Crystal structure of the bora­benzene–2,6-lutidine adduct

In the title compound, C₁₂H₁₄BN, the complete mol­ecule is generated by a crystallographic twofold axis, with two C atoms, the B atom and the N atom lying on the rotation axis. The dihedral angle between the bora­benzene and pyridine rings is 81.20 (6)°. As well as dative electron donation from the N atom to the B atom [B—N = 1.5659 (18) Å], the methyl substituents on the lutidine ring shield the B atom, which further stabilizes the mol­ecule. In the crystal, weak aromatic π–π stacking between the pyridine rings [centroid–centroid separation = 3.6268 (9) Å] is observed, which generates [001] columns of mol­ecules.

1. Related literature

For the synthesis of the title compound, see: Hoic et al. (1996). For a related structure, see: Boese et al. (1985). For bora­benzene adducts as analogues of cyclo­penta­dienyl anions (Cp), see: Bazan et al. (2000); Wang et al. (2002); Cui et al. (2010). For the uses of bora­benzenes and their metal complexes, see: Wang et al. (2002; Jaska et al. (2006).

2. Experimental

2.1. Crystal data

• C₁₂H₁₄BN

• M_r = 183.05

• Monoclinic, C 2/c

• a = 10.008 (2) Å

• b = 14.447 (3) Å

• c = 7.1360 (14) Å

• β = 90.16 (3)°

• V = 1031.8 (4) ų

• Z = 4

• Mo Kα radiation

• μ = 0.07 mm⁻¹

• T = 120 K

• 0.24 × 0.18 × 0.16 mm

2.2. Data collection

• Bruker Kappa APEXII CCD diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 2012) T_min = 0.646, T_max = 0.746

• 7258 measured reflections

• 1482 independent reflections

• 1280 reflections with I > 2σ(I)

• R_int = 0.028

2.3. Refinement

• R[F² > 2σ(F²)] = 0.044

• wR(F²) = 0.120

• S = 1.06

• 1482 reflections

• 67 parameters

• H-atom parameters constrained

• Δρ_max = 0.30 e Å⁻³

• Δρ_min = −0.17 e Å⁻³

Data collection: COLLECT (Bruker, 2008); cell refinement: DENZO/SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO/SCALEPACK; program(s) used to solve structure: SUPERFLIP (Palatinus & Chapuis, 2007); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: CHIMERA (Pettersen et al., 2004); software used to prepare material for publication: SHELXL2014.

Supporting information

S1. Structural commentary

The title compound lies on a two-fold rotational axis, which passes through atoms H3, C3, B1, N1, C6, and H6.

Bora­benzene-2,6-lutidine is an example of nitro­gen-stabilized bora­benzene adducts. The nitro­gen atom of the base (2,5-lutidine) donates an electron pair to the boron atom, and thus stabilizes the bora­benzene ring. Bora­benzene-2,6-lutidine has a zwitterionic nature. The nitro­gen ring bears a positive charge, and the boron ring a negative charge.

Bora­benzenes are analogous to cyclo­penta­dienyl anions (Cp), althought they are generally weaker electron donors than Cp (Bazan et al., 2000; Wang et al., 2002 and Cui et al., 2010). Bora­benzene rings can thus be used as a replacement for Cp when weaker electron donation properties are required. There is a growing inter­est to utilize bora­benzenes and their metal complexes in several applications including catalytic and semiconducting materials as well as light-emitting devices (Wang et al., 2002 and Jaska et al., 2006).

S2. Synthesis and crystallization

The compound was synthesized according to the previously reported procedure (Hoic et al. 1996). X-ray quality crystals were obtained by using the following procedure: In a glove box, bora­benzene-2,6-lutidine was dissolved in pure toluene at room temperature until a saturated solution was obtained. The clear solution was separated and and the solution was allowed to evaporate slowly. Formed crystals were collected from the solution after one week and were immediately taken to an X-ray diffraction analysis. In order to protect the crystals from air and moisture, the crystals were immersed to cryo oil before taking them out from the glove box.

S3. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1. Hydrogen atoms were positioned geometrically and constrained to ride on their parent atoms, with C—H = 0.95-0.98 Å and U_iso = 1.2-1.5 U_eq(parent atom). The highest peak is located 0.69 Å from atom C5 and the deepest hole is located 0.67 Å from atom N1.

Related literature

For the synthesis of the title compound, see: Hoic et al. (1996). For a related structure, see: Boese et al. (1985). For borabenzene adducts as analogues of cyclopentadienyl anions (Cp), see: Bazan et al. (2000); Wang et al. (2002); Cui et al. (2010). For the uses of borabenzenes and their metal complexes, see: Wang et al. (2002; Jaska et al. (2006).

Structure description

The title compound lies on a two-fold rotational axis, which passes through atoms H3, C3, B1, N1, C6, and H6.

Bora­benzene-2,6-lutidine is an example of nitro­gen-stabilized bora­benzene adducts. The nitro­gen atom of the base (2,5-lutidine) donates an electron pair to the boron atom, and thus stabilizes the bora­benzene ring. Bora­benzene-2,6-lutidine has a zwitterionic nature. The nitro­gen ring bears a positive charge, and the boron ring a negative charge.

Bora­benzenes are analogous to cyclo­penta­dienyl anions (Cp), althought they are generally weaker electron donors than Cp (Bazan et al., 2000; Wang et al., 2002 and Cui et al., 2010). Bora­benzene rings can thus be used as a replacement for Cp when weaker electron donation properties are required. There is a growing inter­est to utilize bora­benzenes and their metal complexes in several applications including catalytic and semiconducting materials as well as light-emitting devices (Wang et al., 2002 and Jaska et al., 2006).

For the synthesis of the title compound, see: Hoic et al. (1996). For a related structure, see: Boese et al. (1985). For borabenzene adducts as analogues of cyclopentadienyl anions (Cp), see: Bazan et al. (2000); Wang et al. (2002); Cui et al. (2010). For the uses of borabenzenes and their metal complexes, see: Wang et al. (2002; Jaska et al. (2006).

Synthesis and crystallization

The compound was synthesized according to the previously reported procedure (Hoic et al. 1996). X-ray quality crystals were obtained by using the following procedure: In a glove box, bora­benzene-2,6-lutidine was dissolved in pure toluene at room temperature until a saturated solution was obtained. The clear solution was separated and and the solution was allowed to evaporate slowly. Formed crystals were collected from the solution after one week and were immediately taken to an X-ray diffraction analysis. In order to protect the crystals from air and moisture, the crystals were immersed to cryo oil before taking them out from the glove box.

Refinement details

Crystal data, data collection and structure refinement details are summarized in Table 1. Hydrogen atoms were positioned geometrically and constrained to ride on their parent atoms, with C—H = 0.95-0.98 Å and U_iso = 1.2-1.5 U_eq(parent atom). The highest peak is located 0.69 Å from atom C5 and the deepest hole is located 0.67 Å from atom N1.

Computing details

Data collection: COLLECT (Bruker, 2008); cell refinement: DENZO/SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO/SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SUPERFLIP (Palatinus & Chapuis, 2007); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: CHIMERA (Pettersen et al., 2004); software used to prepare material for publication: SHELXL2014 (Sheldrick, 2015).

Figures

Fig. 1. The molecular structure of the title compound, with atom labels and 50% probability displacement ellipsoids for non-H atoms.

Borabenzene–2,6-lutidine

Crystal data

C12H14BN	F(000) = 392
Mr = 183.05	Dx = 1.178 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
a = 10.008 (2) Å	Cell parameters from 10098 reflections
b = 14.447 (3) Å	θ = 1.0–28.7°
c = 7.1360 (14) Å	µ = 0.07 mm^−1
β = 90.16 (3)°	T = 120 K
V = 1031.8 (4) Å^3	Needle, yellow
Z = 4	0.24 × 0.18 × 0.16 mm

Data collection

Bruker Kappa APEXII CCD diffractometer	1482 independent reflections
Radiation source: fine-focus sealed tube	1280 reflections with I > 2σ(I)
Horizontally mounted graphite crystal monochromator	Rint = 0.028
Detector resolution: 16 pixels mm^-1	θmax = 30.0°, θmin = 4.0°
φ scans and ω scans with κ offset	h = −14→14
Absorption correction: multi-scan (SADABS; Bruker, 2012)	k = −16→20
Tmin = 0.646, Tmax = 0.746	l = −9→9
7258 measured reflections

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.044	H-atom parameters constrained
wR(F^2) = 0.120	w = 1/[σ^2(Fo^2) + (0.0555P)^2 + 0.6142P] where P = (Fo^2 + 2Fc^2)/3
S = 1.06	(Δ/σ)max < 0.001
1482 reflections	Δρmax = 0.30 e Å^−3
67 parameters	Δρmin = −0.17 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
N1	0.5000	0.38254 (7)	0.7500	0.0182 (2)
C1	0.43941 (9)	0.22210 (7)	0.59114 (13)	0.0229 (2)
H1	0.3993	0.2534	0.4883	0.028*
C2	0.44362 (10)	0.12556 (7)	0.59879 (14)	0.0246 (2)
H2	0.4069	0.0910	0.4977	0.030*
C3	0.5000	0.07806 (9)	0.7500	0.0254 (3)
H3	0.5000	0.0123	0.7500	0.031*
C4	0.38816 (9)	0.42921 (7)	0.80474 (12)	0.0197 (2)
C5	0.38693 (9)	0.52523 (7)	0.80370 (13)	0.0225 (2)
H5	0.3086	0.5578	0.8398	0.027*
C6	0.5000	0.57352 (9)	0.7500	0.0241 (3)
H6	0.5000	0.6393	0.7500	0.029*
C7	0.26941 (10)	0.37460 (7)	0.86747 (15)	0.0258 (2)
H7A	0.2957	0.3332	0.9699	0.039*
H7B	0.2351	0.3379	0.7624	0.039*
H7C	0.1996	0.4169	0.9112	0.039*
B1	0.5000	0.27415 (10)	0.7500	0.0195 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0180 (5)	0.0187 (5)	0.0179 (5)	0.000	−0.0021 (4)	0.000
C1	0.0222 (4)	0.0228 (5)	0.0239 (5)	−0.0022 (3)	−0.0018 (3)	0.0003 (3)
C2	0.0222 (4)	0.0235 (5)	0.0282 (5)	−0.0047 (3)	0.0024 (4)	−0.0045 (4)
C3	0.0230 (6)	0.0179 (6)	0.0355 (7)	0.000	0.0068 (5)	0.000
C4	0.0183 (4)	0.0224 (4)	0.0183 (4)	0.0011 (3)	−0.0013 (3)	0.0003 (3)
C5	0.0237 (5)	0.0221 (5)	0.0218 (5)	0.0042 (3)	0.0006 (3)	−0.0004 (3)
C6	0.0309 (7)	0.0193 (6)	0.0220 (6)	0.000	−0.0004 (5)	0.000
C7	0.0195 (4)	0.0268 (5)	0.0312 (5)	−0.0010 (3)	0.0025 (4)	−0.0003 (4)
B1	0.0177 (6)	0.0177 (6)	0.0230 (6)	0.000	−0.0002 (5)	0.000

Geometric parameters (Å, º)

N1—C4^i	1.3647 (11)	C4—C5	1.3874 (13)
N1—C4	1.3647 (11)	C4—C7	1.4961 (13)
N1—B1	1.5659 (18)	C5—C6	1.3843 (12)
C1—C2	1.3964 (14)	C5—H5	0.9500
C1—B1	1.4881 (12)	C6—C5^i	1.3843 (12)
C1—H1	0.9500	C6—H6	0.9500
C2—C3	1.3965 (13)	C7—H7A	0.9800
C2—H2	0.9500	C7—H7B	0.9800
C3—C2^i	1.3966 (13)	C7—H7C	0.9800
C3—H3	0.9500	B1—C1^i	1.4881 (12)
C4^i—N1—C4	120.78 (11)	C6—C5—C4	119.88 (9)
C4^i—N1—B1	119.61 (6)	C6—C5—H5	120.1
C4—N1—B1	119.61 (6)	C4—C5—H5	120.1
C2—C1—B1	117.56 (9)	C5^i—C6—C5	119.48 (13)
C2—C1—H1	121.2	C5^i—C6—H6	120.3
B1—C1—H1	121.2	C5—C6—H6	120.3
C1—C2—C3	122.22 (9)	C4—C7—H7A	109.5
C1—C2—H2	118.9	C4—C7—H7B	109.5
C3—C2—H2	118.9	H7A—C7—H7B	109.5
C2—C3—C2^i	121.13 (13)	C4—C7—H7C	109.5
C2—C3—H3	119.4	H7A—C7—H7C	109.5
C2^i—C3—H3	119.4	H7B—C7—H7C	109.5
N1—C4—C5	119.99 (9)	C1—B1—C1^i	119.30 (12)
N1—C4—C7	118.55 (9)	C1—B1—N1	120.35 (6)
C5—C4—C7	121.46 (8)	C1^i—B1—N1	120.35 (6)
B1—C1—C2—C3	1.10 (12)	C4—C5—C6—C5^i	0.52 (6)
C1—C2—C3—C2^i	−0.59 (7)	C2—C1—B1—C1^i	−0.53 (6)
C4^i—N1—C4—C5	0.52 (6)	C2—C1—B1—N1	179.47 (6)
B1—N1—C4—C5	−179.47 (6)	C4^i—N1—B1—C1	−98.80 (6)
C4^i—N1—C4—C7	−178.65 (9)	C4—N1—B1—C1	81.20 (6)
B1—N1—C4—C7	1.35 (9)	C4^i—N1—B1—C1^i	81.20 (6)
N1—C4—C5—C6	−1.05 (12)	C4—N1—B1—C1^i	−98.80 (6)
C7—C4—C5—C6	178.10 (7)

Symmetry code: (i) −x+1, y, −z+3/2.