Crystal structure and Hirshfeld surface analysis of 3-cyano-phenyl-boronic acid.

In the title compound, C7H6BNO2, the mean plane of the -B(OH)2 group is twisted by 21.28 (6)° relative to the cyano-phenyl ring mean plane. In the crystal, mol-ecules are linked by O-H⋯O and O-H⋯N hydrogen bonds, forming chains propagating along the [101] direction. Offset π-π and B⋯π stacking inter-actions link the chains, forming a three-dimensional network. Hirshfeld surface analysis shows that van der Waals inter-actions constitute a further major contribution to the inter-molecular inter-actions, with H⋯H contacts accounting for 25.8% of the surface.

Chemical context

Boron-containing compounds and particularly aryl­boronic acid are an important class of compounds in the fields of organic and medicinal chemistry, and have played a role in the development of modern organic synthesis, macromolecular chemistry, crystal engineering and mol­ecular recognition (Fujita et al., 2008 ▸; Severin, 2009 ▸). As a result of their peculiar dynamic covalent reactivity with alcohols (Jin et al., 2013 ▸), aryl­boronic acids and their dehydrated derivatives enable the self-assembly of a large variety of architectures resulting from boronate esterification (Takahagi et al. 2009 ▸) as well as boroxine (Côté et al., 2005 ▸) and spiro­borate formation (Du et al., 2016 ▸).

Boronic acids form neutral and charge-assisted homo- and heterodimeric hydrogen-bonding patterns resembling characteristics similar to those found for carb­oxy­lic acids (see Fig. 1 ▸ a). However, the –B(OH)2 moiety contains two O—H hydrogen-bond donors and can, thus, form two O—H⋯X hydrogen bonds and adopt different conformations (see Fig. 1 ▸ b). This enables the generation of hydrogen-bonding networks with increased dimensionality (one to three dimensions) in the solid state (Fournier et al., 2003 ▸; Madura et al., 2015 ▸; Georgiou et al., 2017 ▸). In recent years, boronic acids have also been explored in the context of forming multicomponent mol­ecular complexes with organic carb­oxy­lic acids (–COOH), amides (–CONH2), alcohols (–OH) and pyridines, which are based on mol­ecular recognition processes (Rodríguez-Cuamatzi et al., 2005 ▸; Madura et al., 2014 ▸; Hernández-Paredes et al., 2015 ▸; Campos-Gaxiola et al., 2017 ▸; Pedireddi & Lekshmi, 2004 ▸; Vega et al., 2010 ▸; TalwelkarShimpi et al., 2016 ▸). As part of our ongoing studies in this area, we report herein on the mol­ecular and crystal structures of 3-cyano­phenyl­boronic acid, I. In addition, a Hirshfeld surface analysis was performed to visualize and qu­antify the inter­molecular inter­actions in the crystal structure of compound (I).

Figure 1

(a) Neutral and charge-assisted homo- and heterodimeric hydrogen-bonding motifs involving boronic acids. (b) Conformations of the boronic acid moiety.

Structural commentary

The mol­ecular structure of the title compound (I) is illustrated in Fig. 2 ▸. It can be seen that the –B(OH)2 group adopts the most preferred syn–anti conformation (Lekshmi & Pedireddi, 2007 ▸). As a result of the H⋯H repulsion between the endo-oriented B—OH hydrogen and the C—H hydrogen in position 2 of the aromatic ring, the –B(OH)2 mean plane is twisted by 21.28 (6)° relative to the cyano­phenyl ring mean plane. This torsion disables intra­molecular C—H⋯O hydrogen bonding between the oxygen atom of the exo-oriented B—OH function and weakens the B—C π–π bonding inter­actions (Durka et al., 2012 ▸). The B1—O1, B1—O2 and B1—C1 bond lengths are 1.3455 (17), 1.3661 (18) and 1.5747 (18) Å, respectively. For comparison, in coplanar triphenyl boroxine the B—C bond lengths range from 1.544 (4) to 1.549 (4) Å (Brock et al., 1987 ▸). The C≡N bond length of 1.1416 (18) Å is typical for a bond with triple-bond character.

Figure 2

The mol­ecular structure of the title compound (I), with the atom labeling. Displacement ellipsoids are drawn at the 50% probability level.

Supra­molecular features

In the crystal of (I), the boronic acid mol­ecules are in the first instance associated to form chains through two well-known double-bridged homodimeric motifs based on a –BOH⋯O(H)B– [motif A; graph set (8)] and C—H⋯N≡C hydrogen bonds [motif B; graph set (10)]. This hydrogen-bonding pattern is strengthened further by a –BOH⋯N≡C contact [motif C; graph set (7)] (Fig. 3 ▸ a, Table 1 ▸). In comparison to the crystal structure of 4-cyano­phenyl­boronic acid, where the chains are almost linear (TalwelkarShimpi et al., 2017 ▸), in (I) they have a pronounced zigzag topology. The O1⋯O2i, C2⋯N1ii and O2⋯N1ii separations in motifs A, B and C are 2.796 (1), 3.452 (2) and 2.909 (2) Å, respectively (Table 1 ▸), and are similar to distances reported for related systems (Rodríguez-Cuamatzi et al., 2005 ▸; TalwelkarShimpi et al., 2017 ▸). Within the crystal structure, neighboring tapes are linked through additional C—H⋯O contacts to give an overall two-dimensional network running parallel to (01) with macrocyclic motifs D [graph set (26)], see Fig. 3 ▸ b. The C4⋯O1iii distance is 3.469 (2) Å, see Table 1 ▸. The resulting 2D networks stack in a parallel fashion to form a layered 3D structure based on offset π–π inter­actions between adjacent 3-cyano­phenyl­boronic acid mol­ecules [Cg⋯Cg iv = 3.8064 (8) Å; slippage 1.38 Å; symmetry code (iv) = −1 + x, y, z] and η2-type B⋯π contacts with B⋯C distances of 3.595 (2) and 3.673 (2) Å (Fig. 3 ▸ c). Similar inter­actions are also depicted in mol­ecular crystals formed between 1,4-benzene­diboronic acid and aromatic amine N-oxides (Sarma & Baruah, 2009 ▸; Sarma et al., 2011 ▸).

Figure 3

Hydrogen-bonding motifs and π–π inter­actions found in the crystal structure of (I). [Symmetry codes: (i) 2 − x, 1 − y, 1 − z; (ii) 1 − x, 1 − y, −z; (iii) −1 + x,  − y, − + z; (iv) −1 + x, y, z.]

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1⋯O2i	0.82	1.98	2.796 (1)	170
O2—H2⋯N1ii	0.82	2.12	2.909 (2)	160
C2—H2A⋯N1ii	0.93	2.71	3.452 (2)	138
C4—H4⋯O1iii	0.93	2.67	3.469 (2)	144

Symmetry codes: (i) ; (ii) ; (iii) .

Hirshfeld surface analysis

Hirshfeld surfaces and fingerprint plots were generated for (I) based on the crystallographic information file (CIF) using CrystalExplorer (Hirshfeld, 1977 ▸; McKinnon et al., 2004 ▸). Hirshfeld surfaces enable the visualization of inter­molecular inter­actions by different colors and color intensity, representing short or long contacts and indicating the relative strength of the inter­actions. Fig. 4 ▸ shows the Hirshfeld surface of the title compound mapped over d norm (−0.60 to 0.90 Å) and the shape-index (−1.0 to 1.0 Å). In the d norm map, the vivid red spots in the Hirshfeld surface are due to short normalized O⋯H and N⋯H distances corresponding to O—H⋯O and O—H⋯N inter­actions. The white spots represent the contacts resulting from C—H⋯N hydrogen bonding (Fig. 4 ▸ a). On the shape-index surface for compound (I), convex blue regions represent hydrogen-donor groups and concave red regions represent hydrogen-acceptor groups. The –B(OH)2 group behaves simultaneously as a donor and an acceptor, meanwhile the –C≡N group is an acceptor only. The occurrence of offset π–π inter­actions is indicated by adjacent red and blue triangles (Fig. 4 ▸ b).

Figure 4

Hirshfeld surfaces for compound (I), mapped with d norm (top) and shape-index (bottom).

The two-dimensional fingerprint plots qu­antify the contributions of each type of non-covalent inter­action to the Hirshfeld surface (McKinnon et al., 2007 ▸). The major contribution with 25.8% of the surface is due to H⋯H contacts, which represent van der Waals inter­actions, followed by N⋯H and O⋯H inter­actions, which contribute 23.6 and 20.4%, respectively (these contributions are observed as two sharp peaks in the plot of Fig. 5 ▸). This behavior is usual for strong hydrogen bonds (Spackman & McKinnon, 2002 ▸). Finally, the presence of C⋯C (11.4%) and B⋯C (2.3%) contacts corresponds to the π–π and B⋯π inter­actions, respectively, established in the crystal structure analysis section.

Figure 5

Two-dimensional fingerprints of compound (I), showing H⋯H, N⋯H, O⋯H, C⋯C and C⋯H close contacts.

Experimental

3-Cyano­phenyl­boronic acid and the solvent used in this work are commercially available and were used without further purification. For single-crystal growth, a solution of 3-cyano­phenyl­boronic acid (0.050 g) in 5 ml of ethanol was heated to reflux for 15 min. The solution was left to evaporate slowly at room temperature, giving after one week colorless crystals suitable for single-crystal X-ray diffraction analysis.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2 ▸. Hydrogen atoms were positioned geometrically (O—H = 0.82 Å and C—H = 0.93 Å) and refined using a riding model, with U iso(H) = 1.2U eq(C) and 1.5U eq(O).

Table 2

Experimental details

Crystal data
Chemical formula	C7H6BNO2
M r	146.94
Crystal system, space group	Monoclinic, P21/c
Temperature (K)	293
a, b, c (Å)	3.8064 (2), 16.156 (1), 11.4585 (4)
β (°)	93.472 (4)
V (Å3)	703.36 (6)
Z	4
Radiation type	Mo Kα
μ (mm−1)	0.10
Crystal size (mm)	0.48 × 0.25 × 0.20
Data collection
Diffractometer	Rigaku OD SuperNova Single source at offset EosS2
Absorption correction	Gaussian (CrysAlis PRO; Rigaku OD, 2015 ▸)
T min, T max	0.992, 0.996
No. of measured, independent and observed [I > 2σ(I)] reflections	7332, 1434, 1347
R int	0.023
(sin θ/λ)max (Å−1)	0.625
Refinement
R[F 2 > 2σ(F 2)], wR(F 2), S	0.042, 0.110, 1.09
No. of reflections	1434
No. of parameters	102
H-atom treatment	H-atom parameters constrained
Δρmax, Δρmin (e Å−3)	0.20, −0.24

Computer programs: CrysAlis PRO (Rigaku OD, 2015 ▸), SUPERFLIP (Palatinus & Chapuis, 2007 ▸; Palatinus & van der Lee, 2008 ▸; Palatinus et al., 2012 ▸), SHELXL2016 (Sheldrick, 2015 ▸) and OLEX2 (Dolomanov et al., 2009 ▸).

Crystal structure: contains datablock(s) Global, I. DOI: 10.1107/S2056989018003146/su5425sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S2056989018003146/su5425Isup2.hkl

Click here for additional data file.

Supporting information file. DOI: 10.1107/S2056989018003146/su5425Isup3.cml

CCDC reference: 1825335

Additional supporting information: crystallographic information; 3D view; checkCIF report

C7H6BNO2	F(000) = 304
Mr = 146.94	Dx = 1.388 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 3.8064 (2) Å	Cell parameters from 4312 reflections
b = 16.156 (1) Å	θ = 4.4–29.1°
c = 11.4585 (4) Å	µ = 0.10 mm−1
β = 93.472 (4)°	T = 293 K
V = 703.36 (6) Å3	Block, colourless
Z = 4	0.48 × 0.25 × 0.20 mm

Rigaku OD SuperNova Single source at offset EosS2 diffractometer	1434 independent reflections
Radiation source: micro-focus sealed X-ray tube, SuperNova (Mo) X-ray Source	1347 reflections with I > 2σ(I)
Mirror monochromator	Rint = 0.023
Detector resolution: 8.0945 pixels mm-1	θmax = 26.4°, θmin = 3.6°
ω scans	h = −4→4
Absorption correction: gaussian (CrysAlis PRO; Rigaku OD, 2015)	k = −20→20
Tmin = 0.992, Tmax = 0.996	l = −14→14
7332 measured reflections

Refinement on F2	Primary atom site location: iterative
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.042	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.110	H-atom parameters constrained
S = 1.09	w = 1/[σ2(Fo2) + (0.0566P)2 + 0.1839P] where P = (Fo2 + 2Fc2)/3
1434 reflections	(Δ/σ)max < 0.001
102 parameters	Δρmax = 0.20 e Å−3
0 restraints	Δρmin = −0.24 e Å−3

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.

	x	y	z	Uiso*/Ueq
O2	0.8906 (3)	0.49351 (6)	0.34935 (8)	0.0436 (3)
H2	0.881271	0.482459	0.279381	0.065*
O1	0.8143 (3)	0.60701 (6)	0.47187 (8)	0.0507 (3)
H1	0.900315	0.572989	0.518407	0.076*
N1	0.0762 (4)	0.58588 (8)	−0.12243 (11)	0.0485 (4)
C3	0.3424 (3)	0.65006 (8)	0.06942 (10)	0.0307 (3)
C7	0.1909 (4)	0.61462 (8)	−0.03743 (11)	0.0355 (3)
C1	0.6246 (3)	0.62961 (8)	0.26214 (10)	0.0302 (3)
C2	0.4765 (3)	0.59744 (8)	0.15775 (11)	0.0309 (3)
H2A	0.467006	0.540428	0.146805	0.037*
C4	0.3561 (4)	0.73542 (8)	0.08286 (12)	0.0367 (3)
H4	0.267843	0.770116	0.023320	0.044*
C6	0.6325 (4)	0.71575 (8)	0.27423 (11)	0.0352 (3)
H6	0.727616	0.738593	0.343630	0.042*
C5	0.5031 (4)	0.76802 (8)	0.18615 (12)	0.0400 (3)
H5	0.515094	0.825073	0.196425	0.048*
B1	0.7827 (4)	0.57324 (9)	0.36442 (12)	0.0336 (3)

	U11	U22	U33	U12	U13	U23
O2	0.0679 (7)	0.0371 (5)	0.0242 (5)	0.0103 (5)	−0.0092 (5)	−0.0004 (4)
O1	0.0810 (8)	0.0414 (6)	0.0278 (5)	0.0165 (5)	−0.0120 (5)	−0.0029 (4)
N1	0.0625 (9)	0.0474 (7)	0.0339 (7)	0.0077 (6)	−0.0115 (6)	−0.0044 (5)
C3	0.0303 (6)	0.0361 (7)	0.0254 (6)	0.0025 (5)	−0.0001 (5)	0.0001 (5)
C7	0.0398 (7)	0.0365 (7)	0.0295 (7)	0.0077 (5)	−0.0031 (5)	0.0028 (5)
C1	0.0304 (6)	0.0332 (7)	0.0267 (6)	0.0014 (5)	−0.0002 (5)	0.0017 (5)
C2	0.0343 (7)	0.0291 (6)	0.0290 (6)	0.0019 (5)	−0.0011 (5)	0.0005 (5)
C4	0.0426 (8)	0.0353 (7)	0.0320 (7)	0.0063 (5)	0.0004 (5)	0.0067 (5)
C6	0.0397 (7)	0.0358 (7)	0.0296 (6)	−0.0019 (5)	−0.0016 (5)	−0.0031 (5)
C5	0.0520 (8)	0.0287 (7)	0.0390 (8)	0.0007 (6)	0.0009 (6)	0.0001 (5)
B1	0.0385 (8)	0.0347 (8)	0.0268 (7)	0.0006 (6)	−0.0038 (6)	0.0010 (5)

O2—B1	1.3661 (18)	C1—C2	1.3917 (17)
O1—B1	1.3455 (17)	C1—C6	1.3987 (18)
N1—C7	1.1416 (18)	C1—B1	1.5747 (18)
C3—C7	1.4401 (18)	C4—C5	1.3825 (19)
C3—C2	1.3948 (17)	C6—C5	1.3834 (19)
C3—C4	1.3882 (19)
C2—C3—C7	119.00 (12)	C1—C2—C3	120.50 (12)
C4—C3—C7	119.98 (11)	C5—C4—C3	118.95 (12)
C4—C3—C2	121.02 (12)	C5—C6—C1	122.04 (12)
N1—C7—C3	178.81 (15)	C4—C5—C6	119.98 (12)
C2—C1—C6	117.51 (11)	O2—B1—C1	123.75 (11)
C2—C1—B1	122.70 (11)	O1—B1—O2	119.15 (12)
C6—C1—B1	119.79 (11)	O1—B1—C1	117.10 (12)
C3—C4—C5—C6	−0.2 (2)	C2—C1—B1—O1	−159.37 (13)
C7—C3—C2—C1	−179.96 (12)	C4—C3—C2—C1	0.64 (19)
C7—C3—C4—C5	−179.92 (12)	C6—C1—C2—C3	0.00 (18)
C1—C6—C5—C4	0.9 (2)	C6—C1—B1—O2	−158.17 (13)
C2—C3—C4—C5	−0.5 (2)	C6—C1—B1—O1	21.14 (19)
C2—C1—C6—C5	−0.8 (2)	B1—C1—C2—C3	−179.50 (12)
C2—C1—B1—O2	21.3 (2)	B1—C1—C6—C5	178.76 (13)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···O2i	0.82	1.98	2.796 (1)	170
O2—H2···N1ii	0.82	2.12	2.909 (2)	160
C2—H2A···N1ii	0.93	2.71	3.452 (2)	138
C4—H4···O1iii	0.93	2.67	3.469 (2)	144