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Acta Cryst. (2009). E65, m620    [ doi:10.1107/S1600536809015049 ]

Hexaaquacadmium(II) dipicrate monohydrate

S. Natarajan, K. Moovendaran, S. A. M. B. Dhas, J. Suresh and P. L. N. Lakshman

Abstract top

In the structure of the title compound, [Cd(H2O)6](C6H2N3O7)2·H2O, the CdII ion is located on an inversion center and is coordinated by six water molecules in an octahedral geometry. The picrate anions have no coordination interactions with the CdII ion. The three nitro groups are twisted away from the attached benzene ring, making dihedral angles of 17.89 (3), 27.94 (4) and 13.65 (3)°. There are numerous O-H...O hydrogen bonds in the crystal structure, involving coordinated and uncoordinated water molecules.

Comment top

Picric acid forms salts with many organic and metallic cations (Gartland et al., 1974). Crystal structures have been reported for isomorphous NH4 and K picrates (Maartmann-Moe, 1969), thallium picrate (Herbstein et al., 1977), recently for manganese picrate (Liu et al., 2008) and zinc picrate (Natarajan et al., 2008). This work is part of a systematic investigation on the structures of the metal complexes of picric acid.

In the structure of the title compound, each CdII ion is coordinated by the O atoms of six water molecules (Fig. 1). The Cd—O distances range from 2.219 (3)Å to 2.299 (3)Å. The coordination polyhedra around the CdII ion can be described as a distorted octahedron. The picrate anion adopts a keto form with a C6—O7 bond distance of 1.250 (4)Å; the C1—C6 [1.444 (5)Å] and C5—C6 [1.454 (5)Å] bond distances are longer than the other C—C bond lengths of the benzene ring. The three nitro groups are twisted out of the attached benzene ring by 17.89 (3)° [N1/O1/O2], 27.94 (4)° [N2/O5/O6] and 13.65 (3)° [N3/O3/O4]. The twisting of these nitro groups may be attributed to the O—H···O hydrogen bonding interactions taking place between water and picrate O atoms. The C5—C6—C1 bond angle (111.8 (3)°) is smaller than the corresponding angle in picric acid (116.4 (5)°; Yang et al., 2001). The packing of the molecules is governed by the large number of O—H···O hydrogen bonds (Table 1).

Related literature top

Picric acid forms salts with many organic and metallic cations, see: Gartland et al. (1974). Crystal structures have been reported for isomorphous NH4 and K picrates (Maartmann-Moe, 1969), thallium picrate (Herbstein et al., 1977), manganese picrate (Liu et al., 2008) and zinc picrate (Natarajan et al., 2008). For bond angles in picric acid, see: Yang et al. (2001).

Experimental top

Colorless needle-shaped single crystals of the title compound were grown from a saturated aqueous solution containing picric acid and cadmium chloride in a 1:1 stoichiometric ratio.

Refinement top

O-bound H atoms were located in a difference Fourier map and their positional parameters were refined, with Uiso(H) = 1.5Ueq(O). C-bound H atoms were placed at calculated positions and allowed to ride on their carrier atoms, with C—H = 0.93 Å, and Uiso = 1.2Ueq(C).

Computing details top

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell refinement: CAD-4 EXPRESS (Enraf–Nonius, 1994); data reduction: XCAD4 (Harms & Wocadlo, 1996); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound, showing 30% probability displacement ellipsoids and the atom-numbering scheme.
Hexaaquacadmium(II) dipicrate monohydrate top
Crystal data top
[Cd(H2O)6](C6H2N3O7)2·H2OF000 = 1432
Mr = 712.75Dx = 1.937 Mg m−3
Orthorhombic, PbnbMo Kα radiation
λ = 0.71073 Å
Hall symbol: -P 2bc 2abCell parameters from 25 reflections
a = 7.2823 (2) Åθ = 3–25º
b = 13.2249 (4) ŵ = 1.01 mm−1
c = 25.3798 (8) ÅT = 293 K
V = 2444.27 (13) Å3Block, colourless
Z = 40.18 × 0.15 × 0.11 mm
Data collection top
Nonius MACH-3
diffractometer		Rint = 0.010
Radiation source: fine-focus sealed tubeθmax = 25.0º
Monochromator: graphiteθmin = 2.9º
T = 293 Kh = 0→8
ω–2θ scansk = 0→15
Absorption correction: ψ scan
(North et al., 1968)		l = −1→30
Tmin = 0.834, Tmax = 0.8952 standard reflections
2247 measured reflections every 60 min
2142 independent reflections intensity decay: none
1513 reflections with I > 2σ(I)
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.027H atoms treated by a mixture of
independent and constrained refinement
wR(F2) = 0.084  w = 1/[σ2(Fo2) + (0.0314P)2 + 3.7212P]
where P = (Fo2 + 2Fc2)/3
S = 1.16(Δ/σ)max < 0.001
2142 reflectionsΔρmax = 0.54 e Å−3
220 parametersΔρmin = −0.38 e Å−3
2 restraintsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0029 (2)
Crystal data top
[Cd(H2O)6](C6H2N3O7)2·H2OV = 2444.27 (13) Å3
Mr = 712.75Z = 4
Orthorhombic, PbnbMo Kα
a = 7.2823 (2) ŵ = 1.01 mm−1
b = 13.2249 (4) ÅT = 293 K
c = 25.3798 (8) Å0.18 × 0.15 × 0.11 mm
Data collection top
Nonius MACH-3
diffractometer		1513 reflections with I > 2σ(I)
Absorption correction: ψ scan
(North et al., 1968)		Rint = 0.010
Tmin = 0.834, Tmax = 0.8952 standard reflections
2247 measured reflections every 60 min
2142 independent reflections intensity decay: none
Refinement top
R[F2 > 2σ(F2)] = 0.0272 restraints
wR(F2) = 0.084H atoms treated by a mixture of
independent and constrained refinement
S = 1.16Δρmax = 0.54 e Å−3
2142 reflectionsΔρmin = −0.38 e Å−3
220 parameters
Special details top

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) top
xyzUiso*/Ueq
Cd0.00000.50000.00000.03236 (15)
O110.1978 (4)0.5718 (3)0.05990 (11)0.0393 (7)
O10.4465 (5)0.2509 (2)0.11321 (10)0.0581 (9)
O50.6784 (4)0.6893 (2)0.18800 (10)0.0430 (7)
O70.4862 (4)0.4516 (2)0.10554 (9)0.0390 (7)
O20.3391 (4)0.1969 (2)0.18648 (10)0.0435 (7)
O60.5121 (4)0.6525 (2)0.12019 (9)0.0415 (7)
O40.5772 (5)0.5100 (2)0.34801 (10)0.0463 (7)
N30.5092 (4)0.4393 (2)0.32448 (11)0.0297 (7)
O8−0.0269 (6)0.3512 (2)0.04266 (13)0.0609 (10)
O90.2500 (5)0.4420 (3)−0.03995 (13)0.0554 (9)
O30.4428 (4)0.3650 (2)0.34660 (10)0.0430 (7)
O100.5209 (5)0.3302 (2)0.00923 (13)0.0457 (8)
N20.5770 (4)0.6320 (2)0.16356 (11)0.0301 (7)
C40.5398 (5)0.5320 (3)0.24176 (14)0.0280 (8)
H40.56940.58980.26080.034*
N10.4123 (5)0.2622 (2)0.15992 (11)0.0336 (7)
C20.4606 (5)0.3554 (3)0.23989 (13)0.0290 (8)
H20.43360.29580.25770.035*
C30.5024 (5)0.4423 (3)0.26750 (12)0.0279 (8)
C60.4911 (5)0.4481 (3)0.15474 (13)0.0272 (7)
C10.4592 (5)0.3581 (3)0.18566 (13)0.0286 (8)
C50.5328 (5)0.5350 (3)0.18776 (13)0.0258 (8)
H8W0.517 (8)0.337 (5)0.043 (3)0.09 (2)*
H1W0.172 (8)0.607 (4)0.081 (2)0.07 (2)*
H3W−0.009 (7)0.350 (4)0.074 (2)0.065 (16)*
H5W0.302 (7)0.475 (4)−0.0643 (19)0.063 (16)*
H2W0.276 (8)0.536 (4)0.0788 (19)0.067 (17)*
H6W0.317 (5)0.402 (3)−0.0255 (15)0.045 (13)*
H9W0.612 (8)0.349 (4)−0.0004 (19)0.06 (2)*
H4W−0.007 (7)0.297 (2)0.0302 (19)0.065 (17)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cd0.0329 (2)0.0278 (2)0.0363 (2)0.00038 (17)−0.00396 (18)−0.00312 (16)
O110.0433 (17)0.0432 (17)0.0314 (14)0.0014 (14)−0.0075 (13)−0.0079 (14)
O10.109 (3)0.0353 (16)0.0295 (15)−0.0106 (17)0.0057 (16)−0.0099 (12)
O50.0509 (18)0.0310 (15)0.0470 (15)−0.0088 (13)−0.0122 (14)0.0002 (13)
O70.0649 (19)0.0298 (13)0.0221 (12)0.0003 (13)−0.0042 (13)−0.0018 (11)
O20.0614 (19)0.0269 (15)0.0423 (15)−0.0055 (14)−0.0051 (14)0.0004 (12)
O60.066 (2)0.0324 (14)0.0260 (13)−0.0018 (14)−0.0045 (13)0.0039 (11)
O40.0609 (18)0.0510 (18)0.0270 (13)−0.0151 (16)−0.0020 (13)−0.0087 (13)
N30.0297 (16)0.0375 (18)0.0220 (14)−0.0003 (15)−0.0011 (14)−0.0031 (13)
O80.118 (3)0.0330 (16)0.0312 (16)0.004 (2)−0.0078 (19)0.0040 (13)
O90.058 (2)0.063 (2)0.0451 (17)0.0244 (19)0.0174 (17)0.0129 (17)
O30.0582 (18)0.0428 (16)0.0281 (13)−0.0079 (15)−0.0016 (13)0.0068 (12)
O100.051 (2)0.0435 (17)0.0426 (19)−0.0074 (16)0.0016 (16)−0.0024 (14)
N20.0346 (16)0.0271 (16)0.0286 (15)0.0041 (14)0.0019 (14)−0.0006 (13)
C40.026 (2)0.0300 (17)0.0278 (18)0.0014 (15)−0.0025 (14)−0.0070 (15)
N10.0434 (19)0.0268 (16)0.0306 (16)0.0010 (15)−0.0037 (15)−0.0016 (14)
C20.033 (2)0.0288 (17)0.0255 (18)0.0020 (16)−0.0023 (14)0.0026 (14)
C30.0279 (17)0.0334 (19)0.0225 (16)0.0027 (16)−0.0020 (16)−0.0017 (14)
C60.0287 (18)0.0272 (17)0.0256 (17)0.0017 (15)−0.0010 (16)−0.0022 (14)
C10.035 (2)0.0238 (17)0.0268 (17)0.0012 (16)−0.0043 (15)−0.0030 (14)
C50.028 (2)0.0239 (16)0.0256 (16)0.0022 (14)−0.0013 (14)0.0004 (14)
Geometric parameters (Å, °) top
Cd—O9i2.221 (3)O8—H3W0.79 (5)
Cd—O92.221 (3)O8—H4W0.80 (2)
Cd—O8i2.255 (3)O9—H5W0.85 (5)
Cd—O82.255 (3)O9—H6W0.81 (4)
Cd—O112.299 (3)O10—H8W0.87 (7)
Cd—O11i2.299 (3)O10—H9W0.75 (6)
O11—H1W0.73 (5)N2—C51.459 (5)
O11—H2W0.88 (6)C4—C51.372 (5)
O1—N11.220 (4)C4—C31.382 (5)
O5—N21.226 (4)C4—H40.9300
O7—C61.250 (4)N1—C11.467 (4)
O2—N11.219 (4)C2—C11.377 (5)
O6—N21.228 (4)C2—C31.380 (5)
O4—N31.216 (4)C2—H20.9300
N3—O31.231 (4)C6—C11.444 (5)
N3—C31.447 (4)C6—C51.454 (5)
O9i—Cd—O9180.00 (15)H5W—O9—H6W113 (5)
O9i—Cd—O8i89.37 (14)H8W—O10—H9W108 (5)
O9—Cd—O8i90.63 (14)O5—N2—O6123.3 (3)
O9i—Cd—O890.63 (14)O5—N2—C5117.6 (3)
O9—Cd—O889.37 (14)O6—N2—C5119.1 (3)
O8i—Cd—O8180.00 (16)C5—C4—C3119.3 (3)
O9i—Cd—O1193.97 (13)C5—C4—H4120.4
O9—Cd—O1186.03 (13)C3—C4—H4120.4
O8i—Cd—O1184.41 (13)O2—N1—O1122.7 (3)
O8—Cd—O1195.59 (13)O2—N1—C1117.9 (3)
O9i—Cd—O11i86.03 (13)O1—N1—C1119.4 (3)
O9—Cd—O11i93.97 (13)C1—C2—C3119.2 (3)
O8i—Cd—O11i95.59 (13)C1—C2—H2120.4
O8—Cd—O11i84.41 (13)C3—C2—H2120.4
O11—Cd—O11i180.00 (11)C2—C3—C4121.2 (3)
Cd—O11—H1W126 (5)C2—C3—N3119.5 (3)
Cd—O11—H2W123 (3)C4—C3—N3119.3 (3)
H1W—O11—H2W96 (5)O7—C6—C1124.7 (3)
O4—N3—O3123.4 (3)O7—C6—C5123.5 (3)
O4—N3—C3118.9 (3)C1—C6—C5111.8 (3)
O3—N3—C3117.7 (3)C2—C1—C6124.3 (3)
Cd—O8—H3W118 (4)C2—C1—N1115.1 (3)
Cd—O8—H4W126 (4)C6—C1—N1120.5 (3)
H3W—O8—H4W110 (5)C4—C5—C6124.1 (3)
Cd—O9—H5W122 (3)C4—C5—N2115.9 (3)
Cd—O9—H6W121 (3)C6—C5—N2119.9 (3)
C1—C2—C3—C41.1 (6)O2—N1—C1—C216.5 (5)
C1—C2—C3—N3−178.2 (3)O1—N1—C1—C2−163.9 (4)
C5—C4—C3—C20.8 (6)O2—N1—C1—C6−160.4 (3)
C5—C4—C3—N3−179.8 (3)O1—N1—C1—C619.2 (5)
O4—N3—C3—C2167.0 (3)C3—C4—C5—C6−1.1 (5)
O3—N3—C3—C2−14.0 (5)C3—C4—C5—N2−179.0 (3)
O4—N3—C3—C4−12.3 (5)O7—C6—C5—C4−179.6 (4)
O3—N3—C3—C4166.7 (3)C1—C6—C5—C4−0.4 (5)
C3—C2—C1—C6−2.9 (6)O7—C6—C5—N2−1.8 (5)
C3—C2—C1—N1−179.7 (3)C1—C6—C5—N2177.4 (3)
O7—C6—C1—C2−178.4 (4)O5—N2—C5—C426.6 (5)
C5—C6—C1—C22.5 (5)O6—N2—C5—C4−153.5 (3)
O7—C6—C1—N1−1.8 (6)O5—N2—C5—C6−151.4 (3)
C5—C6—C1—N1179.1 (3)O6—N2—C5—C628.5 (5)
Symmetry codes: (i) −x, −y+1, −z.
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
O11—H1W···O1ii0.73 (5)2.25 (6)2.923 (4)155 (6)
O8—H3W···O3iii0.79 (5)2.09 (5)2.882 (4)172 (5)
O8—H4W···O10iv0.80 (2)1.96 (2)2.758 (5)171 (5)
O9—H5W···O6v0.85 (5)2.59 (5)2.951 (4)107 (4)
O9—H5W···O7v0.85 (5)2.10 (5)2.905 (5)159 (5)
O10—H9W···O11v0.75 (6)2.30 (5)2.993 (5)154 (5)
C4—H4···O2vi0.932.573.195 (4)125
O11—H2W···O60.88 (6)2.54 (5)2.953 (4)109 (4)
O11—H2W···O70.88 (6)2.01 (6)2.877 (4)166 (5)
O9—H6W···O100.81 (4)1.97 (2)2.763 (5)167 (5)
O10—H8W···O10.87 (7)2.18 (7)2.891 (4)140 (5)
O10—H8W···O70.87 (7)2.20 (7)2.936 (4)142 (6)
Symmetry codes: (ii) −x+1/2, y+1/2, z; (iii) −x+1/2, y, −z+1/2; (iv) x−1/2, −y+1/2, −z; (v) −x+1, −y+1, −z; (vi) x, y+1/2, −z+1/2.
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
O11—H1W···O1i0.73 (5)2.25 (6)2.923 (4)155 (6)
O8—H3W···O3ii0.79 (5)2.09 (5)2.882 (4)172 (5)
O8—H4W···O10iii0.80 (2)1.96 (2)2.758 (5)171 (5)
O9—H5W···O6iv0.85 (5)2.59 (5)2.951 (4)107 (4)
O9—H5W···O7iv0.85 (5)2.10 (5)2.905 (5)159 (5)
O10—H9W···O11iv0.75 (6)2.30 (5)2.993 (5)154 (5)
C4—H4···O2v0.932.573.195 (4)125
O11—H2W···O60.88 (6)2.54 (5)2.953 (4)109 (4)
O11—H2W···O70.88 (6)2.01 (6)2.877 (4)166 (5)
O9—H6W···O100.81 (4)1.97 (2)2.763 (5)167 (5)
O10—H8W···O10.87 (7)2.18 (7)2.891 (4)140 (5)
O10—H8W···O70.87 (7)2.20 (7)2.936 (4)142 (6)
Symmetry codes: (i) −x+1/2, y+1/2, z; (ii) −x+1/2, y, −z+1/2; (iii) x−1/2, −y+1/2, −z; (iv) −x+1, −y+1, −z; (v) x, y+1/2, −z+1/2.
Acknowledgements top

The authors thank the DST for the FIST program.

references
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