2-Methyl-4-(4-nitro­phen­yl)but-3-yn-2-ol: crystal structure, Hirshfeld surface analysis and computational chemistry study

Caracelli, I.; Zukerman-Schpector, J.; Schwab, R.S.; Silva, E.M. da; Jotani, M.M.; Tiekink, E.R.T.

doi:10.1107/S2056989019010284

research communications

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ISSN: 2056-9890

Volume 75| Part 8| August 2019| Pages 1232-1238

https://doi.org/10.1107/S2056989019010284

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2-Methyl-4-(4-nitrophenyl)but-3-yn-2-ol: crystal structure, Hirshfeld surface analysis and computational chemistry study

Ignez Caracelli,^a Julio Zukerman-Schpector,^b ‡ Ricardo S. Schwab,^b Everton M. da Silva,^b Mukesh M. Jotani ^c and Edward R. T. Tiekink ^d ^*

^aDepartamento de Física, Universidade Federal de São Carlos, 13565-905 São Carlos, SP, Brazil, ^bDepartamento de Química, Universidade Federal de São Carlos, 13565-905 São Carlos, SP, Brazil, ^cDepartment of Physics, Bhavan's Sheth R. A. College of Science, Ahmedabad, Gujarat 380001, India, and ^dResearch Centre for Crystalline Materials, School of Science and Technology, Sunway University, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia
^*Correspondence e-mail: edwardt@sunway.edu.my

Edited by W. T. A. Harrison, University of Aberdeen, Scotland (Received 17 July 2019; accepted 18 July 2019; online 23 July 2019)

The di-substituted acetylene residue in the title compound, C₁₁H₁₁NO₃, is capped at either end by di-methylhydroxy and 4-nitrobenzene groups; the nitro substituent is close to co-planar with the ring to which it is attached [dihedral angle = 9.4 (3)°]. The most prominent feature of the molecular packing is the formation, via hydroxy-O—H⋯O(hydroxy) hydrogen bonds, of hexameric clusters about a site of symmetry $[\overline{3}]$ . The aggregates are sustained by 12-membered {⋯OH}₆ synthons and have the shape of a flattened chair. The clusters are connected into a three-dimensional architecture by benzene-C—H⋯O(nitro) interactions, involving both nitro-O atoms. The aforementioned interactions are readily identified in the calculated Hirshfeld surface. Computational chemistry indicates there is a significant energy, primarily electrostatic in nature, associated with the hydroxy-O—H⋯O(hydroxy) hydrogen bonds. Dispersion forces are more important in the other identified but, weaker intermolecular contacts.

Keywords: crystal structure; acetylene; hydrogen bonding; Hirshfeld surface analysis; NCI plots; computational chemistry.

CCDC reference: 1941466

1. Chemical context

Protected acetylenes represent a highly privileged class of synthetic intermediates for the construction of a variety of different organic compounds (Tan et al., 2013 ). The preparation of protected arylacetylenes can be achieved by the palladium-catalysed Sonogashira cross-coupling of mono-protected acetylenes, such as trimethylsilylacetylene (TMSA), triisopropysilylacetylene (TIPSA) and 2-methyl-3-butyn-2-ol (MEBYNOL), with aryl halides (Hundertmark et al., 2000 ; Erdélyi & Gogoll, 2001 ). Despite the relevance of protected acetylenes, the release of the protecting group remains a challenge. While trialkylsilyl groups can be readily removed by treatment with bases or fluoride salts under mild reaction conditions, trialkylsilylacetylenes are rather expensive, in comparison to MEYBNOL, thereby limiting their use to small-scale synthesis. Thus, MEBYNOL can be viewed as one alternative to other acetylene sources. Nevertheless, the reaction conditions for the release of the 2-hydroxyisopropyl protecting group usually requires harsh reaction conditions. Hence, several synthetic routes combine the release of the terminal acetylene with a further transformation, without the isolation of the intermediate (Li et al., 2015 ). It was in the context of such considerations that the title acetylene compound, (I), previously reported (Bleicher et al., 1998 ), was isolated and crystallized. Herein, the crystal and molecular structures of (I) are described along with a detailed analysis of the molecular packing by Hirshfeld surface analysis, non-covalent interaction plots and computational chemistry.

2. Structural commentary

The molecular structure of (I), Fig. 1, features a di-substituted acetylene residue. At one end, the acetylene terminates with a di-methylhydroxy substituent and at the other end, with a 4-nitrobenzene group. The nitro group is slightly inclined out of the plane of the benzene ring to which it is connected, with the dihedral angle between the planes being 9.4 (3)°.

Figure 1
The molecular structure of (I)

, showing the atom-labelling scheme and displacement ellipsoids at the 35% probability level.

3. Supramolecular features

The spectacular feature of the molecular packing of (I) is the presence of hexameric clusters connected by hydroxy-O—H⋯O(hydroxy) hydrogen bonds, Table 1. As seen from Fig. 2(a), the six-molecule aggregates are sustained by 12-membered {⋯OH}₆ synthons. The aggregates are disposed about a site of symmetry $[\overline{3}]$ so the rings have the shape of a flattened chair, Fig. 2(b). The crystal also features weak benzene-C—H⋯O(nitro) interactions, involving both nitro-O atoms. In essence, one nitro group of one molecule forms two such interactions with two symmetry-related molecules to form a supramolecular chain along the c-axis direction with helical symmetry (3₁ screw axis), Fig. 3(a). An end-on view of the chain is shown in Fig. 3(b). These weak benzene-C—H⋯O(nitro) interactions serve to link the six-molecule aggregates into a three-dimensional architecture, Fig. 4.

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1O⋯O1ⁱ	0.82	1.87	2.682 (2)	173
C10—H10⋯O3ⁱⁱ	0.93	2.67	3.548 (3)	157
C11—H11⋯O2ⁱⁱⁱ	0.93	2.68	3.467 (3)	143
Symmetry codes: (i) $[x-y+{\script{1\over 3}}, x-{\script{1\over 3}}, -z+{\script{5\over 3}}]$ ; (ii) $[-x+y+{\script{2\over 3}}, -x+{\script{4\over 3}}, z+{\script{1\over 3}}]$ ; (iii) $[-y+{\script{4\over 3}}, x-y+{\script{2\over 3}}, z+{\script{2\over 3}}]$ .

Figure 2
Hydrogen bonding in the crystal of (I)

: (a) an end-on view of the hexagon sustained by hydroxy-O—H⋯O(hydroxy) hydrogen bonding (shown as orange dashed lines) and (b) a side-on view. Non-participating hydrogen atoms have been removed for reasons of clarity.

Figure 3
Details of benzene-C—H⋯O(nitro) interactions (shown as blue dashed lines) in the crystal of (I)

: (a) a view of the supramolecular chain along the c-axis direction and (b) an end-on view of the chain.

Figure 4
A view of the unit-cell contents of (I)

shown in projection down the c axis. The hydroxy-O—H⋯O(hydroxy) hydrogen bonding and benzene-C—H⋯O(nitro) interactions are shown as orange and blue dashed lines, respectively.

4. Hirshfeld surface analysis

The Hirshfeld surface calculations for (I) were performed in accord with protocols described in a recently published paper (Tan et al., 2019 ) employing Crystal Explorer 17 (Turner et al., 2017 ). On the Hirshfeld surfaces mapped over d_norm in Fig. 5(a), the donors and acceptors of O—H⋯O hydrogen bond involving the atoms of the hydroxyl group are characterized as bright-red spots. The faint-red spots near the phenyl-H10, H11 and nitro-O2, O3 atoms on the d_norm-mapped Hirshfeld surface in Fig. 5(b) represent the effect of weak C—H⋯O interactions as listed in Table 1. The Hirshfeld surface mapped over electrostatic potential in Fig. 6 also illustrates the donors and acceptors of the indicated interactions through blue and red regions corresponding to positive and negative electrostatic potentials, respectively. In the view of a surface mapped with the shape-index property, Fig. 7(a), the C—H⋯π/π⋯H—C contacts listed in Table 2 are evident as the blue bump and a bright-orange region about the participating atoms. The overlap between benzene (C6–C11) ring of a reference molecule within the Hirshfeld surface mapped over curvedness and the symmetry related ring, Fig. 7(b) is an indication of the π–π stacking interaction between them [centroid–centroid distance = 3.7873 (14) Å; symmetry operation: 1 − x, 1 − y, 1 − z].

Table 2
Summary of short interatomic contacts (Å) in (I)

The interatomic distances are calculated in Crystal Explorer 17 (Turner et al., 2017) whereby the X—H bond lengths are adjusted to their neutron values.

Contact	Distance	Symmetry operation
O1⋯H3A	2.71	$[{1\over 3}]$ + y, $[{2\over 3}]$ − x + y, $[{5\over 3}]$ − z
O2⋯H2B	2.69	$[{2\over 3}]$ − y, $[{1\over 3}]$ + x − y, − $[{2\over 3}]$ + z
O3⋯H2A	2.69	1 − x, 1 − y, 1 − z
C1⋯H1O	2.85	$[{1\over 3}]$ + y, $[{2\over 3}]$ − x + y, $[{5\over 3}]$ − z
C5⋯H3C	2.79	$[{1\over 3}]$ + y, $[{2\over 3}]$ − x + y, $[{2\over 3}]$ − z
C7⋯H2C	2.85	$[{1\over 3}]$ + y, $[{2\over 3}]$ − x + y, $[{2\over 3}]$ − z
C8⋯H2C	2.80	$[{1\over 3}]$ + y, $[{2\over 3}]$ − x + y, $[{2\over 3}]$ − z

Figure 5
Two views of the Hirshfeld surface for (I)

mapped over d_norm: (a) in the range −0.202 to +1.400 arbitrary units and (b) in the range −0.102 to +1.400 arbitrary units, highlighting, respectively, intermolecular O—H⋯O and C—H⋯O interactions through black dashed lines.

Figure 6
A view of the Hirshfeld surface for (I)

mapped over the electrostatic potential in the range −0.098 to + 0.180 atomic units. The red and blue regions represent negative and positive electrostatic potentials, respectively, and show the acceptors and donors of intermolecular interactions, respectively.

Figure 7
(a) A view of the Hirshfeld surface for (I)

mapped with the shape-index property, highlighting intermolecular C—H⋯π/π⋯H—C contacts by blue bumps and bright-orange concave regions, respectively, and (b) a view of the Hirshfeld surface mapped over curvedness, highlighting π—π contacts between symmetry-related (C6-C11) rings.

The overall two-dimensional fingerprint plot for (I), Fig. 8(a), and those delineated into H⋯H, O⋯H/H⋯O, C⋯H/H⋯C and C⋯C contacts (McKinnon et al., 2007 ) are illustrated in Fig. 8(b)–(e), respectively, and provide more information on the influence of short interatomic contacts upon the molecular packing. The percentage contributions from the different interatomic contacts to the Hirshfeld surface are summarized in Table 3. The greatest contribution to the Hirshfeld surface of 38.2% are derived from H⋯H contacts but these exert a negligible influence on the packing, at least in terms of directional interactions, as the interatomic distances are greater than sum of their van der Waals radii. The pair of long spikes with their tips at d_e + d_i ∼1.8 Å in the fingerprint plot delineated into O⋯H/H⋯O contacts, Fig. 8(c), are due to the presence of the O—H⋯O hydrogen bond, whereas the points corresponding to comparatively weak intermolecular C—H⋯O interactions, Table 1, and the short interatomic O⋯H/H⋯O contacts are merged within the plot, Table 2. The presence of the C—H⋯π contact, formed by the methyl-H2C atom and the benzene (C6–C11) ring, results in short interatomic C⋯H/H⋯C contacts, Table 2 and Fig. 7(a), and by the pair of forceps-like tips at d_e + d_i ∼2.8 Å in Fig. 8(d). The points corresponding to other such short interatomic contacts involving the acetylene-C5 and methyl-C3—H3c atoms at longer separations are merged within the plot. The arrow-shaped distribution of points around d_e + d_i ∼3.6 Å in the fingerprint plot delineated into C⋯C contacts, Fig. 8(e), indicate π–π overlap between symmetry-related benzene (C6–C11) rings, as illustrated in Fig. 7(b). The small percentage contributions from the other interatomic contacts listed in Table 3 have negligible influence upon the molecular packing as their separations are greater than the sum of the respective van der Waals radii.

Table 3
Percentage contributions of interatomic contacts to the Hirshfeld surface for (I)

Contact	Percentage contribution
H⋯H	38.2
O⋯H/H⋯O	32.1
C⋯H/H⋯C	20.0
C⋯C	4.2
N⋯O/O⋯N	1.7
O⋯O	1.6
C⋯N/N⋯C	1.0
N⋯H/H⋯N	0.8
C⋯O/O⋯C	0.4

Figure 8
(a) The full two-dimensional fingerprint plot for (I)

and (b)–(e) those delineated into H⋯H, O⋯H/H⋯O, C⋯H/H⋯C and C⋯C contacts, respectively.

5. Interaction energies

The pairwise interaction energies between the molecules within the crystal were calculated by summing up four energy components comprising electrostatic (E_ele), polarization (E_pol), dispersion (E_dis) and exchange-repulsion (E_rep) terms after applying relevant scale factors (Turner et al., 2017). These energies were obtained by using the wave function calculated at the B3LYP/6-31G(d,p) level. The strength and the nature of intermolecular interactions in terms of their energies are quantitatively summarized in Table 4. The energies calculated for the different intermolecular interactions indicate that the electrostatic contribution is dominant in the O—H⋯O hydrogen bond whereas the dispersive component has a significant influence due to the presence of short interatomic C⋯H/H⋯C and O⋯H/H⋯O contacts occurring between the same pair of molecules. The C—H⋯O2(nitro) interaction has almost the same contributions from the electrostatic and dispersive components. This is in contrast to a major contribution only from the dispersive component for the analogous contact involving the nitro-O3 atom. The dispersion energy component makes the major contribution to the relevant pairs of molecules involved in other short interatomic contacts, Table 4, as well as in C—H⋯π and π–π stacking interactions. It is also evident from a comparison of the total energies of intermolecular interactions, Table 4, that the O—H⋯O hydrogen bond and π–π stacking interaction are stronger than the other interactions, and, of these, the intermolecular C—H⋯O contacts are weaker than the C—H⋯π interactions.

Table 4
Summary of interaction energies (kJ mol⁻¹) calculated for (I)

Contact	R (Å)	E_ele	E_pol	E_dis	E_rep	E_tot
O1—H1O⋯O1ⁱ
H3A⋯O1ⁱ	8.80	−52.3	−12.0	−18.8	72.7	−35.7
H1O⋯C1ⁱ
C10—H10⋯O3ⁱⁱ	8.28	−3.7	−1.4	−9.2	4.9	−9.8
C11—H11⋯O2ⁱⁱⁱ	9.51	−5.8	−1.7	−5.7	5.0	−9.6
O3⋯H2A^iv
(C6–C11)⋯(C6–C11)^iv	4.25	−9.4	−1.8	−47.1	28.9	−34.4
H3C⋯C5^v
H2C⋯C7^v
H2C⋯C8^v	5.78	−2.1	−0.7	−28.6	18.2	−16.4
C2—H2C⋯(C6–C11)^v
Symmetry codes: (i) $[{1\over 3}]$ + x − y, $[{1\over 3}]$ − x, $[{5\over 3}]$ − z; (ii) $[{2\over 3}]$ − x + y, 4/3 − x, $[{1\over 3}]$ + z; (iii) 4/3 − y, $[{2\over 3}]$ + x − y, $[{2\over 3}]$ + z; (iv) 1 − x, 1 − y, 1 − z; (v) $[{1\over 3}]$ + x − y, − $[{1\over 3}]$ + x, $[{2\over 3}]$ − z.

The magnitudes of intermolecular energies are represented graphically by energy frameworks to view the supramolecular architecture of the crystal through the cylinders joining centroids of molecular pairs by using red, green and blue colour codes for the components E_ele, E_disp and E_tot, respectively, Fig. 9. The radius of the cylinder is proportional to the magnitude of interaction energy, which are adjusted to the same scale factor of 30 with a cut-off value of 3 kJ mol⁻¹ within 2 × 2 × 2 unit cells.

Figure 9
A comparison of the energy frameworks calculated for (I)

and viewed down the c axis showing (a) electrostatic potential force, (b) dispersion force and (c) total energy. The energy frameworks were adjusted to the same scale factor of 30 with a cut-off value of 3 kJ mol⁻¹ within 2 × 2 × 2 unit cells.

6. Non-covalent interaction plots

Non-covalent interaction plot (NCIplot) analyses provide a visual representation of the nature of the contact between specified species in crystals (Johnson et al., 2010 ; Contreras-Garcá et al., 2011 ). This method is based on the electron density (and derivatives) and was employed in the present study to confirm the nature of some of the specified intermolecular contacts. The colour-based isosurfaces generated correspond to the values of sign(λ²)ρ(r), where ρ is the electron density and λ² is the second eigenvalue of the Hessian matrix of ρ. Crucially, through a three-colour scheme, a specific interaction can be identified as being attractive or otherwise. Thus, a green isosurface indicates a weakly attractive interaction whereas a blue isosurface indicates an attractive interaction; a repulsive interaction appears red. The isosurfaces for three identified intermolecular interactions are given in the upper view of Fig. 10. Thus, in Fig. 10(a), a green isosurface is apparent for the conventional hydroxy-O—H⋯O(hydroxy) hydrogen bond. Similarly, green isosurfaces are seen between the interacting atoms involved in the phenyl-C—H⋯O(nitro), Fig. 10(b), and the methyl-C—H⋯π(C11–C16), Fig. 10(c), interactions.

Figure 10
Non-covalent interaction plots for (a) hydroxy-O—H⋯O(hydroxy) hydrogen bonding, (b) the phenyl-C—H⋯O(nitro) interactions and (c) the methyl-C—H⋯π(C11–C16) interactions.

The lower views of Fig. 10, show the plots of the RDG versus sign(λ²)ρ(r). The non-covalent interaction peaks appear at density values less than 0.0 atomic units, consistent with their being weakly attractive interactions.

7. Database survey

There are four literature precedents for (I) with varying substitution patterns in the appended benzene ring. These are the unsubstituted `parent' compound [(II); FESMEV; Singelenberg & van Eijck, 1987 ], and the 4-cyano [(III}; HEFDAA; Clegg, 2017 ], 4-methoxy [(IV); YUQPEG; Eissmann et al., 2010 ] and 3-acetyl-4-hydroxy [(V); UVETAS; Hübscher et al., 2016 ] derivatives. Selected geometric parameters for (I)–(IV) are collated in Table 5. Of particular interest in the mode of supramolecular association in their crystals. As seen from Fig. 11, four distinct patterns appear. In (V), three independent molecules comprise the asymmetric unit and these associate about a centre of inversion in space group P2₁/c to form a hexameric clusters via hydroxy-O—H⋯O(hydroxy) hydrogen bonds as seen in (I), Fig. 11(a); intramolecular hydroxy-O—H⋯O(carbonyl) hydrogen bonds are also apparent. In (III), the two independent molecules comprising the asymmetric unit associate about a centre of inversion in space group P2₁/n into a supramolecular dimer via pairs of hydroxy-O—H⋯O(hydroxy) and hydroxy-O—H⋯N(cyano) hydrogen bonds as shown in Fig. 11(b). In this case, one independent hydroxy-oxygen atom and one cyano-nitrogen atom do not accept a hydrogen-bonding interaction. Three crystallographically independent molecules are also found in (II) (space group Pca2₁) and these self-associate to form a supramolecular chain via hydroxy-O—H⋯O(hydroxy) hydrogen bonds with non-crystallographic threefold symmetry, Fig. 11(c). Finally, zigzag supramolecular chains sustained by hydroxy-O—H⋯O(hydroxy) hydrogen bonds are found in the crystal of (IV), Fig. 11(d) in space group Pbca.

Table 5
Geometric data (Å, °) for related 2-methyl-4-(aryl)but-3-yn-2-ol molecules

Compound	Z′	C_ring—C_acetylene	C_acetylene—C_acetylene	C_acetylene—C_quaternary	Supramolecular motif	Reference
(I)	1	1.438 (3)	1.189 (3)	1.471 (3)	hexamer	This work
(II)	3	1.443 (5)	1.211 (5)	1.454 (5)	chain	Singelenberg & van Eijck (1987)
		1.437 (6)	1.192 (6)	1.479 (6)
		1.437 (5)	1.189 (5)	1.479 (5)
(III)	2	1.441 (2)	1.193 (2)	1.490 (2)	dimer	Clegg (2017)
		1.435 (2)	1.1895 (2)	1.480 (2)
(IV)	1	1.4377 (16)	1.2000 (16)	1.4791 (16)	chain	Eissmann et al. (2010)
(V)	3	1.4418 (18)	1.1951 (19)	1.4764 (19)	hexamer	Hübscher et al. (2016)
		1.444 (2)	1.194 (2)	1.4859 (19)
		1.4402 (19)	1.1904 (19)	1.4723 (18)

Figure 11
Supramolecular association via hydroxy-O—H⋯O(hydroxy) hydrogen bonds in (II)–(IV): (a) hexameric cluster in (V), (b) dimeric aggregate sustained by additional hydroxy-O—H⋯N(cyano) hydrogen bonds in (III), (c) views of the supramolecular chain in (II) with non-crystallographic threefold symmetry and (d) views of the zigzag supramolecular chain in (IV).

8. Synthesis and crystallization

The title compound was prepared as per the literature procedure (Bleicher et al., 1998). Yield: 87%. Yellow solid, m.p. 377–379 K. ¹H NMR (400 MHz, CDCl₃): δ = 8.16 (dt, J = 8.9, 2.2 Hz, 2H), 7.54 (dt, J = 8.9, 2.2 Hz, 2H), 2.24 (s, 1H) and 1.63 (s, 6H) ppm. ¹³C NMR (101 MHz, CDCl₃): δ = 147.2, 132.5, 129.8, 123.6, 99.2, 80.5, 66.7 and 31.3 ppm. Irregular colourless crystals of (I) for the X-ray study were grown by slow evaporation of its ethyl acetate solution.

9. Refinement details

Crystal data, data collection and structure refinement details are summarized in Table 6. The carbon-bound H atoms were placed in calculated positions (C—H = 0.93–0.96 Å) and were included in the refinement in the riding-model approximation, with U_iso(H) set to 1.2–1.5U_eq(C). The O-bound H atom was refined with a distance restraint of 0.82±0.01 Å, and with U_iso(H) = 1.5U_eq(O).

Table 6
Experimental details

Crystal data
Chemical formula	C₁₁H₁₁NO₃
M_r	205.21
Crystal system, space group	Trigonal, R $[\overline{3}]$ :H
Temperature (K)	296
a, c (Å)	26.3146 (14), 8.1205 (5)
V (Å³)	4869.8 (6)
Z	18
Radiation type	Mo Kα
μ (mm⁻¹)	0.09
Crystal size (mm)	0.34 × 0.28 × 0.16

Data collection
Diffractometer	Bruker APEXII CCD
Absorption correction	Multi-scan (SADABS; Sheldrick, 1996 )
T_min, T_max	0.440, 0.745
No. of measured, independent and observed [I > 2σ(I)] reflections	10643, 2230, 1513
R_int	0.080
(sin θ/λ)_max (Å⁻¹)	0.627

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.053, 0.149, 1.05
No. of reflections	2230
No. of parameters	139
No. of restraints	1
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.16, −0.27
Computer programs: APEX2 and SAINT (Bruker, 2009 ), SIR2014 (Burla et al., 2015 ), SHELXL2018/3 (Sheldrick, 2015 ), ORTEP-3 for Windows (Farrugia, 2012 ), DIAMOND (Brandenburg, 2006 ), MarvinSketch (ChemAxon, 2010 ) and publCIF (Westrip, 2010 ).

Supporting information

CCDC reference: 1941466

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S2056989019010284/hb7841sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989019010284/hb7841Isup2.hkl

checkCIF report

Computing details top

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SIR2014 (Burla et al., 2015); program(s) used to refine structure: SHELXL2018/3 (Sheldrick, 2015); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012), DIAMOND (Brandenburg, 2006); software used to prepare material for publication: MarvinSketch (ChemAxon, 2010) and publCIF (Westrip, 2010).

2-Methyl-4-(4-nitrophenyl)but-3-yn-2-ol top

Crystal data top

C₁₁H₁₁NO₃	D_x = 1.260 Mg m⁻³
M_r = 205.21	Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3:H	Cell parameters from 2006 reflections
a = 26.3146 (14) Å	θ = 2.7–23.9°
c = 8.1205 (5) Å	µ = 0.09 mm⁻¹
V = 4869.8 (6) Å³	T = 296 K
Z = 18	Irregular, colourles
F(000) = 1944	0.34 × 0.28 × 0.16 mm

Data collection top

Bruker APEXII CCD diffractometer	1513 reflections with I > 2σ(I)
φ and ω scans	R_int = 0.080
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	θ_max = 26.4°, θ_min = 1.6°
T_min = 0.440, T_max = 0.745	h = −32→32
10643 measured reflections	k = −32→32
2230 independent reflections	l = −9→10

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.053	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.149	H-atom parameters constrained
S = 1.05	w = 1/[σ²(F_o²) + (0.0511P)² + 3.9317P] where P = (F_o² + 2F_c²)/3
2230 reflections	(Δ/σ)_max < 0.001
139 parameters	Δρ_max = 0.16 e Å⁻³
1 restraint	Δρ_min = −0.27 e Å⁻³

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

	x	y	z	U_iso*/U_eq
O1	0.56993 (7)	0.33529 (6)	0.78650 (17)	0.0513 (4)
H1O	0.569241	0.305973	0.823659	0.077*
O2	0.54778 (9)	0.61319 (8)	0.0578 (2)	0.0811 (6)
O3	0.62154 (8)	0.66736 (8)	0.2126 (3)	0.0785 (6)
N1	0.58062 (9)	0.61978 (9)	0.1723 (3)	0.0565 (5)
C1	0.53437 (9)	0.31996 (8)	0.6425 (2)	0.0388 (5)
C2	0.47123 (10)	0.27726 (10)	0.6889 (3)	0.0612 (7)
H2A	0.459150	0.293892	0.775102	0.092*
H2B	0.468058	0.241200	0.726620	0.092*
H2C	0.446510	0.269637	0.594458	0.092*
C3	0.55665 (12)	0.29361 (11)	0.5140 (3)	0.0634 (7)
H3A	0.551638	0.257044	0.553954	0.095*
H3B	0.597504	0.320235	0.493279	0.095*
H3C	0.534860	0.286951	0.413769	0.095*
C4	0.54001 (9)	0.37468 (9)	0.5772 (2)	0.0439 (5)
C5	0.54464 (10)	0.41762 (9)	0.5145 (2)	0.0458 (5)
C6	0.55281 (9)	0.46950 (9)	0.4317 (2)	0.0407 (5)
C7	0.51138 (9)	0.46599 (9)	0.3192 (2)	0.0424 (5)
H7	0.477559	0.430184	0.300298	0.051*
C8	0.52018 (9)	0.51543 (9)	0.2351 (2)	0.0441 (5)
H8	0.492523	0.513284	0.159933	0.053*
C9	0.57045 (9)	0.56768 (9)	0.2648 (2)	0.0416 (5)
C10	0.61185 (10)	0.57274 (9)	0.3773 (3)	0.0515 (6)
H10	0.645262	0.608821	0.396842	0.062*
C11	0.60276 (10)	0.52332 (10)	0.4602 (3)	0.0509 (6)
H11	0.630422	0.526000	0.536242	0.061*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0636 (10)	0.0378 (8)	0.0474 (8)	0.0216 (7)	−0.0238 (7)	−0.0036 (6)
O2	0.0870 (14)	0.0812 (13)	0.0791 (12)	0.0450 (11)	−0.0075 (11)	0.0315 (10)
O3	0.0734 (13)	0.0474 (10)	0.1082 (15)	0.0254 (10)	0.0056 (11)	0.0178 (10)
N1	0.0592 (12)	0.0508 (12)	0.0661 (13)	0.0324 (11)	0.0118 (10)	0.0164 (9)
C1	0.0463 (11)	0.0376 (10)	0.0322 (9)	0.0206 (9)	−0.0083 (8)	−0.0026 (8)
C2	0.0501 (14)	0.0552 (14)	0.0690 (15)	0.0191 (12)	−0.0049 (11)	0.0064 (11)
C3	0.0898 (19)	0.0674 (16)	0.0493 (13)	0.0514 (15)	−0.0007 (12)	−0.0056 (11)
C4	0.0518 (12)	0.0460 (12)	0.0365 (10)	0.0264 (10)	−0.0029 (9)	0.0014 (9)
C5	0.0577 (13)	0.0484 (12)	0.0364 (10)	0.0303 (11)	0.0001 (9)	0.0009 (9)
C6	0.0535 (12)	0.0444 (11)	0.0311 (9)	0.0297 (10)	0.0052 (8)	0.0026 (8)
C7	0.0452 (11)	0.0423 (11)	0.0400 (10)	0.0223 (10)	0.0024 (9)	0.0009 (8)
C8	0.0480 (12)	0.0543 (13)	0.0379 (10)	0.0317 (11)	0.0011 (9)	0.0045 (9)
C9	0.0486 (12)	0.0431 (11)	0.0413 (10)	0.0291 (10)	0.0088 (9)	0.0080 (8)
C10	0.0491 (13)	0.0422 (12)	0.0598 (13)	0.0203 (10)	−0.0055 (10)	−0.0006 (10)
C11	0.0566 (14)	0.0538 (13)	0.0468 (11)	0.0310 (11)	−0.0109 (10)	−0.0005 (10)

Geometric parameters (Å, º) top

O1—C1	1.424 (2)	C3—H3C	0.9600
O1—H1O	0.8200	C4—C5	1.189 (3)
O2—N1	1.221 (3)	C5—C6	1.438 (3)
O3—N1	1.219 (2)	C6—C11	1.387 (3)
N1—C9	1.466 (3)	C6—C7	1.390 (3)
C1—C4	1.471 (3)	C7—C8	1.382 (3)
C1—C2	1.516 (3)	C7—H7	0.9300
C1—C3	1.523 (3)	C8—C9	1.371 (3)
C2—H2A	0.9600	C8—H8	0.9300
C2—H2B	0.9600	C9—C10	1.376 (3)
C2—H2C	0.9600	C10—C11	1.375 (3)
C3—H3A	0.9600	C10—H10	0.9300
C3—H3B	0.9600	C11—H11	0.9300

C1—O1—H1O	109.5	H3B—C3—H3C	109.5
O3—N1—O2	123.3 (2)	C5—C4—C1	175.7 (2)
O3—N1—C9	118.5 (2)	C4—C5—C6	176.5 (2)
O2—N1—C9	118.2 (2)	C11—C6—C7	119.25 (18)
O1—C1—C4	106.76 (15)	C11—C6—C5	120.46 (18)
O1—C1—C2	109.11 (16)	C7—C6—C5	120.27 (19)
C4—C1—C2	110.61 (18)	C8—C7—C6	120.36 (19)
O1—C1—C3	110.10 (17)	C8—C7—H7	119.8
C4—C1—C3	108.98 (16)	C6—C7—H7	119.8
C2—C1—C3	111.20 (18)	C9—C8—C7	118.75 (18)
C1—C2—H2A	109.5	C9—C8—H8	120.6
C1—C2—H2B	109.5	C7—C8—H8	120.6
H2A—C2—H2B	109.5	C8—C9—C10	122.25 (18)
C1—C2—H2C	109.5	C8—C9—N1	118.80 (18)
H2A—C2—H2C	109.5	C10—C9—N1	118.95 (19)
H2B—C2—H2C	109.5	C11—C10—C9	118.6 (2)
C1—C3—H3A	109.5	C11—C10—H10	120.7
C1—C3—H3B	109.5	C9—C10—H10	120.7
H3A—C3—H3B	109.5	C10—C11—C6	120.79 (19)
C1—C3—H3C	109.5	C10—C11—H11	119.6
H3A—C3—H3C	109.5	C6—C11—H11	119.6

C11—C6—C7—C8	0.7 (3)	O3—N1—C9—C10	−9.2 (3)
C5—C6—C7—C8	−177.66 (17)	O2—N1—C9—C10	170.3 (2)
C6—C7—C8—C9	0.2 (3)	C8—C9—C10—C11	1.2 (3)
C7—C8—C9—C10	−1.2 (3)	N1—C9—C10—C11	−178.21 (19)
C7—C8—C9—N1	178.28 (17)	C9—C10—C11—C6	−0.3 (3)
O3—N1—C9—C8	171.3 (2)	C7—C6—C11—C10	−0.7 (3)
O2—N1—C9—C8	−9.2 (3)	C5—C6—C11—C10	177.72 (19)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1O···O1ⁱ	0.82	1.87	2.682 (2)	173
C10—H10···O3ⁱⁱ	0.93	2.67	3.548 (3)	157
C11—H11···O2ⁱⁱⁱ	0.93	2.68	3.467 (3)	143

Symmetry codes: (i) x−y+1/3, x−1/3, −z+5/3; (ii) −x+y+2/3, −x+4/3, z+1/3; (iii) −y+4/3, x−y+2/3, z+2/3.

Summary of short interatomic contacts (Å) in (I) top

The interatomic distances are calculated in Crystal Explorer 17 (Turner et al., 2017) whereby the X—H bond lengths are adjusted to their neutron values.

Contact	Distance	Symmetry operation
O1···H3A	2.71	1/3 + y, 2/3 - x + y, 5/3 - z
O2···H2B	2.69	2/3 - y, 1/3 + x - y, -2/3 + z
O3···H2A	2.69	1 - x, 1 - y, 1 - z
C1···H1O	2.85	1/3 + y, 2/3 - x + y, 5/3 - z
C5···H3C	2.79	1/3 + y, 2/3 - x + y, 2/3 - z
C7···H2C	2.85	1/3 + y, 2/3 - x + y, 2/3 - z
C8···H2C	2.80	1/3 + y, 2/3 - x + y, 2/3 - z

Percentage contributions of interatomic contacts to the Hirshfeld surface for (I) top

Contact	Percentage contribution
H···H	38.2
O···H/H···O	32.1
C···H/H···C	20.0
C···C	4.2
N···O/O···N	1.7
O···O	1.6
C···N/N···C	1.0
N···H/H···N	0.8
C···O/O···C	0.4

Summary of interaction energies (kJ mol^-1) calculated for (I) top

Contact	R (Å)	E_ele	E_pol	E_dis	E_rep	E_tot
O1—H1O···O1ⁱ
H3A···O1ⁱ	8.80	-52.3	-12.0	-18.8	72.7	-35.7
H1O···C1ⁱ
C10—H10···O3ⁱⁱ	8.28	-3.7	-1.4	-9.2	4.9	-9.8
C11—H11···O2ⁱⁱⁱ	9.51	-5.8	-1.7	-5.7	5.0	-9.6
O3···H2A^iv
(C6–C11)···(C6–C11)^iv	4.25	-9.4	-1.8	-47.1	28.9	-34.4
H3C···C5^v
H2C···C7^v
H2C···C8^v	5.78	-2.1	-0.7	-28.6	18.2	-16.4
C2—H2C···(C6–C11)^v

Symmetry codes: (i) 1/3 + x - y, 1/3 - x, 5/3 - z; (ii) 2/3 - x + y, 4/3 - x, 1/3 + z; (iii) 4/3 - y, 2/3 + x - y, 2/3 + z; (iv) 1 - x, 1 - y, 1 - z; (v) 1/3 + x - y, - 1/3 + x, 2/3 - z.

Geometric data (Å, °) for related 2-methyl-4-(aryl)but-3-yn-2-ol molecules top

Compound	Z'	C_ring—C_acetylene	C_acetylene—C_acetylene	C_acetylene—C_quaternary	supramolecular motif	Reference
(I)	1	1.438 (3)	1.189 (3)	1.471 (3)	hexamer	This work
(II)	3	1.443 (5)	1.211 (5)	1.454 (5)	chain	Singelenberg & van Eijck (1987)
		1.437 (6)	1.192 (6)	1.479 (6)
		1.437 (5)	1.189 (5)	1.479 (5)
(III)	2	1.441 (2)	1.193 (2)	1.490 (2)	dimer	Clegg (2017)
		1.435 (2)	1.1895 (2)	1.480 (2)
(IV)	1	1.4377 (16)	1.2000 (16)	1.4791 (16)	chain	Eissmann et al. (2010)
(V)	3	1.4418 (18)	1.1951 (19)	1.4764 (19)	hexamer	Hübscher et al. (2016)
		1.444 (2)	1.194 (2)	1.4859 (19)
		1.4402 (19)	1.1904 (19)	1.4723 (18)

Footnotes

‡Additional correspondence author, e-mail: julio@power.ufscar.br.

Acknowledgements

We thank Professor Regina H. A. Santos from IQSC-USP for the X-ray data collection.

Funding information

Funding for this research was provided by GlaxoSmithKline (GSK) and the Brazilian agencies: The National Council for Scientific and Technological Development are thanked for fellowships (CNPq: 308480/2016-3 to IC; 303207/2017-5 to JZS), São Paulo Research Foundation (FAPESP, grants 2013/06558-3 and 2014/50249-8) and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES) – Finance Code 001. Sunway University Sdn Bhd is also thanked for funding (grant No. STR-RCTR-RCCM-001-2019).

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