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Crystal structure of the co-crystalline adduct 1,3,6,8-tetra­aza­tri­cyclo­[4.4.1.13,8]do­decane (TATD)–4-bromo­phenol (1/2)

aUniversidad Nacional de Colombia, Sede Bogotá, Facultad de Ciencias, Departamento de Química, Cra 30 No. 45-03, Bogotá, Código Postal 111321, Colombia, and bInstitut für Anorganische Chemie, J. W. Goethe-Universität Frankfurt, Max-von Laue-Strasse 7, 60438 Frankfurt/Main, Germany
*Correspondence e-mail: ariverau@unal.edu.co

Edited by J. Simpson, University of Otago, New Zealand (Received 27 March 2015; accepted 2 April 2015; online 9 April 2015)

The structure of the 1:2 co-crystalline adduct C8H16N4·2C6H5BrO, (I), from the solid-state reaction of 1,3,6,8-tetra­aza­tri­cyclo­[4.4.1.13,8]dodecane (TATD) and 4-bromo­phenol, has been determined. The asymmetric unit of the title co-crystalline adduct comprises a half mol­ecule of aminal cage polyamine plus a 4-bromo­phenol mol­ecule. A twofold rotation axis generates the other half of the adduct. The primary inter-species association in the title compound is through two inter­molecular O—H⋯N hydrogen bonds. In the crystal, the adducts are linked by weak non-conventional C—H⋯O and C—H⋯Br hydrogen bonds, giving a two-dimensional supra­molecular structure parallel to the bc plane.

1. Chemical context

The main focus of the research in our laboratory is the synthesis of a variety of mol­ecules using cyclic aminals of the adamantane type. The prototype of these reactions is a Mannich-type reaction involving 1,3,6,8-tetra­aza­tri­cyclo­[4.4.1.13,8] dodecane (TATD) (II) with phenols which, in solution, affords di-Mannich bases of type (III) (Rivera et al., 1993[Rivera, A., Gallo, G. I., Gayón, M. E. & Joseph-Nathan, P. (1993). Synth. Commun. 23 2921-2929.], 2005[Rivera, A., Ríos-Motta, J., Quevedo, R. & Joseph-Nathan, P. (2005). Rev. Colomb. Quim. 34 105-115.]). These are common systems for the investigation of hydrogen bonding and proton transfer. Engaged in the development of greener synthetic pathways, we attempted a synthesis of a di-Mannich base under solvent-free conditions by simply grinding TATD and 4-bromo­phenol at room temperature without using any solvent in the initial step. We found that the reaction did not provide the di-Mannich base as desired. Instead, the title compound, (I)[link], was obtained in good yield. The reaction is run in the absence of solvent, there are no by-products, and the work-up procedure is easy. Recrystallization in an appropriate solvent gave the title compound in high yield.

[Scheme 2]
[Scheme 2]

2. Structural commentary

Co-crystal (I)[link] crystallized in the space group Fdd2 with one half-mol­ecule of 1,3,6,8-tetra­aza­tri­cyclo­[4.4.1.13,8]dodecane (TATD) and one mol­ecule of 4-bromo­phenol in the asymmetric unit; a twofold rotation axis generates the other half of the adduct held together by two inter­molecular O—H⋯N hydrogen bonds [O⋯N 2.705 (5) Å; O—H⋯N 158 (7)°)] (Fig. 1[link]). Unlike the situation in a related structure (Rivera et al., (2007[Rivera, A., Ríos-Motta, J., Hernández-Barragán, A. & Joseph-Nathan, P. (2007). J. Mol. Struct. 831, 180-186.]), where a 1:1 adduct formed via an O—H⋯N hydrogen bond between TATD and hydro­quinone, the title compound features an 1:2 adduct. Bond lengths in the TATD and 4-bromo­phenol mol­ecules in (I)[link] are within normal ranges (Allen et al., 1987[Allen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1-19.]) and are comparable to those found in similar structures (Rivera et al., 2007[Rivera, A., Ríos-Motta, J., Hernández-Barragán, A. & Joseph-Nathan, P. (2007). J. Mol. Struct. 831, 180-186.]; Tse et al., 1977[Tse, C.-S., Wong, Y.-S. & Mak, T. C. W. (1977). J. Appl. Cryst. 10, 68-69.]). The H atom of the phenolic –OH group deviates slightly from the benzene ring plane, subtending a torsion angle of 8(5)°.

[Figure 1]
Figure 1
The mol­ecular structure of the title adduct. Displacement ellipsoids are drawn at the 50% probability level. H atoms bonded to C atoms are omitted for clarity. Hydrogen bonds are drawn as dashed lines. Atoms labelled with the suffix A are generated using the symmetry operator (−x − [{1\over 2}], −y − [{1\over 2}], z).

A significant reduction in the O⋯N distance is observed when the distance and angle in the O1—H1⋯N1 hydrogen bond [O⋯N 2.705 (5) Å; O—H⋯N 158 (7)°)] in the title compound are compared to the values found in the TATD:hydro­quinone, 1:1 adduct [O⋯N 2.767 (2) Å; O—H⋯N 156.3 (10)°)] (Rivera et al., 2007[Rivera, A., Ríos-Motta, J., Hernández-Barragán, A. & Joseph-Nathan, P. (2007). J. Mol. Struct. 831, 180-186.]). Also, the C1—O1 bond length observed here [1.355 (6) Å], is shorter than that in the hydro­quinone co-crystal. This indicates an increase in hydrogen-bonding strength in the title compound, which may be due to the considerable differences in the pKa values between the species involved in the hydrogen bond (Majerz et al., 1997[Majerz, I., Malarski, Z. & Sobczyk, L. (1997). Chem. Phys. Lett. 274, 361-364.]). Compared to hydro­quinone (pKa = 9.85), p-bromo­phenol is more acidic (pKa = 9.37) (Lide, 2003[Lide, D. R. (2003). In CRC Handbook of Chemistry and Physics. Boca Raton, FL: CRC Press.]).

3. Supra­molecular features

In the crystal of the title compound, the adducts are weakly linked peripherally through both non-conventional C—H⋯O and C—H⋯Br hydrogen bonds (Table 1[link]) giving a two dimensional supra­molecular structure parallel to the bc plane. (Fig. 2[link]). This is similar to the structure of the 4-bromo­phenol adduct with urotropine (Tse et al., 1977[Tse, C.-S., Wong, Y.-S. & Mak, T. C. W. (1977). J. Appl. Cryst. 10, 68-69.]).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
O1—H1⋯N11 0.78 (7) 1.97 (7) 2.705 (5) 158 (7)
C3—H3⋯O1i 0.95 2.42 3.347 (6) 164
C13—H13A⋯Br1ii 0.99 2.89 3.833 (6) 159
Symmetry codes: (i) [-x-{\script{1\over 2}}, -y-1, z+{\script{1\over 2}}]; (ii) x, y, z-1.
[Figure 2]
Figure 2
The crystal packing of the title compound, showing two of the chains that extend along the crystal c-axis direction. C—H⋯O and C—H⋯Br hydrogen bonds are drawn as dashed lines.

4. Database survey

A database search (CSD version 5.36, November 2014 plus two updates) for 4-bromo­phenol yielded 17 hits with 21 fragments. The mean C—O bond length in these structures is 1.35 (5) Å and the mean C—Br bond length is 1.91 (3) Å. These values are in excellent agreement with those of the title compound, i.e. O1—C1 1.355 (6) and Br1—C4 1.907 (5) Å.

A database search for 1,3,6,8-tetra­aza­tri­cyclo­[4.4.1.13,8]dodecane yielded only three hits, two determinations of the compound itself (Murray-Rust, 1974[Murray-Rust, P. (1974). J. Chem. Soc. Perkin Trans. 2, pp. 1136-1141.]; Rivera et al., 2014[Rivera, A., Ríos-Motta, J. & Bolte, M. (2014). Acta Cryst. E70, o266.]) and a co-crystal of the aminal with hydro­quinone (Rivera et al., 2007[Rivera, A., Ríos-Motta, J., Hernández-Barragán, A. & Joseph-Nathan, P. (2007). J. Mol. Struct. 831, 180-186.]). While the mol­ecules of 1,3,6,8-tetra­aza­tri­cyclo[4.4.1.13,8]dodecane itself have [\overline{4}]2m symmetry, the mol­ecules in the co-crystal of TATD with hydro­quinone have mirror symmetry. In the title compound, on the other hand, the 1,3,6,8-tetra­aza­tri­cyclo­[4.4.1.13,8]dodecane mol­ecule displays C2 symmetry.

5. Synthesis and crystallization

1,3,6,8-tetra­aza­tri­cyclo­[4.4.1.13,8]dodecane (TATD) (0.21g, 1.25 mmol) and 4-bromo­phenol (0.43g, 2.5 mmol) were manually mixed in a mortar with pestle at room temperature for 20 min as required to complete the reaction (TLC). The mixture was then dissolved in a minimum amount of methanol and left to crystallize at room temperature. Subsequent recrystallization with MeOH then yielded the title compound as white crystals in 78% yield, m.p. = 367–368 K.

6. Refinement details

Crystal data, data collection and structure refinement details are summarized in Table 2[link]. All the H atoms were located in a difference electron density map. The hydroxyl H atom was refined freely, while C-bound H atoms were fixed geometric­ally (C—H = 0.95 or 0.99 Å) and refined using a riding-model approximation, with Uiso(H) set to 1.2Ueq of the parent atom.

Table 2
Experimental details

Crystal data
Chemical formula C8H16N4·2C6H5BrO
Mr 514.27
Crystal system, space group Orthorhombic, Fdd2
Temperature (K) 173
a, b, c (Å) 20.693 (2), 21.7954 (18), 9.4649 (9)
V3) 4268.8 (7)
Z 8
Radiation type Mo Kα
μ (mm−1) 3.82
Crystal size (mm) 0.29 × 0.27 × 0.23
 
Data collection
Diffractometer Stoe IPDS II two-circle
Absorption correction Multi-scan (MULABS; Spek, 2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.]; Blessing, 1995[Blessing, R. H. (1995). Acta Cryst. A51, 33-38.])
Tmin, Tmax 0.847, 0.972
No. of measured, independent and observed [I > 2σ(I)] reflections 5997, 1996, 1833
Rint 0.062
(sin θ/λ)max−1) 0.608
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.032, 0.069, 1.01
No. of reflections 1996
No. of parameters 132
No. of restraints 1
H-atom treatment H atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å−3) 0.24, −0.41
Absolute structure Flack x determined using 792 quotients [(I+)−(I)]/[(I+)+(I)] (Parsons et al., 2013[Parsons, S., Flack, H. D. & Wagner, T. (2013). Acta Cryst. B69, 249-259.])
Absolute structure parameter 0.003 (16)
Computer programs: X-AREA (Stoe & Cie, 2001[Stoe & Cie (2001). X-AREA. Stoe & Cie, Darmstadt, Germany.]), SHELXS97 and XP in SHELXTL-Plus (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]), SHELXL2014 (Sheldrick, 2015[Sheldrick, G. M. (2015). Acta Cryst. C71, 3-8.]) and Mercury (Macrae et al., 2006[Macrae, C. F., Edgington, P. R., McCabe, P., Pidcock, E., Shields, G. P., Taylor, R., Towler, M. & van de Streek, J. (2006). J. Appl. Cryst. 39, 453-457.]).

Supporting information


Computing details top

Data collection: X-AREA (Stoe & Cie, 2001); cell refinement: X-AREA (Stoe & Cie, 2001); data reduction: X-AREA (Stoe & Cie, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: XP in SHELXTL-Plus (Sheldrick, 2008) and Mercury (Macrae et al., 2006); software used to prepare material for publication: SHELXL2014 (Sheldrick, 2015).

1,3,6,8-Tetraazatricyclo[4.4.1.13,8]dodecane–4-bromophenol (2/1) top
Crystal data top
C8H16N4·2C6H5BrODx = 1.600 Mg m3
Mr = 514.27Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Fdd2Cell parameters from 7202 reflections
a = 20.693 (2) Åθ = 3.7–26.0°
b = 21.7954 (18) ŵ = 3.82 mm1
c = 9.4649 (9) ÅT = 173 K
V = 4268.8 (7) Å3Block, colourless
Z = 80.29 × 0.27 × 0.23 mm
F(000) = 2080
Data collection top
Stoe IPDS II two-circle
diffractometer
1833 reflections with I > 2σ(I)
Radiation source: Genix 3D IµS microfocus X-ray sourceRint = 0.062
ω scansθmax = 25.6°, θmin = 3.7°
Absorption correction: multi-scan
(MULABS; Spek, 2009; Blessing, 1995)
h = 2224
Tmin = 0.847, Tmax = 0.972k = 2526
5997 measured reflectionsl = 1111
1996 independent reflections
Refinement top
Refinement on F2Hydrogen site location: mixed
Least-squares matrix: fullH atoms treated by a mixture of independent and constrained refinement
R[F2 > 2σ(F2)] = 0.032 w = 1/[σ2(Fo2) + (0.0386P)2]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.069(Δ/σ)max < 0.001
S = 1.01Δρmax = 0.24 e Å3
1996 reflectionsΔρmin = 0.41 e Å3
132 parametersAbsolute structure: Flack x determined using 792 quotients [(I+)-(I-)]/[(I+)+(I-)] (Parsons et al., 2013)
1 restraintAbsolute structure parameter: 0.003 (16)
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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Br10.11272 (3)0.43922 (2)1.02771 (5)0.03734 (18)
O10.2465 (2)0.40437 (17)0.4684 (4)0.0311 (9)
H10.233 (4)0.375 (3)0.432 (7)0.036 (18)*
C10.2172 (3)0.4091 (2)0.5959 (5)0.0232 (11)
C20.2281 (3)0.4622 (2)0.6734 (6)0.0288 (12)
H20.25670.49260.63790.035*
C30.1978 (3)0.4710 (2)0.8016 (5)0.0281 (11)
H30.20480.50770.85360.034*
C40.1570 (3)0.4262 (2)0.8536 (5)0.0246 (10)
C50.1468 (2)0.37234 (18)0.7795 (7)0.0252 (10)
H50.11900.34160.81650.030*
C60.1773 (3)0.3635 (2)0.6514 (5)0.0257 (11)
H60.17110.32630.60090.031*
N110.2299 (2)0.30437 (16)0.3032 (4)0.0241 (9)
N120.2997 (2)0.2824 (2)0.0903 (4)0.0276 (10)
C110.25000.25000.3809 (7)0.0278 (16)
H11A0.21370.23790.44310.033*0.5
H11B0.28630.26210.44310.033*0.5
C120.2756 (3)0.3255 (2)0.1929 (6)0.0354 (14)
H12A0.25420.35920.14040.042*
H12B0.31340.34360.24160.042*
C130.1623 (3)0.3018 (2)0.2559 (7)0.0398 (14)
H13A0.14970.34310.22270.048*
H13B0.13490.29190.33860.048*
C140.1470 (3)0.2560 (3)0.1394 (6)0.0389 (13)
H14A0.11200.22870.17340.047*
H14B0.12980.27900.05740.047*
C150.25000.25000.0114 (7)0.0314 (16)
H15A0.22820.28010.05070.038*0.5
H15B0.27180.21990.05070.038*0.5
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Br10.0464 (3)0.0333 (2)0.0323 (2)0.0043 (3)0.0102 (3)0.0045 (2)
O10.039 (3)0.0219 (18)0.0323 (19)0.0044 (18)0.0097 (17)0.0049 (15)
C10.021 (3)0.022 (2)0.027 (2)0.004 (2)0.001 (2)0.0017 (19)
C20.032 (3)0.020 (2)0.034 (3)0.003 (2)0.003 (2)0.001 (2)
C30.034 (3)0.020 (2)0.030 (3)0.001 (2)0.005 (2)0.005 (2)
C40.029 (3)0.024 (2)0.021 (2)0.004 (2)0.004 (2)0.0013 (18)
C50.026 (3)0.0200 (18)0.030 (2)0.0030 (18)0.001 (3)0.002 (3)
C60.033 (3)0.018 (2)0.027 (2)0.003 (2)0.002 (2)0.0007 (18)
N110.032 (2)0.0210 (18)0.019 (2)0.0012 (17)0.0013 (17)0.0048 (15)
N120.025 (2)0.036 (2)0.0222 (19)0.009 (2)0.0016 (18)0.0016 (17)
C110.043 (5)0.024 (3)0.016 (3)0.005 (3)0.0000.000
C120.050 (4)0.027 (3)0.029 (3)0.014 (3)0.006 (2)0.001 (2)
C130.034 (3)0.041 (3)0.045 (4)0.006 (2)0.002 (3)0.004 (3)
C140.027 (3)0.061 (4)0.029 (3)0.006 (3)0.003 (2)0.001 (3)
C150.034 (4)0.046 (4)0.015 (3)0.006 (3)0.0000.000
Geometric parameters (Å, º) top
Br1—C41.907 (5)N12—C151.453 (6)
O1—C11.355 (6)N12—C14i1.462 (8)
O1—H10.78 (7)C11—N11i1.456 (5)
C1—C21.388 (7)C11—H11A0.9900
C1—C61.393 (7)C11—H11B0.9900
C2—C31.380 (8)C12—H12A0.9900
C2—H20.9500C12—H12B0.9900
C3—C41.381 (7)C13—C141.520 (8)
C3—H30.9500C13—H13A0.9900
C4—C51.384 (7)C13—H13B0.9900
C5—C61.380 (8)C14—N12i1.462 (8)
C5—H50.9500C14—H14A0.9900
C6—H60.9500C14—H14B0.9900
N11—C111.456 (5)C15—N12i1.453 (6)
N11—C131.470 (8)C15—H15A0.9900
N11—C121.482 (7)C15—H15B0.9900
N12—C121.441 (7)
C1—O1—H1107 (5)N11—C11—H11B107.5
O1—C1—C2117.4 (5)N11i—C11—H11B107.5
O1—C1—C6123.1 (5)H11A—C11—H11B107.0
C2—C1—C6119.5 (5)N12—C12—N11119.5 (4)
C3—C2—C1120.4 (5)N12—C12—H12A107.4
C3—C2—H2119.8N11—C12—H12A107.4
C1—C2—H2119.8N12—C12—H12B107.4
C2—C3—C4119.6 (4)N11—C12—H12B107.4
C2—C3—H3120.2H12A—C12—H12B107.0
C4—C3—H3120.2N11—C13—C14116.4 (5)
C3—C4—C5120.8 (5)N11—C13—H13A108.2
C3—C4—Br1119.8 (4)C14—C13—H13A108.2
C5—C4—Br1119.4 (4)N11—C13—H13B108.2
C6—C5—C4119.6 (4)C14—C13—H13B108.2
C6—C5—H5120.2H13A—C13—H13B107.3
C4—C5—H5120.2N12i—C14—C13116.6 (5)
C5—C6—C1120.1 (4)N12i—C14—H14A108.1
C5—C6—H6119.9C13—C14—H14A108.1
C1—C6—H6119.9N12i—C14—H14B108.1
C11—N11—C13113.2 (3)C13—C14—H14B108.1
C11—N11—C12115.3 (4)H14A—C14—H14B107.3
C13—N11—C12113.9 (4)N12i—C15—N12118.2 (6)
C12—N12—C15114.7 (4)N12i—C15—H15A107.8
C12—N12—C14i114.9 (4)N12—C15—H15A107.8
C15—N12—C14i114.8 (4)N12i—C15—H15B107.8
N11—C11—N11i119.3 (5)N12—C15—H15B107.8
N11—C11—H11A107.5H15A—C15—H15B107.1
N11i—C11—H11A107.5
O1—C1—C2—C3177.5 (5)C12—N11—C11—N11i51.2 (3)
C6—C1—C2—C32.7 (8)C15—N12—C12—N1155.6 (7)
C1—C2—C3—C41.0 (8)C14i—N12—C12—N1180.7 (7)
C2—C3—C4—C50.7 (8)C11—N11—C12—N1250.6 (7)
C2—C3—C4—Br1178.0 (4)C13—N11—C12—N1282.8 (6)
C3—C4—C5—C60.6 (8)C11—N11—C13—C1469.9 (6)
Br1—C4—C5—C6178.1 (4)C12—N11—C13—C1464.4 (6)
C4—C5—C6—C11.2 (8)N11—C13—C14—N12i2.4 (7)
O1—C1—C6—C5177.4 (5)C12—N12—C15—N12i53.9 (3)
C2—C1—C6—C52.8 (8)C14i—N12—C15—N12i82.4 (4)
C13—N11—C11—N11i82.4 (4)
Symmetry code: (i) x1/2, y1/2, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H1···N110.78 (7)1.97 (7)2.705 (5)158 (7)
C3—H3···O1ii0.952.423.347 (6)164
C13—H13A···Br1iii0.992.893.833 (6)159
Symmetry codes: (ii) x1/2, y1, z+1/2; (iii) x, y, z1.
 

Acknowledgements

We acknowledge the financial support provided to us by the Dirección de Investigaciones, Sede Bogotá (DIB) at the Universidad Nacional de Colombia. JMU and JJR thank COLCIENCIAS for a fellowship.

References

First citationAllen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1–19.  CSD CrossRef Web of Science Google Scholar
First citationBlessing, R. H. (1995). Acta Cryst. A51, 33–38.  CrossRef CAS Web of Science IUCr Journals Google Scholar
First citationLide, D. R. (2003). In CRC Handbook of Chemistry and Physics. Boca Raton, FL: CRC Press.  Google Scholar
First citationMacrae, C. F., Edgington, P. R., McCabe, P., Pidcock, E., Shields, G. P., Taylor, R., Towler, M. & van de Streek, J. (2006). J. Appl. Cryst. 39, 453–457.  Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
First citationMajerz, I., Malarski, Z. & Sobczyk, L. (1997). Chem. Phys. Lett. 274, 361–364.  CrossRef CAS Web of Science Google Scholar
First citationMurray-Rust, P. (1974). J. Chem. Soc. Perkin Trans. 2, pp. 1136–1141.  Google Scholar
First citationParsons, S., Flack, H. D. & Wagner, T. (2013). Acta Cryst. B69, 249–259.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationRivera, A., Gallo, G. I., Gayón, M. E. & Joseph-Nathan, P. (1993). Synth. Commun. 23 2921–2929.  CrossRef CAS Web of Science Google Scholar
First citationRivera, A., Ríos-Motta, J. & Bolte, M. (2014). Acta Cryst. E70, o266.  CSD CrossRef IUCr Journals Google Scholar
First citationRivera, A., Ríos-Motta, J., Hernández-Barragán, A. & Joseph-Nathan, P. (2007). J. Mol. Struct. 831, 180–186.  Web of Science CSD CrossRef CAS Google Scholar
First citationRivera, A., Ríos-Motta, J., Quevedo, R. & Joseph-Nathan, P. (2005). Rev. Colomb. Quim. 34 105–115.  CAS 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
First citationStoe & Cie (2001). X-AREA. Stoe & Cie, Darmstadt, Germany.  Google Scholar
First citationTse, C.-S., Wong, Y.-S. & Mak, T. C. W. (1977). J. Appl. Cryst. 10, 68–69.  CSD CrossRef IUCr Journals Web of Science Google Scholar

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