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The crystal structure of the title compound, C9H8N+·PF6-, was measured at 145 K. The cationic part of the compound has crystallographically imposed 2/m symmetry with N/C disorder.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270100015742/bj1008sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270100015742/bj1008Isup2.hkl
Contains datablock I

CCDC reference: 159990

Comment top

The quinolizinium ion, the newest of the benzenoid aromatic heterocyclic system having only a single N atom (Bradsher, 1984), and its derivatives form a novel class of compounds whose properties have not yet been studied extensively (Arai & Hida, 1992). The first synthesis of the parent quinolizinium cation was announced by Boekelheide & Gall (1954) and the cation has been assumed from its spectroscopic properties to have a planar structure resembling that of naphthalene (Boekelheide & Gall, 1954). A search of the Cambridge Crystallographic Database (ref?) shows that there have been four papers on single-crystal X-ray structure determinations of the azonia derivatives of polycyclic aromatics: fluoranthene (Boubekeur et al., 1989), 9-phenylanthracene (Maassarani & Pfeffer, 1990), 13-ethoxycarbonylbenzofluoranthene (Florencio et al., 1984) and 2-pyridyldiazaphenanthrene (Elix et al., 1971). No account of the structure of the parent quinolizinium cation has been found in the literature. We therefore decided to determine this structure in detail using the title hexafluorophosphate salt of the cation, (I). \sch

Data collection was undertaken at 145 K in order to minimize the thermal motion of the molecule. Analysis of a structure solution in space group C2 indicated a missing centre of symmetry. When refinement was attempted in the acentric space group, very high correlations were observed between the various parameters. For this reason, we considered a disordered structure in space group C2/m to be the correct solution. In this solution, the heterocyclic cation resides on a 2/m site (Wyckoff position d). The crystallographically imposed disorder causes the ring-shared carbon (C9a) and the ring-shared nitrogen (N5) to occupy a composite atomic site. The observed structure can be thought of as a statistical average between two orientations of the quinolizinium cation. The disorder observed in compound (I) seems to be a common feature in heterocycles which are isostructural with naphthalene. For example, disorder has also been found for quinoline (Kobayashi et al., 1971) and isoquinoline (Hensen et al., 1999).

An ORTEPIII drawing (Johnson & Burnett, 1996) of the cationic part of (I), together with the atomic numbering scheme, is shown in Fig. 1. The quinolizinium ring is planar: the maximum deviation from the best plane through the non-H atoms is for atom C1, which deviates by only 0.010 (1) Å. Bond lengths and angles are listed in Table 1. The most important structural differences between this aromatic cation and naphthalene (Brock & Dunitz, 1982) are contractions of the N—C bond lengths in (I), by 0.04 Å for N5—C9a and by 0.03 Å for N5/C9a—C1.

Related literature top

For related literature, see: Arai & Hida (1992); Boekelheide & Gall (1954); Boubekeur et al. (1989); Bradsher (1984); Brock & Dunitz (1982); Elix et al. (1971); Florencio et al. (1984); Glover & Jones (1958); Hensen et al. (1999); Johnson & Burnett (1996); Kobayashi et al. (1971); Maassarani & Pfeffer (1990); Miyadera & Iwai (1964).

Experimental top

Quinolizinium bromide was prepared according to the method of Glover & Jones (1958) with the modifications of Miyadera & Iwai (1964). The hexafluorophosphate salt was obtained from an aqueous solution of the bromide by treatment with ammonium hexafluorophosphate. Clear colourless needles of quinolizinium hexafluorophosphate, (I) (m.p. 272.5–273 K), were obatined by slow evaporation from acetonitrile.

Refinement top

All H atoms were refined isotropically. Atoms N5 and C9a were placed on the same site, each with occupancy 1/2, and refined with the same displacement parameters.

Computing details top

Data collection: Rigaku/AFC Diffractometer Control Software (Rigaku Corporation, 1995); cell refinement: Rigaku/AFC Diffractometer Control Software; data reduction: TEXSAN (Molecular Structure Corporation, 1998); program(s) used to solve structure: SIR92 (Altomare et al., 1994) and DIRDIF94 (Beurskens et al., 1994); program(s) used to refine structure: SHELXL93 (Sheldrick, 1993); molecular graphics: ORTEPIII (Johnson & Burnett, 1996); software used to prepare material for publication: TEXSAN.

Figures top
[Figure 1] Fig. 1. The molecular structure of the quinolizinium cation in (I) shown with 50% probability ellipsoids. H atoms are drawn as small spheres of arbitrary radii.
Quinolizinium hexafluorophosphate top
Crystal data top
C9H8N+·PF6Dx = 1.825 Mg m3
Mr = 275.13Melting point = 272.5–273 K
Monoclinic, C2/mMo Kα radiation, λ = 0.7107 Å
a = 8.505 (3) ÅCell parameters from 25 reflections
b = 9.541 (3) Åθ = 14–15°
c = 6.827 (2) ŵ = 0.34 mm1
β = 115.33 (3)°T = 145 K
V = 500.7 (3) Å3Needle-like, colourless
Z = 20.44 × 0.30 × 0.20 mm
F(000) = 276.00
Data collection top
Rigaku AFC-7R
diffractometer
Rint = 0.015
Radiation source: Rigaku rotating anodeθmax = 27.5°, θmin = 3.3°
Graphite monochromatorh = 011
ω/2θ scansk = 012
656 measured reflectionsl = 88
615 independent reflections3 standard reflections every 150 reflections
562 reflections with I > 2σ(I) intensity decay: 0.6%
Refinement top
Refinement on F2All H-atom parameters refined
Least-squares matrix: full w = 1/[σ2(Fo2) + (0.0321P)2 + 0.3901P]
where P = (Fo2 + 2Fc2)/3
R[F2 > 2σ(F2)] = 0.025(Δ/σ)max < 0.001
wR(F2) = 0.068Δρmax = 0.29 e Å3
S = 1.09Δρmin = 0.32 e Å3
562 reflectionsExtinction correction: SHELXL93 (Sheldrick, 1993), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
54 parametersExtinction coefficient: 0.020
1 restraint
Crystal data top
C9H8N+·PF6V = 500.7 (3) Å3
Mr = 275.13Z = 2
Monoclinic, C2/mMo Kα radiation
a = 8.505 (3) ŵ = 0.34 mm1
b = 9.541 (3) ÅT = 145 K
c = 6.827 (2) Å0.44 × 0.30 × 0.20 mm
β = 115.33 (3)°
Data collection top
Rigaku AFC-7R
diffractometer
Rint = 0.015
656 measured reflections3 standard reflections every 150 reflections
615 independent reflections intensity decay: 0.6%
562 reflections with I > 2σ(I)
Refinement top
R[F2 > 2σ(F2)] = 0.0251 restraint
wR(F2) = 0.068All H-atom parameters refined
S = 1.09Δρmax = 0.29 e Å3
562 reflectionsΔρmin = 0.32 e Å3
54 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.

Refinement. Refinement based on F2 against all reflections. The weighted R-factor (wR) and goodness of fit (S) are based on F2, conventional R-factors (R) are calculated 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. thus the refinement was done using all reflections. R-factors based on F2 are statistically about twice as large as those based on F, and R-factor based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
P1103/20.0212 (2)
F10.9788 (2)01.2550 (2)0.0361 (3)
F21.1461 (1)0.11821 (9)1.5603 (2)0.0410 (3)
N510.4278 (2)10.0211 (3)0.50
C9a10.4278 (2)10.0211 (3)0.50
C10.9306 (2)0.3562 (1)1.1234 (2)0.0265 (3)
C20.8607 (2)0.4262 (2)1.2391 (2)0.0296 (3)
H10.934 (2)0.259 (2)1.119 (2)0.03610 (5)*
H20.812 (2)0.379 (2)1.318 (3)0.04139 (6)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
P10.0218 (3)0.0199 (3)0.0217 (3)00.0092 (2)0
F10.0454 (7)0.0401 (7)0.0250 (6)00.0171 (5)0
F20.0411 (5)0.0390 (5)0.0466 (5)0.0187 (4)0.0223 (4)0.0105 (4)
N50.0186 (7)0.0203 (8)0.0204 (7)00.0044 (6)0
C9a0.0186 (7)0.0203 (8)0.0204 (7)00.0044 (6)0
C10.0248 (6)0.0245 (6)0.0262 (6)0.0015 (5)0.0070 (5)0.0038 (5)
C20.0259 (6)0.0377 (8)0.0244 (6)0.0023 (5)0.0100 (5)0.0048 (5)
Geometric parameters (Å, º) top
P1—F11.603 (1)N5/C9a—N5/C9aiv1.378 (3)
P1—F1i1.603 (1)N5/C9a—C11.396 (2)
P1—F21.5962 (9)N5/C9a—C1v1.396 (2)
P1—F2ii1.5962 (9)C1—C21.352 (2)
P1—F2i1.5962 (9)C2—C2iv1.408 (3)
P1—F2iii1.5962 (9)
F2—P1—F2ii89.92 (7)F2iii—P1—F190.19 (5)
F2—P1—F2i180.0F2iii—P1—F1i89.81 (5)
F2—P1—F2iii90.08 (7)F1—P1—F1i180.0
F2—P1—F189.81 (5)N5/C9aiv—N5/C9a—C1119.31 (8)
F2—P1—F1i90.19 (5)N5/C9aiv—N5/C9a—C1v119.31 (8)
F2ii—P1—F2i90.08 (7)C1—N5/C9a—C1v121.4 (2)
F2ii—P1—F2iii180.0H1—C1—C2122 (1)
F2ii—P1—F189.81 (5)H1—C1—N5/C9a115 (1)
F2ii—P1—F1i90.19 (5)C2—C1—N5/C9a121.0 (1)
F2i—P1—F2iii89.92 (7)H2—C2—C1121 (1)
F2i—P1—F190.19 (5)H2—C2—C2iv119 (1)
F2i—P1—F1i89.81 (5)C1—C2—C2iv119.65 (9)
N5/C9aiv—N5/C9a—C1—C21.3 (1)C1—N5/C9a—N5/C9aiv—C1iv0.0
N5/C9a—N5/C9aiv—C1vi—C2vi1.3 (1)C1—N5/C9a—N5/C9aiv—C1vi180.0
N5/C9a—C1—C2—C2iv1.3 (1)C1—N5/C9a—C1v—C2v178.7 (1)
N5/C9a—C1v—C2v—C2vi1.3 (1)C1—C2—C2iv—C1iv0.0
Symmetry codes: (i) x+2, y, z+3; (ii) x, y, z; (iii) x+2, y, z+3; (iv) x, y1, z; (v) x+2, y, z+2; (vi) x+2, y1, z+2.

Experimental details

Crystal data
Chemical formulaC9H8N+·PF6
Mr275.13
Crystal system, space groupMonoclinic, C2/m
Temperature (K)145
a, b, c (Å)8.505 (3), 9.541 (3), 6.827 (2)
β (°) 115.33 (3)
V3)500.7 (3)
Z2
Radiation typeMo Kα
µ (mm1)0.34
Crystal size (mm)0.44 × 0.30 × 0.20
Data collection
DiffractometerRigaku AFC-7R
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
656, 615, 562
Rint0.015
(sin θ/λ)max1)0.649
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.025, 0.068, 1.09
No. of reflections562
No. of parameters54
No. of restraints1
H-atom treatmentAll H-atom parameters refined
Δρmax, Δρmin (e Å3)0.29, 0.32

Computer programs: Rigaku/AFC Diffractometer Control Software (Rigaku Corporation, 1995), Rigaku/AFC Diffractometer Control Software, TEXSAN (Molecular Structure Corporation, 1998), SIR92 (Altomare et al., 1994) and DIRDIF94 (Beurskens et al., 1994), SHELXL93 (Sheldrick, 1993), ORTEPIII (Johnson & Burnett, 1996), TEXSAN.

Selected geometric parameters (Å, º) top
P1—F11.603 (1)N5/C9a—C11.396 (2)
P1—F21.5962 (9)C1—C21.352 (2)
N5/C9a—N5/C9ai1.378 (3)C2—C2i1.408 (3)
F2—P1—F2ii89.92 (7)F1—P1—F1iii180.0
F2—P1—F2iii180.0N5/C9ai—N5/C9a—C1119.31 (8)
F2—P1—F2iv90.08 (7)C1—N5/C9a—C1v121.4 (2)
F2—P1—F189.81 (5)C2—C1—N5/C9a121.0 (1)
F2—P1—F1iii90.19 (5)C1—C2—C2i119.65 (9)
Symmetry codes: (i) x, y1, z; (ii) x, y, z; (iii) x+2, y, z+3; (iv) x+2, y, z+3; (v) x+2, y, z+2.
 

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