PMCCPMCCPMCC

Search tips
Search criteria 

Advanced

 
Logo of actaeInternational Union of Crystallographysearchopen accessarticle submissionjournal home pagethis article
 
Acta Crystallogr Sect E Struct Rep Online. 2009 March 1; 65(Pt 3): o620.
Published online 2009 February 28. doi:  10.1107/S1600536809006370
PMCID: PMC2968438

2,2′-(Heptane-1,7-di­yl)dibenz­imidazo­lium chloride nitrate monohydrate

Abstract

In the title compound, C21H26N4 2+·Cl·NO3 ·H2O, the organic cations, anions and water mol­ecules are linked through N—H(...)Cl, N—H(...)O, N—H(...)N and O—H(...)Cl hydrogen bonds, forming a three-dimensional framework, assisted by C—H(...)π inter­actions.

Related literature

For general background regarding inter­actions of linear polyaromatic compounds with cucurbit[n]urils, see: Day & Arnold (2000 [triangle]); Day et al. (2002 [triangle]); Freeman et al. (1981 [triangle]); Kim et al. (2000 [triangle]). For the synthesis, see: Wang & Joullié (1957 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-65-0o620-scheme1.jpg

Experimental

Crystal data

  • C21H26N4 2+·Cl·NO3 ·H2O
  • M r = 449.93
  • Orthorhombic, An external file that holds a picture, illustration, etc.
Object name is e-65-0o620-efi1.jpg
  • a = 24.462 (10) Å
  • b = 5.102 (2) Å
  • c = 18.210 (7) Å
  • V = 2272.5 (15) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.21 mm−1
  • T = 293 K
  • 0.31 × 0.22 × 0.18 mm

Data collection

  • Bruker SMART APEXII CCD area-detector diffractometer
  • Absorption correction: multi-scan (SADABS; Bruker, 2005 [triangle]) T min = 0.939, T max = 0.964
  • 14275 measured reflections
  • 2086 independent reflections
  • 1619 reflections with I > 2σ(I)
  • R int = 0.063

Refinement

  • R[F 2 > 2σ(F 2)] = 0.038
  • wR(F 2) = 0.084
  • S = 1.03
  • 2086 reflections
  • 288 parameters
  • 5 restraints
  • H atoms treated by a mixture of independent and constrained refinement
  • Δρmax = 0.19 e Å−3
  • Δρmin = −0.17 e Å−3

Data collection: APEX2 (Bruker, 2005 [triangle]); cell refinement: SAINT (Bruker, 2005 [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: ORTEP-3 for Windows (Farrugia, 1997 [triangle]); software used to prepare material for publication: WinGX (Farrugia, 1999 [triangle]).

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809006370/ez2159sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809006370/ez2159Isup2.hkl

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

Acknowledgments

We acknowledge the support of the National Natural Science Foundation of China (No. 20662003), the International Collaborative Project of the Ministry of Science and Technology (No. 2007400108) and the Foundation of the Governor of Guizhou Province, China.

supplementary crystallographic information

Comment

This paper describes the preparation and structure of a new linear polyaromatic compound (I) in which the multiple functional groups can develop strong intermolecular interactions with cucurbit[n]urils (CB[n]) (Freeman et al.,1981; Day & Arnold, 2000; Day et al., 2002; Kim et al., 2000).

The molecular structure of (I), shown in Fig. 1, consists of one organic cation, one Cl- anion, one NO3- anion and one lattice water molecule. The two benzimidazole groups of the organic cation are not co-planar, but are oriented at a dihedral angle of 78.42 (6) ° with respect to each other. Molecules are linked via an N1—H1A···Cl1, N2—H2A···O3, N2—H2A···O1, N2—H2A···N5, N3—H3A···O2, N4—H4A···O1W and O1W—H1WA···Cl1 network of hydrogen bonds (Table 1) forming a three-dimensional framework. In addition, C—H···π interactions occur between adjacent organic cations (Table 1, Cg(3) and Cg(4) are the centroids of the C1—C6 and C16—C21 benzene rings, respectively).

Experimental

A solution of o-phenylenediamine (5.40 g, 0.05 mol) and azelaic acid (4.71 g, 0.025 mol) were refluxed for twelve hours in 50 ml of 4M HCl. The reaction mixture was then cooled for one day and the blue crystalline 2,2'-(Heptane-1,7-diyl)dibenzimidazolium dihydrochloride which separated was removed by filtration and dried (Wang et al., 1957). Yield: 31%. The dihydrochloride (2.03 g, 5 mmol) and lanthanum nitrate (3.25 g, 10 mmol) were refluxed for three h in 50 ml water, and the mixture was cooled and filtered. Upon standing at room temperature, crystals of title compound (I) were obtained after several days.

Refinement

The water H atoms were located in a difference Fourier synthesis and refined with distances restrained to O—H = O.82 (2) Å and H—H =1.37 (4) Å, with Uiso(H) =1.2Ueq(O). All other H atoms were placed in calculated positions and refined as riding, with C—H = 0.93–0.97 Å, N—H = 0.86 Å, and with Uiso(H) = 1.2 Ueq (C, N). In the absence of significant anomalous scattering, Friedel equivalents (900 pairs) were merged before the final refinement.

Figures

Fig. 1.
The molecular structure of (I), shown with the atom-labelling scheme and 50% probability displacement ellipsoids.

Crystal data

C21H26N42+·Cl·NO3·H2OF(000) = 952
Mr = 449.93Dx = 1.315 Mg m3
Orthorhombic, Pca21Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2c -2acCell parameters from 3986 reflections
a = 24.462 (10) Åθ = 1.7–25.1°
b = 5.102 (2) ŵ = 0.21 mm1
c = 18.210 (7) ÅT = 293 K
V = 2272.5 (15) Å3Prism, colorless
Z = 40.31 × 0.22 × 0.18 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer2086 independent reflections
Radiation source: fine-focus sealed tube1619 reflections with I > 2σ(I)
graphiteRint = 0.063
[var phi] and ω scansθmax = 25.1°, θmin = 1.7°
Absorption correction: multi-scan (SADABS; Bruker, 2005)h = −26→29
Tmin = 0.939, Tmax = 0.964k = −6→6
14275 measured reflectionsl = −21→21

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)] = 0.038Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.084H atoms treated by a mixture of independent and constrained refinement
S = 1.03w = 1/[σ2(Fo2) + (0.0385P)2 + 0.1227P] where P = (Fo2 + 2Fc2)/3
2086 reflections(Δ/σ)max < 0.001
288 parametersΔρmax = 0.19 e Å3
5 restraintsΔρmin = −0.17 e Å3

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
C10.31252 (16)0.2574 (8)0.5321 (2)0.0467 (10)
H10.33580.12580.51560.056*
C20.28978 (16)0.4345 (8)0.4846 (2)0.0538 (11)
H20.29750.42260.43470.065*
C30.25529 (18)0.6318 (8)0.5097 (3)0.0548 (11)
H30.24100.74960.47580.066*
C40.24142 (16)0.6603 (7)0.5822 (3)0.0504 (11)
H40.21800.79230.59810.061*
C50.26436 (14)0.4805 (7)0.6308 (2)0.0409 (9)
C60.29941 (15)0.2824 (7)0.60581 (19)0.0391 (9)
C70.29322 (16)0.2498 (7)0.7275 (2)0.0397 (9)
C80.30248 (17)0.1623 (8)0.8034 (2)0.0487 (10)
H8A0.3179−0.01290.80230.058*
H8B0.26750.15160.82820.058*
C90.34010 (15)0.3376 (7)0.8482 (2)0.0443 (10)
H9A0.32350.50920.85370.053*
H9B0.37450.35940.82240.053*
C100.35076 (16)0.2195 (7)0.9238 (2)0.0440 (10)
H10A0.31590.17960.94660.053*
H10B0.37030.05550.91760.053*
C110.38324 (16)0.3936 (8)0.9753 (2)0.0445 (10)
H11A0.36400.55840.98180.053*
H11B0.41850.43160.95340.053*
C120.39191 (15)0.2656 (7)1.0503 (2)0.0478 (11)
H12A0.35710.19851.06750.057*
H12B0.41630.11731.04420.057*
C130.41530 (16)0.4448 (8)1.1086 (2)0.0479 (10)
H13A0.38910.58201.11970.057*
H13B0.44830.52711.09010.057*
C140.42850 (16)0.2939 (7)1.1783 (2)0.0475 (9)
H14A0.39780.18101.18990.057*
H14B0.45980.18191.16880.057*
C150.44061 (15)0.4573 (7)1.2432 (2)0.0415 (9)
C160.47804 (15)0.7535 (7)1.3163 (2)0.0424 (9)
C170.44065 (15)0.6095 (8)1.3572 (2)0.0442 (10)
C180.43226 (17)0.6605 (9)1.4312 (2)0.0579 (12)
H180.40770.56271.45890.070*
C190.46186 (18)0.8618 (10)1.4617 (3)0.0627 (12)
H190.45710.90061.51120.075*
C200.4989 (2)1.0102 (10)1.4205 (3)0.0607 (12)
H200.51761.14731.44280.073*
C210.50813 (17)0.9566 (8)1.3469 (2)0.0528 (11)
H210.53331.05191.31940.063*
N10.31566 (11)0.1448 (6)0.66844 (17)0.0403 (7)
H1A0.33710.01130.66850.048*
N20.26120 (12)0.4500 (6)0.70671 (16)0.0417 (8)
H2A0.24180.54470.73570.050*
N30.41815 (12)0.4278 (6)1.30898 (16)0.0429 (8)
H3A0.39350.31421.32010.051*
N40.47645 (12)0.6521 (6)1.24534 (17)0.0430 (8)
H4A0.49560.70691.20880.052*
N50.32105 (13)0.8845 (7)1.2993 (2)0.0466 (8)
O10.32896 (15)0.9063 (7)1.23308 (19)0.0857 (11)
O20.34026 (11)1.0441 (6)1.34445 (16)0.0608 (8)
O1W0.46016 (12)0.2164 (7)0.62756 (17)0.0558 (8)
O30.29200 (12)0.6979 (5)1.32219 (16)0.0584 (8)
Cl10.40293 (4)−0.28231 (18)0.68522 (7)0.0628 (3)
H1WA0.4422 (19)0.087 (7)0.654 (3)0.11 (2)*
H1WB0.4403 (18)0.347 (6)0.633 (3)0.10 (2)*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
C10.039 (2)0.050 (2)0.051 (3)−0.0075 (19)0.001 (2)−0.007 (2)
C20.052 (3)0.058 (3)0.051 (3)−0.013 (2)−0.005 (2)0.001 (2)
C30.055 (3)0.058 (3)0.052 (3)−0.014 (2)−0.015 (2)0.010 (2)
C40.041 (2)0.039 (2)0.072 (3)−0.0037 (18)−0.011 (2)0.003 (2)
C50.038 (2)0.042 (2)0.042 (2)−0.0061 (18)−0.0078 (19)−0.0017 (19)
C60.034 (2)0.040 (2)0.043 (2)−0.0050 (17)−0.0119 (18)−0.0048 (18)
C70.036 (2)0.040 (2)0.043 (2)−0.0067 (18)−0.0029 (18)0.0000 (18)
C80.047 (2)0.049 (2)0.050 (3)−0.009 (2)−0.0036 (19)0.003 (2)
C90.044 (2)0.040 (2)0.049 (2)−0.0033 (18)−0.0060 (19)0.0042 (19)
C100.043 (2)0.041 (2)0.048 (2)−0.0021 (18)−0.0019 (19)0.0014 (19)
C110.039 (2)0.050 (2)0.045 (2)0.0013 (18)−0.0053 (18)0.0036 (19)
C120.046 (3)0.048 (3)0.049 (3)−0.0009 (19)−0.001 (2)0.004 (2)
C130.046 (2)0.044 (2)0.053 (2)−0.0043 (19)−0.006 (2)0.004 (2)
C140.055 (2)0.043 (2)0.044 (2)0.0017 (18)−0.004 (2)−0.001 (2)
C150.039 (2)0.040 (2)0.046 (2)0.0059 (18)−0.0013 (19)0.004 (2)
C160.035 (2)0.044 (2)0.049 (2)0.0078 (18)−0.0055 (19)−0.002 (2)
C170.037 (2)0.049 (2)0.046 (2)0.0086 (19)−0.002 (2)−0.005 (2)
C180.049 (3)0.075 (3)0.050 (3)0.008 (2)0.002 (2)−0.004 (2)
C190.056 (3)0.076 (3)0.055 (3)0.010 (3)−0.009 (2)−0.022 (3)
C200.058 (3)0.052 (3)0.072 (3)0.007 (2)−0.025 (2)−0.010 (2)
C210.042 (2)0.050 (3)0.066 (3)0.005 (2)−0.015 (2)0.000 (2)
N10.0339 (16)0.0401 (17)0.047 (2)0.0016 (14)−0.0051 (16)−0.0020 (16)
N20.0368 (17)0.0398 (18)0.049 (2)0.0008 (15)−0.0004 (15)−0.0055 (15)
N30.0347 (17)0.0455 (19)0.048 (2)0.0013 (15)0.0025 (15)0.0002 (17)
N40.0441 (19)0.0424 (18)0.043 (2)0.0015 (15)−0.0007 (16)0.0003 (15)
N50.0362 (18)0.042 (2)0.062 (2)0.0067 (16)−0.0008 (18)0.0029 (19)
O10.105 (3)0.096 (3)0.056 (2)−0.042 (2)0.014 (2)−0.002 (2)
O20.0548 (18)0.0584 (18)0.069 (2)−0.0157 (15)0.0000 (16)−0.0166 (17)
O1W0.0483 (18)0.058 (2)0.061 (2)−0.0063 (16)0.0040 (15)−0.0109 (17)
O30.0575 (18)0.0548 (18)0.0628 (19)−0.0141 (15)−0.0010 (16)0.0030 (15)
Cl10.0477 (6)0.0446 (5)0.0960 (9)0.0035 (5)−0.0071 (6)0.0021 (6)

Geometric parameters (Å, °)

C1—C21.369 (5)C13—C141.519 (5)
C1—C61.385 (5)C13—H13A0.9700
C1—H10.9300C13—H13B0.9700
C2—C31.391 (6)C14—C151.477 (5)
C2—H20.9300C14—H14A0.9700
C3—C41.372 (6)C14—H14B0.9700
C3—H30.9300C15—N31.326 (5)
C4—C51.393 (5)C15—N41.326 (5)
C4—H40.9300C16—C211.387 (5)
C5—N21.393 (4)C16—C171.389 (5)
C5—C61.402 (5)C16—N41.393 (5)
C6—N11.397 (4)C17—C181.388 (5)
C7—N11.320 (5)C17—N31.390 (5)
C7—N21.341 (4)C18—C191.374 (6)
C7—C81.471 (5)C18—H180.9300
C8—C91.520 (5)C19—C201.398 (7)
C8—H8A0.9700C19—H190.9300
C8—H8B0.9700C20—C211.387 (6)
C9—C101.527 (5)C20—H200.9300
C9—H9A0.9700C21—H210.9300
C9—H9B0.9700N1—H1A0.8600
C10—C111.516 (5)N2—H2A0.8600
C10—H10A0.9700N3—H3A0.8600
C10—H10B0.9700N4—H4A0.8600
C11—C121.528 (5)N5—O11.227 (4)
C11—H11A0.9700N5—O21.248 (4)
C11—H11B0.9700N5—O31.259 (4)
C12—C131.514 (5)O1W—H1WA0.927 (19)
C12—H12A0.9700O1W—H1WB0.83 (2)
C12—H12B0.9700
C2—C1—C6117.2 (4)H12A—C12—H12B107.5
C2—C1—H1121.4C12—C13—C14111.1 (3)
C6—C1—H1121.4C12—C13—H13A109.4
C1—C2—C3121.1 (4)C14—C13—H13A109.4
C1—C2—H2119.4C12—C13—H13B109.4
C3—C2—H2119.4C14—C13—H13B109.4
C4—C3—C2122.9 (4)H13A—C13—H13B108.0
C4—C3—H3118.6C15—C14—C13115.2 (3)
C2—C3—H3118.6C15—C14—H14A108.5
C3—C4—C5116.3 (4)C13—C14—H14A108.5
C3—C4—H4121.9C15—C14—H14B108.5
C5—C4—H4121.9C13—C14—H14B108.5
N2—C5—C4133.0 (4)H14A—C14—H14B107.5
N2—C5—C6106.0 (3)N3—C15—N4109.5 (3)
C4—C5—C6121.0 (4)N3—C15—C14125.2 (4)
C1—C6—N1132.7 (4)N4—C15—C14125.4 (4)
C1—C6—C5121.5 (4)C21—C16—C17122.0 (4)
N1—C6—C5105.7 (3)C21—C16—N4131.6 (4)
N1—C7—N2108.8 (3)C17—C16—N4106.4 (3)
N1—C7—C8125.3 (4)C18—C17—C16121.2 (4)
N2—C7—C8125.9 (4)C18—C17—N3132.8 (4)
C7—C8—C9114.7 (3)C16—C17—N3106.0 (3)
C7—C8—H8A108.6C19—C18—C17117.1 (4)
C9—C8—H8A108.6C19—C18—H18121.5
C7—C8—H8B108.6C17—C18—H18121.5
C9—C8—H8B108.6C18—C19—C20121.9 (4)
H8A—C8—H8B107.6C18—C19—H19119.0
C8—C9—C10110.8 (3)C20—C19—H19119.0
C8—C9—H9A109.5C21—C20—C19121.2 (4)
C10—C9—H9A109.5C21—C20—H20119.4
C8—C9—H9B109.5C19—C20—H20119.4
C10—C9—H9B109.5C20—C21—C16116.6 (4)
H9A—C9—H9B108.1C20—C21—H21121.7
C11—C10—C9114.6 (3)C16—C21—H21121.7
C11—C10—H10A108.6C7—N1—C6110.0 (3)
C9—C10—H10A108.6C7—N1—H1A125.0
C11—C10—H10B108.6C6—N1—H1A125.0
C9—C10—H10B108.6C7—N2—C5109.4 (3)
H10A—C10—H10B107.6C7—N2—H2A125.3
C10—C11—C12112.0 (3)C5—N2—H2A125.3
C10—C11—H11A109.2C15—N3—C17109.3 (3)
C12—C11—H11A109.2C15—N3—H3A125.3
C10—C11—H11B109.2C17—N3—H3A125.3
C12—C11—H11B109.2C15—N4—C16108.9 (3)
H11A—C11—H11B107.9C15—N4—H4A125.6
C13—C12—C11114.9 (3)C16—N4—H4A125.6
C13—C12—H12A108.5O1—N5—O2121.9 (4)
C11—C12—H12A108.5O1—N5—O3118.9 (4)
C13—C12—H12B108.5O2—N5—O3119.2 (4)
C11—C12—H12B108.5H1WA—O1W—H1WB104 (4)
C6—C1—C2—C30.4 (5)N4—C16—C17—N3−0.1 (4)
C1—C2—C3—C4−0.8 (6)C16—C17—C18—C191.0 (6)
C2—C3—C4—C50.6 (6)N3—C17—C18—C19−179.2 (4)
C3—C4—C5—N2178.3 (4)C17—C18—C19—C200.1 (6)
C3—C4—C5—C6−0.2 (5)C18—C19—C20—C21−1.3 (7)
C2—C1—C6—N1−178.1 (4)C19—C20—C21—C161.4 (6)
C2—C1—C6—C50.0 (5)C17—C16—C21—C20−0.3 (5)
N2—C5—C6—C1−179.0 (3)N4—C16—C21—C20178.8 (4)
C4—C5—C6—C1−0.1 (5)N2—C7—N1—C61.5 (4)
N2—C5—C6—N1−0.4 (4)C8—C7—N1—C6−177.9 (3)
C4—C5—C6—N1178.5 (3)C1—C6—N1—C7177.7 (4)
N1—C7—C8—C9104.1 (4)C5—C6—N1—C7−0.7 (4)
N2—C7—C8—C9−75.1 (5)N1—C7—N2—C5−1.8 (4)
C7—C8—C9—C10−175.5 (3)C8—C7—N2—C5177.6 (3)
C8—C9—C10—C11−174.1 (3)C4—C5—N2—C7−177.4 (4)
C9—C10—C11—C12179.3 (3)C6—C5—N2—C71.3 (4)
C10—C11—C12—C13−169.9 (3)N4—C15—N3—C17−0.8 (4)
C11—C12—C13—C14−173.5 (3)C14—C15—N3—C17177.8 (3)
C12—C13—C14—C15−167.8 (3)C18—C17—N3—C15−179.2 (4)
C13—C14—C15—N3130.3 (4)C16—C17—N3—C150.5 (4)
C13—C14—C15—N4−51.3 (5)N3—C15—N4—C160.7 (4)
C21—C16—C17—C18−0.9 (6)C14—C15—N4—C16−177.9 (3)
N4—C16—C17—C18179.7 (3)C21—C16—N4—C15−179.7 (4)
C21—C16—C17—N3179.3 (3)C17—C16—N4—C15−0.4 (4)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
N1—H1A···Cl10.862.223.066 (3)168
N2—H2A···O3i0.861.942.778 (4)164
N2—H2A···O1i0.862.533.243 (4)141
N2—H2A···N5i0.862.593.436 (5)168
N3—H3A···O2ii0.861.952.807 (4)177
N4—H4A···O1Wiii0.861.872.730 (4)173
O1W—H1WA···Cl10.93 (2)2.19 (2)3.088 (4)163 (4)
O1W—H1WB···Cl1iv0.83 (2)2.31 (3)3.099 (3)159 (5)
C10—H10A···Cg(3)v0.973.364.148 (4)140
C11—H11B···Cg(4)vi0.973.214.047 (4)146

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

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: EZ2159).

References

  • Bruker (2005). APEX2, SAINT and SADABS Bruker AXS Inc., Madison, Wisconsin, USA.
  • Day, A. I. & Arnold, A. P. (2000). Patent No. WO/2000/068232.
  • Day, A. I., Blanch, R. J., Arnold, A. P., Lorenzo, S., Lewis, G. R. & Dance, I. (2002). Angew. Chem. Int. Ed. Engl. 41, 275–277. [PubMed]
  • Farrugia, L. J. (1997). J. Appl. Cryst.30, 565.
  • Farrugia, L. J. (1999). J. Appl. Cryst.32, 837–838.
  • Flack, H. D. (1983). Acta Cryst. A39, 876–881.
  • Freeman, W. A., Mock, W. L. & Shih, N. Y. (1981). J. Am. Chem. Soc.103, 7367–7370.
  • Kim, J., Jung, I. S., Kim, S.-Y., Lee, E., Kang, J.-K., Sakamoto, S., Yamaguchi, K. & Kim, K. (2000). J. Am. Chem. Soc.122, 540–541.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Wang, L. L. Y. & Joullié, M. M. (1957). J. Am. Chem. Soc.79, 5706–5708.

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