supplementary materials


ff2091 scheme

Acta Cryst. (2012). E68, o3500    [ doi:10.1107/S160053681204860X ]

N,N,N',N'-Tetramethylguanidinium tetraphenylborate

I. Tiritiris

Abstract top

In the title salt, C5H14N3+·C24H20B-, the C-N bond lengths in the central CN3 unit are 1.3322 (11), 1.3385 (12) and 1.3422 (12) Å, indicating partial double-bond character. The central C atom is bonded to the three N atoms in a nearly ideal trigonal-planar geometry [N-C-N angles = 119.51 (8), 119.81 (9) and 120.69 (8)°] and the positive charge is delocalized in the CN3 plane. The bond lengths between the N atoms and the terminal methyl groups all have values close to a typical single bond [1.4597 (12)-1.4695 (13) Å]. The crystal packing is caused by electrostatic interactions between cations and anions.

Comment top

Salts with the N,N,N',N'-tetramethylguanidinium ion (tmg+) are usually synthesized by protonation of the base N,N, N',N'-tetramethylguanidine with the appropriate acids. Until now, the crystal structures of several tmgX salts were elucidated (tmgCl: Fischer & Jones, 2002; tmgBr: Berg et al., 2010; tmgHCO3: Tiritiris et al., 2011; tmgH2PO4: Criado et al., 2000; tmg+ pentachlorophenolate as complex with pentachlorophenol: Kanters et al., 1992; tmgSbCl4: Bujak et al., 1999). Starting from the salt tmgCl (Fischer & Jones, 2002) by reacting with sodium tetraphenylborate, it was possible to achieve an anion exchange and to obtain the title compound. According to the structure analysis, the C1–N1 bond is 1.3385 (12) Å, C1–N2 = 1.3322 (11) Å and C1–N3 = 1.3422 (12) Å, showing partial double-bond character. The N–C1–N angles are: 120.69 (8)° (N1–C1–N2), 119.51 (8)° (N1–C1–N3) and 119.81 (9)° (N2–C1–N3), which indicates a nearly ideal trigonal-planar surrounding of the carbon centre by the nitrogen atoms (Fig. 1). The positive charge is completely delocalized on the CN3 plane. The bonds between the N atoms and the terminal C-methyl groups, all have values close to a typical single bond [1.4597 (12)–1.4695 (13) Å]. The bond lengths and angles in the tetraphenylborate ion are in good agreement with the data from the crystal structure analysis of potassium tetraphenylborate (Wong et al., 2004) or rubidium tetraphenylborate (Pajzderska et al., 2002). Since there exist no hydrogen bonds in the title compound, crystal packing is caused by electrostatic interactions between cations and anions.

Related literature top

For related structures, see: Fischer & Jones (2002); Berg et al. (2010); Tiritiris et al. (2011); Criado et al. (2000); Kanters et al. (1992); Bujak et al. (1999); Wong et al. (2004); Pajzderska et al. (2002).

Experimental top

The title compound was obtained in an anion exchange reaction by reacting 2.0 g (13 mmol) of N,N,N',N'-tetramethylguanidinium chloride (Fischer & Jones, 2002) with 4.45 g (13 mmol) of sodium tetraphenylborate in 50 ml of acetonitrile at room temperature. After heating the mixture for 10 minutes at 353 K, the precipitated sodium chloride was filtered off. After evaporation of the solvent a colorless solid has been obtained. The title compound was recrystallized from a saturated acetonitrile solution and after several days at 273 K, colorless single crystals were formed. Yield: 5.2 g (92%).

Refinement top

The N-bound H atoms were located in a difference Fourier map and were refined freely [N—H = 0.90 (2)–0.91 (2) Å]. The hydrogen atoms of the methyl groups were allowed to rotate with a fixed angle around the C–N bond to best fit the experimental electron density, with U(H) set to 1.5 Ueq(C) and d(C—H) = 0.98 Å. The H atoms in the aromatic rings were placed in calculated positions with (C—H) = 0.95 Å. They were included in the refinement in the riding model approximation, with U(H) set to 1.2 Ueq(C).

Computing details top

Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT (Bruker, 2008); data reduction: SAINT (Bruker, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The structure of the title compound with atom labels and 50% probability displacement ellipsoids.
N,N,N',N'-Tetramethylguanidinium tetraphenylborate top
Crystal data top
C5H14N3+·C24H20BF(000) = 936
Mr = 435.40Dx = 1.169 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 52874 reflections
a = 10.9512 (5) Åθ = 2.0–30.6°
b = 18.1315 (9) ŵ = 0.07 mm1
c = 12.5453 (7) ÅT = 100 K
β = 96.594 (2)°Block, colourless
V = 2474.5 (2) Å30.23 × 0.16 × 0.12 mm
Z = 4
Data collection top
Bruker Kappa APEXII DUO
diffractometer
6738 reflections with I > 2σ(I)
Radiation source: sealed tubeRint = 0.021
Graphite monochromatorθmax = 30.6°, θmin = 2.0°
φ scans, and ω scansh = 1515
52874 measured reflectionsk = 2525
7573 independent reflectionsl = 1217
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.041Hydrogen site location: difference Fourier map
wR(F2) = 0.112H atoms treated by a mixture of independent and constrained refinement
S = 1.04 w = 1/[σ2(Fo2) + (0.0559P)2 + 0.9205P]
where P = (Fo2 + 2Fc2)/3
7573 reflections(Δ/σ)max < 0.001
310 parametersΔρmax = 0.40 e Å3
0 restraintsΔρmin = 0.31 e Å3
Crystal data top
C5H14N3+·C24H20BV = 2474.5 (2) Å3
Mr = 435.40Z = 4
Monoclinic, P21/nMo Kα radiation
a = 10.9512 (5) ŵ = 0.07 mm1
b = 18.1315 (9) ÅT = 100 K
c = 12.5453 (7) Å0.23 × 0.16 × 0.12 mm
β = 96.594 (2)°
Data collection top
Bruker Kappa APEXII DUO
diffractometer
Rint = 0.021
52874 measured reflectionsθmax = 30.6°
7573 independent reflectionsStandard reflections: 0
6738 reflections with I > 2σ(I)
Refinement top
R[F2 > 2σ(F2)] = 0.041H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.112Δρmax = 0.40 e Å3
S = 1.04Δρmin = 0.31 e Å3
7573 reflectionsAbsolute structure: ?
310 parametersFlack parameter: ?
0 restraintsRogers parameter: ?
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
xyzUiso*/Ueq
N10.74190 (7)0.06305 (5)0.71562 (6)0.01888 (15)
N20.60284 (7)0.13924 (5)0.78860 (6)0.02054 (16)
N30.80829 (8)0.14087 (5)0.85684 (7)0.02289 (17)
H300.8870 (16)0.1353 (9)0.8435 (13)0.041 (4)*
H310.7911 (15)0.1668 (9)0.9157 (13)0.038 (4)*
C10.71704 (8)0.11437 (5)0.78672 (7)0.01750 (16)
C20.67627 (9)0.06015 (6)0.60739 (8)0.02425 (19)
H2A0.61990.10220.59680.036*
H2B0.62940.01410.59830.036*
H2C0.73550.06230.55460.036*
C30.85459 (8)0.01960 (6)0.73372 (8)0.02234 (18)
H3A0.92180.04630.70560.034*
H3B0.84230.02790.69690.034*
H3C0.87540.01130.81090.034*
C40.57784 (10)0.20819 (6)0.84245 (8)0.0281 (2)
H4A0.57150.19840.91850.042*
H4B0.50040.22920.80890.042*
H4C0.64490.24310.83610.042*
C50.49544 (9)0.09133 (6)0.76198 (8)0.0262 (2)
H5A0.52300.04080.75100.039*
H5B0.44760.10910.69620.039*
H5C0.44410.09210.82100.039*
B10.77207 (8)0.10576 (5)0.22287 (7)0.01225 (15)
C60.62087 (7)0.10464 (4)0.20365 (6)0.01299 (14)
C70.56097 (8)0.08674 (5)0.10126 (7)0.01578 (15)
H7A0.60980.07580.04540.019*
C80.43355 (8)0.08443 (5)0.07831 (7)0.01832 (16)
H8A0.39730.07190.00820.022*
C90.35964 (8)0.10055 (5)0.15814 (8)0.02010 (17)
H9A0.27260.10000.14300.024*
C100.41494 (8)0.11741 (6)0.26041 (8)0.02207 (18)
H10A0.36540.12810.31590.026*
C110.54315 (8)0.11869 (5)0.28233 (7)0.01841 (16)
H11A0.57870.12950.35330.022*
C120.82722 (7)0.13031 (4)0.34510 (6)0.01287 (14)
C130.78885 (8)0.19702 (5)0.38812 (7)0.01620 (15)
H13A0.72680.22500.34710.019*
C140.83773 (8)0.22387 (5)0.48811 (7)0.01935 (17)
H14A0.80770.26870.51440.023*
C150.93051 (9)0.18509 (6)0.54945 (7)0.02074 (18)
H15A0.96380.20280.61790.025*
C160.97343 (8)0.12013 (5)0.50873 (7)0.01963 (17)
H16A1.03810.09370.54880.024*
C170.92193 (8)0.09334 (5)0.40884 (7)0.01579 (15)
H17A0.95220.04840.38320.019*
C180.81527 (7)0.02273 (4)0.19171 (6)0.01238 (14)
C190.79975 (7)0.03773 (5)0.25931 (6)0.01439 (15)
H190.76840.02890.32570.017*
C200.82836 (8)0.10987 (5)0.23308 (7)0.01630 (16)
H20A0.81650.14900.28120.020*
C210.87440 (8)0.12473 (5)0.13634 (7)0.01601 (15)
H210.89550.17370.11840.019*
C220.88900 (8)0.06665 (5)0.06645 (7)0.01521 (15)
H22A0.91920.07590.00030.018*
C230.85949 (7)0.00525 (5)0.09407 (6)0.01382 (15)
H23A0.86980.04390.04480.017*
C240.82661 (8)0.16882 (4)0.14711 (6)0.01348 (14)
C250.95325 (8)0.17168 (5)0.13683 (7)0.01668 (16)
H25A1.00530.13450.17070.020*
C261.00537 (9)0.22663 (5)0.07917 (7)0.02039 (17)
H26A1.09120.22620.07370.024*
C270.93187 (10)0.28230 (5)0.02953 (7)0.02249 (18)
H27A0.96680.31970.01060.027*
C280.80688 (9)0.28248 (5)0.03943 (7)0.02106 (18)
H28A0.75600.32070.00710.025*
C290.75587 (8)0.22642 (5)0.09701 (7)0.01653 (16)
H29A0.67010.22740.10240.020*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
N10.0149 (3)0.0227 (4)0.0191 (3)0.0019 (3)0.0022 (3)0.0004 (3)
N20.0162 (3)0.0255 (4)0.0199 (3)0.0044 (3)0.0020 (3)0.0012 (3)
N30.0170 (4)0.0286 (4)0.0225 (4)0.0026 (3)0.0004 (3)0.0053 (3)
C10.0158 (4)0.0202 (4)0.0166 (4)0.0012 (3)0.0024 (3)0.0027 (3)
C20.0218 (4)0.0321 (5)0.0184 (4)0.0026 (4)0.0003 (3)0.0018 (3)
C30.0159 (4)0.0233 (4)0.0280 (4)0.0023 (3)0.0035 (3)0.0016 (3)
C40.0294 (5)0.0328 (5)0.0222 (4)0.0154 (4)0.0027 (4)0.0002 (4)
C50.0144 (4)0.0379 (6)0.0262 (5)0.0005 (4)0.0025 (3)0.0076 (4)
B10.0119 (4)0.0130 (4)0.0121 (4)0.0004 (3)0.0021 (3)0.0005 (3)
C60.0131 (3)0.0122 (3)0.0138 (3)0.0006 (3)0.0019 (3)0.0006 (3)
C70.0157 (4)0.0173 (4)0.0143 (3)0.0000 (3)0.0014 (3)0.0001 (3)
C80.0166 (4)0.0200 (4)0.0174 (4)0.0012 (3)0.0020 (3)0.0019 (3)
C90.0126 (4)0.0237 (4)0.0235 (4)0.0002 (3)0.0001 (3)0.0020 (3)
C100.0140 (4)0.0312 (5)0.0217 (4)0.0004 (3)0.0048 (3)0.0035 (3)
C110.0142 (4)0.0250 (4)0.0162 (4)0.0002 (3)0.0027 (3)0.0035 (3)
C120.0122 (3)0.0137 (3)0.0131 (3)0.0007 (3)0.0030 (3)0.0006 (3)
C130.0160 (4)0.0152 (4)0.0173 (4)0.0001 (3)0.0020 (3)0.0024 (3)
C140.0192 (4)0.0196 (4)0.0198 (4)0.0037 (3)0.0047 (3)0.0067 (3)
C150.0195 (4)0.0267 (4)0.0159 (4)0.0072 (3)0.0014 (3)0.0047 (3)
C160.0160 (4)0.0254 (4)0.0167 (4)0.0015 (3)0.0017 (3)0.0006 (3)
C170.0143 (3)0.0175 (4)0.0155 (3)0.0006 (3)0.0014 (3)0.0005 (3)
C180.0103 (3)0.0136 (3)0.0131 (3)0.0000 (3)0.0011 (2)0.0009 (3)
C190.0138 (3)0.0151 (4)0.0146 (3)0.0008 (3)0.0028 (3)0.0001 (3)
C200.0160 (4)0.0135 (4)0.0194 (4)0.0018 (3)0.0022 (3)0.0014 (3)
C210.0137 (3)0.0132 (3)0.0210 (4)0.0008 (3)0.0015 (3)0.0031 (3)
C220.0139 (3)0.0167 (4)0.0154 (3)0.0006 (3)0.0029 (3)0.0036 (3)
C230.0136 (3)0.0143 (3)0.0136 (3)0.0003 (3)0.0018 (3)0.0003 (3)
C240.0157 (3)0.0128 (3)0.0122 (3)0.0005 (3)0.0030 (3)0.0022 (3)
C250.0158 (4)0.0174 (4)0.0173 (4)0.0017 (3)0.0039 (3)0.0026 (3)
C260.0208 (4)0.0228 (4)0.0188 (4)0.0074 (3)0.0077 (3)0.0048 (3)
C270.0317 (5)0.0199 (4)0.0170 (4)0.0089 (4)0.0076 (3)0.0009 (3)
C280.0302 (5)0.0153 (4)0.0180 (4)0.0007 (3)0.0038 (3)0.0022 (3)
C290.0196 (4)0.0147 (4)0.0157 (3)0.0007 (3)0.0038 (3)0.0001 (3)
Geometric parameters (Å, º) top
N1—C11.3385 (12)C11—H11A0.9500
N1—C31.4597 (12)C12—C171.4050 (11)
N1—C21.4624 (12)C12—C131.4081 (11)
N2—C11.3322 (11)C13—C141.3939 (12)
N2—C41.4617 (13)C13—H13A0.9500
N2—C51.4695 (13)C14—C151.3927 (13)
N3—C11.3422 (12)C14—H14A0.9500
N3—H300.903 (17)C15—C161.3872 (14)
N3—H310.914 (16)C15—H15A0.9500
C2—H2A0.9800C16—C171.4008 (12)
C2—H2B0.9800C16—H16A0.9500
C2—H2C0.9800C17—H17A0.9500
C3—H3A0.9800C18—C231.4042 (11)
C3—H3B0.9800C18—C191.4083 (11)
C3—H3C0.9800C19—C201.3931 (12)
C4—H4A0.9800C19—H190.9500
C4—H4B0.9800C20—C211.3930 (12)
C4—H4C0.9800C20—H20A0.9500
C5—H5A0.9800C21—C221.3911 (12)
C5—H5B0.9800C21—H210.9500
C5—H5C0.9800C22—C231.3964 (11)
B1—C181.6388 (12)C22—H22A0.9500
B1—C241.6423 (12)C23—H23A0.9500
B1—C121.6436 (12)C24—C291.4051 (12)
B1—C61.6458 (12)C24—C251.4085 (11)
C6—C111.3988 (11)C25—C261.3916 (12)
C6—C71.4114 (11)C25—H25A0.9500
C7—C81.3926 (12)C26—C271.3927 (14)
C7—H7A0.9500C26—H26A0.9500
C8—C91.3891 (13)C27—C281.3886 (14)
C8—H8A0.9500C27—H27A0.9500
C9—C101.3885 (13)C28—C291.3999 (12)
C9—H9A0.9500C28—H28A0.9500
C10—C111.3996 (12)C29—H29A0.9500
C10—H10A0.9500
C1—N1—C3120.30 (8)C6—C11—C10122.44 (8)
C1—N1—C2121.86 (8)C6—C11—H11A118.8
C3—N1—C2116.21 (8)C10—C11—H11A118.8
C1—N2—C4121.58 (8)C17—C12—C13115.15 (7)
C1—N2—C5121.62 (9)C17—C12—B1124.75 (7)
C4—N2—C5115.04 (8)C13—C12—B1119.76 (7)
C1—N3—H30119.6 (10)C14—C13—C12122.98 (8)
C1—N3—H31120.5 (10)C14—C13—H13A118.5
H30—N3—H31119.9 (14)C12—C13—H13A118.5
N2—C1—N1120.69 (8)C15—C14—C13120.08 (8)
N2—C1—N3119.81 (9)C15—C14—H14A120.0
N1—C1—N3119.51 (8)C13—C14—H14A120.0
N1—C2—H2A109.5C16—C15—C14118.80 (8)
N1—C2—H2B109.5C16—C15—H15A120.6
H2A—C2—H2B109.5C14—C15—H15A120.6
N1—C2—H2C109.5C15—C16—C17120.34 (8)
H2A—C2—H2C109.5C15—C16—H16A119.8
H2B—C2—H2C109.5C17—C16—H16A119.8
N1—C3—H3A109.5C16—C17—C12122.61 (8)
N1—C3—H3B109.5C16—C17—H17A118.7
H3A—C3—H3B109.5C12—C17—H17A118.7
N1—C3—H3C109.5C23—C18—C19115.29 (7)
H3A—C3—H3C109.5C23—C18—B1123.60 (7)
H3B—C3—H3C109.5C19—C18—B1120.89 (7)
N2—C4—H4A109.5C20—C19—C18122.86 (8)
N2—C4—H4B109.5C20—C19—H19118.6
H4A—C4—H4B109.5C18—C19—H19118.6
N2—C4—H4C109.5C21—C20—C19120.08 (8)
H4A—C4—H4C109.5C21—C20—H20A120.0
H4B—C4—H4C109.5C19—C20—H20A120.0
N2—C5—H5A109.5C22—C21—C20118.81 (8)
N2—C5—H5B109.5C22—C21—H21120.6
H5A—C5—H5B109.5C20—C21—H21120.6
N2—C5—H5C109.5C21—C22—C23120.25 (8)
H5A—C5—H5C109.5C21—C22—H22A119.9
H5B—C5—H5C109.5C23—C22—H22A119.9
C18—B1—C24111.55 (6)C22—C23—C18122.68 (8)
C18—B1—C12112.71 (6)C22—C23—H23A118.7
C24—B1—C12103.43 (6)C18—C23—H23A118.7
C18—B1—C6105.47 (6)C29—C24—C25115.45 (8)
C24—B1—C6110.52 (6)C29—C24—B1123.91 (7)
C12—B1—C6113.31 (6)C25—C24—B1120.40 (7)
C11—C6—C7115.29 (7)C26—C25—C24122.75 (8)
C11—C6—B1125.30 (7)C26—C25—H25A118.6
C7—C6—B1119.40 (7)C24—C25—H25A118.6
C8—C7—C6123.03 (8)C25—C26—C27120.06 (9)
C8—C7—H7A118.5C25—C26—H26A120.0
C6—C7—H7A118.5C27—C26—H26A120.0
C9—C8—C7119.84 (8)C28—C27—C26119.13 (8)
C9—C8—H8A120.1C28—C27—H27A120.4
C7—C8—H8A120.1C26—C27—H27A120.4
C10—C9—C8118.95 (8)C27—C28—C29120.02 (9)
C10—C9—H9A120.5C27—C28—H28A120.0
C8—C9—H9A120.5C29—C28—H28A120.0
C9—C10—C11120.43 (8)C28—C29—C24122.58 (8)
C9—C10—H10A119.8C28—C29—H29A118.7
C11—C10—H10A119.8C24—C29—H29A118.7
C4—N2—C1—N1162.47 (9)C14—C15—C16—C171.56 (14)
C5—N2—C1—N133.40 (13)C15—C16—C17—C120.81 (14)
C4—N2—C1—N317.62 (13)C13—C12—C17—C160.93 (12)
C5—N2—C1—N3146.51 (9)B1—C12—C17—C16174.07 (8)
C3—N1—C1—N2160.77 (9)C24—B1—C18—C2318.25 (10)
C2—N1—C1—N234.35 (13)C12—B1—C18—C23134.10 (8)
C3—N1—C1—N319.15 (13)C6—B1—C18—C23101.77 (8)
C2—N1—C1—N3145.74 (9)C24—B1—C18—C19167.38 (7)
C18—B1—C6—C11120.33 (9)C12—B1—C18—C1951.53 (10)
C24—B1—C6—C11118.97 (9)C6—B1—C18—C1972.59 (9)
C12—B1—C6—C113.41 (11)C23—C18—C19—C201.29 (12)
C18—B1—C6—C758.20 (9)B1—C18—C19—C20176.11 (7)
C24—B1—C6—C762.51 (9)C18—C19—C20—C210.06 (13)
C12—B1—C6—C7178.06 (7)C19—C20—C21—C221.08 (12)
C11—C6—C7—C81.24 (13)C20—C21—C22—C230.91 (12)
B1—C6—C7—C8179.91 (8)C21—C22—C23—C180.40 (12)
C6—C7—C8—C90.29 (14)C19—C18—C23—C221.47 (12)
C7—C8—C9—C101.19 (14)B1—C18—C23—C22176.12 (7)
C8—C9—C10—C110.50 (15)C18—B1—C24—C29133.43 (8)
C7—C6—C11—C101.94 (13)C12—B1—C24—C29105.16 (8)
B1—C6—C11—C10179.48 (9)C6—B1—C24—C2916.43 (11)
C9—C10—C11—C61.14 (15)C18—B1—C24—C2552.52 (10)
C18—B1—C12—C1713.50 (11)C12—B1—C24—C2568.88 (9)
C24—B1—C12—C17107.12 (9)C6—B1—C24—C25169.53 (7)
C6—B1—C12—C17133.19 (8)C29—C24—C25—C261.38 (12)
C18—B1—C12—C13173.65 (7)B1—C24—C25—C26175.91 (8)
C24—B1—C12—C1365.73 (9)C24—C25—C26—C270.66 (13)
C6—B1—C12—C1353.96 (10)C25—C26—C27—C280.67 (13)
C17—C12—C13—C141.98 (12)C26—C27—C28—C291.20 (14)
B1—C12—C13—C14175.49 (8)C27—C28—C29—C240.42 (14)
C12—C13—C14—C151.30 (14)C25—C24—C29—C280.84 (12)
C13—C14—C15—C160.55 (14)B1—C24—C29—C28175.15 (8)
Acknowledgements top

The author thanks Dr W. Frey (Institut für Organische Chemie, Universität Stuttgart) for the data collection.

references
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