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Acta Crystallogr Sect E Struct Rep Online. 2008 January 1; 64(Pt 1): m243–m244.
Published online 2007 December 21. doi:  10.1107/S1600536807067220
PMCID: PMC2915162

Bis(3,5-dimethyl­pyrazole)[N-salicyl­idene-β-alaninato(2–)]copper(II) dihydrate

Abstract

In the title compound, [Cu(C10H10NO3)(C5H8N2)2]·2H2O, the CuII atom is coordinated by three N atoms and two O atoms in a distorted square-pyramidal geometry. The crystal packing is stabilized by inter­molecular O—H(...)O and N—H(...)O hydrogen bonds.

Related literature

For related literature, see: Plesch et al. (1997 [triangle]); Raso et al. (1996 [triangle], 1999 [triangle]); Warda (1997 [triangle], 1998a [triangle],b [triangle],c [triangle]).

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Object name is e-64-0m243-scheme1.jpg

Experimental

Crystal data

  • [Cu(C10H10NO3)(C5H8N2)2]·2H2O
  • M r = 483.02
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-64-0m243-efi1.jpg
  • a = 19.619 (4) Å
  • b = 8.2103 (15) Å
  • c = 13.890 (3) Å
  • β = 91.493 (2)°
  • V = 2236.7 (7) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 1.02 mm−1
  • T = 298 (2) K
  • 0.40 × 0.20 × 0.10 mm

Data collection

  • Bruker SMART CCD area-detector diffractometer
  • Absorption correction: multi-scan (SADABS; Sheldrick, 1996 [triangle]) T min = 0.686, T max = 0.905
  • 11230 measured reflections
  • 3965 independent reflections
  • 3446 reflections with I > 2σ(I)
  • R int = 0.020

Refinement

  • R[F 2 > 2σ(F 2)] = 0.028
  • wR(F 2) = 0.075
  • S = 1.05
  • 3965 reflections
  • 301 parameters
  • 4 restraints
  • H atoms treated by a mixture of independent and constrained refinement
  • Δρmax = 0.24 e Å−3
  • Δρmin = −0.30 e Å−3

Data collection: SMART (Bruker, 2000 [triangle]); cell refinement: SAINT (Bruker, 2000 [triangle]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997 [triangle]); molecular graphics: SHELXTL (Sheldrick, 2000 [triangle]); software used to prepare material for publication: SHELXTL.

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

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536807067220/zl2042sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536807067220/zl2042Isup2.hkl

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

Acknowledgments

This research was supported by the National Sciences Foundation of China (grant No. 20405011), the Social Development Foundation of Jiangsu Province (grant No. BS2006038) and the High Technology Research Foundation of Jiangsu Province (grant No. BG2007025).

supplementary crystallographic information

Comment

Copper (II) complexes of tridentate Schiff base ligands of the N-alkylidene or N-arylidene aminoacidato type have attracted considerable interest due to their richness in structural diversity, their electrochemical properties and also due to their use as potential models for a number of important biological systems (Raso et al., 1999; Raso et al., 1996). Several stuctural studies have been performed on Schiff base copper (II) complexes derived from salicylaldehyde and animo acids (Warda, 1997, 1998a,b,c). In this context we present here the crystal structure of the title CuII complex, (N-salicylidene-β-alanine)(3,5-dimethylprazole)2]copper(II), in the form of its dihydrate.

The structure consists of monomeric units with a square pyramidal copper center (Fig. 1). The four basal positions are occupied by the tridentate, dianionic Schiff base ligand, which furnishes an ONO donor set, with the fourth position occupied by a 3, 5-dimethylprazole N. The coordination sphere is completed by the nitrogen atom of the remaining 3,5-dimethylprazole ligand at the apical position. The two nitrogen heterocycles are planar and exhibit an angle of 37.1° and 79.7° with the plane of the tridentate Schiff base, respectively.

Two solvate water molecules are present in the crystal lattice and hydrogen bonded with each other and the N—H groups of the 3,5-dimethylprazole ligands (see hydrogen bonding table). The interesting intermolecuelar hydrogen-bonding network also stabilizes the crystal structure as a whole. H atoms of O(2w) hydrogen bond to the neighboring carboxylate oxygen O2 and H atoms of O(1w) to form H-bonds to form a two dimensional sheet (Fig. 2). A network of oxygen atoms is formed by above H-bonds (Fig. 3). In addition, all the 3,5-dimethylprazole N—H protons are hydrogen bonded to adjacent water molecules O(1w).

Experimental

The title compound was synthesized as described in the literature (Plesch et al., 1997). To β-alanine (1.00 mmol) and lithium hydroxide monohydrate (1.00 mmol) in 10 ml of methanol was added salicylaldehyde (1.00 mmol in 10 ml of methanol). The yellow solution was stirred for 1.0 h at room temperature prior to cooling in an ice bath. The resultant mixture was added dropwise to copper (II) acetate monohydrate (1.00 mmol) and 3,5-dimethylpyrazole (2.00 mmol) in an aqueous methanolic solution (20 ml, 1;1 v/v), and heated with stirring for 2.0 h at 333 K. The dark green solution was filtered and left for several days, dark blue crystals had formed that were filtered off, washed with water, and dried under vacuum. Analysis found: C 50.12, H 6.04, N 14.93%; calculated: C 49.73, H 6.05, N 14.49%.

Refinement

The positions of the H atoms of the water molecules were located in difference Fourier maps and refined freely along with an isotropic displacement parameter. Other H atoms were positioned geometrically and refined as riding atoms, with C—H = 0.93 (CH) and 0.97 Å (CH2) and Uiso(H) = 1.2Ueq(C), with C—H = 0.96 Å (CH3) and Uiso(H) = 1.5Ueq(C), and with N—H = 0.86 Å (NH) and Uiso(H) = 1.2Ueq(N).

Figures

Fig. 1.
The structure of the title compound, showing 30% probability displacement ellipsoids and the atom-numbering scheme.
Fig. 2.
Two-dimensional network of the title compound formed by hydrogen bonds (dashed lines).
Fig. 3.
The Plot of oxygen cluster formed between the title compound and water by hydrogen bonds (dashed lines).

Crystal data

[Cu(C10H10NO3)(C5H8N2)2]·2H2OF000 = 1012
Mr = 483.02Dx = 1.434 Mg m3
Monoclinic, P21/cMo Kα radiation λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 5668 reflections
a = 19.619 (4) Åθ = 2.7–27.5º
b = 8.2103 (15) ŵ = 1.02 mm1
c = 13.890 (3) ÅT = 298 (2) K
β = 91.493 (2)ºBlock, blue
V = 2236.7 (7) Å30.40 × 0.20 × 0.10 mm
Z = 4

Data collection

Bruker SMART CCD area-detector diffractometer3965 independent reflections
Radiation source: fine-focus sealed tube3446 reflections with I > 2σ(I)
Monochromator: graphiteRint = 0.020
T = 298(2) Kθmax = 25.1º
[var phi] and ω scansθmin = 2.7º
Absorption correction: multi-scan(SADABS; Sheldrick, 1996)h = −18→23
Tmin = 0.686, Tmax = 0.905k = −9→9
11230 measured reflectionsl = −16→15

Refinement

Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.028H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.075  w = 1/[σ2(Fo2) + (0.0352P)2 + 1.1315P] where P = (Fo2 + 2Fc2)/3
S = 1.05(Δ/σ)max = 0.001
3965 reflectionsΔρmax = 0.24 e Å3
301 parametersΔρmin = −0.30 e Å3
4 restraintsExtinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0056 (4)

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
Cu10.274799 (12)0.57312 (3)0.850618 (16)0.02768 (10)
C10.41151 (10)0.4081 (3)0.95032 (15)0.0337 (5)
C20.41039 (10)0.4380 (3)0.84957 (16)0.0344 (5)
C30.46327 (11)0.3676 (3)0.79666 (18)0.0436 (5)
H30.46540.38860.73100.052*
C40.51165 (12)0.2691 (3)0.8394 (2)0.0492 (6)
H40.54530.22320.80200.059*
C50.51139 (12)0.2369 (3)0.9370 (2)0.0520 (6)
H50.54370.16750.96500.062*
C60.46268 (11)0.3089 (3)0.99167 (18)0.0453 (6)
H60.46350.29171.05790.054*
C70.36357 (11)0.4848 (3)1.01174 (15)0.0347 (5)
H70.37290.48001.07770.042*
C80.26606 (11)0.6335 (3)1.05720 (15)0.0400 (5)
H8A0.25520.74451.03850.048*
H8B0.29090.63711.11850.048*
C90.20079 (12)0.5386 (3)1.06855 (15)0.0408 (5)
H9A0.17480.58981.11870.049*
H9B0.21250.42971.09040.049*
C100.15528 (11)0.5240 (3)0.97922 (15)0.0347 (5)
C110.25299 (12)0.4552 (3)0.63387 (14)0.0351 (5)
C120.19798 (13)0.4452 (3)0.56921 (16)0.0447 (6)
H120.19860.40320.50710.054*
C130.14291 (12)0.5086 (3)0.61390 (16)0.0428 (6)
C140.07053 (15)0.5313 (5)0.5804 (2)0.0755 (9)
H14A0.04070.50580.63190.113*
H14B0.06080.46030.52680.113*
H14C0.06360.64230.56080.113*
C150.32401 (13)0.4047 (4)0.61519 (18)0.0553 (7)
H15A0.35370.49740.62110.083*
H15B0.32630.36080.55130.083*
H15C0.33810.32320.66110.083*
C160.30024 (11)0.9729 (3)0.83353 (15)0.0348 (5)
C170.26279 (12)1.1159 (3)0.81797 (15)0.0384 (5)
H170.28011.22060.81120.046*
C180.13169 (13)1.1672 (3)0.80069 (19)0.0516 (6)
H18A0.12461.19070.73350.077*
H18B0.13531.26730.83610.077*
H18C0.09391.10500.82340.077*
C190.37518 (13)0.9516 (3)0.8431 (2)0.0542 (7)
H19A0.38560.83820.85190.081*
H19B0.39221.01210.89780.081*
H19C0.39620.99060.78600.081*
C250.19588 (12)1.0715 (2)0.81468 (14)0.0341 (5)
N10.30915 (9)0.5592 (2)0.98439 (12)0.0309 (4)
N20.23273 (8)0.5216 (2)0.71677 (11)0.0299 (4)
N30.16542 (9)0.5538 (2)0.70181 (13)0.0365 (4)
H3A0.14010.59820.74400.044*
N40.25830 (9)0.8452 (2)0.83905 (12)0.0335 (4)
N50.19496 (9)0.9095 (2)0.82779 (12)0.0328 (4)
H5A0.15820.85270.82890.039*
O10.17828 (7)0.55934 (18)0.89740 (10)0.0343 (3)
O20.09666 (8)0.4747 (3)0.99071 (12)0.0606 (5)
O30.36475 (7)0.5303 (2)0.80579 (10)0.0399 (4)
O1W0.05960 (9)0.7752 (3)0.79001 (15)0.0595 (5)
O2W0.99231 (9)0.4897 (3)0.85715 (12)0.0528 (4)
H2WA0.9600 (11)0.500 (4)0.8961 (17)0.067 (9)*
H1WA0.0321 (12)0.706 (3)0.810 (2)0.072 (10)*
H2WB1.0271 (9)0.476 (4)0.8928 (16)0.058 (9)*
H1WB0.0404 (14)0.833 (3)0.7478 (17)0.076 (10)*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
Cu10.02796 (15)0.02971 (15)0.02528 (14)0.00149 (10)−0.00086 (10)0.00056 (10)
C10.0271 (10)0.0321 (11)0.0416 (12)−0.0041 (9)−0.0038 (9)0.0014 (9)
C20.0248 (10)0.0335 (12)0.0449 (12)−0.0045 (9)−0.0013 (9)0.0002 (9)
C30.0332 (12)0.0468 (14)0.0512 (13)0.0005 (10)0.0059 (10)−0.0008 (11)
C40.0309 (12)0.0410 (14)0.0759 (18)0.0018 (10)0.0055 (12)−0.0046 (12)
C50.0307 (12)0.0446 (15)0.0803 (19)0.0048 (10)−0.0062 (12)0.0098 (13)
C60.0359 (12)0.0456 (14)0.0537 (14)−0.0031 (11)−0.0097 (11)0.0095 (11)
C70.0357 (12)0.0363 (12)0.0317 (11)−0.0081 (10)−0.0078 (9)0.0032 (9)
C80.0468 (13)0.0445 (13)0.0286 (10)0.0028 (11)−0.0035 (10)−0.0091 (10)
C90.0422 (13)0.0541 (15)0.0263 (11)0.0059 (11)0.0041 (9)0.0004 (10)
C100.0330 (12)0.0415 (13)0.0300 (11)0.0045 (10)0.0059 (9)−0.0005 (9)
C110.0477 (13)0.0314 (11)0.0263 (10)−0.0006 (9)0.0025 (9)0.0011 (8)
C120.0604 (16)0.0487 (14)0.0247 (11)−0.0051 (12)−0.0035 (11)−0.0023 (10)
C130.0454 (14)0.0493 (14)0.0330 (11)−0.0087 (11)−0.0105 (10)0.0027 (10)
C140.0520 (17)0.113 (3)0.0606 (18)−0.0044 (17)−0.0240 (14)−0.0052 (18)
C150.0554 (16)0.0716 (19)0.0392 (13)0.0129 (14)0.0088 (12)−0.0129 (12)
C160.0413 (12)0.0326 (12)0.0308 (11)−0.0064 (10)0.0041 (9)−0.0008 (9)
C170.0527 (14)0.0254 (11)0.0372 (11)−0.0079 (10)0.0015 (10)0.0021 (9)
C180.0555 (16)0.0375 (14)0.0612 (15)0.0095 (11)−0.0110 (12)−0.0007 (12)
C190.0431 (14)0.0492 (16)0.0703 (18)−0.0084 (12)0.0010 (13)−0.0038 (13)
C250.0485 (13)0.0274 (11)0.0262 (10)0.0008 (9)−0.0030 (9)0.0004 (8)
N10.0312 (9)0.0327 (10)0.0285 (9)−0.0025 (7)−0.0023 (7)−0.0033 (7)
N20.0317 (9)0.0307 (9)0.0271 (8)0.0010 (7)−0.0015 (7)−0.0007 (7)
N30.0330 (10)0.0436 (11)0.0328 (9)0.0002 (8)−0.0015 (8)−0.0035 (8)
N40.0357 (10)0.0283 (9)0.0364 (9)−0.0011 (8)−0.0008 (8)0.0014 (7)
N50.0347 (10)0.0272 (9)0.0363 (9)−0.0022 (7)−0.0032 (8)−0.0008 (7)
O10.0303 (8)0.0470 (9)0.0256 (7)−0.0002 (6)0.0016 (6)0.0016 (6)
O20.0342 (9)0.1061 (16)0.0418 (9)−0.0092 (10)0.0075 (7)0.0070 (10)
O30.0344 (8)0.0507 (10)0.0346 (8)0.0080 (7)0.0022 (6)0.0064 (7)
O1W0.0404 (10)0.0616 (13)0.0760 (13)−0.0042 (9)−0.0066 (10)0.0187 (11)
O2W0.0421 (10)0.0761 (13)0.0402 (10)−0.0044 (10)0.0021 (8)−0.0014 (9)

Geometric parameters (Å, °)

Cu1—O31.9191 (15)C12—C131.363 (3)
Cu1—N11.9634 (17)C12—H120.9300
Cu1—O12.0211 (15)C13—N31.340 (3)
Cu1—N22.0584 (16)C13—C141.495 (4)
Cu1—N42.2625 (18)C14—H14A0.9600
C1—C61.404 (3)C14—H14B0.9600
C1—C21.420 (3)C14—H14C0.9600
C1—C71.432 (3)C15—H15A0.9600
C2—O31.310 (2)C15—H15B0.9600
C2—C31.411 (3)C15—H15C0.9600
C3—C41.370 (3)C16—N41.336 (3)
C3—H30.9300C16—C171.399 (3)
C4—C51.381 (4)C16—C191.483 (3)
C4—H40.9300C17—C251.362 (3)
C5—C61.371 (4)C17—H170.9300
C5—H50.9300C18—C251.493 (3)
C6—H60.9300C18—H18A0.9600
C7—N11.279 (3)C18—H18B0.9600
C7—H70.9300C18—H18C0.9600
C8—N11.468 (3)C19—H19A0.9600
C8—C91.511 (3)C19—H19B0.9600
C8—H8A0.9700C19—H19C0.9600
C8—H8B0.9700C25—N51.343 (3)
C9—C101.514 (3)N2—N31.357 (2)
C9—H9A0.9700N3—H3A0.8600
C9—H9B0.9700N4—N51.355 (2)
C10—O21.234 (3)N5—H5A0.8600
C10—O11.267 (2)O1W—H1WA0.836 (10)
C11—N21.343 (3)O1W—H1WB0.839 (10)
C11—C121.389 (3)O2W—H2WA0.849 (10)
C11—C151.483 (3)O2W—H2WB0.840 (10)
O3—Cu1—N190.03 (7)C12—C13—C14131.6 (2)
O3—Cu1—O1166.22 (7)C13—C14—H14A109.5
N1—Cu1—O189.65 (6)C13—C14—H14B109.5
O3—Cu1—N291.13 (7)H14A—C14—H14B109.5
N1—Cu1—N2164.27 (7)C13—C14—H14C109.5
O1—Cu1—N285.52 (6)H14A—C14—H14C109.5
O3—Cu1—N4106.80 (7)H14B—C14—H14C109.5
N1—Cu1—N499.76 (7)C11—C15—H15A109.5
O1—Cu1—N486.82 (6)C11—C15—H15B109.5
N2—Cu1—N494.91 (6)H15A—C15—H15B109.5
C6—C1—C2119.7 (2)C11—C15—H15C109.5
C6—C1—C7119.0 (2)H15A—C15—H15C109.5
C2—C1—C7121.18 (19)H15B—C15—H15C109.5
O3—C2—C3119.9 (2)N4—C16—C17110.2 (2)
O3—C2—C1123.36 (19)N4—C16—C19120.9 (2)
C3—C2—C1116.7 (2)C17—C16—C19128.9 (2)
C4—C3—C2121.8 (2)C25—C17—C16106.40 (19)
C4—C3—H3119.1C25—C17—H17126.8
C2—C3—H3119.1C16—C17—H17126.8
C3—C4—C5121.2 (2)C25—C18—H18A109.5
C3—C4—H4119.4C25—C18—H18B109.5
C5—C4—H4119.4H18A—C18—H18B109.5
C6—C5—C4118.8 (2)C25—C18—H18C109.5
C6—C5—H5120.6H18A—C18—H18C109.5
C4—C5—H5120.6H18B—C18—H18C109.5
C5—C6—C1121.7 (2)C16—C19—H19A109.5
C5—C6—H6119.2C16—C19—H19B109.5
C1—C6—H6119.2H19A—C19—H19B109.5
N1—C7—C1126.09 (19)C16—C19—H19C109.5
N1—C7—H7117.0H19A—C19—H19C109.5
C1—C7—H7117.0H19B—C19—H19C109.5
N1—C8—C9111.26 (18)N5—C25—C17106.07 (19)
N1—C8—H8A109.4N5—C25—C18121.7 (2)
C9—C8—H8A109.4C17—C25—C18132.3 (2)
N1—C8—H8B109.4C7—N1—C8119.03 (17)
C9—C8—H8B109.4C7—N1—Cu1124.89 (15)
H8A—C8—H8B108.0C8—N1—Cu1116.00 (13)
C8—C9—C10116.01 (18)C11—N2—N3104.85 (16)
C8—C9—H9A108.3C11—N2—Cu1137.47 (15)
C10—C9—H9A108.3N3—N2—Cu1117.63 (13)
C8—C9—H9B108.3C13—N3—N2112.44 (18)
C10—C9—H9B108.3C13—N3—H3A123.8
H9A—C9—H9B107.4N2—N3—H3A123.8
O2—C10—O1123.1 (2)C16—N4—N5104.60 (17)
O2—C10—C9116.86 (19)C16—N4—Cu1133.74 (15)
O1—C10—C9120.03 (19)N5—N4—Cu1121.46 (13)
N2—C11—C12109.6 (2)C25—N5—N4112.71 (18)
N2—C11—C15124.32 (19)C25—N5—H5A123.6
C12—C11—C15126.0 (2)N4—N5—H5A123.6
C13—C12—C11107.2 (2)C10—O1—Cu1131.28 (13)
C13—C12—H12126.4C2—O3—Cu1125.34 (14)
C11—C12—H12126.4H1WA—O1W—H1WB110 (3)
N3—C13—C12105.9 (2)H2WA—O2W—H2WB104 (3)
N3—C13—C14122.5 (2)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
N3—H3A···O1W0.862.253.041 (3)153
N5—H5A···O1W0.862.092.911 (3)159
O1W—H1WA···O2Wi0.836 (10)2.053 (14)2.858 (3)161 (3)
O2W—H2WB···O2ii0.840 (10)1.902 (12)2.729 (2)168 (3)
O2W—H2WA···O2iii0.849 (10)1.960 (13)2.791 (2)166 (3)
O1W—H1WB···O2Wiv0.839 (10)2.033 (11)2.865 (3)172 (3)

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

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: ZL2042).

References

  • Bruker (2000). SMART (Version 5.625) and SAINT (Version 6.3). Bruker AXS Inc., Madison, Wisconsin, USA.
  • Plesch, G., Friebel, C., Warda, S. A., Sivý, J. & Švajlenová, O. (1997). Transition Met. Chem.22, 433–440.
  • Raso, A. G., Fiol, J. J., Badenas, F. & Quiros, M. (1996). Polyhedron, 18, 4407–4413.
  • Raso, A. G., Fiol, J. J., Zafra, A. L., Cabrero, A., Mata, I. & Molins, E. (1999). Polyhedron, 18, 871–878.
  • Sheldrick, G. M. (1996). SADABS Version 2.10. University of Göttingen, Germany.
  • Sheldrick, G. M. (1997). SHELXS97 and SHELXL97 University of Göttingen, Germany.
  • Sheldrick, G. M. (2000). SHELXTL Version 6.1. Bruker AXS Inc., Madison, Wisconsin, USA.
  • Warda, S. A. (1997). Acta Cryst. C53, 1759–1761.
  • Warda, S. A. (1998a). Acta Cryst. C54, 187–189.
  • Warda, S. A. (1998b). Acta Cryst. C54, 768–770.
  • Warda, S. A. (1998c). Acta Cryst. C54, 1754–1755.

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