Low-temperature redetermination of 1,3-bis­(penta­fluoro­phen­yl)triazene

Eschwege, K.G. von; Kuhn, A.

doi:10.1107/S1600536810045447

organic compounds

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Volume 66| Part 12| December 2010| Page o3177

https://doi.org/10.1107/S1600536810045447

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Low-temperature redetermination of 1,3-bis(pentafluorophenyl)triazene

Karel G. von Eschwege ^a ^* and Annemarie Kuhn ^a

^aDepartment of Chemistry, University of the Free State, PO Box 339, Bloemfontein 9300, South Africa
^*Correspondence e-mail: veschwkg@ufs.ac.za

(Received 5 November 2010; accepted 5 November 2010; online 13 November 2010)

The crystal structure of the title compound, (C₆F₅)₂N₃H, is stabilized by N—H⋯N hydrogen bonding, forming centrosymmetric dimers organized in a herringbone motif. Important geometrical parameters are N—N = 1.272 (2) and 1.330 (2) Å and N—N—N = 112.56 (15)°. The dihedral angle between C₆F₅ groups is 21.22 (9)°. The room temperature structure was reported by Leman et al. (1993). Inorg. Chem. 32, 4324–4336]. In the current determination, the data were collected to a higher θ angle, resulting in higher precision for the C—C bond lengths(0.001–0.005 versus 0.003 Å).

Related literature

Average bond lengths were obtained from the Cambridge Structural Database (Allen, 2000 ); For the synthesis of nitroformazans, see: Pelkis et al. (1957 ); and for the synthesis of triazenes, see: Brooke et al. (1965 ). For use of triazenes in both synthesis and as metal coordinating ligands, see: Leman et al. (1993 ).

Experimental

Crystal data

C₁₂HF₁₀N₃
M_r = 377.16
Monoclinic, P 2₁ /c
a = 9.9930 (8) Å
b = 9.4850 (8) Å
c = 12.9200 (11) Å
β = 95.585 (2)°
V = 1218.79 (18) Å³
Z = 4
Mo Kα radiation
μ = 0.23 mm⁻¹
T = 100 K
0.3 × 0.19 × 0.15 mm

Data collection

Bruker X8 APEXII 4K Kappa CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker; 2004 ) T_min = 0.933, T_max = 0.966
12525 measured reflections
3013 independent reflections
2177 reflections with I > 2σ(I)
R_int = 0.039

Refinement

R[F² > 2σ(F²)] = 0.039
wR(F²) = 0.107
S = 1.07
3013 reflections
226 parameters
H-atom parameters constrained
Δρ_max = 0.36 e Å⁻³
Δρ_min = −0.31 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N3—H3⋯N1ⁱ	0.88	2.23	3.076 (2)	162
Symmetry code: (i) -x+1, -y, -z+1.

Data collection: APEX2 (Bruker, 2005 ); cell refinement: SAINT-Plus (Bruker, 2004); data reduction: SAINT-Plus and XPREP (Bruker, 2004); program(s) used to solve structure: SIR97 (Altomare et al., 1999 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ); molecular graphics: DIAMOND (Brandenburg & Putz, 2005 ); software used to prepare material for publication: WinGX (Farrugia, 1999 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: https://doi.org/10.1107/S1600536810045447/kp2288sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810045447/kp2288Isup2.hkl

checkCIF report

Comment top

A series of dithizones with varying number of fluorines on the phenyl rings were synthesised. During this process the nitroformazan precursor is initially prepared from the substituted aniline, as described by Pelkis et al., 1957. In the final step the nitro group is substituted by sulfur, to form dithizone. However, during the first step to prepare pentafluorophenyldithizone it was found that, contrary to expectation, a triazene formed instead of the usual nitroformazan. Previous studies show the extensive use of triazenes in both synthesis and as metal coordinating ligand, as illustrated by Leman et al., 1993. Triazenes, in general, are traditionally synthesised slightly different, according to a method by Brooke et al., 1965.

The title compound (Fig.1) and geometrical data are within expected values (average values obtained from the Cambridge Structural Database; Allen, 200). The C₆F₅ groups are twisted out of the plane formed by the N—N═N fragment 30.91 (16)° for ring C1—C6 and 38.49 (13)° for ring C7—C12. Hydrogen bonding (Fig. 2, Table 1) creates a centrosymmetric dimers that organise in a herring-bone motif along the c axis (Fig. 3).

Related literature top

For general bacground bond-length data, see: Allen et al. (1987); For the synthesis of nitroformazans, see: Pelkis et al. (1957); and for the synthesis of triazenes, see: Brooke et al. (1965). For use of triazenes in both synthesis and as metal coordinating ligands, see: Leman et al. (1993).

Experimental top

Reagent chemicals and solvents were purchased from Sigma-Aldrich and used without further purification. For the synthesis 2,3,4,5,6 pentafluoroaniline (5 g, 27.3 mmol) was added to a mixture of concentrated hydrochloric acid (20 mL) and water (35 mL) at 273 K, and diazotized by the slow addition of sodium nitrite (3 g, 43 mmol), stirring for 30 min. The resulting solution was added, with stirring, to a cold mixture of sodium acetate (80 g), glacial acetic acid (45 mL) and water (25 mL). Nitromethane (5.0 g, 82 mmol) was added after 10 min. While heating at 343 K and stirring for 20 h the colour changed to dark-red. Filtering the precipitated 1,3 bis-pentafluorophenyltriazene off, gave the product in 52% yield. Crystals suitable for X-ray crystallography were grown from a mixture of dichloromethane and methanol. Although this method is typically used for the preparation of nitroformazan as precursor for the synthesis of dithizone, nitromethane did not serve here as coupling reagent in the synthesis of this highly fluorinated compound. The unexpected outcome is ascribed to the large electron-withdrawing capacity of the five fluorines on each phenyl ring.

Structure description top

Computing details top

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT-Plus (Bruker, 2004); data reduction: SAINT-Plus and XPREP (Bruker, 2004); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top

	Fig. 1. A view of (I). Displacement ellipsoids are drawn at the 30% probability level.
	Fig. 2. Hydrogen bonding of (I) showing the dimeric units formed.
	Fig. 3. Packing diagram of (I) showing the herring-bone motif.

1,3-bis(pentafluorophenyl)triazene top

Crystal data top

C₁₂HF₁₀N₃	F(000) = 736
M_r = 377.16	D_x = 2.055 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 2521 reflections
a = 9.9930 (8) Å	θ = 3.5–28.1°
b = 9.4850 (8) Å	µ = 0.23 mm⁻¹
c = 12.9200 (11) Å	T = 100 K
β = 95.585 (2)°	Cuboid, red
V = 1218.79 (18) Å³	0.3 × 0.19 × 0.15 mm
Z = 4

Data collection top

Bruker X8 APEXII 4K Kappa CCD diffractometer	3013 independent reflections
Graphite monochromator	2177 reflections with I > 2σ(I)
Detector resolution: 8.4 pixels mm^-1	R_int = 0.039
φ scans	θ_max = 28.3°, θ_min = 2.7°
Absorption correction: multi-scan (SADABS; Bruker; 2004)	h = −12→13
T_min = 0.933, T_max = 0.966	k = −12→12
12525 measured reflections	l = −17→17

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)] = 0.039	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.107	H-atom parameters constrained
S = 1.07	w = 1/[σ²(F_o²) + (0.0438P)² + 0.6444P] where P = (F_o² + 2F_c²)/3
3013 reflections	(Δ/σ)_max < 0.001
226 parameters	Δρ_max = 0.36 e Å⁻³
0 restraints	Δρ_min = −0.31 e Å⁻³

Crystal data top

C₁₂HF₁₀N₃	V = 1218.79 (18) Å³
M_r = 377.16	Z = 4
Monoclinic, P2₁/c	Mo Kα radiation
a = 9.9930 (8) Å	µ = 0.23 mm⁻¹
b = 9.4850 (8) Å	T = 100 K
c = 12.9200 (11) Å	0.3 × 0.19 × 0.15 mm
β = 95.585 (2)°

Data collection top

Bruker X8 APEXII 4K Kappa CCD diffractometer	3013 independent reflections
Absorption correction: multi-scan (SADABS; Bruker; 2004)	2177 reflections with I > 2σ(I)
T_min = 0.933, T_max = 0.966	R_int = 0.039
12525 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.039	0 restraints
wR(F²) = 0.107	H-atom parameters constrained
S = 1.07	Δρ_max = 0.36 e Å⁻³
3013 reflections	Δρ_min = −0.31 e Å⁻³
226 parameters

Special details top

Experimental. The intensity data was collected on a Bruker X8 Apex II 4 K Kappa CCD diffractometer using an exposure time of 10 s/frame. A total of 1126 frames were collected with a frame width of 0.5° covering up to θ = 28.33° with 98.8% completeness accomplished.

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
N1	0.32054 (15)	−0.00606 (18)	0.51342 (13)	0.0176 (4)
N2	0.29181 (15)	0.01759 (18)	0.41693 (13)	0.0170 (4)
N3	0.39984 (15)	0.04639 (18)	0.36826 (13)	0.0187 (4)
H3	0.4793	0.0554	0.4034	0.022*
C1	0.38491 (18)	0.0620 (2)	0.26046 (15)	0.0161 (4)
C2	0.28659 (18)	−0.0055 (2)	0.19428 (16)	0.0170 (4)
C3	0.27844 (18)	0.0129 (2)	0.08793 (16)	0.0183 (4)
C4	0.37001 (19)	0.0977 (2)	0.04420 (16)	0.0198 (4)
C5	0.46978 (19)	0.1626 (2)	0.10765 (16)	0.0199 (4)
C6	0.47531 (18)	0.1467 (2)	0.21357 (16)	0.0184 (4)
C7	0.20622 (17)	−0.0486 (2)	0.56306 (15)	0.0156 (4)
C8	0.20040 (18)	−0.0106 (2)	0.66629 (16)	0.0178 (4)
C9	0.09951 (19)	−0.0571 (2)	0.72416 (15)	0.0190 (4)
C10	0.00216 (18)	−0.1471 (2)	0.67859 (16)	0.0187 (4)
C11	0.00446 (18)	−0.1863 (2)	0.57591 (16)	0.0174 (4)
C12	0.10529 (18)	−0.1381 (2)	0.51888 (15)	0.0165 (4)
F2	0.19834 (11)	−0.09374 (13)	0.23200 (9)	0.0218 (3)
F3	0.18284 (12)	−0.05460 (13)	0.02754 (9)	0.0254 (3)
F4	0.36352 (12)	0.11346 (14)	−0.05941 (9)	0.0272 (3)
F5	0.56138 (12)	0.24230 (14)	0.06517 (10)	0.0283 (3)
F6	0.57237 (11)	0.21376 (13)	0.27471 (9)	0.0246 (3)
F8	0.29674 (11)	0.07433 (13)	0.71246 (9)	0.0241 (3)
F9	0.09641 (12)	−0.01701 (14)	0.82274 (9)	0.0269 (3)
F10	−0.09396 (11)	−0.19674 (13)	0.73422 (10)	0.0243 (3)
F11	−0.09111 (11)	−0.27180 (13)	0.53101 (10)	0.0245 (3)
F12	0.10472 (11)	−0.18344 (13)	0.42082 (9)	0.0218 (3)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
N1	0.0153 (7)	0.0214 (9)	0.0163 (9)	0.0000 (6)	0.0024 (6)	−0.0012 (7)
N2	0.0160 (7)	0.0181 (9)	0.0172 (9)	0.0000 (6)	0.0031 (6)	−0.0005 (7)
N3	0.0142 (7)	0.0247 (10)	0.0172 (9)	−0.0037 (7)	0.0009 (6)	0.0012 (7)
C1	0.0152 (8)	0.0164 (10)	0.0167 (10)	0.0014 (7)	0.0017 (7)	0.0008 (8)
C2	0.0158 (8)	0.0147 (10)	0.0209 (11)	0.0001 (7)	0.0035 (7)	0.0003 (8)
C3	0.0173 (9)	0.0182 (10)	0.0190 (11)	0.0016 (8)	−0.0006 (8)	−0.0006 (8)
C4	0.0244 (10)	0.0200 (11)	0.0155 (10)	0.0055 (8)	0.0040 (8)	0.0026 (8)
C5	0.0193 (9)	0.0177 (11)	0.0236 (11)	0.0004 (8)	0.0070 (8)	0.0035 (9)
C6	0.0150 (8)	0.0167 (10)	0.0230 (11)	−0.0002 (7)	−0.0003 (8)	−0.0013 (8)
C7	0.0138 (8)	0.0171 (10)	0.0159 (10)	0.0027 (7)	0.0014 (7)	0.0014 (8)
C8	0.0144 (8)	0.0186 (11)	0.0199 (11)	0.0000 (7)	−0.0003 (7)	−0.0018 (8)
C9	0.0210 (9)	0.0226 (11)	0.0134 (10)	0.0053 (8)	0.0023 (8)	0.0014 (8)
C10	0.0163 (9)	0.0192 (11)	0.0215 (11)	0.0035 (8)	0.0060 (8)	0.0069 (8)
C11	0.0155 (8)	0.0152 (10)	0.0211 (11)	−0.0005 (7)	−0.0009 (7)	0.0004 (8)
C12	0.0176 (9)	0.0187 (10)	0.0130 (10)	0.0025 (7)	0.0004 (7)	−0.0002 (8)
F2	0.0208 (5)	0.0244 (7)	0.0203 (6)	−0.0077 (5)	0.0023 (5)	0.0023 (5)
F3	0.0293 (6)	0.0275 (7)	0.0183 (7)	−0.0069 (5)	−0.0036 (5)	−0.0011 (5)
F4	0.0334 (7)	0.0318 (8)	0.0171 (7)	0.0016 (6)	0.0055 (5)	0.0032 (5)
F5	0.0265 (6)	0.0308 (7)	0.0292 (7)	−0.0082 (5)	0.0106 (5)	0.0064 (6)
F6	0.0197 (5)	0.0285 (7)	0.0252 (7)	−0.0087 (5)	−0.0005 (5)	−0.0005 (5)
F8	0.0226 (6)	0.0298 (7)	0.0195 (7)	−0.0071 (5)	0.0004 (5)	−0.0053 (5)
F9	0.0304 (6)	0.0342 (8)	0.0168 (6)	−0.0011 (5)	0.0060 (5)	−0.0033 (5)
F10	0.0212 (6)	0.0270 (7)	0.0260 (7)	−0.0008 (5)	0.0098 (5)	0.0048 (5)
F11	0.0198 (5)	0.0260 (7)	0.0274 (7)	−0.0088 (5)	−0.0002 (5)	−0.0008 (5)
F12	0.0241 (6)	0.0249 (7)	0.0162 (6)	−0.0046 (5)	0.0018 (5)	−0.0029 (5)

Geometric parameters (Å, º) top

N1—N2	1.272 (2)	C5—C6	1.373 (3)
N1—C7	1.422 (2)	C6—F6	1.349 (2)
N2—N3	1.330 (2)	C7—C8	1.388 (3)
N3—C1	1.394 (2)	C7—C12	1.397 (3)
N3—H3	0.88	C8—F8	1.349 (2)
C1—C6	1.391 (3)	C8—C9	1.385 (3)
C1—C2	1.394 (3)	C9—F9	1.332 (2)
C2—F2	1.341 (2)	C9—C10	1.382 (3)
C2—C3	1.380 (3)	C10—F10	1.340 (2)
C3—F3	1.336 (2)	C10—C11	1.380 (3)
C3—C4	1.380 (3)	C11—F11	1.341 (2)
C4—F4	1.342 (2)	C11—C12	1.383 (3)
C4—C5	1.373 (3)	C12—F12	1.337 (2)
C5—F5	1.345 (2)

N2—N1—C7	112.19 (15)	F6—C6—C1	118.53 (18)
N1—N2—N3	112.56 (15)	C5—C6—C1	122.21 (18)
N2—N3—C1	118.78 (15)	C8—C7—C12	117.02 (17)
N2—N3—H3	120.6	C8—C7—N1	118.04 (17)
C1—N3—H3	120.6	C12—C7—N1	124.61 (18)
C6—C1—C2	116.55 (18)	F8—C8—C9	118.51 (18)
C6—C1—N3	119.05 (17)	F8—C8—C7	119.02 (17)
C2—C1—N3	124.38 (17)	C9—C8—C7	122.46 (18)
F2—C2—C3	117.62 (17)	F9—C9—C10	120.19 (17)
F2—C2—C1	120.85 (18)	F9—C9—C8	120.73 (18)
C3—C2—C1	121.51 (18)	C10—C9—C8	119.08 (18)
F3—C3—C2	119.36 (17)	F10—C10—C11	120.04 (18)
F3—C3—C4	120.34 (18)	F10—C10—C9	120.00 (18)
C2—C3—C4	120.28 (18)	C11—C10—C9	119.95 (17)
F4—C4—C5	120.47 (18)	F11—C11—C10	120.08 (17)
F4—C4—C3	120.24 (18)	F11—C11—C12	119.65 (18)
C5—C4—C3	119.27 (19)	C10—C11—C12	120.28 (18)
F5—C5—C6	120.39 (18)	F12—C12—C11	117.55 (17)
F5—C5—C4	119.46 (19)	F12—C12—C7	121.24 (17)
C6—C5—C4	120.14 (18)	C11—C12—C7	121.18 (18)
F6—C6—C5	119.25 (17)

C7—N1—N2—N3	−174.92 (16)	N3—C1—C6—C5	177.51 (18)
N1—N2—N3—C1	174.28 (17)	N2—N1—C7—C8	−147.83 (18)
N2—N3—C1—C6	152.97 (18)	N2—N1—C7—C12	38.9 (3)
N2—N3—C1—C2	−29.0 (3)	C12—C7—C8—F8	179.22 (17)
C6—C1—C2—F2	177.31 (17)	N1—C7—C8—F8	5.4 (3)
N3—C1—C2—F2	−0.7 (3)	C12—C7—C8—C9	−0.5 (3)
C6—C1—C2—C3	−1.0 (3)	N1—C7—C8—C9	−174.24 (18)
N3—C1—C2—C3	−179.05 (18)	F8—C8—C9—F9	1.1 (3)
F2—C2—C3—F3	1.3 (3)	C7—C8—C9—F9	−179.21 (18)
C1—C2—C3—F3	179.65 (17)	F8—C8—C9—C10	−178.35 (17)
F2—C2—C3—C4	−177.26 (17)	C7—C8—C9—C10	1.3 (3)
C1—C2—C3—C4	1.1 (3)	F9—C9—C10—F10	−1.5 (3)
F3—C3—C4—F4	0.2 (3)	C8—C9—C10—F10	177.96 (17)
C2—C3—C4—F4	178.76 (17)	F9—C9—C10—C11	178.85 (17)
F3—C3—C4—C5	−178.06 (18)	C8—C9—C10—C11	−1.7 (3)
C2—C3—C4—C5	0.5 (3)	F10—C10—C11—F11	1.4 (3)
F4—C4—C5—F5	−0.1 (3)	C9—C10—C11—F11	−178.93 (17)
C3—C4—C5—F5	178.22 (18)	F10—C10—C11—C12	−178.43 (17)
F4—C4—C5—C6	179.63 (18)	C9—C10—C11—C12	1.2 (3)
C3—C4—C5—C6	−2.1 (3)	F11—C11—C12—F12	−2.0 (3)
F5—C5—C6—F6	1.1 (3)	C10—C11—C12—F12	177.86 (17)
C4—C5—C6—F6	−178.58 (18)	F11—C11—C12—C7	179.80 (17)
F5—C5—C6—C1	−178.10 (18)	C10—C11—C12—C7	−0.3 (3)
C4—C5—C6—C1	2.2 (3)	C8—C7—C12—F12	−178.17 (17)
C2—C1—C6—F6	−179.85 (17)	N1—C7—C12—F12	−4.9 (3)
N3—C1—C6—F6	−1.7 (3)	C8—C7—C12—C11	0.0 (3)
C2—C1—C6—C5	−0.6 (3)	N1—C7—C12—C11	173.28 (18)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N3—H3···N1ⁱ	0.88	2.23	3.076 (2)	162

Symmetry code: (i) −x+1, −y, −z+1.

Experimental details

Crystal data
Chemical formula	C₁₂HF₁₀N₃
M_r	377.16
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	100
a, b, c (Å)	9.9930 (8), 9.4850 (8), 12.9200 (11)
β (°)	95.585 (2)
V (Å³)	1218.79 (18)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.23
Crystal size (mm)	0.3 × 0.19 × 0.15

Data collection
Diffractometer	Bruker X8 APEXII 4K Kappa CCD
Absorption correction	Multi-scan (SADABS; Bruker; 2004)
T_min, T_max	0.933, 0.966
No. of measured, independent and observed [I > 2σ(I)] reflections	12525, 3013, 2177
R_int	0.039
(sin θ/λ)_max (Å⁻¹)	0.668

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.039, 0.107, 1.07
No. of reflections	3013
No. of parameters	226
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.36, −0.31

Computer programs: APEX2 (Bruker, 2005), SAINT-Plus (Bruker, 2004), SAINT-Plus and XPREP (Bruker, 2004), SIR97 (Altomare et al., 1999), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg & Putz, 2005), WinGX (Farrugia, 1999).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N3—H3···N1ⁱ	0.88	2.23	3.076 (2)	162.2

Symmetry code: (i) −x+1, −y, −z+1.

Acknowledgements

Financial assistance from the National Research Foundation of South Africa is gratefully acknowledged.

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