2-Acetyl­phenyl­boronic acid monohydrate

The title compound, C₈H₉BO₃·H₂O, displays extensive intermolecular hydrogen bonding of mol­ecules of 2-acetyl­phenyl­boronic acid with each other and with mol­ecules of water, producing infinite, two-dimensional molecular layers. There is no intramolecular hydrogen bonding between the ortho C=O and (HO)₂B substituents.

Key indicators

• Single-crystal X-ray study
• T = 296 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.034
• wR factor = 0.101
• Data-to-parameter ratio = 12.8

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

---

S1. Comment

We are investigating the hydrogen-bonding pattern and subsequent stability of a series of o-substituted phenylboronic acids exhibiting an intramolecular bonding pattern of the type B—O—H···Y where Y is any O, N or F atom of the ortho-substituent and is thereby capable of forming stable hydrogen-bonded intramolecular rings. In our search for phenylboronic acids with such substitution patterns, especially with ortho C═O substitution, we found that although the crystal structure and hydrogen-bonding pattern of 2-formylphenylboronic acid has been reported (Scouten et al., 1994), no report of the crystal structure of the related 2-acetylphenylboronic acid has appeared. We now report the structure of 2-acetylphenylboronic acid monohydrate, (I), which we obtained on crystallization of 2-acetylphenylboronic acid from water. We shall subsequently report the structure of the anhydrous compound and compare it to that of the monohydrate (I) as well as that of anhydrous 2-formylphenylboronic acid reported by Scouten et al. (1994), to determine any differences in the pattern of hydrogen bonding.

The structure of (I) with its atom numbering is shown in Fig. 1. The plane formed by O1/B1/O2 is at an angle of 78.21 (16)° to that of the phenyl-ring plane, while the C2/C7/O3/C8 plane is nearly coplanar with the phenyl ring, the angle being 7.75 (9)°. Other geometric values of interest are given in Table 1. As is readily apparent from Fig. 2, there is no intramolecular hydrogen bonding in (I), in contrast to that exhibited in the structure of anhydrous 2-formylphenylboronic acid (Scouten et al., 1994), but there is an extensive system of intermolecular hydrogen bonding, producing infinite two-dimensional molecular sheets parallel to (100). Detailed hydrogen-bond geometry is given in Table 2. The carbonyl O atom of a molecule of (I) hydrogen bonds with one of the H atoms of the B(OH)₂ group of another molecule but not with water molecules, and there is no hydrogen bonding between the B(OH)₂ groups themselves. The latter hydrogen bond extensively with water molecules and both are hydrogen-bond donors and acceptors. The absence of water in anhydrous crystalline 2-acetylphenylboronic acid will most likely produce an entirely different picture.

S2. Experimental

Anhydrous 2-acetylphenylboronic acid, a powder melting at 441–443 K (decomposition), was purchased from COMBI-BLOCKS Inc. Very slow crystallization from a water solution over a period of several days afforded the title crystalline monohydrate, (I), used for this study. It melted slowly with decomposition between 361 and 366 K, becoming a viscous amber oil above 391 K, which partly became an amorphous solid at room temperature after several days. Scouten et al. (1994) reported that their 2-formylphenylboronic acid hydrate also melted over a similar range, 383–393 K, but resolidified at 398–403 K.

S3. Refinement

The atomic coordinates of the water H atoms were refined with fixed isotropic displacement values. The rotational orientations of the methyl and hydroxyl H atoms were refined by the circular Fourier method available in SHELXL97 (Sheldrick, 1997). All non-water H atoms were treated as riding, with C—H distances in the range 0.82–0.96 Å.

Computing details

Data collection: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1996); cell refinement: MSC/AFC Diffractometer Control Software; data reduction: PROCESS in TEXSAN (Molecular Structure Corporation, 1997); program(s) used to solve structure: SIR92 (Burla et al., 1989); program(s) used to refine structure: LS in TEXSAN and SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and PLATON (Spek, 2000); software used to prepare material for publication: TEXSAN, SHELXL97 and PLATON.

Figures

	Fig. 1. The molecular structure and atom-numbering scheme for (I), with displacement ellipsoids at the 50% probablilty level.
	Fig. 2. View of the molecular packing and hydrogen bonding in (I), viewed down the a* axis. The structure is made up of infinite hydrogen-bonded sheets which are parallel to (100). [Symmetry codes: (i) x, 1/2 − y, 1/2 + z; (ii) −x, 1/2 + y, 3/2 − z; (iii) −x, −1/2 + y, 3/2 − z.]

2-Acetylphenylboronic acid monohydrate

Crystal data

C8H9BO3·H2O	F(000) = 384
Mr = 181.98	Dx = 1.323 Mg m^−3
Monoclinic, P21/c	Melting point = 361–366 K
Hall symbol: -P 2ybc	Mo Kα radiation, λ = 0.71069 Å
a = 7.884 (4) Å	Cell parameters from 25 reflections
b = 8.1279 (17) Å	θ = 11.1–11.3°
c = 14.500 (3) Å	µ = 0.10 mm^−1
β = 100.47 (2)°	T = 296 K
V = 913.7 (5) Å^3	Irregular fragment, colorless
Z = 4	0.46 × 0.38 × 0.38 mm

Data collection

Rigaku AFC-5S diffractometer	Rint = 0.007
Radiation source: fine-focus sealed tube	θmax = 25.1°, θmin = 2.6°
Graphite monochromator	h = 0→9
ω scans	k = 0→9
1745 measured reflections	l = −17→16
1621 independent reflections	3 standard reflections every 100 reflections
1229 reflections with I > 2σ(I)	intensity decay: 0.1%

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.034	Hydrogen site location: geom and difmap
wR(F^2) = 0.101	H atoms treated by a mixture of independent and constrained refinement
S = 1.02	w = 1/[σ^2(Fo^2) + (0.049P)^2 + 0.2641P] where P = (Fo^2 + 2Fc^2)/3
1621 reflections	(Δ/σ)max < 0.001
127 parameters	Δρmax = 0.18 e Å^−3
0 restraints	Δρmin = −0.16 e Å^−3

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
B1	0.2163 (2)	0.3166 (2)	0.84250 (12)	0.0317 (4)
O1	0.11618 (15)	0.37909 (15)	0.90149 (8)	0.0439 (3)
O2	0.17570 (15)	0.35552 (14)	0.74975 (8)	0.0395 (3)
O3	0.12290 (15)	0.02518 (15)	0.81585 (8)	0.0459 (3)
O4	0.1406 (2)	0.13897 (19)	0.59246 (10)	0.0619 (4)
C1	0.39463 (19)	0.22800 (19)	0.87776 (10)	0.0308 (4)
C2	0.4189 (2)	0.0578 (2)	0.86680 (10)	0.0329 (4)
C3	0.5802 (2)	−0.0133 (2)	0.89367 (12)	0.0441 (4)
C4	0.7199 (2)	0.0812 (3)	0.93241 (13)	0.0520 (5)
C5	0.6993 (2)	0.2466 (3)	0.94448 (12)	0.0500 (5)
C6	0.5387 (2)	0.3197 (2)	0.91717 (11)	0.0417 (4)
C7	0.2649 (2)	−0.0411 (2)	0.82794 (11)	0.0362 (4)
C8	0.2806 (3)	−0.2192 (2)	0.80393 (14)	0.0554 (5)
H1	0.1508	0.3448	0.9548	0.066*
H2	0.0845	0.4065	0.7398	0.059*
H3	0.5941	−0.1257	0.8854	0.053*
H4	0.8278	0.0329	0.9503	0.062*
H5	0.7934	0.3105	0.9711	0.060*
H6	0.5272	0.4324	0.9254	0.050*
H8a	0.3122	−0.2819	0.8606	0.083*
H8b	0.3676	−0.2317	0.7660	0.083*
H8c	0.1721	−0.2581	0.7699	0.083*
H4a	0.164 (3)	0.205 (3)	0.6397 (17)	0.074*
H4b	0.078 (3)	0.059 (3)	0.6037 (17)	0.074*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
B1	0.0333 (9)	0.0281 (8)	0.0338 (9)	−0.0022 (7)	0.0060 (7)	−0.0022 (7)
O1	0.0462 (7)	0.0528 (8)	0.0344 (6)	0.0175 (6)	0.0116 (5)	0.0029 (5)
O2	0.0434 (7)	0.0417 (7)	0.0336 (6)	0.0095 (5)	0.0074 (5)	0.0027 (5)
O3	0.0391 (7)	0.0391 (7)	0.0561 (8)	−0.0027 (5)	−0.0001 (6)	−0.0042 (6)
O4	0.0852 (11)	0.0636 (10)	0.0421 (8)	−0.0282 (8)	0.0257 (7)	−0.0142 (7)
C1	0.0331 (8)	0.0332 (8)	0.0274 (7)	−0.0007 (6)	0.0086 (6)	−0.0015 (6)
C2	0.0351 (8)	0.0367 (9)	0.0280 (7)	0.0039 (7)	0.0085 (6)	−0.0001 (6)
C3	0.0442 (10)	0.0476 (10)	0.0423 (10)	0.0145 (8)	0.0129 (8)	0.0035 (8)
C4	0.0327 (10)	0.0765 (14)	0.0470 (10)	0.0132 (9)	0.0073 (8)	0.0066 (10)
C5	0.0324 (9)	0.0746 (14)	0.0415 (10)	−0.0099 (9)	0.0027 (7)	−0.0040 (9)
C6	0.0416 (10)	0.0443 (10)	0.0392 (9)	−0.0068 (8)	0.0074 (7)	−0.0058 (8)
C7	0.0483 (10)	0.0322 (8)	0.0291 (8)	−0.0013 (7)	0.0101 (7)	−0.0001 (6)
C8	0.0744 (14)	0.0359 (10)	0.0566 (12)	−0.0008 (9)	0.0140 (10)	−0.0087 (9)

Geometric parameters (Å, º)

O1—B1	1.363 (2)	O4—H4a	0.86 (2)
O2—B1	1.362 (2)	O4—H4b	0.85 (3)
C1—B1	1.579 (2)	O1—H1	0.8200
O3—C7	1.226 (2)	O2—H2	0.8200
C2—C7	1.480 (2)	C3—H3	0.9300
C7—C8	1.500 (2)	C4—H4	0.9300
C1—C6	1.392 (2)	C5—H5	0.9300
C1—C2	1.409 (2)	C6—H6	0.9300
C2—C3	1.387 (2)	C8—H8a	0.9600
C3—C4	1.376 (3)	C8—H8b	0.9600
C4—C5	1.370 (3)	C8—H8c	0.9600
C5—C6	1.390 (3)
C6—C1—B1	120.04 (14)	B1—O1—H1	109.5
C2—C1—B1	122.83 (14)	B1—O2—H2	109.5
O2—B1—O1	118.28 (15)	C4—C3—H3	119.8
O2—B1—C1	117.48 (14)	C2—C3—H3	119.8
O1—B1—C1	123.35 (14)	C5—C4—H4	120.1
C6—C1—C2	117.04 (15)	C3—C4—H4	120.1
C4—C3—C2	120.45 (17)	C4—C5—H5	119.8
C5—C4—C3	119.72 (17)	C6—C5—H5	119.8
C4—C5—C6	120.42 (17)	C5—C6—H6	119.3
C5—C6—C1	121.43 (17)	C1—C6—H6	119.3
C3—C2—C1	120.94 (15)	C7—C8—H8a	109.5
C3—C2—C7	121.85 (15)	C7—C8—H8b	109.5
C1—C2—C7	117.19 (14)	C7—C8—H8c	109.5
O3—C7—C2	118.74 (14)	H8b—C8—H8c	109.5
O3—C7—C8	120.20 (16)	H8a—C8—H8b	109.5
C2—C7—C8	121.06 (16)	H8a—C8—H8c	109.5
H4a—O4—H4b	112 (2)
B1—C1—C2—C3	176.06 (14)	C1—C2—C7—O3	−7.0 (2)
B1—C1—C6—C5	−176.69 (15)	C3—C2—C7—C8	−8.3 (2)
B1—C1—C2—C7	−5.5 (2)	C1—C2—C7—C8	173.28 (15)
C6—C1—B1—O2	95.82 (18)	C6—C1—C2—C3	−0.5 (2)
C2—C1—B1—O2	−80.66 (19)	C1—C2—C3—C4	0.5 (2)
C6—C1—B1—O1	−73.1 (2)	C2—C3—C4—C5	0.0 (3)
C2—C1—B1—O1	110.38 (18)	C3—C4—C5—C6	−0.5 (3)
C6—C1—C2—C7	177.96 (13)	C4—C5—C6—C1	0.5 (3)
C7—C2—C3—C4	−177.87 (15)	C2—C1—C6—C5	0.0 (2)
C3—C2—C7—O3	171.49 (15)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···O4^i	0.82	2.02	2.745 (2)	148
O2—H2···O3^ii	0.82	1.94	2.745 (2)	166
O4—H4a···O2	0.86 (2)	2.00 (2)	2.854 (2)	170 (2)
O4—H4b···O1^iii	0.85 (2)	2.11 (2)	2.938 (2)	165 (2)

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