2-(3-Meth­oxy­phen­yl)-1,3-dihydro-1,3,2-benzodiaza­borole

Ross S Robinson; Siphamandla Sithebe; Matthew P Akerman

doi:10.1107/S1600536812028437

. 2012 Jun 30;68(Pt 7):o2241. doi: 10.1107/S1600536812028437

2-(3-Methoxyphenyl)-1,3-dihydro-1,3,2-benzodiazaborole

Ross S Robinson ^a,^*, Siphamandla Sithebe ^a, Matthew P Akerman ^a

PMCID: PMC3394032 PMID: 22798897

Abstract

The title compound, C₁₃H₁₃BN₂O, is one in a series of 1,3,2-benzodiazaboroles featuring a 2-methoxyphenyl substitution at the 2-position in the nitrogen–boron heterocyle. The dihedral angle between the mean planes of the benzodiazaborole and 2-methoxyphenyl ring systems is 21.5 (1)°. There is an intermolecular hydrogen bond between one of the NH groups and the methoxy O atom. This hydrogen bond leads to an infinite hydrogen-bonded chain colinear with the a axis.

Related literature

For the synthesis of the title compound, see: Sithebe et al. (2011 ▶); Weber et al. (2009 ▶, 2011 ▶). For related derivatives as well as their photoluminiscence studies, see: Weber et al. (2010 ▶); Maruyama & Kawanishi (2002 ▶). For structures of related compounds, see: Slabber et al. (2011 ▶); Akerman et al. (2011 ▶). For applications of 1,3,2-diazaborolyl compounds, see: Schwedler et al. (2011 ▶).

Experimental

Crystal data

C₁₃H₁₃BN₂O
M _r = 224.06
Orthorhombic,
a = 7.549 (5) Å
b = 12.230 (5) Å
c = 12.308 (5) Å
V = 1136.3 (10) Å³
Z = 4
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 110 K
0.50 × 0.40 × 0.40 mm

Data collection

Oxford Diffraction Xcalibur 2 CCD diffractometer
Absorption correction: multi-scan (Blessing, 1995 ▶) T _min = 0.960, T _max = 0.968
11586 measured reflections
2125 independent reflections
1939 reflections with I > 2σ(I)
R _int = 0.031

Refinement

R[F ² > 2σ(F ²)] = 0.034
wR(F ²) = 0.094
S = 1.05
2125 reflections
164 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.32 e Å⁻³
Δρ_min = −0.20 e Å⁻³

Data collection: CrysAlis CCD (Oxford Diffraction, 2008 ▶); cell refinement: CrysAlis CCD; data reduction: CrysAlis RED (Oxford Diffraction, 2008 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: Mercury (Macrae et al., 2006 ▶) and POV-RAY (Cason et al., 2002 ▶); software used to prepare material for publication: publCIF (Westrip, 2010 ▶).

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536812028437/nk2170sup1.cif

e-68-o2241-sup1.cif^{(20.9KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812028437/nk2170Isup2.hkl

e-68-o2241-Isup2.hkl^{(102.4KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536812028437/nk2170Isup3.cml

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N2—H102⋯O001ⁱ	0.89 (2)	2.40 (2)	3.201 (2)	151 (2)

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Symmetry code: (i) Inline graphic .

Acknowledgments

We gratefully acknowledge the National Research Foundation and the University of KwaZulu Natal for financial assistance.

supplementary crystallographic information

Comment

Molecular compounds functionalized with 1,3,2-diazaborolyl groups have received considerable attention and have been investigated for their optical, electronic and ion sensing abilities, making them possible candidates for use in advanced material science (Schwedler et al.,2011). Rapid developments in the chemistry of 1,3,2-diazaborolyl containing compounds, due to their photoluminescence characteristics and unusual stability, have been observed in recent years. Unlike most triarylborane compounds which require dimesitylborolyl moieties for the enhancement of their stability, 2-arylbenzo-1,3,2-diazaborole compounds have been reported to be water and air stable without any additional dimesityl groups (Weber et al., 2009). To gain insight into the intriguing characteristics exhibited by these compounds, we (Sithebe et al., 2011) and other researchers (Maruyama et al., 2002 and Weber et al. 2011) have directed our reseach focus towards the investigation of the photophysical studies as well as the determination of the crystal structures of 1,3,2-benzodiazaborolyl compounds.

The molecule features a 1,3,2-benzodiazaborolyl backbone with a five-membered diazaborole ring substituted with hydrogen atoms at the 1- and 3-positions, and a 3-methoxyphenyl ring at the 2-position. The 1,3,2-benzodiazaborolyl backbone of the molecule is essentially planar, however, the 3-methoxyphenyl ring at the 2-position, is rotated out of plane with a dihedral angle of 21.5 (1)°. The two N—B bonds are approximately equal (averaged to 1.433 (2) Å). The N1—B—N2 bond angle is 105.2 (1)°, the N1—B—C1 and N2—B—C1 bond angles are slighly different, measuring 125.4 (1)° and 129.3 (1)°, respectively (refer to Figure 1 for the atom numbering scheme). These bond lengths and angles compare favourably to those of previously reported diazaborolyl systems (Weber et al., 2009). The molecules are linked through hydrogen bonding forming infinite, one-dimensional chains co-linear with the a-axis (Figure 2). The amine NH acts as the hydrogen bond donor and the etheryl oxygen atom the H-bond acceptor. The hydrogen bond lengths and bond angles are summarized in Table 1.

Experimental

3-Methoxyphenylboronic acid (1.00 g, 5.18 mmol) and o-phenylenediamine (0.56 g, 5.18 mmol) were dissolved in toluene (80 ml) in a two neck flask equipped with a Dean and Stark Apparatus, magnetic stirrer bar and reflux condenser. The mixture was heated under reflux overnight and the solvent was removed in vacuo, affording 2-{3-methoxyphenyl}benzo-1,3,2-diazaborole as an off-white solid. The desired product was purified using a flash column and radial chromatography using Hexane: Ethyl acetate (8:2) as the eluent. Crystals suitable for X-ray difraction were grown by slow evaporation of a n-hexane:dicloromethane (6:4) solution.