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organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 68| Part 2| February 2012| Page o483
doi:10.1107/S1600536812001729

2-Ethyl 4-methyl 5-ethyl-3-methyl-1H-pyrrole-2,4-di­carboxyl­ate

Gui-Fen Lu,a* Min Zhu,a Wei-Hua Zhua and Zhong-Ping Oua

aSchool of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013, People's Republic of China
*Correspondence e-mail: luguifen8012@yahoo.com.cn

(Received 6 January 2012; accepted 14 January 2012; online 21 January 2012)

The title pyrrole derivative compound, C12H17NO4, was synthesized from methyl 3-oxopenta­noate by a Knorr-type reaction and contains a pyrrole ring to which two diagonal alk­oxy­carbonyl groups and two diagonal alkyl substituents are attached. The methyl­carbonyl and ethyl­carbonyl substituents are approximately co-planar with the pyrrole ring, making dihedral angles of 5.64 (2) and 3.44 (1)°, respectively. In the crystal, adjacent mol­ecules are assembled by pairs of N—H⋯O hydrogen bonds into dimers in a head-to-head mode.

Related literature

For applications of polysubstituted pyrroles, see: Brockmann & Tour, (1995[Brockmann, T. W. & Tour, J. M. (1995). J. Am. Chem. Soc. 117, 4437-4447.]); Guilard et al. (2001[Guilard, R., Gross, C. P., Bolze, F., Jerome, F., Ou, Z. P., Shao, J. G., Fischer, J., Weiss, R. & Kadish, K. M. (2001). Inorg. Chem. 40, 4845-4855.]); Trofimov et al. (2004[Trofimov, B. A., Sobenina, L. N., Demenev, A. P. & Mikhaleva, A. (2004). Chem. Rev. 104, 2481-2506.]). For related structures, see: Lu et al. (2011[Lu, G.-F., Lin, W.-S., Zhu, W.-H. & Ou, Z.-P. (2011). Acta Cryst. E67, o2097.]); Takaya et al. (2001[Takaya, H., Kojima, S. & Murahashi, S. I. (2001). Org. Lett. 3, 421-424.]). For complexes of pyrrole derivatives, see: Fan et al. (2008[Fan, H., Peng, J. N., Hamann, M. T. & Hu, J. F. (2008). Chem. Rev. 108, 264-287.]); Ou et al. (2009[Ou, Z. P., Zhu, W. H., Zhou, F., Zhao, X. F. & Ji, X. L. (2009). Fine Chem. 26, 609-612.]); Paixão et al. (2003[Paixão, J. A., Ramos Silva, M., Matos Beja, A., Sobral, A. J. F. N., Lopes, S. H. & Rocha Gonsalves, A. M. d'A. (2003). Acta Cryst. E59, o94-o96.]); Yamamoto et al. (1986[Yamamoto, N., Machida, K., Taga, T. & Ogoshi, H. (1986). Acta Cryst. C42, 1573-1576.]).

[Scheme 1]

Experimental

Crystal data

  • C12H17NO4

  • Mr = 239.27

  • Triclinic, [P \overline 1]

  • a = 7.2827 (10) Å

  • b = 8.8573 (12) Å

  • c = 11.1806 (16) Å

  • α = 77.948 (2)°

  • β = 73.135 (2)°

  • γ = 69.970 (2)°

  • V = 643.62 (15) Å3

  • Z = 2

  • Mo Kα radiation

  • μ = 0.09 mm−1

  • T = 293 K

  • 0.15 × 0.12 × 0.06 mm
Data collection

  • Bruker APEXII CCD area-detector diffractometer

  • Absorption correction: multi-scan (SADABS; Sheldrick, 2003[Sheldrick, G. M. (2003). SADABS. University of Göttingen, Germany.]) Tmin = 0.986, Tmax = 0.995

  • 3249 measured reflections

  • 2255 independent reflections

  • 1891 reflections with I > 2σ(I)

  • Rint = 0.018
Refinement

  • R[F2 > 2σ(F2)] = 0.067

  • wR(F2) = 0.220

  • S = 1.11

  • 2255 reflections

  • 159 parameters

  • 1 restraint

  • H atoms treated by a mixture of independent and constrained refinement

  • Δρmax = 0.51 e Å−3

  • Δρmin = −0.36 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A D⋯A D—H⋯A
N1—H1A⋯O1i 0.84 (1) 2.07 (1) 2.883 (3) 165 (2)
Symmetry code: (i) -x, -y+1, -z.

Data collection: APEX2 (Bruker, 2004[Bruker (2004). APEX2. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT-Plus (Bruker, 2001[Bruker (2001). SAINT-Plus. Bruker AXS Inc., Madison,Wisconsin, USA.]); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: XP in SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536812001729/vm2149sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536812001729/vm2149Isup2.hkl

Supporting information file. DOI: 10.1107/S1600536812001729/vm2149Isup3.cml

checkCIF report


Comment top

Polysubstituted pyrroles have been paid much attention because of their wide application in the preparation of porphyrins (Trofimov et al., 2004), corroles (Guilard et al., 2001) and as monomers for polymer chemistry (Brockmann & Tour, 1995; Paixão et al., 2003). In view of the importance of the 2-(alkoxycarbonyl)pyrrole derivatives (Fan et al., 2008; Lu et al., 2011; Takaya et al., 2001), the title compound was synthesized and characterized by X-ray diffraction.

As shown in Fig. 1, the compound has a five-membered pyrrole ring as skeleton and four substituents. The methoxycarbonyl and ethoxycarbonyl groups are located on two diagonal carbon atoms of the pyrrole skeleton, which is also true for the methyl and ethyl substituents, forming an asymmetrical molecule. Adjacent molecules are assembled in a head to head mode by hydrogen bonding between the donor atom N1 and acceptor atom O1 (symmetry code: -x, 1 - y, -z) (Table 1, Fig. 2). The bond distances are in the normal range of the similar species reported by Yamamoto et al. (1986).

Related literature top

For applications of polysubstituted pyrroles, see: Brockmann & Tour, (1995); Guilard et al. (2001); Trofimov et al. (2004). For related structures, see: Lu et al. (2011); Takaya et al. (2001). For complexes of pyrrole derivatives, see: Fan et al. (2008); Ou et al. (2009); Paixão et al. (2003); Yamamoto et al. (1986).

Experimental top

The title compound was synthesized from ethyl acetoacetate and methyl 3-oxopentanoate through oximination, Claisen condensation and reductive condensation according to the method reported by Ou et al. (2009). Single crystals suitable for X-ray measurements were grown from ethanol by slowly evaporation at room temperature.

Refinement top

All the non-hydrogen atoms were refined anisotropically by full-matrix least-squares calculations on F2. All H atoms (except H1a) were placed in geometrically idealized positions and treated as riding on their parent atoms with C—H = 0.97 Å, Uiso = 1.2Ueq (C) for methylene atoms and C—H = 0.96 Å, Uiso = 1.5Ueq (C) for methyl atoms. The H1a atom has located in a difference map and refined with Uiso = 1.5Ueq (N). The command 'DFIX' has been used to restrain the distance of H1a—N1 = 0.83 Å.

Computing details top

Data collection: APEX2 (Bruker, 2004); cell refinement: SAINT-Plus (Bruker, 2001); data reduction: SAINT-Plus (Bruker, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. Molecular structure with the unique atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level.
[Figure 2] Fig. 2. Dimer formation in the crystal packing.
2-Ethyl 4-methyl 5-ethyl-3-methyl-1H-pyrrole-2,4-dicarboxylate top
Crystal data top
C12H17NO4Z = 2
Mr = 239.27F(000) = 256
Triclinic, P1Dx = 1.235 Mg m−3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71073 Å
a = 7.2827 (10) ÅCell parameters from 1663 reflections
b = 8.8573 (12) Åθ = 2.4–26.8°
c = 11.1806 (16) ŵ = 0.09 mm−1
α = 77.948 (2)°T = 293 K
β = 73.135 (2)°Sheet, colorless
γ = 69.970 (2)°0.15 × 0.12 × 0.06 mm
V = 643.62 (15) Å3
Data collection top
Bruker APEXII CCD area-detector
diffractometer		2255 independent reflections
Radiation source: fine-focus sealed tube1891 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.018
ϕ and ω scansθmax = 25.0°, θmin = 2.9°
Absorption correction: multi-scan
(SADABS; Sheldrick, 2003)		h = −8→6
Tmin = 0.986, Tmax = 0.995k = −10→9
3249 measured reflectionsl = −13→13
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)] = 0.067H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.220 w = 1/[σ2(Fo2) + (0.1366P)2 + 0.1514P]
where P = (Fo2 + 2Fc2)/3
S = 1.11(Δ/σ)max < 0.001
2255 reflectionsΔρmax = 0.51 e Å−3
159 parametersΔρmin = −0.36 e Å−3
1 restraintExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.046 (17)
Crystal data top
C12H17NO4γ = 69.970 (2)°
Mr = 239.27V = 643.62 (15) Å3
Triclinic, P1Z = 2
a = 7.2827 (10) ÅMo Kα radiation
b = 8.8573 (12) ŵ = 0.09 mm−1
c = 11.1806 (16) ÅT = 293 K
α = 77.948 (2)°0.15 × 0.12 × 0.06 mm
β = 73.135 (2)°
Data collection top
Bruker APEXII CCD area-detector
diffractometer		2255 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 2003)		1891 reflections with I > 2σ(I)
Tmin = 0.986, Tmax = 0.995Rint = 0.018
3249 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0671 restraint
wR(F2) = 0.220H atoms treated by a mixture of independent and constrained refinement
S = 1.11Δρmax = 0.51 e Å−3
2255 reflectionsΔρmin = −0.36 e Å−3
159 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
C100.3898 (4)−0.0962 (3)−0.1197 (2)0.0550 (6)
H10A0.4158−0.2064−0.08080.082*
H10B0.5149−0.0720−0.15530.082*
H10C0.3217−0.0814−0.18490.082*
C110.2132 (4)−0.1884 (3)0.1807 (2)0.0560 (6)
C120.3494 (6)−0.4707 (4)0.1703 (3)0.0963 (11)
H12A0.4249−0.54450.10890.144*
H12B0.2222−0.48990.20980.144*
H12C0.4232−0.48710.23280.144*
O40.3164 (3)−0.3073 (2)0.10932 (18)0.0785 (6)
O30.1512 (4)−0.2162 (3)0.29184 (19)0.0950 (8)
H1A0.020 (3)0.3365 (14)0.079 (2)0.052 (7)*
C10.1913 (3)0.1820 (3)−0.04297 (19)0.0461 (5)
C20.2603 (3)0.0150 (2)−0.02273 (19)0.0439 (5)
C30.1853 (3)−0.0280 (3)0.1078 (2)0.0470 (6)
C40.0707 (3)0.1150 (3)0.1615 (2)0.0491 (6)
C50.2114 (4)0.3014 (3)−0.1527 (2)0.0569 (6)
C60.3253 (8)0.3461 (4)−0.3746 (3)0.1147 (15)
H6A0.19020.4037−0.38520.138*
H6B0.38890.4250−0.37210.138*
C70.4382 (8)0.2543 (6)−0.4772 (3)0.1304 (17)
H7A0.44600.3259−0.55470.196*
H7B0.37300.1779−0.48010.196*
H7C0.57150.1974−0.46590.196*
C8−0.0423 (4)0.1442 (3)0.2940 (2)0.0621 (7)
H8A−0.15650.24090.29210.075*
H8B−0.09400.05400.33440.075*
C90.0830 (5)0.1639 (4)0.3707 (3)0.0857 (9)
H9A0.00280.18230.45420.129*
H9B0.13220.25460.33240.129*
H9C0.19460.06760.37480.129*
N10.0782 (3)0.2382 (2)0.07013 (17)0.0503 (5)
O10.1384 (3)0.4462 (2)−0.15035 (18)0.0821 (7)
O20.3170 (3)0.2368 (2)−0.25857 (16)0.0748 (6)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C100.0654 (14)0.0407 (12)0.0528 (13)−0.0105 (10)−0.0084 (10)−0.0104 (10)
C110.0628 (13)0.0460 (13)0.0535 (13)−0.0180 (10)−0.0088 (10)0.0016 (10)
C120.130 (3)0.0388 (15)0.097 (2)−0.0178 (16)−0.016 (2)0.0119 (14)
O40.1114 (15)0.0334 (10)0.0680 (12)−0.0114 (9)−0.0062 (11)0.0025 (8)
O30.1393 (19)0.0586 (12)0.0578 (12)−0.0263 (12)0.0044 (12)0.0097 (9)
C10.0501 (11)0.0386 (11)0.0423 (11)−0.0088 (8)−0.0071 (8)−0.0033 (8)
C20.0436 (10)0.0389 (11)0.0467 (11)−0.0113 (9)−0.0087 (8)−0.0047 (8)
C30.0480 (11)0.0404 (11)0.0495 (12)−0.0137 (9)−0.0083 (9)−0.0025 (9)
C40.0478 (11)0.0438 (12)0.0483 (12)−0.0118 (9)−0.0047 (9)−0.0027 (9)
C50.0677 (14)0.0397 (12)0.0484 (13)−0.0075 (10)−0.0055 (10)−0.0003 (9)
C60.183 (4)0.0601 (18)0.0511 (17)−0.014 (2)0.007 (2)0.0112 (14)
C70.186 (4)0.123 (3)0.0515 (19)−0.033 (3)−0.008 (2)0.001 (2)
C80.0667 (14)0.0542 (14)0.0494 (13)−0.0144 (11)0.0032 (11)−0.0029 (10)
C90.104 (2)0.101 (2)0.0500 (15)−0.0386 (19)−0.0048 (14)−0.0093 (15)
N10.0533 (10)0.0370 (10)0.0479 (11)−0.0050 (8)−0.0044 (8)−0.0040 (8)
O10.1135 (15)0.0386 (10)0.0600 (11)−0.0033 (9)0.0023 (10)0.0007 (8)
O20.1088 (14)0.0453 (10)0.0434 (10)−0.0087 (9)0.0013 (9)−0.0001 (7)
Geometric parameters (Å, º) top
C10—C21.500 (3)C4—C81.498 (3)
C10—H10A0.9600C5—O11.211 (3)
C10—H10B0.9600C5—O21.331 (3)
C10—H10C0.9600C6—C71.428 (5)
C11—O31.197 (3)C6—O21.447 (3)
C11—O41.330 (3)C6—H6A0.9700
C11—C31.463 (3)C6—H6B0.9700
C12—O41.436 (3)C7—H7A0.9600
C12—H12A0.9600C7—H7B0.9600
C12—H12B0.9600C7—H7C0.9600
C12—H12C0.9600C8—C91.491 (4)
C1—N11.380 (3)C8—H8A0.9700
C1—C21.381 (3)C8—H8B0.9700
C1—C51.451 (3)C9—H9A0.9600
C2—C31.422 (3)C9—H9B0.9600
C3—C41.401 (3)C9—H9C0.9600
C4—N11.335 (3)N1—H1A0.839 (10)
C2—C10—H10A109.5O2—C5—C1113.5 (2)
C2—C10—H10B109.5C7—C6—O2108.8 (3)
H10A—C10—H10B109.5C7—C6—H6A109.9
C2—C10—H10C109.5O2—C6—H6A109.9
H10A—C10—H10C109.5C7—C6—H6B109.9
H10B—C10—H10C109.5O2—C6—H6B109.9
O3—C11—O4121.4 (2)H6A—C6—H6B108.3
O3—C11—C3126.0 (2)C6—C7—H7A109.5
O4—C11—C3112.6 (2)C6—C7—H7B109.5
O4—C12—H12A109.5H7A—C7—H7B109.5
O4—C12—H12B109.5C6—C7—H7C109.5
H12A—C12—H12B109.5H7A—C7—H7C109.5
O4—C12—H12C109.5H7B—C7—H7C109.5
H12A—C12—H12C109.5C9—C8—C4113.3 (2)
H12B—C12—H12C109.5C9—C8—H8A108.9
C11—O4—C12117.6 (2)C4—C8—H8A108.9
N1—C1—C2108.30 (19)C9—C8—H8B108.9
N1—C1—C5117.4 (2)C4—C8—H8B108.9
C2—C1—C5134.3 (2)H8A—C8—H8B107.7
C1—C2—C3105.90 (18)C8—C9—H9A109.5
C1—C2—C10126.4 (2)C8—C9—H9B109.5
C3—C2—C10127.7 (2)H9A—C9—H9B109.5
C4—C3—C2107.89 (19)C8—C9—H9C109.5
C4—C3—C11122.8 (2)H9A—C9—H9C109.5
C2—C3—C11129.3 (2)H9B—C9—H9C109.5
N1—C4—C3107.36 (19)C4—N1—C1110.53 (19)
N1—C4—C8121.0 (2)C4—N1—H1A125.5 (17)
C3—C4—C8131.6 (2)C1—N1—H1A124.0 (17)
O1—C5—O2122.4 (2)C5—O2—C6117.1 (2)
O1—C5—C1124.1 (2)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1A···O1i0.84 (1)2.07 (1)2.883 (3)165 (2)
Symmetry code: (i) −x, −y+1, −z.

Experimental details

Crystal data
Chemical formulaC12H17NO4
Mr239.27
Crystal system, space groupTriclinic, P1
Temperature (K)293
a, b, c (Å)7.2827 (10), 8.8573 (12), 11.1806 (16)
α, β, γ (°)77.948 (2), 73.135 (2), 69.970 (2)
V (Å3)643.62 (15)
Z2
Radiation typeMo Kα
µ (mm−1)0.09
Crystal size (mm)0.15 × 0.12 × 0.06
Data collection
DiffractometerBruker APEXII CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Sheldrick, 2003)
Tmin, Tmax0.986, 0.995
No. of measured, independent and
observed [I > 2σ(I)] reflections		3249, 2255, 1891
Rint0.018
(sin θ/λ)max (Å−1)0.595
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.067, 0.220, 1.11
No. of reflections2255
No. of parameters159
No. of restraints1
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å−3)0.51, −0.36

Computer programs: APEX2 (Bruker, 2004), SAINT-Plus (Bruker, 2001), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), XP in SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1A···O1i0.839 (10)2.065 (12)2.883 (3)165 (2)
Symmetry code: (i) −x, −y+1, −z.
 

Acknowledgements

The project was supported by the Natural Science Foundation of China (No. 21001054) and the Jiangsu Higher Education Institutions (No. 10KJB150003). The Foundation of UJS (Nos. 09JDG055 and 1143002064) is also gratefully acknowledged.

References

First citationBrockmann, T. W. & Tour, J. M. (1995). J. Am. Chem. Soc. 117, 4437–4447.  CrossRef CAS Web of Science Google Scholar
 First citationBruker (2001). SAINT-Plus. Bruker AXS Inc., Madison,Wisconsin, USA.  Google Scholar
 First citationBruker (2004). APEX2. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
 First citationFan, H., Peng, J. N., Hamann, M. T. & Hu, J. F. (2008). Chem. Rev. 108, 264–287.  Web of Science CrossRef PubMed CAS Google Scholar
 First citationGuilard, R., Gross, C. P., Bolze, F., Jerome, F., Ou, Z. P., Shao, J. G., Fischer, J., Weiss, R. & Kadish, K. M. (2001). Inorg. Chem. 40, 4845–4855.  Web of Science CSD CrossRef PubMed CAS Google Scholar
 First citationLu, G.-F., Lin, W.-S., Zhu, W.-H. & Ou, Z.-P. (2011). Acta Cryst. E67, o2097.  Web of Science CSD CrossRef IUCr Journals Google Scholar
 First citationOu, Z. P., Zhu, W. H., Zhou, F., Zhao, X. F. & Ji, X. L. (2009). Fine Chem. 26, 609-612.  CAS Google Scholar
 First citationPaixão, J. A., Ramos Silva, M., Matos Beja, A., Sobral, A. J. F. N., Lopes, S. H. & Rocha Gonsalves, A. M. d'A. (2003). Acta Cryst. E59, o94–o96.  Web of Science CSD CrossRef IUCr Journals Google Scholar
 First citationSheldrick, G. M. (2003). SADABS. University of Göttingen, Germany.  Google Scholar
 First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar
 First citationTakaya, H., Kojima, S. & Murahashi, S. I. (2001). Org. Lett. 3, 421–424.  Web of Science CSD CrossRef PubMed CAS Google Scholar
 First citationTrofimov, B. A., Sobenina, L. N., Demenev, A. P. & Mikhaleva, A. (2004). Chem. Rev. 104, 2481–2506.  Web of Science CrossRef PubMed CAS Google Scholar
 First citationYamamoto, N., Machida, K., Taga, T. & Ogoshi, H. (1986). Acta Cryst. C42, 1573–1576.  CSD CrossRef CAS Web of Science IUCr Journals Google Scholar

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ISSN: 2056-9890
Volume 68| Part 2| February 2012| Page o483
doi:10.1107/S1600536812001729
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