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

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 71| Part 4| April 2015| Pages o227-o228

Crystal structure of 4-azido­methyl-6-iso­propyl-2H-chromen-2-one

CROSSMARK_Color_square_no_text.svg

aDepartment of Studies in Chemistry, Central College Campus, Bangalore University, Bangalore 560 001, Karnataka, India
*Correspondence e-mail: noorsb@rediffmail.com

Edited by A. J. Lough, University of Toronto, Canada (Received 15 February 2015; accepted 3 March 2015; online 7 March 2015)

In the title mol­ecule, C13H13N3O2, the benzo­pyran ring system is essentially planar, with a maximum deviation of 0.017 (1) Å. In the crystal, weak C—H⋯O hydrogen bonds link mol­ecules into ladders along [010]. In addition, ππ inter­actions between inversion-related mol­ecules, with centroid–centroid distances in the range 3.679 (2)–3.876 (2) Å, complete a two-dimensional network parallel to (001).

1. Related literature

For therapeutic properties of coumarin derivatives, see: Lacy & O'Kennedy (2004[Lacy, A. & O'Kennedy, R. (2004). Curr. Pharm. Des. 10, 3797-3811.]); Mustafa et al. (2011[Mustafa, M. S., El-Abadelah, M. M., Zihlif, M. A., Naffa, R. G. & Mubarak, M. S. (2011). Molecules, 16, 4305-4317.]). For the biological activity of 2H-chromen-2-ones, see: Naik et al. (2012[Naik, R. J., Kulkarni, M. V., Pai, K. S. R. & Nayak, P. G. (2012). Chem. Biol. Drug Des. 80, 516-523.]). For applications of organic azides, see: Kusanur et al. (2010[Kusanur, R. A., Kulkarni, M. V., Kulkarni, G. M., Nayak, S. K., Guru Row, T. N., Ganesan, K. & Sun, C. M. (2010). J. Heterocycl. Chem. 47, 91-97.]). For structural features of coumarins, see: Moorthy et al. (2003[Moorthy, J. N., Venkatakrishnan, P. & Singh, A. S. (2003). CrystEngComm, 5, 507-513.]). For related structures, see: Gowda et al. (2010[Gowda, R., Basanagouda, M., Kulkarni, M. V. & Gowda, K. V. A. (2010). Acta Cryst. E66, o2906.]); Fun et al. (2011[Fun, H.-K., Goh, J. H., Wu, D. & Zhang, Y. (2011). Acta Cryst. E67, o136.]); Nagarajaiah et al. (2013[Nagarajaiah, H., Puttaraju, K. B., Shivashankar, K. & Begum, N. S. (2013). Acta Cryst. E69, o1056.]).

[Scheme 1]

2. Experimental

2.1. Crystal data

  • C13H13N3O2

  • Mr = 243.26

  • Triclinic, [P \overline 1]

  • a = 6.895 (2) Å

  • b = 7.862 (2) Å

  • c = 11.592 (4) Å

  • α = 72.218 (6)°

  • β = 79.662 (5)°

  • γ = 82.430 (6)°

  • V = 586.7 (3) Å3

  • Z = 2

  • Mo Kα radiation

  • μ = 0.10 mm−1

  • T = 100 K

  • 0.18 × 0.16 × 0.16 mm

2.2. Data collection

  • Bruker SMART APEX CCD detector diffractometer

  • Absorption correction: multi-scan (SADABS; Bruker, 1998[Bruker. (1998). SMART, SAINT and SADABS. Bruker Axs Inc., Madison, Wisconcin, USA.]) Tmin = 0.983, Tmax = 0.985

  • 3059 measured reflections

  • 2026 independent reflections

  • 1644 reflections with I > 2σ(I)

  • Rint = 0.013

2.3. Refinement

  • R[F2 > 2σ(F2)] = 0.051

  • wR(F2) = 0.150

  • S = 1.07

  • 2026 reflections

  • 165 parameters

  • H-atom parameters constrained

  • Δρmax = 0.34 e Å−3

  • Δρmin = −0.26 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
C5—H5⋯O2i 0.95 2.56 3.498 (2) 168
C13—H13C⋯O2ii 0.98 2.55 3.524 (3) 172
Symmetry codes: (i) x, y-1, z; (ii) -x, -y+1, -z+1.

Data collection: SMART (Bruker, 1998[Bruker. (1998). SMART, SAINT and SADABS. Bruker Axs Inc., Madison, Wisconcin, USA.]); cell refinement: SAINT (Bruker, 1998[Bruker. (1998). SMART, SAINT and SADABS. Bruker Axs Inc., Madison, Wisconcin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015[Sheldrick, G. M. (2015). Acta Cryst. C71, 3-8.]); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012[Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849-854.]) and PLATON (Spek, 2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.]); software used to prepare material for publication: WinGX (Farrugia, 2012[Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849-854.]).

Supporting information


Comment top

Coumarins are of great interest due to their biological properties (Lacy & Kennedy 2004). In particular, their physiological, bacteriostatic and anti- tumour activity (Mustafa et al., 2011) makes these compounds attractive for further backbone derivatization and screening for their therapeutic properties. In view of their extensive natural occurrence and biocompatibility, 2H-chromen-2-ones have been found to exhibit variety of biological activities (Naik et al., 2012). In addition, organic azides are an important class of 1,3-dipoles, which have been recently recognized as crucial functional groups in click chemistry (Kusanur et al., 2010). In view of the above, the title compound was isolated and the crystal structure is presented herein.

In the title compound (Fig. 1), the benzopyran ring system is essentially planar with a maximum deviation of 0.017 (1)Å for atom C10. Atom N1 of the azido group deviates by 0.168 (2)Å from the mean-plane of the benzopyran ring system while atoms N2 and N3, deviate by -0.489 (1) and -1.013 (2)Å, respectively from the opposite face of this ring system. In the crystal, weak C—H···O hydrogen bonds link molecules into ladders along [010] (Table 1, Fig.2). In addition, ππ interactions between inversion related molecules, with centroid–centroid distances in the range 3.679 (2)–3.876 (2)Å, complete a two-dimensional network parallel to (001).

Related literature top

For therapeutic properties of coumarin derivatives, see: Lacy & O'Kennedy (2004); Mustafa et al. (2011). For the biological activity of 2H-chromen-2-ones, see: Naik et al. (2012). For applications of organic azides, see: Kusanur et al. (2010). For structural features of coumarins, see: Moorthy et al. (2003). For related structures, see: Gowda et al. (2010); Fun et al. (2011); Nagarajaiah et al. (2013).

Experimental top

4-Bromomethyl-6-isopropylcoumarin (0.01 mol) was taken in acetone (20 ml) in a round bottomed flask. To this, sodium azide (0.012 mol, 0.78 g) in 5 ml of water was added drop wise with stirring for 3 hrs (reaction was monitored by TLC). The reaction mixture was poured into ice cold water, separated solid was filtered and recrystallized from ethyl acetate. (Yield 85%; colorless solid; mp 360 K).

Refinement top

H atoms were placed in calculated positions in a riding-model approximation with C—H = 0.95, 0.98 and 0.99Å for aromatic, methyl and methylene H-atoms respectively, with Uiso(H) = 1.5Ueq(C) for methyl H atoms and Uiso(H) = 1.2Ueq(C) for other hydrogen atoms.

Structure description top

Coumarins are of great interest due to their biological properties (Lacy & Kennedy 2004). In particular, their physiological, bacteriostatic and anti- tumour activity (Mustafa et al., 2011) makes these compounds attractive for further backbone derivatization and screening for their therapeutic properties. In view of their extensive natural occurrence and biocompatibility, 2H-chromen-2-ones have been found to exhibit variety of biological activities (Naik et al., 2012). In addition, organic azides are an important class of 1,3-dipoles, which have been recently recognized as crucial functional groups in click chemistry (Kusanur et al., 2010). In view of the above, the title compound was isolated and the crystal structure is presented herein.

In the title compound (Fig. 1), the benzopyran ring system is essentially planar with a maximum deviation of 0.017 (1)Å for atom C10. Atom N1 of the azido group deviates by 0.168 (2)Å from the mean-plane of the benzopyran ring system while atoms N2 and N3, deviate by -0.489 (1) and -1.013 (2)Å, respectively from the opposite face of this ring system. In the crystal, weak C—H···O hydrogen bonds link molecules into ladders along [010] (Table 1, Fig.2). In addition, ππ interactions between inversion related molecules, with centroid–centroid distances in the range 3.679 (2)–3.876 (2)Å, complete a two-dimensional network parallel to (001).

For therapeutic properties of coumarin derivatives, see: Lacy & O'Kennedy (2004); Mustafa et al. (2011). For the biological activity of 2H-chromen-2-ones, see: Naik et al. (2012). For applications of organic azides, see: Kusanur et al. (2010). For structural features of coumarins, see: Moorthy et al. (2003). For related structures, see: Gowda et al. (2010); Fun et al. (2011); Nagarajaiah et al. (2013).

Computing details top

Data collection: SMART (Bruker, 1998); cell refinement: SAINT (Bruker, 1998); data reduction: SAINT (Bruker, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and PLATON (Spek, 2009); software used to prepare material for publication: WinGX (Farrugia, 2012).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound. Displacement ellipsoids are drawn at the 50% probability level. H atoms are presented as small spheres of arbitrary radius.
[Figure 2] Fig. 2. Part of the crystal structure with weak hydrogen bonds shown as dashed lines. Only H atoms involved in hydrogen bonds are shown.
4-Azidomethyl-6-isopropyl-2H-chromen-2-one top
Crystal data top
C13H13N3O2Z = 2
Mr = 243.26F(000) = 256
Triclinic, P1Dx = 1.377 Mg m3
a = 6.895 (2) ÅMo Kα radiation, λ = 0.71073 Å
b = 7.862 (2) ÅCell parameters from 2028 reflections
c = 11.592 (4) Åθ = 1.9–25.0°
α = 72.218 (6)°µ = 0.10 mm1
β = 79.662 (5)°T = 100 K
γ = 82.430 (6)°Block, colourless
V = 586.7 (3) Å30.18 × 0.16 × 0.16 mm
Data collection top
Bruker SMART APEX CCD detector
diffractometer
1644 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.013
ω scansθmax = 25.0°, θmin = 1.9°
Absorption correction: multi-scan
(SADABS; Bruker, 1998)
h = 87
Tmin = 0.983, Tmax = 0.985k = 98
3059 measured reflectionsl = 139
2026 independent reflections
Refinement top
Refinement on F20 restraints
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.051H-atom parameters constrained
wR(F2) = 0.150 w = 1/[σ2(Fo2) + (0.0929P)2 + 0.0624P]
where P = (Fo2 + 2Fc2)/3
S = 1.07(Δ/σ)max < 0.001
2026 reflectionsΔρmax = 0.34 e Å3
165 parametersΔρmin = 0.26 e Å3
Crystal data top
C13H13N3O2γ = 82.430 (6)°
Mr = 243.26V = 586.7 (3) Å3
Triclinic, P1Z = 2
a = 6.895 (2) ÅMo Kα radiation
b = 7.862 (2) ŵ = 0.10 mm1
c = 11.592 (4) ÅT = 100 K
α = 72.218 (6)°0.18 × 0.16 × 0.16 mm
β = 79.662 (5)°
Data collection top
Bruker SMART APEX CCD detector
diffractometer
2026 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 1998)
1644 reflections with I > 2σ(I)
Tmin = 0.983, Tmax = 0.985Rint = 0.013
3059 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0510 restraints
wR(F2) = 0.150H-atom parameters constrained
S = 1.07Δρmax = 0.34 e Å3
2026 reflectionsΔρmin = 0.26 e Å3
165 parameters
Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
O10.21989 (18)0.72869 (15)0.55787 (11)0.0218 (4)
O20.25015 (19)0.97173 (16)0.40014 (12)0.0275 (4)
N10.3566 (3)0.5078 (2)0.18653 (14)0.0295 (4)
N20.2838 (2)0.46732 (19)0.11032 (14)0.0224 (4)
N30.2296 (3)0.4459 (2)0.02953 (15)0.0347 (5)
C10.3110 (3)0.3983 (2)0.31451 (15)0.0208 (4)
H1A0.42220.30690.33610.025*
H1B0.19110.33540.32450.025*
C20.2481 (3)0.8106 (2)0.43304 (16)0.0215 (4)
C30.2742 (3)0.6957 (2)0.35451 (16)0.0206 (4)
H30.28980.74880.26830.025*
C40.2773 (2)0.5161 (2)0.39858 (16)0.0185 (4)
C50.2560 (2)0.2462 (2)0.58662 (16)0.0190 (4)
H50.27450.16670.53740.023*
C60.2339 (3)0.1765 (2)0.71344 (16)0.0197 (4)
C70.2029 (3)0.2955 (2)0.78447 (17)0.0223 (4)
H70.18480.24960.87120.027*
C80.1980 (3)0.4781 (2)0.73103 (16)0.0212 (4)
H80.17810.55760.78030.025*
C90.2226 (2)0.5440 (2)0.60513 (16)0.0190 (4)
C100.2516 (2)0.4322 (2)0.52983 (16)0.0175 (4)
C110.2405 (3)0.0239 (2)0.77465 (16)0.0231 (5)
H110.28250.08530.70930.028*
C120.3913 (3)0.0852 (2)0.86437 (18)0.0292 (5)
H12A0.52300.05420.82050.044*
H12B0.39270.21520.90120.044*
H12C0.35460.02530.92890.044*
C130.0355 (3)0.0808 (2)0.83985 (18)0.0286 (5)
H13A0.01610.01130.89760.043*
H13B0.04570.20870.88440.043*
H13C0.05420.05880.77920.043*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0290 (7)0.0150 (7)0.0213 (7)0.0018 (5)0.0036 (6)0.0053 (5)
O20.0367 (8)0.0165 (7)0.0283 (8)0.0043 (6)0.0056 (6)0.0040 (6)
N10.0438 (10)0.0293 (9)0.0185 (9)0.0163 (8)0.0034 (7)0.0065 (7)
N20.0261 (9)0.0182 (8)0.0198 (8)0.0039 (6)0.0012 (7)0.0014 (6)
N30.0430 (11)0.0413 (11)0.0214 (9)0.0155 (8)0.0077 (8)0.0046 (8)
C10.0241 (9)0.0201 (9)0.0164 (9)0.0060 (7)0.0017 (7)0.0017 (7)
C20.0219 (9)0.0200 (10)0.0217 (10)0.0025 (7)0.0040 (7)0.0038 (8)
C30.0210 (9)0.0211 (9)0.0187 (9)0.0045 (7)0.0032 (7)0.0031 (8)
C40.0142 (8)0.0213 (9)0.0200 (9)0.0023 (7)0.0033 (7)0.0051 (7)
C50.0184 (9)0.0196 (9)0.0200 (9)0.0016 (7)0.0027 (7)0.0075 (8)
C60.0203 (9)0.0180 (9)0.0205 (9)0.0031 (7)0.0032 (7)0.0044 (7)
C70.0238 (9)0.0243 (10)0.0181 (9)0.0041 (7)0.0030 (7)0.0042 (8)
C80.0235 (9)0.0208 (9)0.0218 (10)0.0008 (7)0.0026 (8)0.0105 (8)
C90.0185 (9)0.0151 (9)0.0227 (10)0.0011 (7)0.0037 (7)0.0040 (7)
C100.0148 (8)0.0191 (9)0.0192 (9)0.0025 (7)0.0028 (7)0.0057 (7)
C110.0298 (10)0.0193 (9)0.0189 (10)0.0029 (8)0.0013 (8)0.0046 (7)
C120.0289 (10)0.0215 (10)0.0317 (11)0.0016 (8)0.0049 (9)0.0004 (8)
C130.0334 (11)0.0213 (10)0.0305 (11)0.0061 (8)0.0070 (9)0.0036 (8)
Geometric parameters (Å, º) top
O1—C21.382 (2)C6—C71.398 (3)
O1—C91.386 (2)C6—C111.515 (2)
O2—C21.207 (2)C7—C81.378 (2)
N1—N21.228 (2)C7—H70.9500
N1—C11.471 (2)C8—C91.378 (3)
N2—N31.133 (2)C8—H80.9500
C1—C41.508 (2)C9—C101.391 (3)
C1—H1A0.9900C11—C121.531 (3)
C1—H1B0.9900C11—C131.532 (3)
C2—C31.442 (3)C11—H111.0000
C3—C41.346 (2)C12—H12A0.9800
C3—H30.9500C12—H12B0.9800
C4—C101.450 (2)C12—H12C0.9800
C5—C61.391 (2)C13—H13A0.9800
C5—C101.407 (2)C13—H13B0.9800
C5—H50.9500C13—H13C0.9800
C2—O1—C9121.36 (14)C7—C8—C9119.10 (17)
N2—N1—C1116.42 (14)C7—C8—H8120.5
N3—N2—N1171.49 (17)C9—C8—H8120.5
N1—C1—C4109.91 (14)C8—C9—O1115.88 (16)
N1—C1—H1A109.7C8—C9—C10122.21 (16)
C4—C1—H1A109.7O1—C9—C10121.90 (16)
N1—C1—H1B109.7C9—C10—C5117.60 (16)
C4—C1—H1B109.7C9—C10—C4117.48 (15)
H1A—C1—H1B108.2C5—C10—C4124.92 (16)
O2—C2—O1116.82 (16)C6—C11—C12111.82 (15)
O2—C2—C3126.20 (17)C6—C11—C13111.03 (15)
O1—C2—C3116.98 (15)C12—C11—C13110.35 (15)
C4—C3—C2122.54 (17)C6—C11—H11107.8
C4—C3—H3118.7C12—C11—H11107.8
C2—C3—H3118.7C13—C11—H11107.8
C3—C4—C10119.70 (16)C11—C12—H12A109.5
C3—C4—C1121.56 (16)C11—C12—H12B109.5
C10—C4—C1118.72 (15)H12A—C12—H12B109.5
C6—C5—C10121.25 (16)C11—C12—H12C109.5
C6—C5—H5119.4H12A—C12—H12C109.5
C10—C5—H5119.4H12B—C12—H12C109.5
C5—C6—C7118.58 (16)C11—C13—H13A109.5
C5—C6—C11121.29 (16)C11—C13—H13B109.5
C7—C6—C11120.13 (16)H13A—C13—H13B109.5
C8—C7—C6121.25 (17)C11—C13—H13C109.5
C8—C7—H7119.4H13A—C13—H13C109.5
C6—C7—H7119.4H13B—C13—H13C109.5
N2—N1—C1—C4140.65 (17)C2—O1—C9—C8178.30 (14)
C9—O1—C2—O2177.52 (15)C2—O1—C9—C100.6 (2)
C9—O1—C2—C31.9 (2)C8—C9—C10—C50.2 (3)
O2—C2—C3—C4177.40 (17)O1—C9—C10—C5178.68 (14)
O1—C2—C3—C41.9 (3)C8—C9—C10—C4179.50 (15)
C2—C3—C4—C100.7 (3)O1—C9—C10—C40.6 (2)
C2—C3—C4—C1178.12 (15)C6—C5—C10—C90.5 (3)
N1—C1—C4—C35.5 (2)C6—C5—C10—C4178.70 (15)
N1—C1—C4—C10173.34 (14)C3—C4—C10—C90.6 (2)
C10—C5—C6—C71.3 (3)C1—C4—C10—C9179.43 (15)
C10—C5—C6—C11179.43 (15)C3—C4—C10—C5178.67 (16)
C5—C6—C7—C81.3 (3)C1—C4—C10—C50.2 (2)
C11—C6—C7—C8179.40 (15)C5—C6—C11—C12126.86 (18)
C6—C7—C8—C90.6 (3)C7—C6—C11—C1253.9 (2)
C7—C8—C9—O1178.76 (14)C5—C6—C11—C13109.42 (19)
C7—C8—C9—C100.2 (3)C7—C6—C11—C1369.9 (2)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C5—H5···O2i0.952.563.498 (2)168
C13—H13C···O2ii0.982.553.524 (3)172
Symmetry codes: (i) x, y1, z; (ii) x, y+1, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C5—H5···O2i0.952.563.498 (2)168
C13—H13C···O2ii0.982.553.524 (3)172
Symmetry codes: (i) x, y1, z; (ii) x, y+1, z+1.
 

Acknowledgements

MSK thanks the UGC for a UGC–BSR meritorious fellowship. KSS and DS are thankful to the Council of Scientific and Industrial Research, New Delhi, India, for financial assistance [grant No. 02 (0172)/13/EMR-II].

References

First citationBruker. (1998). SMART, SAINT and SADABS. Bruker Axs Inc., Madison, Wisconcin, USA.  Google Scholar
First citationFarrugia, L. J. (2012). J. Appl. Cryst. 45, 849–854.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationFun, H.-K., Goh, J. H., Wu, D. & Zhang, Y. (2011). Acta Cryst. E67, o136.  Web of Science CrossRef IUCr Journals Google Scholar
First citationGowda, R., Basanagouda, M., Kulkarni, M. V. & Gowda, K. V. A. (2010). Acta Cryst. E66, o2906.  Web of Science CSD CrossRef IUCr Journals Google Scholar
First citationKusanur, R. A., Kulkarni, M. V., Kulkarni, G. M., Nayak, S. K., Guru Row, T. N., Ganesan, K. & Sun, C. M. (2010). J. Heterocycl. Chem. 47, 91–97.  CAS Google Scholar
First citationLacy, A. & O'Kennedy, R. (2004). Curr. Pharm. Des. 10, 3797–3811.  Web of Science CrossRef PubMed CAS Google Scholar
First citationMoorthy, J. N., Venkatakrishnan, P. & Singh, A. S. (2003). CrystEngComm, 5, 507–513.  Web of Science CSD CrossRef CAS Google Scholar
First citationMustafa, M. S., El-Abadelah, M. M., Zihlif, M. A., Naffa, R. G. & Mubarak, M. S. (2011). Molecules, 16, 4305–4317.  Web of Science CrossRef CAS PubMed Google Scholar
First citationNagarajaiah, H., Puttaraju, K. B., Shivashankar, K. & Begum, N. S. (2013). Acta Cryst. E69, o1056.  CSD CrossRef IUCr Journals Google Scholar
First citationNaik, R. J., Kulkarni, M. V., Pai, K. S. R. & Nayak, P. G. (2012). Chem. Biol. Drug Des. 80, 516–523.  Web of Science CrossRef CAS PubMed Google Scholar
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationSheldrick, G. M. (2015). Acta Cryst. C71, 3–8.  Web of Science CrossRef IUCr Journals Google Scholar
First citationSpek, A. L. (2009). Acta Cryst. D65, 148–155.  Web of Science CrossRef CAS IUCr Journals Google Scholar

This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 71| Part 4| April 2015| Pages o227-o228
Follow Acta Cryst. E
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds