2-(6-Bromopyridin-3-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane and (6-bromopyridin-3-yl)boronic acid, new bifunctional building blocks for combinatorial chemistry

The first comparative study between two new heterocyclic boron derivatives, viz. a (6-bromo­pyridin-3-yl)­boronic ester, C₁₁H₁₅BBrNO₂, and (6-bromo­pyridin-3-yl)­boronic acid, C₅H₅BBrNO₂, shows a small but not significant difference in their C-B bond lengths, which cannot explain the experimentally observed difference in their stabilities. The crystal packing of the boronic ester consists principally of van der Waals interactions, while the boronic acid mol­ecules interact in their crystal through hydrogen bonds.

S1. Comment

For the past few years, we have been focusing on a general method for the synthesis of new pyridinylboronic acids and esters of use in combinatorial approaches, with the aim of obtaining mild and flexible strategies for the design of new pyridine libraries. In particular, we have concentrated on the synthesis of new (halopyridinyl)boronic acids and esters likely to offer a double reactivity, via their boronic moiety and their halogen atom. We have recently published a very efficient and general method for the synthesis and isolation of novel (6-halopyridin-3-yl)boronic acids and esters (Bouillon et al., 2002a). In this paper, the crystal structure of 2-(6-bromopyridin-3-yl)-4,4,5,5-tetramethyl-1,3-dioxaborolane, (I), is described. Even though the structure of (6-bromopyridin-3-yl)boronic acid, (II), has already been solved (Parry et al., 2002), we report this structure here also, as solved in our laboratory, in order to make a comparison between the ester and its corresponding acid. The structural data for the (6-halopyridin-3-yl)boronic acid are not available in the Cambridge Structural Database (CSD, Version 5.23; Allen, 2002) as of the time of writing. \sch

Figs. 1 and 2 show views of the asymmetric units of the ester, (I), and the acid, (II), respectively. The asymmetric unit consists of one molecule for both compounds.

The five-membered ring in (I) is in a half-chair conformation and its best plane is oriented approximately coplanar to the pyridine ring, at an angle of 2.6 (3)°. The deviation of the BO₂ group from a coplanar arrangement with respect to the pyridine ring is about 6.5 (6)° in (I), compared with 10.5 (5)° in (II). The greater deviation in (II) most probably results from crystal packing interactions. In the crystal of (II), the packing is principally mediated by electrostatic interactions (hydrogen bonds), with the molecules grouped into dimers. The two molecules in a dimer are coplanar, facing each other via the boronic acid groups (Fig. 3), and they are linked by a pair of symmetry-equivalent O2—HO2···O1 hydrogen bonds (Fig. 3, Table 3) related by inversion centres. Furthermore, the presence of one hydrogen acceptor, atom N1 in the six-membered ring, allows interaction between neighbouring dimers through another hydrogen bond, O1—HO1···N1(1 − x, y − 1/2, 3/2 − z). The involvement of O atoms in several hydrogen bonds influences the spatial orientation of the boronic acid group in (II). In contrast, the crystal packing of (I) is mediated principally by van der Waals interactions, and the orientation of the boronic group is dictated only by its position in the ester ring.

In (I), a shorter bond length is observed for the C—B bond, with C5—B 1.557 (6) Å (Table 1), compared with C5—B 1.580 (5) Å in (II) (Table 2). Another difference observed in the spatial arrangement of the BO₂ group concerns the C—B—O bond angles. In (II), a slight asymmetry is observed between these angles (Table 2) which is not detected in (I) (Table 1). The existence of this asymmetry in (II) is probably due to the involvement of the boronic group of the acid in intermolecular interactions, which is not the case in (I).

In the five-membered ring of (I), an elongation of the displacement ellipsoids in a direction perpendicular to the mean plane of the five-membered ring is observed. This is the result of either static or dynamic conformational disorder, which is not of sufficient magnitude (if static) to permit refinement of separate atoms for the disordered congeners. The disorder, which is progressively greater as one traverses the ring from B out to the tetramethylethylene fragment, also affects the terminal methyl groups. The individual atomic sites were modelled with anisotropic displacement parameters so as to reproduce correctly the average scattering density in this part of the cell in a manner consistent with such a disorder. The bond distances, especially those involving the methyl C atoms, should be considered `apparent distances' and it is not recommended that they be used in comparisons with other C—C distances. The C—CH₃ distances (Table 1) differ significantly from the reference value of 1.53 Å (Glusker et al., 1994).

As has already been mentioned, the molecules of (I) interact principally through van der Waals interactions. Dimeric aggregation can be seen in the crystal packing. Two molecules are oriented facing each other via their boronic ester groups, related by inversion centres. The intermolecular distances between methyl C atoms are in the vicinity of 4 Å. These dimers interact through weak electrostatic interactions between Br atoms and methyl groups. Strong interactions between the N and B atoms are not observed, either in the crystal packing of the ester, (I), or in that of the acid, (II).

The observed difference between the C—B bond length in the boronic ester and boronic acid is not statistically significant and cannot in itself explain the greater experimentally observed stability of the ester compound with respect to the boronic acid during chemical reactions. We are currently working to characterize other isomers of these pyridinyl boronic acid and pyrinidyl boronate esters, for which we have recently published the syntheses (Bouillon et al., 2002b,c).

S2. Experimental

The title compounds were synthesized from 2,5-dibromopyridine using the method described by Bouillon et al. (2002a). Suitable crystals of the title ester, (I), and the acid, (II), were obtained by slow evaporation from acetonitrile at room temperature.

S3. Refinement

The possibility of disorder of the pyridinyl ring in (I) by rotation of 180° about the C5—B bond was tested. Only one of the two possible orientations led to a stable refinement, and this is the position described here for (I). The full PLATON check indicates small displacement parameters for atom C2 compared with its neighbours. Atom C2 has three neighbouring atoms, C3, N1 and Br1. The displacement parameters of atoms C2, N1 and C3, all part of the pyridine ring, are comparable [U_eq(C2) = 0.0657, U_eq(C3) = 0.0689 and U_eq(N1) = 0.0709 Ų]. The only significant difference is between the displacement parameters of C2 and Br1 [U_eq(Br1) = 0.1081 Ų], which is exocyclic. Furthermore, during the refinement, density peaks corresponding to H atoms were observed, and a density peak was detected in the vicinity of atom C3, but none in the vicinity of atom N1. H-atom parameters were constrained, with C—H distances in the range 0.93–0.96 Å and O—H distances of 0.82 Å. Is this added text OK?

Computing details

For both compounds, data collection: CAD-4-PC Software (Enraf-Nonius, 1996); cell refinement: CAD-4-PC Software (Enraf-Nonius, 1996); data reduction: JANA98 (Petříček & Dušek, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. A view of the molecule of the ester, (I), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small circles of arbitrary radii.
	Fig. 2. A view of the molecule of the acid, (II), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small circles of arbitrary radii.
	Fig. 3. A view of the hydrogen bonds (dotted lines) in the crystal packing of (II).

(I) 2-(6-bromopyridin-3-yl)-4,4,5,5-tetramethyl-1,3-dioxaborolane

Crystal data

C11H15BBrNO2	Dx = 1.454 Mg m^−3
Mr = 283.96	Melting point: 365 K
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71069 Å
a = 6.4672 (4) Å	Cell parameters from 25 reflections
b = 12.4977 (10) Å	θ = 18–25°
c = 16.1074 (8) Å	µ = 3.15 mm^−1
β = 95.024 (6)°	T = 293 K
V = 1296.88 (15) Å^3	Prism, dark white grey
Z = 4	0.60 × 0.44 × 0.36 mm
F(000) = 576

Data collection

Enraf-Nonius CAD4 diffractometer	1849 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.048
Graphite monochromator	θmax = 30.0°, θmin = 2.1°
θ/2θ scans	h = −9→9
Absorption correction: gaussian (JANA98; Petříček & Dušek, 1998)	k = 0→17
Tmin = 0.241, Tmax = 0.358	l = 0→22
3893 measured reflections	3 standard reflections every 60 min
3772 independent reflections	intensity decay: 8.1%

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)] = 0.068	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.217	H-atom parameters constrained
S = 1.02	w = 1/[σ^2(Fo^2) + (0.0981P)^2 + 1.1126P] where P = (Fo^2 + 2Fc^2)/3
3772 reflections	(Δ/σ)max = 0.001
149 parameters	Δρmax = 0.54 e Å^−3
0 restraints	Δρmin = −0.74 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.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

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

	x	y	z	Uiso*/Ueq
Br1	1.02733 (12)	0.76997 (6)	0.40268 (3)	0.1081 (4)
N1	1.0439 (6)	0.8746 (3)	0.5517 (2)	0.0709 (10)
C6	0.9638 (7)	0.9211 (4)	0.6163 (3)	0.0646 (11)
H6	1.0562	0.9479	0.6588	0.077*
C5	0.7544 (6)	0.9326 (3)	0.6249 (2)	0.0520 (9)
C4	0.6191 (7)	0.8947 (4)	0.5595 (3)	0.0606 (10)
H4	0.4765	0.9022	0.5614	0.073*
C3	0.6959 (8)	0.8462 (4)	0.4921 (3)	0.0691 (12)
H3	0.6084	0.8197	0.4480	0.083*
C2	0.9087 (8)	0.8387 (4)	0.4930 (3)	0.0658 (12)
B	0.6782 (7)	0.9857 (4)	0.7042 (3)	0.0527 (11)
O1	0.8077 (4)	1.0143 (3)	0.77008 (18)	0.0752 (10)
O2	0.4777 (5)	1.0103 (3)	0.7128 (2)	0.0765 (10)
C7	0.6859 (8)	1.0767 (6)	0.8259 (3)	0.095 (2)
C8	0.4689 (8)	1.0497 (5)	0.7978 (3)	0.0837 (16)
C71	0.7754 (11)	1.0712 (7)	0.9104 (3)	0.118 (3)
H71A	0.7915	0.9976	0.9269	0.178*
H71B	0.6860	1.1067	0.9461	0.178*
H71C	0.9087	1.1056	0.9147	0.178*
C72	0.7112 (14)	1.2007 (5)	0.7954 (5)	0.128 (3)
H72A	0.6705	1.2483	0.8378	0.192*
H72B	0.6246	1.2125	0.7448	0.192*
H72C	0.8534	1.2139	0.7859	0.192*
C81	0.419 (2)	0.9437 (9)	0.8510 (5)	0.222 (7)
H81A	0.3569	0.9646	0.9006	0.333*
H81B	0.5450	0.9054	0.8660	0.333*
H81C	0.3240	0.8985	0.8178	0.333*
C82	0.3002 (10)	1.1264 (8)	0.8023 (5)	0.136 (3)
H82A	0.3265	1.1883	0.7695	0.203*
H82B	0.2912	1.1473	0.8592	0.203*
H82C	0.1717	1.0940	0.7810	0.203*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.1483 (7)	0.1144 (6)	0.0665 (4)	0.0478 (4)	0.0376 (4)	−0.0118 (3)
N1	0.067 (2)	0.081 (3)	0.067 (2)	0.018 (2)	0.0190 (19)	−0.005 (2)
C6	0.062 (3)	0.073 (3)	0.060 (2)	0.007 (2)	0.011 (2)	−0.006 (2)
C5	0.058 (2)	0.051 (2)	0.0481 (19)	0.0055 (18)	0.0109 (17)	−0.0022 (17)
C4	0.062 (3)	0.063 (3)	0.056 (2)	0.003 (2)	0.0063 (19)	−0.002 (2)
C3	0.082 (3)	0.073 (3)	0.051 (2)	0.006 (2)	0.004 (2)	−0.008 (2)
C2	0.094 (3)	0.058 (3)	0.048 (2)	0.015 (2)	0.020 (2)	−0.0034 (19)
B	0.058 (3)	0.053 (3)	0.048 (2)	−0.001 (2)	0.008 (2)	−0.0021 (19)
O1	0.0526 (17)	0.112 (3)	0.0610 (17)	0.0118 (17)	0.0046 (14)	−0.0305 (18)
O2	0.0530 (17)	0.115 (3)	0.0617 (17)	0.0034 (17)	0.0081 (13)	−0.0300 (18)
C7	0.059 (3)	0.159 (6)	0.068 (3)	0.012 (3)	0.008 (2)	−0.052 (4)
C8	0.067 (3)	0.125 (5)	0.061 (3)	0.004 (3)	0.019 (2)	−0.035 (3)
C71	0.106 (5)	0.189 (8)	0.059 (3)	0.020 (5)	−0.002 (3)	−0.043 (4)
C72	0.174 (8)	0.072 (4)	0.150 (7)	−0.017 (4)	0.079 (6)	−0.036 (4)
C81	0.381 (17)	0.189 (10)	0.115 (6)	−0.180 (11)	0.129 (8)	−0.046 (6)
C82	0.070 (4)	0.201 (9)	0.136 (6)	0.013 (5)	0.014 (4)	−0.091 (6)

Geometric parameters (Å, º)

Br1—C2	1.907 (4)	C7—C8	1.475 (8)
N1—C2	1.309 (6)	C7—C72	1.638 (11)
N1—C6	1.336 (5)	C8—C82	1.459 (9)
C6—C5	1.381 (6)	C8—C81	1.626 (11)
C6—H6	0.9300	C71—H71A	0.9600
C5—C4	1.393 (6)	C71—H71B	0.9600
C5—B	1.557 (6)	C71—H71C	0.9600
C4—C3	1.373 (6)	C72—H72A	0.9600
C4—H4	0.9300	C72—H72B	0.9600
C3—C2	1.378 (7)	C72—H72C	0.9600
C3—H3	0.9300	C81—H81A	0.9600
B—O1	1.342 (5)	C81—H81B	0.9600
B—O2	1.351 (6)	C81—H81C	0.9600
O1—C7	1.469 (5)	C82—H82A	0.9600
O2—C8	1.461 (5)	C82—H82B	0.9600
C7—C71	1.434 (7)	C82—H82C	0.9600
C2—N1—C6	115.6 (4)	O2—C8—C7	104.5 (4)
N1—C6—C5	125.0 (4)	C82—C8—C81	108.9 (7)
N1—C6—H6	117.5	O2—C8—C81	104.2 (5)
C5—C6—H6	117.5	C7—C8—C81	104.7 (7)
C6—C5—C4	116.4 (4)	C7—C71—H71A	109.5
C6—C5—B	120.7 (4)	C7—C71—H71B	109.5
C4—C5—B	122.9 (4)	H71A—C71—H71B	109.5
C3—C4—C5	120.1 (4)	C7—C71—H71C	109.5
C3—C4—H4	119.9	H71A—C71—H71C	109.5
C5—C4—H4	119.9	H71B—C71—H71C	109.5
C4—C3—C2	116.9 (4)	C7—C72—H72A	109.5
C4—C3—H3	121.6	C7—C72—H72B	109.5
C2—C3—H3	121.6	H72A—C72—H72B	109.5
N1—C2—C3	125.9 (4)	C7—C72—H72C	109.5
N1—C2—Br1	114.6 (4)	H72A—C72—H72C	109.5
C3—C2—Br1	119.4 (4)	H72B—C72—H72C	109.5
O1—B—O2	113.3 (4)	C8—C81—H81A	109.5
O1—B—C5	122.8 (4)	C8—C81—H81B	109.5
O2—B—C5	123.9 (4)	H81A—C81—H81B	109.5
B—O1—C7	107.1 (3)	C8—C81—H81C	109.5
B—O2—C8	106.9 (4)	H81A—C81—H81C	109.5
C71—C7—O1	111.2 (5)	H81B—C81—H81C	109.5
C71—C7—C8	125.0 (6)	C8—C82—H82A	109.5
O1—C7—C8	103.8 (4)	C8—C82—H82B	109.5
C71—C7—C72	106.6 (6)	H82A—C82—H82B	109.5
O1—C7—C72	104.3 (5)	C8—C82—H82C	109.5
C8—C7—C72	104.0 (6)	H82A—C82—H82C	109.5
C82—C8—O2	111.0 (5)	H82B—C82—H82C	109.5
C82—C8—C7	122.1 (6)

(II) (6-bromopyridin-3-yl)boronic acid

Crystal data

C5H5BBrNO2	Dx = 1.881 Mg m^−3
Mr = 201.82	Melting point: 471 K
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71069 Å
a = 7.4991 (9) Å	Cell parameters from 25 reflections
b = 6.9178 (5) Å	θ = 18–25°
c = 13.8251 (15) Å	µ = 5.70 mm^−1
β = 96.574 (12)°	T = 293 K
V = 712.49 (13) Å^3	Prism, dark white grey
Z = 4	0.65 × 0.40 × 0.18 mm
F(000) = 392

Data collection

Enraf-Nonius CAD4 diffractometer	1326 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.041
Graphite monochromator	θmax = 30.0°, θmin = 2.7°
θ/2θ scans	h = −10→10
Absorption correction: gaussian (JANA98; Petříček & Dušek, 1998 )	k = 0→9
Tmin = 0.073, Tmax = 0.381	l = 0→19
2150 measured reflections	3 standard reflections every 60 min
2071 independent reflections	intensity decay: 2.4%

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)] = 0.049	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.129	H-atom parameters constrained
S = 1.03	w = 1/[σ^2(Fo^2) + (0.0712P)^2] where P = (Fo^2 + 2Fc^2)/3
2071 reflections	(Δ/σ)max < 0.001
93 parameters	Δρmax = 0.62 e Å^−3
0 restraints	Δρmin = −0.83 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.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

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

	x	y	z	Uiso*/Ueq
Br1	0.11277 (7)	1.01578 (6)	0.71020 (3)	0.0592 (2)
C2	0.2009 (5)	0.7877 (5)	0.6555 (2)	0.0365 (7)
N1	0.3126 (4)	0.6833 (4)	0.71513 (19)	0.0386 (7)
C6	0.3734 (5)	0.5189 (5)	0.6787 (3)	0.0406 (8)
H6	0.4520	0.4436	0.7197	0.049*
C5	0.3272 (5)	0.4537 (5)	0.5843 (3)	0.0354 (7)
C4	0.2116 (5)	0.5739 (5)	0.5247 (2)	0.0402 (8)
H4	0.1779	0.5395	0.4602	0.048*
C3	0.1474 (5)	0.7420 (5)	0.5605 (3)	0.0445 (8)
H3	0.0700	0.8221	0.5213	0.053*
B	0.3973 (6)	0.2559 (6)	0.5458 (3)	0.0382 (8)
O1	0.5286 (4)	0.1495 (3)	0.59621 (16)	0.0420 (6)
H1	0.5675	0.2074	0.6459	0.063*
O2	0.3193 (4)	0.1942 (4)	0.45869 (17)	0.0527 (7)
H2	0.3723	0.0983	0.4420	0.079*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.0663 (3)	0.0394 (2)	0.0734 (3)	0.0160 (2)	0.0140 (2)	−0.00905 (17)
C2	0.0370 (19)	0.0257 (15)	0.0475 (18)	0.0023 (14)	0.0083 (15)	−0.0007 (13)
N1	0.0442 (18)	0.0303 (13)	0.0406 (14)	0.0022 (13)	0.0017 (12)	−0.0037 (11)
C6	0.047 (2)	0.0332 (17)	0.0397 (17)	0.0049 (16)	−0.0035 (15)	−0.0023 (13)
C5	0.0364 (19)	0.0285 (15)	0.0407 (17)	−0.0032 (14)	0.0027 (14)	−0.0026 (13)
C4	0.043 (2)	0.0362 (17)	0.0393 (17)	−0.0011 (16)	−0.0029 (15)	−0.0038 (14)
C3	0.044 (2)	0.0386 (18)	0.0484 (19)	0.0063 (17)	−0.0054 (16)	0.0022 (15)
B	0.042 (2)	0.0328 (18)	0.0392 (19)	0.0017 (17)	0.0041 (16)	−0.0039 (15)
O1	0.0527 (16)	0.0340 (12)	0.0384 (12)	0.0066 (12)	0.0016 (11)	−0.0072 (9)
O2	0.0610 (19)	0.0419 (15)	0.0513 (15)	0.0108 (13)	−0.0100 (13)	−0.0157 (11)

Geometric parameters (Å, º)

Br1—C2	1.901 (3)	C4—C3	1.372 (5)
C2—N1	1.321 (4)	C4—H4	0.9300
C2—C3	1.366 (5)	C3—H3	0.9300
N1—C6	1.344 (4)	B—O2	1.347 (4)
C6—C5	1.386 (5)	B—O1	1.356 (5)
C6—H6	0.9300	O1—H1	0.8200
C5—C4	1.400 (5)	O2—H2	0.8200
C5—B	1.580 (5)
N1—C2—C3	124.7 (3)	C3—C4—H4	119.7
N1—C2—Br1	115.4 (2)	C5—C4—H4	119.7
C3—C2—Br1	119.8 (3)	C2—C3—C4	117.8 (3)
C2—N1—C6	116.5 (3)	C2—C3—H3	121.1
N1—C6—C5	124.7 (3)	C4—C3—H3	121.1
N1—C6—H6	117.7	O2—B—O1	120.2 (3)
C5—C6—H6	117.7	O2—B—C5	116.7 (3)
C6—C5—C4	115.6 (3)	O1—B—C5	123.1 (3)
C6—C5—B	122.8 (3)	B—O1—H1	109.5
C4—C5—B	121.6 (3)	B—O2—H2	109.5
C3—C4—C5	120.7 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2···O1^i	0.82	1.96	2.780 (3)	173
O1—H1···N1^ii	0.82	2.03	2.750 (3)	146

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