1,1-Di­fluoro-3-phenyl-9-(pyridin-2-yl)-1H-1λ4,11λ4-1,3,5,2-oxadi­aza­borinino[3,4-a][1,8]naphthyridine

Wang, B.Z.; Zhou, Y.; Zhou, J.P.; Luo, J.S.; Chi, S.M.

doi:10.1107/S2414314616011299

organic compounds

IUCrDATA

ISSN: 2414-3146

Volume 1| Part 7| July 2016| x161129

https://doi.org/10.1107/S2414314616011299

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1,1-Difluoro-3-phenyl-9-(pyridin-2-yl)-1H-1λ⁴,11λ⁴-1,3,5,2-oxadiazaborinino[3,4-a][1,8]naphthyridine

Bang Zhong Wang,^a Yong Zhou,^a Jun Ping Zhou,^a Jian Song Luo ^a and Shao Ming Chi ^a ^*

^aCollege of Chemistry and Chemical Engineering, Yunnan Normal University, Kunming 650500, People's Republic of China
^*Correspondence e-mail: chishaoming@gmail.com

Edited by H. Stoeckli-Evans, University of Neuchâtel, Switzerland (Received 21 June 2016; accepted 11 July 2016; online 22 July 2016)

In the title compound, C₂₀H₁₃BF₂N₄O, the central fused three-ring oxadiazaborininonaphthyridine system is planar (r.m.s. deviation of 0.03 Å). The phenyl ring lies in the plane of this ring system, making a dihedral angle of 0.61 (14)°, and is inclined to the pyridine ring by 9.02 (19)°. In the crystal, molecules are connected by C—H⋯F hydrogen bonds, forming chains propagating along the b-axis direction. The chains are linked by offset π–π interactions [intercentroid distance = 3.4550 (13) Å], forming a three-dimensional supramolecular architecture.

Keywords: crystal structure; 1,8-naphthyridine derivative; BF₂ complexes; hydrogen bonding; offset π–π interactions.

CCDC reference: 1492104

Structure description

Over the past decade, BF₂ complexes have been known to be fluorescent dyes with high fluorescence quantum yields (Zheng et al., 2015 ), sharp fluorescence peaks (Du et al., 2014 ), high extinction coefficients (Kubota et al., 2010 ) and high chemical stability (Li et al., 2010 ). They are widely applied as sensors (Gonçalves, 2009 ; Kobayashi et al., 2010 ; Tachikawa et al., 2010 ), photodynamic therapy agents (Lovell et al., 2010 ; Ozlem & Akkaya, 2009 ), photo-electric materials (Gomez-Duran et al., 2010 ; Lovell et al., 2010; Ortiz et al., 2010 ; Ozlem & Akkaya, 2008) and light-harvesting materials (Erten-Ela et al., 2008 ; Rousseau et al., 2009 ). 1,8-Naphthyridines have attracted interest due to their diverse coordination modes and have been used as ion probes (Liu et al., 2014 ), as luminescent materials (Li et al., 2014 ) and in biochemistry (Zhao et al., 2014 ). The above observations prompted us to synthesize the title compound, which is a novel BF₂ complex based on a 1,8-naphthyridine derivative, and we report herein on its crystal structure.

The molecular structure of the title compound is shown in Fig. 1. It contains naphthyridine, pyridyl and phenyl rings. The naphthyridine ring system is fused with a difluororoxadiazaborinino unit. The fused oxadiazaborininonaphthyridine ring system is planar (r.m.s. deviation of 0.03 Å). The phenyl ring (C1–C6) lies in the plane of this ring system, making a dihedral angle of 0.61 (14)°, and is inclined to the pyridine ring (N4/C16–C20) by 9.02 (19)°.

Figure 1
The molecular structure of the title compound, showing the atom labelling. Displacement ellipsoids are drawn at the 50% probability level

In the crystal, molecules are linked by C—H⋯F hydrogen bonds, forming chains along the b-axis direction (Fig. 2 and Table 1). The chains are linked via offset π–π interactions [Cg2⋯Cg5ⁱ = 3.519 (2) Å, interplanar distance = 3.4550 (13) Å, slippage = 0.629 Å; Cg2 and Cg5 are the centroids of rings N2/C8–C11/C15 and C1–C6, respectively; symmetry code: (i) x − $[{1\over 2}]$ , −y + $[{1\over 2}]$ , z − $[{1\over 2}]$ ], forming a three-dimensional supramolecular architecture (Fig. 3).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C10—H10⋯F2ⁱ	0.93	2.47	3.353 (4)	160
Symmetry code: (i) $[-x+{\script{1\over 2}}, y+{\script{1\over 2}}, -z+{\script{3\over 2}}]$ .

Figure 2
A view along the a axis of the crystal packing of the title compound. Hydrogen bonds are shown as dashed lines (Table 1

Figure 3
A view along the c axis of the crystal packing of the title compound. Hydrogen bonds are shown as dashed lines (Table 1

) and, of the H atoms, only H10 is shown for clarity.

Owing to the shortage of BF₂ complexes based on 1,8-naphthyridine derivatives, there are few examples of similar compounds in the literature. A search of the Cambridge Structural Database (Version 5.37, November 2015; Groom et al., 2016 ) revealed the structure of one very similar compound viz. 1,1-difluoro-7,9-dimethyl-3-phenyl-1H-[1,3,5,2]oxadiazaborinino-[3,4-a][1,8] naphthyridin-11-ium-1-uide (Wu et al., 2012 ).

Synthesis and crystallization

BF₃·OEt₂ (2 ml, 16 mmol) was added dropwise to an ice-cooled solution of 2,6-lutidine (1 ml) and N-[7-(pyridin-2-yl)-1,8-naphthyridin-2-yl]benzamide (0.326 g,1 mmol) in anhydrous CH₂Cl₂ (80 ml) under a nitrogen atmosphere. After the mixture was stirred for 24 h at room temperature, the reaction was quenched by 20 ml distilled water. The aqueous layer was extracted with CH₂Cl₂ (3 × 100 ml), the organic layer was dried with Na₂SO₄ and the solvent was removed under reduced pressure. The residue was purified by silica gel chromatography using CH₂Cl₂ as eluent to give the pure product as a bright-yellow powder (yield 0.184 g, 50%). Crystals of the title compound were obtained from the CH₂Cl₂ solution by slow evaporation of the solvent at room temperature.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2.

Table 2
Experimental details

Crystal data
Chemical formula	C₂₀H₁₃BF₂N₄O
M_r	374.15
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	293
a, b, c (Å)	10.144 (2), 16.276 (3), 10.491 (2)
β (°)	101.27 (3)
V (Å³)	1698.8 (6)
Z	4
Radiation type	Mo Kα
μ (mm⁻¹)	0.11
Crystal size (mm)	0.28 × 0.26 × 0.24

Data collection
Diffractometer	Rigaku R-AXIS RAPID
Absorption correction	Multi-scan (ABSCOR; Higashi, 1995 )
T_min, T_max	0.970, 0.975
No. of measured, independent and observed [I > 2σ(I)] reflections	14275, 3328, 1795
R_int	0.058
(sin θ/λ)_max (Å⁻¹)	0.617

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.069, 0.233, 1.05
No. of reflections	3328
No. of parameters	253
No. of restraints	4
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.45, −0.36
Computer programs: PROCESS-AUTO (Rigaku, 1998 ), CrystalStructure (Rigaku/MSC, 2006 ), SHELXS97 and SHELXL97 (Sheldrick, 2008 ) and PLATON (Spek, 2009 ).

Structural data

CCDC reference: 1492104

Crystal structure: contains datablocks I, Global. DOI: https://doi.org/10.1107/S2414314616011299/su4056sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314616011299/su4056Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2414314616011299/su4056Isup3.cml

checkCIF report

Computing details top

Data collection: PROCESS-AUTO (Rigaku, 1998); cell refinement: PROCESS-AUTO (Rigaku, 1998); data reduction: CrystalStructure (Rigaku/MSC, 2006); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).

1,1-Difluoro-3-phenyl-9-(pyridin-2-yl)-1H-1λ⁴,11λ⁴-1,3,5,2-oxadiazaborinino[3,4-a][1,8]naphthyridine top

Crystal data top

C₂₀H₁₃BF₂N₄O	F(000) = 768
M_r = 374.15	D_x = 1.463 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 3328 reflections
a = 10.144 (2) Å	θ = 3.1–26.0°
b = 16.276 (3) Å	µ = 0.11 mm⁻¹
c = 10.491 (2) Å	T = 293 K
β = 101.27 (3)°	Blcok, yellow
V = 1698.8 (6) Å³	0.28 × 0.26 × 0.24 mm
Z = 4

Data collection top

Rigaku R-AXIS RAPID diffractometer	3328 independent reflections
Radiation source: fine-focus sealed tube	1795 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.058
ω scans	θ_max = 26.0°, θ_min = 3.1°
Absorption correction: multi-scan (ABSCOR; Higashi, 1995)	h = −12→12
T_min = 0.970, T_max = 0.975	k = −20→20
14275 measured reflections	l = −12→12

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.069	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.233	H-atom parameters constrained
S = 1.05	w = 1/[σ²(F_o²) + (0.1317P)² + 0.0306P] where P = (F_o² + 2F_c²)/3
3328 reflections	(Δ/σ)_max < 0.001
253 parameters	Δρ_max = 0.45 e Å⁻³
4 restraints	Δρ_min = −0.36 e Å⁻³

Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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
B1	0.3307 (4)	0.1319 (2)	0.8391 (4)	0.0577 (10)
F1	0.27253 (19)	0.09215 (12)	0.9281 (2)	0.0773 (7)
F2	0.3042 (2)	0.09408 (11)	0.7184 (2)	0.0786 (7)
N1	0.5098 (3)	0.27104 (16)	0.9010 (3)	0.0570 (7)
N2	0.2844 (3)	0.22483 (15)	0.8257 (2)	0.0504 (7)
N3	0.0659 (3)	0.17947 (15)	0.7507 (3)	0.0535 (7)
N4	−0.0920 (3)	0.0434 (2)	0.6740 (4)	0.0949 (12)
O1	0.4774 (2)	0.13081 (12)	0.8848 (3)	0.0672 (7)
C1	0.7405 (3)	0.0970 (2)	0.9777 (4)	0.0613 (9)
H1	0.6790	0.0543	0.9577	0.074*
C2	0.8750 (4)	0.0794 (2)	1.0225 (4)	0.0719 (11)
H2	0.9042	0.0252	1.0326	0.086*
C3	0.9666 (4)	0.1439 (3)	1.0526 (4)	0.0727 (11)
H3	1.0572	0.1324	1.0819	0.087*
C4	0.9246 (4)	0.2231 (3)	1.0396 (4)	0.0715 (11)
H4	0.9865	0.2655	1.0605	0.086*
C5	0.7901 (3)	0.2411 (2)	0.9953 (3)	0.0621 (9)
H5	0.7618	0.2955	0.9876	0.075*
C6	0.6967 (3)	0.17794 (19)	0.9622 (3)	0.0531 (8)
C7	0.5527 (3)	0.19527 (19)	0.9122 (3)	0.0552 (8)
C8	0.3758 (4)	0.28545 (19)	0.8567 (3)	0.0549 (8)
C9	0.3336 (4)	0.36894 (19)	0.8446 (4)	0.0636 (9)
H9	0.3962	0.4106	0.8687	0.076*
C10	0.2031 (4)	0.3884 (2)	0.7983 (3)	0.0640 (10)
H10	0.1771	0.4432	0.7895	0.077*
C11	0.1074 (3)	0.32651 (18)	0.7638 (3)	0.0546 (8)
C12	−0.0303 (4)	0.3392 (2)	0.7114 (3)	0.0659 (10)
H12	−0.0628	0.3924	0.6957	0.079*
C13	−0.1156 (4)	0.2745 (2)	0.6837 (3)	0.0646 (10)
H13	−0.2067	0.2828	0.6516	0.077*
C14	−0.0629 (3)	0.1947 (2)	0.7048 (3)	0.0563 (9)
C15	0.1487 (3)	0.24382 (18)	0.7802 (3)	0.0496 (8)
C16	−0.1497 (3)	0.1216 (2)	0.6737 (3)	0.0572 (8)
C17	−0.2834 (3)	0.1330 (2)	0.6458 (3)	0.0524 (8)
H17	−0.3203	0.1853	0.6456	0.063*
C18	−0.3609 (4)	0.0675 (3)	0.6185 (4)	0.0758 (11)
H18	−0.4535	0.0753	0.6016	0.091*
C19	−0.3142 (4)	−0.0101 (3)	0.6137 (4)	0.0780 (12)
H19	−0.3731	−0.0538	0.5910	0.094*
C20	−0.1784 (4)	−0.0228 (2)	0.6429 (5)	0.0837 (12)
H20	−0.1440	−0.0757	0.6419	0.100*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
B1	0.057 (2)	0.0370 (19)	0.076 (3)	−0.0016 (17)	0.004 (2)	−0.0001 (18)
F1	0.0656 (13)	0.0590 (12)	0.1045 (17)	−0.0053 (10)	0.0094 (12)	0.0308 (11)
F2	0.0820 (14)	0.0531 (12)	0.0938 (16)	0.0081 (10)	0.0004 (12)	−0.0231 (11)
N1	0.0582 (17)	0.0447 (15)	0.0673 (18)	−0.0051 (13)	0.0103 (14)	−0.0005 (13)
N2	0.0567 (16)	0.0411 (14)	0.0544 (16)	−0.0004 (12)	0.0133 (13)	0.0007 (11)
N3	0.0548 (16)	0.0471 (16)	0.0562 (17)	0.0044 (13)	0.0046 (13)	0.0014 (12)
N4	0.087 (2)	0.0626 (16)	0.127 (3)	0.0002 (13)	0.003 (2)	−0.010 (2)
O1	0.0544 (14)	0.0393 (12)	0.1033 (19)	−0.0023 (10)	0.0044 (13)	−0.0031 (12)
C1	0.055 (2)	0.057 (2)	0.072 (2)	−0.0048 (16)	0.0136 (17)	−0.0061 (17)
C2	0.064 (2)	0.069 (2)	0.082 (3)	0.0039 (19)	0.013 (2)	0.001 (2)
C3	0.054 (2)	0.088 (3)	0.078 (3)	−0.003 (2)	0.0167 (18)	0.002 (2)
C4	0.063 (2)	0.079 (3)	0.073 (3)	−0.023 (2)	0.0134 (19)	−0.004 (2)
C5	0.062 (2)	0.058 (2)	0.065 (2)	−0.0068 (17)	0.0100 (17)	0.0013 (17)
C6	0.057 (2)	0.0548 (19)	0.0487 (19)	−0.0083 (16)	0.0122 (15)	−0.0020 (15)
C7	0.064 (2)	0.0468 (18)	0.055 (2)	−0.0083 (16)	0.0139 (16)	−0.0018 (15)
C8	0.072 (2)	0.0411 (17)	0.054 (2)	−0.0048 (16)	0.0174 (17)	0.0001 (14)
C9	0.081 (2)	0.0392 (17)	0.074 (2)	−0.0091 (17)	0.026 (2)	−0.0030 (16)
C10	0.085 (3)	0.0416 (17)	0.070 (2)	0.0082 (18)	0.026 (2)	0.0065 (16)
C11	0.070 (2)	0.0410 (17)	0.054 (2)	0.0042 (16)	0.0153 (17)	0.0020 (14)
C12	0.079 (3)	0.053 (2)	0.067 (2)	0.0212 (19)	0.0168 (19)	0.0050 (17)
C13	0.064 (2)	0.064 (2)	0.064 (2)	0.0207 (19)	0.0080 (18)	0.0035 (18)
C14	0.062 (2)	0.0571 (19)	0.050 (2)	0.0088 (17)	0.0111 (16)	0.0020 (15)
C15	0.0597 (19)	0.0423 (17)	0.0487 (18)	0.0033 (15)	0.0153 (15)	0.0007 (14)
C16	0.0476 (13)	0.0684 (17)	0.0537 (19)	0.0024 (15)	0.0051 (14)	−0.0013 (16)
C17	0.0486 (13)	0.0595 (18)	0.0468 (18)	0.0159 (12)	0.0034 (14)	−0.0014 (14)
C18	0.053 (2)	0.092 (3)	0.078 (3)	−0.0055 (17)	0.0013 (18)	−0.007 (2)
C19	0.064 (3)	0.078 (3)	0.085 (3)	−0.011 (2)	−0.003 (2)	−0.001 (2)
C20	0.072 (3)	0.062 (2)	0.110 (3)	0.0032 (16)	0.001 (2)	−0.001 (2)

Geometric parameters (Å, º) top

B1—F1	1.362 (5)	C3—C4	1.355 (6)
B1—F2	1.386 (5)	C4—C5	1.384 (5)
B1—O1	1.472 (5)	C5—C6	1.395 (4)
B1—N2	1.582 (4)	C6—C7	1.480 (5)
N1—C7	1.306 (4)	C8—C9	1.423 (5)
N1—C8	1.368 (4)	C9—C10	1.356 (5)
N2—C8	1.350 (4)	C10—C11	1.396 (5)
N2—C15	1.400 (4)	C11—C15	1.410 (4)
N3—C14	1.325 (4)	C11—C12	1.413 (5)
N3—C15	1.341 (4)	C12—C13	1.358 (5)
N4—C20	1.387 (5)	C13—C14	1.405 (5)
N4—C16	1.400 (5)	C14—C16	1.478 (5)
O1—C7	1.296 (4)	C16—C17	1.344 (4)
C1—C2	1.383 (5)	C17—C18	1.322 (5)
C1—C6	1.390 (5)	C18—C19	1.353 (5)
C2—C3	1.396 (5)	C19—C20	1.367 (5)

F1—B1—F2	112.6 (3)	N2—C8—N1	123.2 (3)
F1—B1—O1	108.5 (3)	N2—C8—C9	119.7 (3)
F2—B1—O1	107.2 (3)	N1—C8—C9	117.1 (3)
F1—B1—N2	110.7 (3)	C10—C9—C8	120.7 (3)
F2—B1—N2	110.0 (3)	C9—C10—C11	120.4 (3)
O1—B1—N2	107.7 (3)	C10—C11—C15	118.8 (3)
C7—N1—C8	119.0 (3)	C10—C11—C12	125.4 (3)
C8—N2—C15	120.3 (3)	C15—C11—C12	115.8 (3)
C8—N2—B1	120.0 (3)	C13—C12—C11	120.7 (3)
C15—N2—B1	119.7 (3)	C12—C13—C14	118.5 (3)
C14—N3—C15	117.8 (3)	N3—C14—C13	123.2 (3)
C20—N4—C16	117.4 (3)	N3—C14—C16	115.6 (3)
C7—O1—B1	125.2 (3)	C13—C14—C16	121.2 (3)
C2—C1—C6	120.4 (3)	N3—C15—N2	115.9 (3)
C1—C2—C3	119.4 (4)	N3—C15—C11	124.0 (3)
C4—C3—C2	120.6 (4)	N2—C15—C11	120.1 (3)
C3—C4—C5	120.3 (4)	C17—C16—N4	122.0 (3)
C4—C5—C6	120.3 (3)	C17—C16—C14	118.0 (3)
C1—C6—C5	118.9 (3)	N4—C16—C14	120.0 (3)
C1—C6—C7	119.5 (3)	C18—C17—C16	117.9 (3)
C5—C6—C7	121.5 (3)	C17—C18—C19	124.2 (4)
O1—C7—N1	125.0 (3)	C18—C19—C20	118.5 (4)
O1—C7—C6	115.0 (3)	C19—C20—N4	119.9 (4)
N1—C7—C6	120.0 (3)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C10—H10···F2ⁱ	0.93	2.47	3.353 (4)	160

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

Acknowledgements

Support from the `Spring Sunshine' Plan of Ministry of Education of China (grant No. Z2011125) and the National Natural Science Foundation of China (grant No. 21262049).

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