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Acta Crystallogr Sect E Struct Rep Online. 2010 July 1; 66(Pt 7): m843.
Published online 2010 June 26. doi:  10.1107/S1600536810023767
PMCID: PMC3006931

Hexaaqua­chromium(III) pyridine-2,4,6-tricarboxyl­ate dihydrate

Abstract

The chromium(III) atom in the title salt, [Cr(H2O)6](C8H2NO6)·2H2O, has an octa­hedral coordination geometry. In the crystal, the cation, anion and uncoordinated water mol­ecules, both of which are disordered over two positions in a 1:1 ratio, are linked by O—H(...)O hydrogen bonds.

Related literature

For the crystal structure of hexa­aqua­chromium(III) acetate, see: Eshel & Bino (2001 [triangle]). For the synthesis of 2,4,6-pyridine­tricarb­oxy­lic acid, see: Syper et al. (1980 [triangle]).

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Object name is e-66-0m843-scheme1.jpg

Experimental

Crystal data

  • [Cr(H2O)6](C8H2NO6)·2H2O
  • M r = 404.23
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-66-0m843-efi1.jpg
  • a = 7.8610 (3) Å
  • b = 16.9269 (5) Å
  • c = 11.6823 (4) Å
  • β = 100.649 (1)°
  • V = 1527.70 (9) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.83 mm−1
  • T = 293 K
  • 0.11 × 0.07 × 0.05 mm

Data collection

  • Bruker Kappa APEXII diffractometer
  • Absorption correction: multi-scan (SADABS; Sheldrick, 1996 [triangle]) T min = 0.915, T max = 0.960
  • 14299 measured reflections
  • 3507 independent reflections
  • 2486 reflections with I > 2σ(I)
  • R int = 0.060

Refinement

  • R[F 2 > 2σ(F 2)] = 0.050
  • wR(F 2) = 0.152
  • S = 0.98
  • 3507 reflections
  • 235 parameters
  • H-atom parameters constrained
  • Δρmax = 0.64 e Å−3
  • Δρmin = −0.54 e Å−3

Data collection: APEX2 (Bruker, 2009 [triangle]); cell refinement: SAINT (Bruker, 2009 [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: X-SEED (Barbour, 2001 [triangle]); software used to prepare material for publication: publCIF (Westrip, 2010 [triangle]).

Table 1
Selected bond lengths (Å)
Table 2
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810023767/jh2167sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810023767/jh2167Isup2.hkl

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

Acknowledgments

We thank GC University and the University of Malaya for supporting this study.

supplementary crystallographic information

Comment

The pyridine-2,4,6-tricarboxylate anion is a multifunctional ligand having nitrogen-donor as well as several oxygen-donor sites. Chelation to chromium is expected. However, its reaction with the chromium(III) ion gave instead a salt in which the cation is coordinated by water molecules only (Scheme I, Fig. 1). Interestingly, the only report of a hexaaquachromium carboxylate crystal structure appears to be that of the acetate, an industrially important chemical (Eshel & Bino, 2001). There are no lattice water molecules in the crystal structure.

Experimental

Pyridine-2,4,6-tricarboxylicacid was prepared by the oxidation of 2,4,6-trimethylpyridine with potassium permanganate(Syper et al., 1980). Chromium chloride hexahydrate (0.03 g, 0.13 mmol) was dissolved in water (10 ml) and this was mixed with the acid (0.11 g, 0.50 mmol) dissolved in water (10 ml). The solution was briefly heated and then set aside for the growth of light purple crystals over several days.

Refinement

Carbon-bound H-atoms were placed in calculated positions (C–H 0.93 Å) and were included in the refinement in the riding model approximation, with U(H) set to 1.2 to 1.5U(C).

The two water moleces are both disordered over two positions that, from symmetry considerations, must be in a 1:1 ratio. The water H-atoms were placed in chemically sensible positions on the basis of hydrogen bonding but were not refined (O–H 0.84 Å).

Figures

Fig. 1.
Thermal ellipsoid plot (Barbour, 2001) of [Cr(H2O)6](C8H2NO6).2H2O at the 50% probability level; hydrogen atoms are drawn as spheres of arbitrary radius.

Crystal data

[Cr(H2O)6](C8H2NO6)·2H2OF(000) = 836
Mr = 404.23Dx = 1.758 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 2431 reflections
a = 7.8610 (3) Åθ = 2.6–24.6°
b = 16.9269 (5) ŵ = 0.83 mm1
c = 11.6823 (4) ÅT = 293 K
β = 100.649 (1)°Prism, purple
V = 1527.70 (9) Å30.11 × 0.07 × 0.05 mm
Z = 4

Data collection

Bruker Kappa APEXII diffractometer3507 independent reflections
Radiation source: fine-focus sealed tube2486 reflections with I > 2σ(I)
graphiteRint = 0.060
[var phi] and ω scansθmax = 27.5°, θmin = 2.1°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)h = −10→10
Tmin = 0.915, Tmax = 0.960k = −21→21
14299 measured reflectionsl = −15→14

Refinement

Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.050Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.152H-atom parameters constrained
S = 0.98w = 1/[σ2(Fo2) + (0.0867P)2 + 0.7924P] where P = (Fo2 + 2Fc2)/3
3507 reflections(Δ/σ)max = 0.001
235 parametersΔρmax = 0.64 e Å3
0 restraintsΔρmin = −0.54 e Å3

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)

xyzUiso*/UeqOcc. (<1)
Cr10.54053 (7)0.15648 (3)0.39171 (4)0.02536 (19)
O10.4502 (3)0.36658 (14)0.53968 (19)0.0282 (6)
O20.3235 (4)0.37338 (16)0.3540 (2)0.0408 (7)
O3−0.0565 (4)0.6012 (2)0.2197 (2)0.0684 (11)
O4−0.1258 (3)0.68517 (15)0.3489 (2)0.0386 (7)
O50.2467 (3)0.66964 (13)0.7612 (2)0.0307 (6)
O60.3712 (4)0.55364 (15)0.8057 (2)0.0395 (7)
O1w0.5769 (4)0.22599 (15)0.5287 (2)0.0506 (9)
H110.55170.27400.52680.076*
H120.64080.21480.59210.076*
O2w0.4111 (3)0.23657 (14)0.29037 (19)0.0293 (6)
H210.39120.27860.32350.044*
H220.31940.22040.24830.044*
O3w0.5096 (3)0.08414 (13)0.26061 (19)0.0313 (6)
H310.47650.10510.19540.047*
H320.44700.04480.26750.047*
O4w0.6735 (4)0.07453 (15)0.4853 (2)0.0419 (7)
H410.65140.05800.54870.063*
H420.73680.04180.45920.063*
O5w0.7577 (3)0.19559 (15)0.3495 (2)0.0378 (6)
H510.79380.15650.31700.057*
H520.82170.20300.41450.057*
O6w0.3271 (4)0.11722 (18)0.4342 (2)0.0448 (7)
H610.24180.10820.38100.067*
H620.29970.10850.49910.067*
N10.3130 (3)0.50687 (15)0.5851 (2)0.0211 (6)
C10.3554 (4)0.39985 (19)0.4552 (3)0.0236 (7)
C20.2751 (4)0.47842 (18)0.4768 (3)0.0216 (7)
C30.1641 (4)0.5174 (2)0.3883 (3)0.0245 (7)
H30.14170.49680.31320.029*
C40.0871 (4)0.58741 (19)0.4134 (3)0.0234 (7)
C50.1272 (4)0.61709 (19)0.5264 (3)0.0232 (7)
H50.07780.66390.54620.028*
C60.2426 (4)0.57513 (18)0.6089 (3)0.0215 (7)
C70.2909 (4)0.60201 (19)0.7341 (3)0.0250 (7)
C8−0.0413 (5)0.6290 (2)0.3203 (3)0.0308 (8)
O7w0.2400 (7)0.4369 (3)0.1235 (4)0.0362 (12)0.50
H710.13490.43210.12750.054*0.50
H720.30620.42470.18590.054*0.50
O8w−0.0236 (8)0.3188 (3)0.0680 (5)0.0536 (16)0.50
H81−0.08880.32360.11710.080*0.50
H820.02660.27510.08140.080*0.50
O7w'0.1532 (10)0.3598 (4)0.1183 (6)0.0642 (19)0.50
H730.20430.37160.18570.096*0.50
H740.13740.31070.11590.096*0.50
O8w'0.0632 (8)0.5126 (4)0.0562 (5)0.0511 (15)0.50
H830.02620.54020.10620.077*0.50
H840.08550.46670.08190.077*0.50

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
Cr10.0390 (3)0.0177 (3)0.0159 (3)0.0005 (2)−0.0040 (2)−0.0007 (2)
O10.0399 (14)0.0225 (12)0.0204 (12)0.0080 (10)0.0004 (10)−0.0002 (9)
O20.0606 (18)0.0325 (14)0.0237 (13)0.0142 (13)−0.0072 (12)−0.0098 (11)
O30.078 (2)0.105 (3)0.0187 (14)0.061 (2)0.0003 (14)0.0002 (15)
O40.0399 (15)0.0322 (14)0.0374 (15)0.0130 (12)−0.0090 (12)−0.0016 (12)
O50.0469 (16)0.0169 (12)0.0250 (12)0.0030 (10)−0.0022 (11)−0.0040 (9)
O60.0665 (19)0.0258 (13)0.0215 (12)0.0134 (12)−0.0041 (12)−0.0021 (10)
O1w0.094 (2)0.0261 (14)0.0208 (13)0.0157 (14)−0.0177 (14)−0.0072 (11)
O2w0.0361 (14)0.0213 (12)0.0255 (12)0.0018 (10)−0.0077 (10)−0.0021 (10)
O3w0.0541 (16)0.0202 (12)0.0169 (11)−0.0106 (11)−0.0007 (11)−0.0009 (9)
O4w0.074 (2)0.0245 (14)0.0222 (12)0.0123 (13)−0.0027 (13)0.0049 (10)
O5w0.0334 (14)0.0268 (14)0.0489 (16)−0.0008 (11)−0.0039 (12)−0.0021 (12)
O6w0.0473 (17)0.061 (2)0.0250 (13)−0.0072 (14)0.0043 (12)0.0031 (13)
N10.0249 (14)0.0167 (13)0.0201 (13)−0.0004 (10)0.0002 (11)0.0011 (10)
C10.0268 (17)0.0210 (16)0.0221 (16)−0.0021 (13)0.0022 (13)−0.0014 (13)
C20.0234 (16)0.0192 (16)0.0207 (15)−0.0014 (13)0.0005 (13)0.0025 (12)
C30.0247 (17)0.0285 (18)0.0186 (15)0.0015 (14)−0.0001 (13)−0.0018 (13)
C40.0233 (16)0.0245 (17)0.0212 (16)−0.0009 (13)0.0013 (13)0.0063 (13)
C50.0235 (16)0.0195 (16)0.0262 (16)0.0015 (13)0.0032 (13)−0.0005 (13)
C60.0232 (16)0.0190 (16)0.0210 (16)−0.0056 (12)0.0009 (13)0.0001 (12)
C70.0310 (18)0.0204 (16)0.0221 (16)−0.0020 (14)0.0012 (13)−0.0009 (13)
C80.0286 (18)0.038 (2)0.0249 (18)0.0067 (15)0.0019 (14)0.0095 (15)
O7w0.038 (3)0.041 (3)0.027 (3)−0.005 (2)0.001 (2)0.002 (2)
O8w0.052 (4)0.036 (3)0.063 (4)0.005 (3)−0.016 (3)0.002 (3)
O7w'0.095 (6)0.051 (4)0.046 (4)0.003 (4)0.012 (4)0.008 (3)
O8w'0.059 (4)0.048 (4)0.050 (3)0.004 (3)0.019 (3)−0.006 (3)

Geometric parameters (Å, °)

Cr1—O1w1.964 (2)O6w—H610.8391
Cr1—O2w1.957 (2)O6w—H620.8385
Cr1—O3w1.941 (2)N1—C61.332 (4)
Cr1—O4w1.947 (2)N1—C21.335 (4)
Cr1—O5w1.977 (3)C1—C21.513 (5)
Cr1—O6w1.952 (3)C2—C31.390 (4)
O1—C11.255 (4)C3—C41.386 (5)
O2—C11.246 (4)C3—H30.9300
O3—C81.251 (5)C4—C51.392 (4)
O4—C81.240 (4)C4—C81.514 (4)
O5—C71.254 (4)C5—C61.391 (4)
O6—C71.254 (4)C5—H50.9300
O1w—H110.8363C6—C71.512 (4)
O1w—H120.8369O7w—H710.8401
O2w—H210.8381O7w—H720.8400
O2w—H220.8398O8w—H810.8400
O3w—H310.8370O8w—H820.8400
O3w—H320.8395O7w'—H730.8400
O4w—H410.8393O7w'—H740.8399
O4w—H420.8390O8w'—H830.8400
O5w—H510.8387O8w'—H840.8400
O5w—H520.8387
O3w—Cr1—O4w88.26 (11)Cr1—O6w—H62131.7
O3w—Cr1—O6w89.85 (11)H61—O6w—H62109.5
O4w—Cr1—O6w90.70 (13)C6—N1—C2118.8 (3)
O3w—Cr1—O2w89.10 (10)O2—C1—O1124.8 (3)
O4w—Cr1—O2w176.95 (11)O2—C1—C2117.2 (3)
O6w—Cr1—O2w90.82 (11)O1—C1—C2118.0 (3)
O3w—Cr1—O1w177.52 (10)N1—C2—C3122.2 (3)
O4w—Cr1—O1w89.26 (11)N1—C2—C1116.6 (3)
O6w—Cr1—O1w89.96 (13)C3—C2—C1121.2 (3)
O2w—Cr1—O1w93.38 (10)C4—C3—C2119.2 (3)
O3w—Cr1—O5w90.16 (11)C4—C3—H3120.4
O4w—Cr1—O5w88.84 (12)C2—C3—H3120.4
O6w—Cr1—O5w179.54 (12)C3—C4—C5118.6 (3)
O2w—Cr1—O5w89.63 (10)C3—C4—C8120.3 (3)
O1w—Cr1—O5w90.00 (13)C5—C4—C8121.1 (3)
Cr1—O1w—H11124.3C6—C5—C4118.5 (3)
Cr1—O1w—H12124.0C6—C5—H5120.8
H11—O1w—H12110.1C4—C5—H5120.8
Cr1—O2w—H21115.4N1—C6—C5122.8 (3)
Cr1—O2w—H22115.0N1—C6—C7115.0 (3)
H21—O2w—H22109.5C5—C6—C7122.1 (3)
Cr1—O3w—H31115.0O5—C7—O6123.8 (3)
Cr1—O3w—H32114.5O5—C7—C6119.1 (3)
H31—O3w—H32109.5O6—C7—C6117.0 (3)
Cr1—O4w—H41123.8O4—C8—O3125.3 (3)
Cr1—O4w—H42124.0O4—C8—C4118.8 (3)
H41—O4w—H42109.5O3—C8—C4115.8 (3)
Cr1—O5w—H51103.2H71—O7w—H72112.7
Cr1—O5w—H52103.1H81—O8w—H82106.5
H51—O5w—H52109.4H73—O7w'—H74108.0
Cr1—O6w—H61118.7H83—O8w'—H84110.0
C6—N1—C2—C3−0.3 (5)C2—N1—C6—C51.9 (5)
C6—N1—C2—C1−178.7 (3)C2—N1—C6—C7179.1 (3)
O2—C1—C2—N1−178.7 (3)C4—C5—C6—N1−1.7 (5)
O1—C1—C2—N10.5 (5)C4—C5—C6—C7−178.8 (3)
O2—C1—C2—C32.9 (5)N1—C6—C7—O5171.9 (3)
O1—C1—C2—C3−177.8 (3)C5—C6—C7—O5−10.8 (5)
N1—C2—C3—C4−1.3 (5)N1—C6—C7—O6−9.4 (5)
C1—C2—C3—C4177.0 (3)C5—C6—C7—O6167.8 (3)
C2—C3—C4—C51.4 (5)C3—C4—C8—O4170.1 (3)
C2—C3—C4—C8−176.9 (3)C5—C4—C8—O4−8.2 (5)
C3—C4—C5—C60.0 (5)C3—C4—C8—O3−7.7 (5)
C8—C4—C5—C6178.3 (3)C5—C4—C8—O3174.0 (4)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
O1w—H11···O10.841.782.592 (3)164
O1w—H12···O5i0.841.932.757 (3)167
O2w—H21···O20.841.752.565 (3)164
O2w—H22···O4ii0.841.822.662 (3)177
O3w—H31···O1iii0.841.862.670 (3)164
O3w—H32···O6iii0.841.852.667 (3)163
O4w—H41···O6i0.841.742.555 (4)162
O4w—H42···O7wiv0.842.052.798 (6)149
O4w—H42···O8w'iv0.841.692.448 (7)149
O5w—H51···O3iv0.842.383.070 (5)140
O5w—H52···O8wv0.842.012.812 (6)161
O6w—H61···O3ii0.841.702.533 (4)172
O6w—H62···O7wvi0.841.782.600 (6)165
O6w—H62···O7w'vi0.842.042.780 (7)148
O7w—H72···O20.842.132.860 (6)146
O7w—H71···O8w0.842.322.865 (8)123
O8w—H82···O4ii0.841.832.649 (6)164
O8w—H81···O5vii0.842.062.896 (8)178
O7w'—H73···O20.842.022.840 (7)167
O7w'—H74···O4ii0.842.172.993 (7)167
O8w'—H83···O30.841.892.729 (6)179
O8w'—H84···O7w'0.841.912.744 (9)171

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

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: JH2167).

References

  • Barbour, L. J. (2001). J. Supramol. Chem.1, 189–191.
  • Bruker (2009). APEX2 and SAINT Bruker AXS Inc., Madison, Wisconsin, USA.
  • Eshel, M. & Bino, A. (2001). Inorg. Chim. Acta, 320, 127–132.
  • Sheldrick, G. M. (1996). SADABS University of Göttingen, Germany.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Syper, L., Kloc, K. & Mlochowski, J. (1980). Tetrahedron, 36, 123–129.
  • Westrip, S. P. (2010). J. Appl. Cryst.43 Submitted.

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