2-(4-Chloro­phen­yl)naphtho­[1,8-de][1,3,2]diaza­borinane

Matthew P Akerman; Ross S Robinson; Cathryn A Slabber

doi:10.1107/S1600536811025487

. 2011 Jul 2;67(Pt 8):o1873. doi: 10.1107/S1600536811025487

2-(4-Chlorophenyl)naphtho[1,8-de][1,3,2]diazaborinane

Matthew P Akerman ^a,^*, Ross S Robinson ^a, Cathryn A Slabber ^a

PMCID: PMC3212269 PMID: 22090926

Abstract

The title compound, C₁₆H₁₂BClN₂, is one in a series of diazaborinanes, derived from 1,8-diaminonaphthalene, featuring substitution at the 1, 2 and 3 positions in the nitrogen-boron heterocycle. The structure deviates from planarity, the torsion angle subtended by the p-chlorophenyl ring relative to the nitrogen–boron heterocycle being −44-.3(3)°. The molecules form infinite chains with strong interactions between the vacant pz orbital of the B atom and the π-system of an adjacent molecule. The distance between the B atom and the 10-atom centroid of an adjacent naphthalene ring is 3.381 (4) Å. One N-H H atom is weakly hydrogen bonded to the Cl atom of an adjacent molecule. This combination of intermolecular interactions leads to the formation of an infinite two-dimensional network perpendicular to the c axis.

Related literature

For the synthesis of related compounds, see: Letsinger & Hamilton (1958 ▶); Pailer & Fenzl (1961 ▶); Kaupp et al. (2003 ▶); Slabber 2011 ▶. For single-crystal X-ray structures and luminescence studies of related compounds, see: Weber, et al. (2009 ▶).

Experimental

Crystal data

C₁₆H₁₂BClN₂
M _r = 278.54
Monoclinic,
a = 4.7165 (2) Å
b = 10.2815 (4) Å
c = 13.5711 (6) Å
β = 96.555 (4)°
V = 653.79 (5) Å³
Z = 2
Mo Kα radiation
μ = 0.28 mm⁻¹
T = 296 K
0.50 × 0.15 × 0.07 mm

Data collection

Oxford Diffraction Xcalibur 2 CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2003 ▶) T _min = 0.896, T _max = 0.981
4902 measured reflections
2286 independent reflections
2011 reflections with I > 2σ(I)
R _int = 0.027

Refinement

R[F ² > 2σ(F ²)] = 0.039
wR(F ²) = 0.098
S = 1.00
2286 reflections
189 parameters
1 restraint
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.15 e Å⁻³
Δρ_min = −0.25 e Å⁻³
Absolute structure: Flack (1983 ▶), 924 Friedel pairs
Flack parameter: 0.05 (7)

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: WinGX (Farrugia, 1999 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶).

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536811025487/om2441sup1.cif

e-67-o1873-sup1.cif^{(17.9KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811025487/om2441Isup2.hkl

e-67-o1873-Isup2.hkl^{(110KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536811025487/om2441Isup3.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—H2⋯Clⁱ	0.78 (2)	2.93 (2)	3.666 (2)	158 (2)

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Symmetry code: (i) Inline graphic .

Acknowledgments

We would like to thank the University of KwaZulu-Natal and the National Research Foundation for their support and funding.

supplementary crystallographic information

Comment

The structure of the title compound is nominally planar with a slight rotation of the p-chlorophenyl ring relative to the naphthalene rings and boron-nitrogen heterocycle. The N1—B—C11—C12 torsion angle is -4.3 (3)° (refer to Figure 1 for the atom numbering scheme). The orientation of the heterocycle relative to the diazaborolyl groups is critical, since as the rings approach co-planarity there is more effective overlap of the π-systems of the boron atom and the carbon atom to which it is attached. The bond lengths N1—B and N2—B are approximately equal, measuring 1.416 (3) and 1.405 (3) Å, respectively, while the B—C11 bond length is 1.568 (4) Å. The Cl—C14 bond length is 1.736 (2) Å. The N1—B—N2 bond angle is 115.6 (2)°, the N1—B—C11 and N2—B—C11 bond angles are equal, both measuring 122.2 (2)°. These bond length and angles are comparable to those of previously reported diazaborolyl systems (Weber et al., 2009).

Examination of the title compound showed that there is a short contact between the boron atom and the naphthalene rings of an adjacent molecule. The distance from the boron atom to the 10-atom naphthalene centroid is 3.381 (4) Å. These B-π interaction link the molecules, forming infinite, one-dimensional chains. Adjacent one dimensional chains are then weakly hydrogen-bonded together by a N-H hydrogen atom and the chlorine atom of the adjacent molecule. These hydrogen bonds are likely to be very weak as they are only nominally shorter than the sum of the van der Waals radii (0.022 Å shorter) (Table 1). The combination of intermolecular interactions results in the formation of infinite, two-dimensional sheets (Figure 2). The two-dimensional sheet runs perpendicular to the c axis.

Experimental

To a solution of 1,8-diaminonaphthalene in toluene (4.11 mmol in 50 ml, 0.82M) (Letsinger & Hamilton, 1958; Slabber, 2011) was added the 3-chlorophenylboronic acid (4.11 mmol) in one portion. The round-bottomed flask was equipped with a Dean and Stark trap, and the solution was stirred and heated to reflux for 3 h. The solvent was removed in vacuo and column chromatography of the crude solid using silica gel as the stationary phase and eluting with CH₂Cl₂ yielded pale green crystalline material upon evaporation of the eluent with a yield of 66%. Recrystallization of the material from dichloromethane yielded crystals suitable for single-crystal X-ray diffraction analysis were grown.