755 (17)0.0521 (7)
H40.29430.51920.36470.062*
C50.2626 (4)0.53625 (15)0.48998 (16)0.0422 (6)
C60.1751 (4)0.41803 (14)0.57678 (18)0.0453 (6)
C70.1415 (4)0.33680 (15)0.5682 (2)0.0560 (7)
H70.13210.31410.51520.067*
C80.1226 (5)0.29138 (18)0.6368 (2)0.0701 (9)
H80.09900.23720.63190.084*
C90.1388 (5)0.32670 (19)0.7145 (2)0.0775 (10)
H90.13070.29650.76300.093*
C100.1669 (5)0.40655 (19)0.7188 (2)0.0683 (9)
H100.17540.42990.77160.082*
C11−0.0798 (5)0.68817 (17)0.65826 (18)0.0563 (7)
C12−0.1694 (5)0.7671 (2)0.6603 (2)0.0754 (10)
H12−0.29970.76830.66440.090*
C13−0.0862 (5)0.83305 (18)0.6571 (2)0.0721 (9)
H130.04440.83150.65540.087*
C14−0.1757 (7)0.91429 (18)0.6557 (3)0.0959 (13)
H14A−0.12770.94500.70210.144*
H14B−0.30960.90900.65980.144*
H14C−0.14680.94070.60430.144*
C150.1754 (6)0.58252 (16)0.8511 (2)0.0631 (9)
C160.0514 (6)0.59332 (19)0.9235 (2)0.0745 (10)
H160.10900.60010.97580.089*
C17−0.1279 (6)0.59403 (19)0.9198 (2)0.0773 (10)
H17−0.18590.58720.86760.093*
C18−0.2546 (7)0.6052 (2)0.9948 (3)0.1070 (14)
H18A−0.34090.64800.98370.160*
H18B−0.17880.61751.04350.160*
H18C−0.32370.55721.00430.160*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
Co10.0445 (2)0.0376 (2)0.0428 (2)−0.00619 (15)0.00895 (16)−0.00716 (14)
O10.0614 (14)0.0476 (11)0.0846 (15)−0.0100 (10)0.0218 (11)−0.0174 (10)
O20.0703 (15)0.0618 (13)0.0802 (15)−0.0159 (12)0.0099 (12)−0.0233 (11)
O30.0850 (17)0.0835 (16)0.0595 (14)−0.0191 (13)0.0220 (12)−0.0124 (11)
O40.093 (2)0.118 (2)0.0690 (16)0.0104 (17)0.0052 (15)−0.0033 (14)
O50.0630 (17)0.228 (3)0.0674 (17)−0.041 (2)0.0048 (15)−0.017 (2)
N10.0458 (13)0.0382 (12)0.0554 (14)−0.0025 (10)0.0067 (11)−0.0051 (9)
N210.0585 (14)0.0348 (11)0.0503 (13)−0.0029 (10)0.0036 (11)−0.0050 (10)
N30.0517 (14)0.0442 (12)0.0516 (13)0.0028 (10)0.0041 (11)0.0049 (10)
C10.0578 (18)0.0402 (15)0.0656 (19)−0.0085 (13)0.0111 (15)−0.0056 (13)
C20.0615 (19)0.0414 (15)0.073 (2)−0.0018 (14)0.0145 (16)0.0057 (14)
C30.064 (2)0.0547 (18)0.0603 (18)0.0048 (15)0.0145 (15)0.0132 (14)
C40.0575 (18)0.0479 (16)0.0511 (16)0.0027 (13)0.0071 (14)−0.0032 (12)
C50.0385 (14)0.0350 (13)0.0532 (15)0.0028 (11)0.0041 (12)−0.0015 (12)
C60.0395 (15)0.0384 (14)0.0580 (17)0.0002 (11)0.0040 (12)0.0024 (12)
C70.0597 (19)0.0378 (15)0.0705 (19)−0.0017 (13)0.0034 (15)−0.0011 (13)
C80.070 (2)0.0445 (17)0.096 (3)0.0004 (16)0.0031 (19)0.0151 (17)
C90.095 (3)0.060 (2)0.078 (2)−0.0021 (19)0.006 (2)0.0249 (18)
C100.089 (3)0.0603 (19)0.0561 (19)−0.0026 (17)0.0034 (17)0.0115 (15)
C110.061 (2)0.0526 (17)0.0557 (17)−0.0032 (15)0.0156 (15)−0.0144 (14)
C120.067 (2)0.064 (2)0.096 (3)−0.0001 (18)0.0172 (19)−0.0176 (18)
C130.085 (3)0.059 (2)0.072 (2)−0.0010 (18)0.0074 (18)−0.0033 (16)
C140.133 (4)0.057 (2)0.098 (3)0.024 (2)0.007 (3)0.0036 (18)
C150.092 (3)0.0445 (17)0.054 (2)0.0105 (17)0.0142 (19)0.0013 (13)
C160.100 (3)0.064 (2)0.060 (2)0.008 (2)0.011 (2)0.0003 (15)
C170.096 (3)0.057 (2)0.080 (2)−0.005 (2)0.017 (2)−0.0024 (16)
C180.124 (4)0.090 (3)0.109 (3)−0.006 (3)0.056 (3)−0.014 (2)

Geometric parameters (Å, °)

Co1—O31.943 (2)C4—H40.9300
Co1—O11.997 (2)C6—C71.394 (3)
Co1—N11.998 (2)C7—C81.346 (4)
Co1—N32.020 (2)C7—H70.9300
Co1—O52.215 (3)C8—C91.379 (5)
O1—C111.261 (4)C8—H80.9300
O2—C111.244 (3)C9—C101.360 (4)
O3—C151.269 (4)C9—H90.9300
O4—C151.238 (5)C10—H100.9300
O5—H5B0.888 (15)C11—C121.474 (4)
O5—H5A0.892 (15)C12—C131.260 (4)
N1—C51.334 (3)C12—H120.9300
N1—C11.354 (3)C13—C141.508 (4)
N21—C51.374 (3)C13—H130.9300
N21—C61.376 (3)C14—H14A0.9600
N21—H210.8600C14—H14B0.9600
N3—C61.336 (3)C14—H14C0.9600
N3—C101.352 (4)C15—C161.483 (5)
C1—C21.351 (4)C16—C171.275 (5)
C1—H10.9300C16—H160.9300
C2—C31.385 (4)C17—C181.527 (5)
C2—H20.9300C17—H170.9300
C3—C41.358 (4)C18—H18A0.9600
C3—H30.9300C18—H18B0.9600
C4—C51.403 (4)C18—H18C0.9600
O3—Co1—O187.19 (9)C8—C7—C6119.8 (3)
O3—Co1—N1175.67 (10)C8—C7—H7120.1
O1—Co1—N189.07 (8)C6—C7—H7120.1
O3—Co1—N392.23 (9)C7—C8—C9118.8 (3)
O1—Co1—N3156.63 (9)C7—C8—H8120.6
N1—Co1—N390.34 (8)C9—C8—H8120.6
O3—Co1—O593.20 (10)C10—C9—C8118.7 (3)
O1—Co1—O597.04 (13)C10—C9—H9120.6
N1—Co1—O589.44 (10)C8—C9—H9120.6
N3—Co1—O5106.31 (13)N3—C10—C9124.0 (3)
C11—O1—Co1112.95 (18)N3—C10—H10118.0
C15—O3—Co1128.7 (2)C9—C10—H10118.0
Co1—O5—H5B143 (4)O2—C11—O1123.2 (3)
Co1—O5—H5A101 (4)O2—C11—C12118.6 (3)
H5B—O5—H5A115 (5)O1—C11—C12118.2 (3)
C5—N1—C1117.3 (2)C13—C12—C11126.1 (4)
C5—N1—Co1126.52 (17)C13—C12—H12116.9
C1—N1—Co1116.10 (18)C11—C12—H12116.9
C5—N21—C6131.9 (2)C12—C13—C14126.9 (4)
C5—N21—H21114.0C12—C13—H13116.5
C6—N21—H21114.0C14—C13—H13116.5
C6—N3—C10116.1 (3)C13—C14—H14A109.5
C6—N3—Co1125.48 (18)C13—C14—H14B109.5
C10—N3—Co1118.2 (2)H14A—C14—H14B109.5
C2—C1—N1124.1 (3)C13—C14—H14C109.5
C2—C1—H1117.9H14A—C14—H14C109.5
N1—C1—H1117.9H14B—C14—H14C109.5
C1—C2—C3117.9 (3)O4—C15—O3125.7 (3)
C1—C2—H2121.1O4—C15—C16117.4 (3)
C3—C2—H2121.1O3—C15—C16116.9 (4)
C4—C3—C2120.0 (3)C17—C16—C15125.2 (4)
C4—C3—H3120.0C17—C16—H16117.4
C2—C3—H3120.0C15—C16—H16117.4
C3—C4—C5118.7 (3)C16—C17—C18124.9 (4)
C3—C4—H4120.7C16—C17—H17117.6
C5—C4—H4120.7C18—C17—H17117.6
N1—C5—N21120.9 (2)C17—C18—H18A109.5
N1—C5—C4121.9 (2)C17—C18—H18B109.5
N21—C5—C4117.2 (2)H18A—C18—H18B109.5
N3—C6—N21121.0 (2)C17—C18—H18C109.5
N3—C6—C7122.5 (3)H18A—C18—H18C109.5
N21—C6—C7116.5 (3)H18B—C18—H18C109.5
O3—Co1—O1—C11−76.9 (2)Co1—N1—C5—C4173.3 (2)
N1—Co1—O1—C11100.9 (2)C6—N21—C5—N1−11.6 (4)
N3—Co1—O1—C1112.2 (3)C6—N21—C5—C4169.0 (3)
O5—Co1—O1—C11−169.8 (2)C3—C4—C5—N11.7 (4)
O1—Co1—O3—C15−84.9 (3)C3—C4—C5—N21−178.9 (3)
N3—Co1—O3—C15118.5 (3)C10—N3—C6—N21−175.6 (3)
O5—Co1—O3—C1512.0 (3)Co1—N3—C6—N2110.4 (4)
O1—Co1—N1—C5−140.0 (2)C10—N3—C6—C73.5 (4)
N3—Co1—N1—C516.6 (2)Co1—N3—C6—C7−170.5 (2)
O5—Co1—N1—C5123.0 (3)C5—N21—C6—N39.1 (4)
O1—Co1—N1—C136.6 (2)C5—N21—C6—C7−170.0 (3)
N3—Co1—N1—C1−166.8 (2)N3—C6—C7—C8−2.5 (5)
O5—Co1—N1—C1−60.5 (2)N21—C6—C7—C8176.7 (3)
O3—Co1—N3—C6157.8 (2)C6—C7—C8—C9−0.6 (5)
O1—Co1—N3—C669.7 (3)C7—C8—C9—C102.2 (5)
N1—Co1—N3—C6−18.8 (2)C6—N3—C10—C9−1.8 (5)
O5—Co1—N3—C6−108.3 (2)Co1—N3—C10—C9172.7 (3)
O3—Co1—N3—C10−16.1 (3)C8—C9—C10—N3−1.1 (6)
O1—Co1—N3—C10−104.2 (3)Co1—O1—C11—O2−3.8 (4)
N1—Co1—N3—C10167.4 (2)Co1—O1—C11—C12177.7 (2)
O5—Co1—N3—C1077.8 (3)O2—C11—C12—C13−164.5 (3)
C5—N1—C1—C22.3 (4)O1—C11—C12—C1314.1 (5)
Co1—N1—C1—C2−174.6 (2)C11—C12—C13—C14177.4 (3)
N1—C1—C2—C30.3 (5)Co1—O3—C15—O4−20.5 (5)
C1—C2—C3—C4−1.9 (5)Co1—O3—C15—C16160.5 (2)
C2—C3—C4—C50.9 (4)O4—C15—C16—C17171.8 (3)
C1—N1—C5—N21177.4 (2)O3—C15—C16—C17−9.0 (5)
Co1—N1—C5—N21−6.1 (4)C15—C16—C17—C18−180.0 (3)
C1—N1—C5—C4−3.2 (4)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
O5—H5A···O40.892 (15)1.73 (3)2.577 (4)156 (6)
O5—H5B···O2i0.888 (15)1.86 (2)2.729 (3)166 (5)
N21—H21···O2ii0.861.952.798 (3)168
C8—H8···O4iii0.932.473.356 (4)160

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

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: SI2078).

References

  • Addison, A. W., Rao, T. N., Reedijk, J., van Rijn, J. & Verschoor, G. C. (1984). J. Chem. Soc. Dalton Trans. pp. 1349–1356.
  • Bruker (2004). APEX2 and SMART Bruker AXS Inc., Madison, Wisconsin, USA.
  • Chang, H.-C., Li, J.-T., Wang, C.-C., Lin, T.-W., Lee, H.-C., Lee, G.-H. & Peng, S.-M. (1999). Eur. J. Inorg. Chem. pp. 1243–1251.
  • Peng, S.-M., Wang, C.-C., Jang, Y.-L., Chen, Y.-H., Li, F.-Y., Mou, C.-Y. & Leung, M.-K. (2000). J. Magn. Magn. Mater.209, 80–83.
  • Sheldrick, G. M. (2004). SADABS University of Göttingen, Germany.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Wu, J. (2007). Acta Cryst. E63, o4413.
  • Xu, C., Qiao, H.-B., Mao, H.-Y., Zhang, H.-Y., Wu, Q.-A., Liu, H.-L. & Zhu, Y. (2004). J. Zheng Zhou Univ.36, 67–70.
  • Zhang, L. (2007). Acta Cryst. E63, m2950.

Articles from Acta Crystallographica Section E: Structure Reports Online are provided here courtesy of International Union of Crystallography