[μ-Bis(5,7-dimethyl-1,8-naphthyridin-2-yl)diazene]bis­[difluoridoboron(III)]

Li, X.-S.; Mo, J.; Yuan, L.; Liu, J.-H.; Zhang, S.-M.

doi:10.1107/S1600536809022491

organic compounds

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ISSN: 2056-9890

Volume 65| Part 7| July 2009| Page o1673

doi:10.1107/S1600536809022491

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[μ-Bis(5,7-dimethyl-1,8-naphthyridin-2-yl)diazene]bis[difluoridoboron(III)]

Xin-Sheng Li,^a Juan Mo,^a ^* Li Yuan,^a Jian-Hua Liu ^a and Su-Mei Zhang ^a

^aCollege of Animal Husbandry and Veterinary Studies, Henan Agricultural University, Zhengzhou, Henan Province 450002, People's Republic of China
^*Correspondence e-mail: mojuan52@126.com

(Received 21 May 2009; accepted 12 June 2009; online 24 June 2009)

In the title compound, C₂₀H₁₈B₂F₄N₆, the bis(5,7-dimethyl-1,8-naphthyridin-2-yl)diazene molecule is bisected by a symmetry centre midway between the central N atoms of the diazene group. Each of the symmetry-related halves of the molecule binds to a B atom through an N,N′-bite. Two terminal F ions complete the distorted BN₂F₂ tetrahedral geometry around each B atom. The BF₂ plane is almost perpendicular to the boron–naphthyridine ring plane, with a dihedral angle of 87.8 (2)°. The main interactions in the crystal structure are some C—H⋯F hydrogen bonds and π–π contacts between 1,8-naphthyridine rings [centroid–centroid distance = 4.005 (1) Å].

Related literature

For 1,8-naphthyridine deriatives, see: Gavrilova & Bosnich (2004 ); Goswami & Mukherjee (1997 ); Nakatani et al. (2000 ).

Experimental

Crystal data

C₂₀H₁₈B₂F₄N₆
M_r = 440.02
Orthorhombic, P b c a
a = 8.5379 (17) Å
b = 14.696 (3) Å
c = 15.467 (3) Å
V = 1940.6 (7) Å³
Z = 4
Mo Kα radiation
μ = 0.12 mm⁻¹
T = 272 K
0.10 × 0.08 × 0.06 mm

Data collection

Bruker SMART CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2003 ) T_min = 0.985, T_max = 0.994
14645 measured reflections
2221 independent reflections
1714 reflections with I > 2σ(I)
R_int = 0.058

Refinement

R[F² > 2σ(F²)] = 0.045
wR(F²) = 0.127
S = 1.07
2221 reflections
148 parameters
H-atom parameters constrained
Δρ_max = 0.32 e Å⁻³
Δρ_min = −0.24 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C1—H1C⋯F1ⁱ	0.96	2.54	3.291 (2)	135
C8—H8⋯F1ⁱⁱ	0.93	2.48	3.2434 (19)	140
Symmetry codes: (i) $[x+{\script{1\over 2}}, -y+{\script{1\over 2}}, -z+2]$ ; (ii) $[-x+{\script{1\over 2}}, y-{\script{1\over 2}}, z]$ .

Data collection: SMART (Bruker, 2000 ); cell refinement: SAINT (Bruker, 2000); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL.

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809022491/bg2262sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809022491/bg2262Isup2.hkl

checkCIF report

Comment top

The deriatives of 1,8-naphthyridine have been widely utilized as mono-nucleating and dinucleating ligands in coordination chemistry or as antimycobacterial and antimicrobial agents (Gavrilova & Bosnich, 2004; Goswami et al., 1997; Nakatani et al., 2000). Here, we report the crystal structure of the centrosymmetric dinuclear title compound, C₂₀H₁₈B₂F₄N₆, where the di-5,7-dimethyl-1,8-naphthyl-2,2'-diazene (ddnd) ligand is halved by a symmetry centre midway the central nitrogens in the diazene group, and where each boron atom is coordinated by a N,N' bite of the ddnd ligand and two terminal F ions. The result is a distorted BN₂F₂ tetrahedral geometry, with a N—B—N bite angle of 94.35 (11)°. The compound skeleton is formed by four conjugated heterocyclic rings which are nearly coplanar; the least-squares plane through B1,N1,N2,C2->C10 has a mean deviation of 0.02 Å. The BF₂ plane is almost perpendicular to the boron-nathphyridine ring plane, with a dihedral angle of 92.2 (2) °.

There are two main C—H···F hydrogen bonding interactions involving F1 as an acceptor and two C—H donor sets, C1—H1C, C8—H8. There is also a π-π stacking interaction between adjacent parallel naphthyridyl rings: with a closest C—C distance of 3.499 (1) Å and a centroid to centroid distance of 4.005 (1) Å. Via these interactions (with H-bonding mainly in the (100) plane and π-π stacking along the [100] direction ) the compound forms a three-dimensional network structure as shown in Fig. 2.

Related literature top

For 1,8-naphthyridine deriatives, see: Gavrilova & Bosnich (2004); Goswami et al. (1997); Nakatani et al. (2000).

Experimental top

A cold solution of 7-amino-2,4-dimethyl-1,8naphthyridine (2 g) in water (100 mL) was added dropwise to 150 ml of a 10% NaOCl solution. The mixture was stirred at 0 degree and a dark green precipitate formed. Filtration was performed a few minutes after the end of addition, and the aqueous phase and the precipitate were extracted with diethyl ether. The ether phases were gathered, dried on MgSO₄, and evaporated. The crude product was purified by chromatography on Al₂O₃ (eluent: acetone/hexane 1/10). Recrystallization in water yielded ddnd as green product. Yield: 70%.

The ddnd (0.34 g, 1 mmol) ligand was dissolved in 50 ml newly dry dichloromethane and then treated with triethylamine (3 ml) and boron trifluoride etherate (3 ml). After stirring for 30 min, the solution was washed with water, dried over Na₂SO₄, and concentrated at reduced pressure. Single crystals of (I) suitable for an X-ray study were obtained by slow evaporation of an CHCl₃/hexane solution (50% v/v) over a period of one month.

Computing details top

Data collection: SMART (Bruker, 2000); cell refinement: SAINT (Bruker, 2000); data reduction: SAINT (Bruker, 2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top

	Fig. 1. Molecular structure of the title compound showing the atom-numbering scheme and displacement ellipsoids drawn at the 40% probability level. (Symmetry code: -x, -y, 2 - z).
	Fig. 2. The crystal packing of the title compound, viewed along the a axis. Hydrogen bonds are shown as dashed lines.

[µ-Bis(5,7-dimethyl-1,8-naphthyridin-2-yl)diazene]bis[difluoridoboron(III)] top

Crystal data top

C₂₀H₁₈B₂F₄N₆	F(000) = 904
M_r = 440.02	D_x = 1.506 Mg m⁻³
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 3723 reflections
a = 8.5379 (17) Å	θ = 3.1–27.5°
b = 14.696 (3) Å	µ = 0.12 mm⁻¹
c = 15.467 (3) Å	T = 272 K
V = 1940.6 (7) Å³	Block, brown
Z = 4	0.10 × 0.08 × 0.06 mm

Data collection top

Bruker SMART CCD area-detector diffractometer	2221 independent reflections
Radiation source: fine-focus sealed tube	1714 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.058
ϕ and ω scans	θ_max = 27.5°, θ_min = 3.1°
Absorption correction: multi-scan (SADABS; Sheldrick, 2003)	h = −9→11
T_min = 0.985, T_max = 0.994	k = −19→15
14645 measured reflections	l = −20→19

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.045	H-atom parameters constrained
wR(F²) = 0.127	w = 1/[σ²(F_o²) + (0.0655P)² + 0.3984P] where P = (F_o² + 2F_c²)/3
S = 1.07	(Δ/σ)_max = 0.002
2221 reflections	Δρ_max = 0.32 e Å⁻³
148 parameters	Δρ_min = −0.24 e Å⁻³
0 restraints	Extinction correction: SHELXL, Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.012 (2)

Crystal data top

C₂₀H₁₈B₂F₄N₆	V = 1940.6 (7) Å³
M_r = 440.02	Z = 4
Orthorhombic, Pbca	Mo Kα radiation
a = 8.5379 (17) Å	µ = 0.12 mm⁻¹
b = 14.696 (3) Å	T = 272 K
c = 15.467 (3) Å	0.10 × 0.08 × 0.06 mm

Data collection top

Bruker SMART CCD area-detector diffractometer	2221 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 2003)	1714 reflections with I > 2σ(I)
T_min = 0.985, T_max = 0.994	R_int = 0.058
14645 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.045	0 restraints
wR(F²) = 0.127	H-atom parameters constrained
S = 1.07	Δρ_max = 0.32 e Å⁻³
2221 reflections	Δρ_min = −0.24 e Å⁻³
148 parameters

Special details top

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 (Å²) top

	x	y	z	U_iso*/U_eq
F1	0.11305 (12)	0.18492 (6)	1.00731 (7)	0.0319 (3)
F2	−0.00219 (12)	0.14892 (7)	0.87999 (7)	0.0323 (3)
N1	0.36490 (16)	0.15195 (8)	0.86608 (9)	0.0227 (3)
N2	0.20684 (15)	0.04677 (8)	0.93336 (9)	0.0221 (3)
N3	0.03539 (17)	−0.04321 (8)	1.00022 (10)	0.0260 (4)
B1	0.0693 (2)	0.11566 (11)	0.95247 (13)	0.0243 (4)
C1	0.5141 (2)	0.26721 (11)	0.79215 (12)	0.0319 (4)
H1A	0.4310	0.2784	0.7517	0.048*
H1B	0.6132	0.2741	0.7635	0.048*
H1C	0.5071	0.3099	0.8390	0.048*
C2	0.50004 (19)	0.17214 (10)	0.82689 (11)	0.0254 (4)
C3	0.6203 (2)	0.10902 (11)	0.81609 (12)	0.0279 (4)
H3	0.7136	0.1272	0.7903	0.033*
C4	0.60339 (19)	0.02021 (11)	0.84293 (11)	0.0264 (4)
C5	0.7318 (2)	−0.04743 (12)	0.82761 (13)	0.0345 (4)
H5A	0.7073	−0.0835	0.7776	0.052*
H5B	0.7418	−0.0863	0.8772	0.052*
H5C	0.8287	−0.0158	0.8182	0.052*
C6	0.46063 (19)	−0.00410 (10)	0.88339 (11)	0.0235 (4)
C7	0.4213 (2)	−0.09362 (10)	0.91393 (11)	0.0252 (4)
H7	0.4938	−0.1404	0.9078	0.030*
C8	0.2814 (2)	−0.11140 (10)	0.95139 (11)	0.0245 (4)
H8	0.2559	−0.1699	0.9696	0.029*
C9	0.17464 (19)	−0.03837 (10)	0.96207 (11)	0.0226 (4)
C10	0.34843 (19)	0.06558 (10)	0.89359 (11)	0.0217 (4)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
F1	0.0394 (6)	0.0203 (5)	0.0361 (7)	−0.0040 (4)	0.0109 (5)	−0.0022 (4)
F2	0.0286 (6)	0.0336 (5)	0.0347 (7)	0.0027 (4)	0.0020 (5)	0.0125 (4)
N1	0.0224 (7)	0.0230 (6)	0.0227 (8)	−0.0048 (5)	0.0010 (6)	0.0018 (5)
N2	0.0233 (7)	0.0184 (6)	0.0245 (8)	−0.0016 (5)	0.0034 (6)	0.0027 (5)
N3	0.0261 (7)	0.0154 (6)	0.0366 (9)	0.0022 (5)	0.0087 (6)	0.0039 (5)
B1	0.0260 (10)	0.0187 (8)	0.0283 (11)	−0.0004 (6)	0.0047 (8)	0.0029 (7)
C1	0.0326 (10)	0.0296 (8)	0.0335 (10)	−0.0099 (7)	0.0043 (8)	0.0039 (7)
C2	0.0269 (9)	0.0285 (8)	0.0207 (9)	−0.0076 (6)	−0.0011 (7)	0.0000 (6)
C3	0.0224 (9)	0.0368 (9)	0.0245 (9)	−0.0059 (7)	0.0019 (7)	0.0007 (7)
C4	0.0224 (8)	0.0345 (8)	0.0223 (9)	−0.0009 (6)	−0.0015 (7)	−0.0018 (7)
C5	0.0274 (9)	0.0419 (10)	0.0341 (11)	0.0045 (7)	0.0049 (8)	−0.0006 (8)
C6	0.0224 (8)	0.0282 (8)	0.0198 (9)	0.0010 (6)	0.0001 (7)	−0.0007 (6)
C7	0.0272 (9)	0.0251 (7)	0.0234 (9)	0.0044 (6)	0.0000 (7)	−0.0013 (6)
C8	0.0279 (9)	0.0193 (7)	0.0262 (9)	0.0017 (6)	0.0012 (7)	0.0009 (6)
C9	0.0245 (8)	0.0190 (7)	0.0244 (9)	−0.0005 (6)	0.0027 (7)	0.0023 (6)
C10	0.0221 (8)	0.0232 (7)	0.0197 (8)	−0.0028 (6)	0.0008 (7)	0.0001 (6)

Geometric parameters (Å, º) top

F1—B1	1.377 (2)	C2—C3	1.394 (2)
F2—B1	1.367 (2)	C3—C4	1.377 (2)
N1—C2	1.337 (2)	C3—H3	0.9300
N1—C10	1.3461 (19)	C4—C6	1.416 (2)
N2—C9	1.3559 (18)	C4—C5	1.499 (2)
N2—C10	1.384 (2)	C5—H5A	0.9600
N2—B1	1.579 (2)	C5—H5B	0.9600
N3—C9	1.329 (2)	C5—H5C	0.9600
N3—N3ⁱ	1.407 (2)	C6—C10	1.411 (2)
N3—B1ⁱ	1.571 (2)	C6—C7	1.438 (2)
B1—N3ⁱ	1.571 (2)	C7—C8	1.353 (2)
C1—C2	1.502 (2)	C7—H7	0.9300
C1—H1A	0.9600	C8—C9	1.417 (2)
C1—H1B	0.9600	C8—H8	0.9300
C1—H1C	0.9600

C2—N1—C10	116.28 (14)	C3—C4—C6	117.55 (15)
C9—N2—C10	120.45 (13)	C3—C4—C5	120.28 (16)
C9—N2—B1	112.31 (13)	C6—C4—C5	122.16 (15)
C10—N2—B1	127.23 (12)	C4—C5—H5A	109.5
C9—N3—N3ⁱ	109.50 (15)	C4—C5—H5B	109.5
C9—N3—B1ⁱ	138.76 (12)	H5A—C5—H5B	109.5
N3ⁱ—N3—B1ⁱ	111.70 (16)	C4—C5—H5C	109.5
F2—B1—F1	111.22 (13)	H5A—C5—H5C	109.5
F2—B1—N3ⁱ	111.75 (14)	H5B—C5—H5C	109.5
F1—B1—N3ⁱ	111.63 (14)	C10—C6—C4	116.79 (14)
F2—B1—N2	114.07 (15)	C10—C6—C7	117.96 (15)
F1—B1—N2	112.80 (14)	C4—C6—C7	125.25 (15)
N3ⁱ—B1—N2	94.35 (11)	C8—C7—C6	121.57 (14)
C2—C1—H1A	109.5	C8—C7—H7	119.2
C2—C1—H1B	109.5	C6—C7—H7	119.2
H1A—C1—H1B	109.5	C7—C8—C9	118.11 (14)
C2—C1—H1C	109.5	C7—C8—H8	120.9
H1A—C1—H1C	109.5	C9—C8—H8	120.9
H1B—C1—H1C	109.5	N3—C9—N2	112.09 (13)
N1—C2—C3	122.85 (14)	N3—C9—C8	125.89 (13)
N1—C2—C1	115.96 (15)	N2—C9—C8	122.02 (15)
C3—C2—C1	121.16 (15)	N1—C10—N2	114.83 (13)
C4—C3—C2	121.17 (16)	N1—C10—C6	125.31 (15)
C4—C3—H3	119.4	N2—C10—C6	119.85 (13)
C2—C3—H3	119.4

C9—N2—B1—F2	−114.73 (16)	B1ⁱ—N3—C9—N2	−178.24 (19)
C10—N2—B1—F2	66.2 (2)	N3ⁱ—N3—C9—C8	179.03 (18)
C9—N2—B1—F1	117.11 (15)	B1ⁱ—N3—C9—C8	1.5 (3)
C10—N2—B1—F1	−61.9 (2)	C10—N2—C9—N3	178.49 (15)
C9—N2—B1—N3ⁱ	1.44 (17)	B1—N2—C9—N3	−0.6 (2)
C10—N2—B1—N3ⁱ	−177.59 (15)	C10—N2—C9—C8	−1.3 (2)
C10—N1—C2—C3	−1.4 (2)	B1—N2—C9—C8	179.64 (15)
C10—N1—C2—C1	176.83 (15)	C7—C8—C9—N3	−177.38 (17)
N1—C2—C3—C4	2.4 (3)	C7—C8—C9—N2	2.3 (3)
C1—C2—C3—C4	−175.71 (16)	C2—N1—C10—N2	−179.60 (14)
C2—C3—C4—C6	−1.2 (3)	C2—N1—C10—C6	−0.7 (2)
C2—C3—C4—C5	177.65 (17)	C9—N2—C10—N1	178.44 (15)
C3—C4—C6—C10	−0.7 (2)	B1—N2—C10—N1	−2.6 (2)
C5—C4—C6—C10	−179.57 (16)	C9—N2—C10—C6	−0.5 (2)
C3—C4—C6—C7	178.76 (16)	B1—N2—C10—C6	178.48 (16)
C5—C4—C6—C7	−0.1 (3)	C4—C6—C10—N1	1.8 (3)
C10—C6—C7—C8	0.0 (2)	C7—C6—C10—N1	−177.73 (16)
C4—C6—C7—C8	−179.45 (17)	C4—C6—C10—N2	−179.38 (15)
C6—C7—C8—C9	−1.7 (2)	C7—C6—C10—N2	1.1 (2)
N3ⁱ—N3—C9—N2	−0.7 (2)

Symmetry code: (i) −x, −y, −z+2.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C1—H1C···F1ⁱⁱ	0.96	2.54	3.291 (2)	135
C8—H8···F1ⁱⁱⁱ	0.93	2.48	3.2434 (19)	140

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

Experimental details

Crystal data
Chemical formula	C₂₀H₁₈B₂F₄N₆
M_r	440.02
Crystal system, space group	Orthorhombic, Pbca
Temperature (K)	272
a, b, c (Å)	8.5379 (17), 14.696 (3), 15.467 (3)
V (Å³)	1940.6 (7)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.12
Crystal size (mm)	0.10 × 0.08 × 0.06

Data collection
Diffractometer	Bruker SMART CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Sheldrick, 2003)
T_min, T_max	0.985, 0.994
No. of measured, independent and observed [I > 2σ(I)] reflections	14645, 2221, 1714
R_int	0.058
(sin θ/λ)_max (Å⁻¹)	0.650

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.045, 0.127, 1.07
No. of reflections	2221
No. of parameters	148
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.32, −0.24

Computer programs: SMART (Bruker, 2000), SAINT (Bruker, 2000), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C1—H1C···F1ⁱ	0.96	2.54	3.291 (2)	135
C8—H8···F1ⁱⁱ	0.93	2.48	3.2434 (19)	140

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

Acknowledgements

We thank Henan Agricultural University for the generous support of this study.

References

Bruker (2000). SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Gavrilova, A. L. & Bosnich, B. (2004). Chem. Rev. 104, 349–384. Web of Science CrossRef PubMed CAS Google Scholar
Goswami, S. & Mukherjee, R. (1997). Tetrahedron Lett. 38, 1619–1622. CrossRef CAS Web of Science Google Scholar
Nakatani, K., Sando, S. & Saito, I. (2000). J. Am. Chem. Soc. 122, 2172–2177. Web of Science CrossRef CAS Google Scholar
Sheldrick, G. M. (2003). SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar