Crystal structure of 4-(meth­oxy­carbon­yl)phenyl­boronic acid

In the crystal of the title compound, mol­ecules are linked via O—H⋯O and C—H⋯O hydrogen bonds, forming undulating sheets parallel to (10). The sheets are linked via C—H⋯π and offset face-to-face π-inter­actions, between inversion-related mol­ecules [inter-centroid distance = 3.7843 (16) Å], forming a three-dimensional structure.

Abstract

In the title compound, C₈H₉BO₄, the meth­oxy­carbonyl group is rotated out of the plane of the benzene ring by 7.70 (6)°. In the crystal, mol­ecules are linked via pairs of O—H⋯O hydrogen bonds, involving the boronic acid OH groups, forming inversion dimers. The dimers are linked via O—H⋯O hydrogen bonds, involving a boronic acid OH group and the carbonyl O atom, forming undulating sheets parallel to (10-2). Within the sheets there are also C—H⋯O hydrogen bonds present, also involving the carbonyl O atom. The sheets are linked via C—H⋯π and offset face-to-face π-inter­actions between inversion-related mol­ecules [inter-centroid distance = 3.7843 (16) Å, inter­planar distance = 3.3427 (4) Å and offset = 1.744 Å], forming a three-dimensional structure.

Chemical context  

Boronic acids have been widely studied, mainly due to their roles in coupling reactions such as Suzuki (Suzuki, 2011 ▸), Chan–Lam (Lam et al., 2000 ▸) and Liebeskind–Srogl (Liebeskind & Srogl, 2000 ▸). Complexes of boronic acids are well known, and many examples have been structurally characterized (e.g., Roşca et al., 2012 ▸; Filthaus et al., 2008 ▸; Cyrański et al., 2008 ▸; Rettig & Trotter, 1977 ▸). Many examples exist of similar compounds such as 2-methyl­imidazolium (4-carb­oxy­benzene)(2-methyl­imidazol­yl)boronate monohydrate (Aakeröy et al., 2005 ▸) and 4-carb­oxy­phenyl­boronic acid (SeethaLekshmi & Pedireddi, 2007 ▸). However, no examples of meth­oxy-protected derivatives have been published to date. We report herein on the crystal structure of the title compound, the 4-(meth­oxy­carbon­yl) derivative of phenyl­boronic acid.

Structural commentary  

The title mol­ecule, Fig. 1 ▸, is almost completely planar with the meth­oxy­carbonyl group inclined to the benzene ring by 7.70 (6)°. The angle around atom B1, O1—B1—O2 is 118.16 (9)°, very close to the ideal value of 120°. The bond lengths and angles are similar to those reported for 4-carb­oxy­phenyl­boronic acid derivatives (SeethaLekshmi & Pedireddi, 2007 ▸) in which the carb­oxy­lic group is rotated from the plane of the benzene ring by ca 13.83–26.44°, and the O—B—O bond angles are in the range of ca 118.1–122.5°. Aakeröy et al. (2005 ▸) reported the structures of 4-acetyl­pyridine oxime 4-carb­oxy­benzene­boronate dihydrate and 4-acetyl­pyridine oxime 4-carb­oxy­benzene­boronate dihydrate in which the 4-carb­oxy groups are inclined to the benzene ring by ca 10.45–14.08°, close to the value observed for the meth­oxy­carbonyl group in the title compound.

Figure 1.

The mol­ecular structure of the title compound, showing the atom labelling. Displacement ellipsoids are drawn at the 50% probability level.

Supra­molecular features  

In the crystal of the title compound, there are hydrogen bonds between the carbonyl atom O4 and the hy­droxy group O2–H2A of the boronic acid and atom O2 of the boronic acid with a D⋯ A distance of 2.753 (1) Å (Fig. 2 ▸ and Table 1 ▸). The hy­droxy group O1–-H1A of the boronic acid is in an inversion-related hydrogen-bonded network with the oxygen O2 of the boronic acid at a distance of 2.762 (1) Å (Fig. 2 ▸ and Table 1 ▸).

Figure 2.

Hydrogen bonding (dashed lines) in the crystal of the title compound [see Table 1 ▸ for details; symmetry codes: (A) −x + 2, −y + 1, −z + 2; (B) −x + 1, y − , −z + ]. Displacement ellipsoids are drawn at the 50% probability level.

Table 1. Hydrogen-bond geometry (, ).

Cg is the centroid of ring C1C6.

DHA	DH	HA	D A	DHA
O1H1AO2i	0.86(2)	1.90(2)	2.762(1)	178.4(18)
O2H2AO4ii	0.84(2)	1.94(2)	2.753(1)	162.2(16)
C2H2O4ii	0.95	2.59	3.500(1)	160
C5H5Cg iii	0.95	2.75	3.534(1)	141

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

The presence of the meth­oxy group on the carbonyl removes hydrogen-bond donation of the carb­oxy­lic acid seen in related structures. Atom C8 creates a shield around atom O3, removing its ability to participate in hydrogen bonding due to steric effects. It is noteworthy that the meth­oxy protecting group is small compared to other protecting groups and therefore exhibits no steric effects on the hydrogen-bonding capabilities to atom O4 in this structure, as seen in other examples. As exemplified by the work of Lemmerer (2012 ▸), most literature examples exhibit an almost exclusive head-to-tail hydrogen-bonding network between the boronic and carb­oxy­lic acids whereas the title compound exhibits exclusively head-to-head hydrogen-bonding inter­actions with the boronic acid subunit. This is due to the steric effects and removal of hydrogen-donating abilities in the meth­oxy­carbonyl subunit (Fig. 2 ▸). The group can still act as a hydrogen acceptor, as shown in the packing diagram (Fig. 2 ▸). Atom O4 can accept H atoms from the hy­droxy group O2—H2A to create an offset face-to-face overlap in the packing unit. Yang et al. (2005 ▸) published a structure of the boronic ester deriv­ative of the title compound. This structure showed similar effects, however no hydrogen bonds were visible in the reported structure.

Hydrogen bonding and π-stacking within the unit cell forms a strong set of dimeric pairs. This can be easily observed in Fig. 3 ▸. These dimeric pairs line up to form a zigzag stacking pattern with a consistent spacing throughout the unit cell. This is aided by the hydrogen bond between O4 and O2—H2A [2.753 (1) Å] and a close contact between atom O4 and the hydrogen on atom C2 at a distance of 2.59 Å. The unit cell consists of four mol­ecular units which form π-aggregated pairs in a head-to-tail fashion and are stabilized through offset face-to-face π-inter­actions [inter-centroid distance = 3.7843 (16) Å; inter-planar distance = 3.3427 (4) Å, offset = 1.744 Å]; see Fig. 4 ▸. The hy­droxy group O1—H1A of the boronic acid is in an inversion-related hydrogen-bonded network with the oxygen O2 of the boronic acid at a distance of 2.762 (1) Å, forming a head-to-head hydrogen-bonded network with adjacent mol­ecules (Fig. 5 ▸). There are also C—H⋯π inter­actions (Table 1 ▸) present between the undulating sheets parallel to (10). The sum of all of these inter­molecular inter­actions leads to the formation of a three-dimensional structure.

Figure 3.

View of the π-aggregated structure as viewed approximately along the a axis.

Figure 4.

A view approximately along the b axis, showing the offset face-to-face π-inter­actions involving inversion-related mol­ecules.

Figure 5.

Crystal packing diagram of the title compound viewed along the c axis, showing the offset face-to-face π-inter­actions involving inversion-related mol­ecules (dashed lines; see Table 1 ▸ for details).

Database survey  

A search of the Cambridge Structural Database (Version 5.36, update Nov. 2014; Groom & Allen, 2014 ▸) gave fourteen hits for free carb­oxy­lic acid derivatives of the title compound and one for the boronic ester. Soundararajan et al. (1993 ▸) published a structure of 4-carb­oxy-2-nitro­benzene­boronic acid. The carb­oxy­lic group deviated from the mean plane with an angle of ca 5.84° and the O—B—O bond angle was ca 119.88°. Aakeröy et al. (2004 ▸) reported the structure of a 4-carb­oxy­benzene­boronic acid 4,4′-bi­pyridine derivative with the carb­oxy­lic group being rotated from the plane by ca 4.20° and an O—B—O bond angle of ca 118.09°. They also reported the structures of 2-methyl­imidazolium(4-carb­oxy­benzene)(2-methyl­imidazol­yl)boronate monohydrate, tris­(4-(di­methyl­amino)­pyridinium) bis­(4-(di­methyl­amino)­pyridine) tris­(4-carb­oxy­benzene­boronate) trihydrate and 4-acetyl­pyridine oxime 4-carb­oxy­benzene­boronate dihydrate which presented out-of-plane tilt angles of ca 10.45–27.74° and O—B—O bond angles of ca 114.23–124.94° (Aakeröy et al., 2005 ▸).

SeethaLekshmi & Pedireddi (2006 ▸) reported on a selection of carboxyl­ato­phenyl­boronic acid derivatives, hexa­aqua-M(II) bis­(4-carboxyl­ato­phenyl­boronic acid) tetra­hydrate, where M is nickel, manganese or cobalt. These structures where similar to the title compound and exhibited similar characteristics for the O—B—O bond angle and the out-of-plane tilt of the carboxyl acid group compared to the title compound. The carb­oxy­lic group deviated from the plane with an angle of ca 3.40–4.53° and the O—B—O bond angles were in the range of ca 121.43–122.18° (SeethaLekshmi & Pedireddi, 2006 ▸). They also published a selection of 4-carb­oxy­phenyl­boronic acids including the monohydrate and the hydrate derivatives of this compound. The carb­oxy­lic group deviated from the mean plane with an angle of ca 13.83–26.44° and the O—B—O bond angles were in the range of ca 118.08–122.50° (SeethaLekshmi & Pedireddi, 2007 ▸).

The structure of bis­(8-chloro-1-methyl-6-phenyl-4H-[1,2,4]triazolo[4,3-a][1,4]benzodiazepine) 4-(di­hydroxy­bor­yl)benzoic acid monohydrate exhibited a tilt angle of ca 2.14° for the carb­oxy­lic group and an O—B—O bond angle of ca 126.53° (Varughese et al., 2011 ▸). Likewise, the relevant values in the structure of a cyclo­penta­naminium 4-(di­hydroxy­bor­yl)benzoate trihydrate were ca 29.67 and 126.53°, respectively (Lemmerer, 2012 ▸). Finally, methyl 4-(4,4,5,5-tetra­methyl-1,3,2-dioxaborolan-2-yl)benzoate showed similar features to the title compound with a meth­oxy­carbonyl deviation from the ring plane of ca 4.97° (Yang et al., 2005 ▸).

Synthesis and crystallization  

The compound was purchased from Alfa Aesar and was purified with silica gel column chromatography using CH₂Cl₂:MeOH (19:1). The compound was then crystallized from a solution of 1% MeOH in CH₂Cl₂ layered with hexane to give a single crystal suitable for X-ray diffraction.

Refinement  

Crystal data, data collection and structure refinement details are summarized in Table 2 ▸. The donor OH H atoms were located in a difference Fourier map and freely refined. The C-bound H atoms were placed in their expected calculated positions and refined as riding: C—H = 0.95–0.98 Å with U _iso(H) = 1.5U _eq(C) for methyl H atoms and 1.2U _iso(C) for other H atoms.

Table 2. Experimental details.

Crystal data
Chemical formula	C8H9BO4
M r	179.96
Crystal system, space group	Monoclinic, P21/c
Temperature (K)	100
a, b, c ()	11.2449(6), 12.0672(6), 6.8598(3)
()	105.121(1)
V (3)	898.61(8)
Z	4
Radiation type	Mo K
(mm1)	0.10
Crystal size (mm)	0.35 0.10 0.10
Data collection
Diffractometer	Bruker SMART APEXII area detector
Absorption correction	Multi-scan (SADABS; Bruker, 2014 ▸)
T min, T max	0.706, 0.746
No. of measured, independent and observed [I > 2(I)] reflections	31992, 2056, 1872
R int	0.021
(sin /)max (1)	0.649
Refinement
R[F 2 > 2(F 2)], wR(F 2), S	0.032, 0.094, 1.10
No. of reflections	2056
No. of parameters	126
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
max, min (e 3)	0.39, 0.22

Computer programs: APEX2 and SAINT-Plus (Bruker, 2014 ▸), SHELXT (Sheldrick, 2015a ▸), XP in SHELXTL (Sheldrick, 2008 ▸), SHELXL2014 (Sheldrick, 2015b ▸) and publCIF (Westrip, 2010 ▸).

Supplementary Material

CCDC reference: 1416885

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

supplementary crystallographic information

Crystal data

C8H9BO4	F(000) = 376
Mr = 179.96	Dx = 1.330 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 11.2449 (6) Å	Cell parameters from 9864 reflections
b = 12.0672 (6) Å	θ = 2.5–31.1°
c = 6.8598 (3) Å	µ = 0.10 mm−1
β = 105.121 (1)°	T = 100 K
V = 898.61 (8) Å3	Block, white
Z = 4	0.35 × 0.10 × 0.10 mm

Data collection

Bruker SMART APEXII area-detector diffractometer	2056 independent reflections
Radiation source: sealed tube	1872 reflections with I > 2σ(I)
Detector resolution: 8.258 pixels mm-1	Rint = 0.021
φ and ω scans	θmax = 27.5°, θmin = 1.9°
Absorption correction: multi-scan (SADABS; Bruker, 2014)	h = −14→14
Tmin = 0.706, Tmax = 0.746	k = −15→15
31992 measured reflections	l = −8→8

Refinement

Refinement on F2	0 restraints
Least-squares matrix: full	Hydrogen site location: mixed
R[F2 > 2σ(F2)] = 0.032	H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.094	w = 1/[σ2(Fo2) + (0.0494P)2 + 0.2551P] where P = (Fo2 + 2Fc2)/3
S = 1.10	(Δ/σ)max < 0.001
2056 reflections	Δρmax = 0.39 e Å−3
126 parameters	Δρmin = −0.22 e Å−3

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
O1	0.90580 (7)	0.61792 (6)	0.84477 (13)	0.0258 (2)
H1A	0.9797 (19)	0.5946 (15)	0.897 (3)	0.054 (5)*
C1	0.67921 (8)	0.57954 (8)	0.78322 (14)	0.0163 (2)
B1	0.81840 (10)	0.54762 (9)	0.87529 (16)	0.0185 (2)
O2	0.85621 (7)	0.45309 (6)	0.98510 (12)	0.02287 (19)
H2A	0.8020 (17)	0.4076 (14)	0.997 (3)	0.046 (4)*
C2	0.58139 (9)	0.51156 (8)	0.80135 (14)	0.0166 (2)
H2	0.5989	0.4434	0.8724	0.020*
O3	0.21983 (6)	0.60624 (6)	0.54273 (12)	0.02136 (18)
C3	0.45926 (9)	0.54182 (8)	0.71743 (14)	0.0161 (2)
H3	0.3942	0.4945	0.7303	0.019*
O4	0.27900 (6)	0.77238 (6)	0.45341 (11)	0.02041 (18)
C4	0.43313 (8)	0.64218 (8)	0.61442 (13)	0.0153 (2)
C5	0.52908 (9)	0.71113 (8)	0.59350 (14)	0.0169 (2)
H5	0.5112	0.7793	0.5227	0.020*
C6	0.65052 (9)	0.67947 (8)	0.67660 (15)	0.0177 (2)
H6	0.7153	0.7263	0.6610	0.021*
C7	0.30450 (8)	0.68109 (8)	0.52886 (14)	0.0163 (2)
C8	0.09288 (9)	0.64329 (9)	0.47857 (19)	0.0271 (2)
H8A	0.0381	0.5827	0.4945	0.041*
H8B	0.0813	0.7065	0.5614	0.041*
H8C	0.0735	0.6657	0.3364	0.041*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
O1	0.0150 (4)	0.0242 (4)	0.0365 (4)	−0.0005 (3)	0.0034 (3)	0.0100 (3)
C1	0.0156 (4)	0.0176 (5)	0.0155 (4)	0.0006 (3)	0.0036 (3)	−0.0014 (4)
B1	0.0160 (5)	0.0190 (5)	0.0199 (5)	0.0002 (4)	0.0035 (4)	0.0001 (4)
O2	0.0144 (3)	0.0211 (4)	0.0314 (4)	−0.0013 (3)	0.0029 (3)	0.0073 (3)
C2	0.0180 (5)	0.0156 (4)	0.0162 (4)	0.0017 (3)	0.0045 (3)	0.0007 (3)
O3	0.0147 (3)	0.0180 (4)	0.0306 (4)	0.0001 (3)	0.0046 (3)	0.0004 (3)
C3	0.0162 (4)	0.0160 (4)	0.0165 (4)	−0.0010 (3)	0.0051 (3)	−0.0017 (3)
O4	0.0190 (3)	0.0188 (4)	0.0232 (4)	0.0034 (3)	0.0051 (3)	0.0029 (3)
C4	0.0159 (4)	0.0162 (4)	0.0136 (4)	0.0014 (3)	0.0036 (3)	−0.0025 (3)
C5	0.0195 (5)	0.0156 (4)	0.0158 (4)	0.0011 (3)	0.0050 (3)	0.0010 (3)
C6	0.0166 (4)	0.0182 (5)	0.0188 (4)	−0.0015 (3)	0.0054 (3)	0.0007 (3)
C7	0.0172 (4)	0.0170 (4)	0.0148 (4)	0.0004 (3)	0.0045 (3)	−0.0031 (3)
C8	0.0147 (5)	0.0260 (5)	0.0396 (6)	0.0013 (4)	0.0053 (4)	0.0015 (5)

Geometric parameters (Å, º)

O1—B1	1.3552 (13)	C3—C4	1.3942 (13)
O1—H1A	0.86 (2)	C3—H3	0.9500
C1—C2	1.4034 (13)	O4—C7	1.2191 (12)
C1—C6	1.4035 (13)	C4—C5	1.3992 (13)
C1—B1	1.5752 (14)	C4—C7	1.4880 (13)
B1—O2	1.3720 (13)	C5—C6	1.3891 (13)
O2—H2A	0.841 (18)	C5—H5	0.9500
C2—C3	1.3923 (13)	C6—H6	0.9500
C2—H2	0.9500	C8—H8A	0.9800
O3—C7	1.3336 (12)	C8—H8B	0.9800
O3—C8	1.4503 (12)	C8—H8C	0.9800
B1—O1—H1A	113.1 (12)	C5—C4—C7	117.91 (8)
C2—C1—C6	118.00 (8)	C6—C5—C4	119.75 (9)
C2—C1—B1	122.77 (8)	C6—C5—H5	120.1
C6—C1—B1	119.23 (8)	C4—C5—H5	120.1
O1—B1—O2	118.16 (9)	C5—C6—C1	121.19 (9)
O1—B1—C1	118.02 (9)	C5—C6—H6	119.4
O2—B1—C1	123.82 (9)	C1—C6—H6	119.4
B1—O2—H2A	118.0 (12)	O4—C7—O3	123.30 (9)
C3—C2—C1	121.43 (9)	O4—C7—C4	123.32 (9)
C3—C2—H2	119.3	O3—C7—C4	113.37 (8)
C1—C2—H2	119.3	O3—C8—H8A	109.5
C7—O3—C8	115.73 (8)	O3—C8—H8B	109.5
C2—C3—C4	119.48 (9)	H8A—C8—H8B	109.5
C2—C3—H3	120.3	O3—C8—H8C	109.5
C4—C3—H3	120.3	H8A—C8—H8C	109.5
C3—C4—C5	120.15 (9)	H8B—C8—H8C	109.5
C3—C4—C7	121.91 (8)
C2—C1—B1—O1	178.38 (9)	C7—C4—C5—C6	178.03 (8)
C6—C1—B1—O1	−1.02 (14)	C4—C5—C6—C1	−0.52 (14)
C2—C1—B1—O2	−1.88 (15)	C2—C1—C6—C5	0.81 (14)
C6—C1—B1—O2	178.73 (9)	B1—C1—C6—C5	−179.77 (9)
C6—C1—C2—C3	−0.29 (14)	C8—O3—C7—O4	−5.45 (14)
B1—C1—C2—C3	−179.69 (9)	C8—O3—C7—C4	174.59 (8)
C1—C2—C3—C4	−0.52 (14)	C3—C4—C7—O4	173.53 (9)
C2—C3—C4—C5	0.82 (14)	C5—C4—C7—O4	−4.78 (14)
C2—C3—C4—C7	−177.45 (8)	C3—C4—C7—O3	−6.51 (13)
C3—C4—C5—C6	−0.31 (14)	C5—C4—C7—O3	175.18 (8)

Hydrogen-bond geometry (Å, º)

Cg is the centroid of ring C1–C6.

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1A···O2i	0.86 (2)	1.90 (2)	2.762 (1)	178.4 (18)
O2—H2A···O4ii	0.84 (2)	1.94 (2)	2.753 (1)	162.2 (16)
C2—H2···O4ii	0.95	2.59	3.500 (1)	160
C5—H5···Cgiii	0.95	2.75	3.534 (1)	141

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