organic compounds
N,N,N′,N′,4-pentamethyl-4-(trimethylsilyloxy)pent-2-eneamidinium bromide
of 2-bromo-3-dimethylamino-aFakultät Chemie/Organische Chemie, Hochschule Aalen, Beethovenstrasse 1, D-73430 Aalen, Germany
*Correspondence e-mail: willi.kantlehner@hs-aalen.de
The reaction of the orthoamide 1,1,1-tris(dimethylamino)-4-methyl-4-(trimethylsilyloxy)pent-2-yne with bromine in benzene, yields the title salt, C15H33BrN3OSi+·Br−. The C—N bond lengths in the amidinium unit are 1.319 (6) and 1.333 (6) Å, indicating double-bond character, pointing towards charge delocalization within the NCN plane. The C—Br bond length of 1.926 (5) Å is characteristic for a C—Br single bond. Additionally, there is a bromine–bromine interaction [3.229 (3) Å] present involving the anion and cation. In the crystal, weak C—H⋯Br interactions between the methyl H atoms of the cation and the bromide ions are present.
Keywords: crystal structure; bromide; amidinium; salt; Br⋯Br interactions; C—H⋯Br interactions.
CCDC reference: 1441961
1. Related literature
For the nature of halogen–halogen interactions in crystals, see: Desiraju & Parthasarathy (1989). For the synthesis of alkynyl orthoamides and propiolamidinium salts, see: Weingärtner et al. (2011). For the synthesis of vinylogous guanidinium iodides and bromides, see: Kantlehner et al. (2012a). For the of 3-phenyl-N,N,N′,N′′-tetramethyl-1-ethyne-1-carboximidamidium bromide, see: Tiritiris & Kantlehner (2012b).
2. Experimental
2.1. Crystal data
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2.3. Refinement
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Data collection: APEX2 (Bruker, 2008); cell SAINT (Bruker, 2008); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: SHELXL2014.
Supporting information
CCDC reference: 1441961
To (2.10 g, 7.0 mmol) 4-methyl-4-trimethylsilyloxy-1,1,1- tris(dimethylamino)pent-2-yne in 50 ml benzene was added dropwise under ice/water cooling, elemental bromine (1.12 g, 7.0 mmol) in benzene. After stirring for two hours at room temperature, a yellow precipitate was collected by filtration. The title compound crystallized from a saturated acetonitrile solution after several days at 273 K, forming yellow single crystals. Yield: 2.77 g (80%).
The hydrogen atoms of the methyl groups were allowed to rotate with a fixed angle around the C–N, C–C and C–Si bonds to best fit the experimental electron density, with Uiso(H) set to 1.5 Ueq(C) and d(C—H) = 0.98 Å.
Orthoamide derivatives of alkynecarboxylic acids are prepared from N,N,N',N',N'',N''- hexaalkylguanidinium chlorides and terminal
Their conversion into propiolamidinium chlorides by reaction with benzoyl chloride and into propiolamidinium triflates by reaction with triethylsilyl trifluoromethanesulfonate is well known in literature (Weingärtner et al., 2011). Alkyne orthoamides are transformed by elemental iodine or bromine to vinylogous guanidinium iodides or bromides (Kantlehner et al., 2012a). Phenyl substituted alkyne orthoamides like 3,3,3-Tris(dimethylamino)-1-phenyl- prop-1-yne (Weingärtner et al., 2011) behave differently, it reacts with bromine to give 3-Phenyl-N,N,N',N''- tetramethyl-1-ethyne-1-carboximidamidium bromide (Tiritiris & Kantlehner, 2012b). According to the structure analysis of the title compound, the C–N bond lengths in the amidinium unit are 1.319 (6) and 1.333 (6) Å, indicating double bond character. The positive charge in the cation is distributed between both dimethylamino groups. The bromine atom Br2 and the 3-dimethylamino group are in cis position due to sterical reasons (Fig. 1). The angle between the planes N1/C5/N2 and C10/C7/N3 is 85.1 (1)°. Other prominent bond parameters in the cation are: C6–Br2 = 1.926 (5) Å and C6–C7 = 1.327 (7) Å, characteristic for a C–Br single and C–C double bond, respectively. Additionally, an bromine-bromine interaction [d(Br···Br) = 3.229 (3) Å] between the anion and cation has been determined, which is shorter than the sum of their van der Waals radii (Desiraju & Parthasarathy, 1989). Week C–H···Br interactions between the hydrogen atoms of –N(CH3)2 and –SiCH3 groups and the bromide ions are present (Fig. 2), ranging from 2.81 to 2.87 Å (Tab. 1). Typical values of Br···Br, C···Br and H···Br interactions in bromohydrocarbon crystals were considered by Desiraju and Parthasarathy having less than 3.72, 3.61 and 3.06 Å, respectively (Desiraju & Parthasarathy, 1989).For the nature of halogen–halogen interactions in crystals, see: Desiraju & Parthasarathy (1989). For the synthesis of alkynyl orthoamides and propiolamidinium salts, see: Weingärtner et al. (2011). For synthesis of vinylogous guanidinium iodides and bromides, see: Kantlehner et al. (2012a). For the
of 3-phenyl-N,N,N',N''-tetramethyl-1-ethyne-1-carboximidamidium bromide, see: Tiritiris & Kantlehner (2012b).Data collection: APEX2 (Bruker, 2008); cell
SAINT (Bruker, 2008); data reduction: SAINT (Bruker, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: SHELXL2014 (Sheldrick, 2015).C15H33BrN3OSi+·Br− | Dx = 1.464 Mg m−3 |
Mr = 459.33 | Mo Kα radiation, λ = 0.71073 Å |
Orthorhombic, Pbca | Cell parameters from 32287 reflections |
a = 13.3524 (5) Å | θ = 1.5–28.3° |
b = 11.3802 (3) Å | µ = 3.95 mm−1 |
c = 27.4261 (14) Å | T = 100 K |
V = 4167.5 (3) Å3 | Block, yellow |
Z = 8 | 0.45 × 0.30 × 0.15 mm |
F(000) = 1888 |
Bruker Kappa APEXII DUO diffractometer | 5164 independent reflections |
Radiation source: fine-focus sealed tube | 3394 reflections with I > 2σ(I) |
Triumph monochromator | Rint = 0.095 |
φ scans, and ω scans | θmax = 28.3°, θmin = 1.5° |
Absorption correction: multi-scan (Blessing, 1995) | h = −17→10 |
Tmin = 0.285, Tmax = 0.530 | k = −15→15 |
32287 measured reflections | l = −36→36 |
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)] = 0.061 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.099 | H-atom parameters constrained |
S = 1.17 | w = 1/[σ2(Fo2) + 19.9082P] where P = (Fo2 + 2Fc2)/3 |
5164 reflections | (Δ/σ)max < 0.001 |
210 parameters | Δρmax = 1.10 e Å−3 |
0 restraints | Δρmin = −1.88 e Å−3 |
C15H33BrN3OSi+·Br− | V = 4167.5 (3) Å3 |
Mr = 459.33 | Z = 8 |
Orthorhombic, Pbca | Mo Kα radiation |
a = 13.3524 (5) Å | µ = 3.95 mm−1 |
b = 11.3802 (3) Å | T = 100 K |
c = 27.4261 (14) Å | 0.45 × 0.30 × 0.15 mm |
Bruker Kappa APEXII DUO diffractometer | 5164 independent reflections |
Absorption correction: multi-scan (Blessing, 1995) | 3394 reflections with I > 2σ(I) |
Tmin = 0.285, Tmax = 0.530 | Rint = 0.095 |
32287 measured reflections |
R[F2 > 2σ(F2)] = 0.061 | 0 restraints |
wR(F2) = 0.099 | H-atom parameters constrained |
S = 1.17 | w = 1/[σ2(Fo2) + 19.9082P] where P = (Fo2 + 2Fc2)/3 |
5164 reflections | Δρmax = 1.10 e Å−3 |
210 parameters | Δρmin = −1.88 e Å−3 |
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. |
x | y | z | Uiso*/Ueq | ||
Br1 | 0.54519 (4) | 0.73694 (4) | 0.13843 (2) | 0.01487 (12) | |
Br2 | 0.45103 (4) | 0.23306 (5) | 0.24383 (2) | 0.01507 (12) | |
N1 | 0.5406 (3) | 0.3518 (3) | 0.13946 (16) | 0.0147 (9) | |
C1 | 0.4511 (4) | 0.4276 (4) | 0.1374 (2) | 0.0213 (12) | |
H1A | 0.3938 | 0.3816 | 0.1258 | 0.032* | |
H1B | 0.4633 | 0.4930 | 0.1149 | 0.032* | |
H1C | 0.4367 | 0.4585 | 0.1700 | 0.032* | |
C2 | 0.6368 (4) | 0.4157 (5) | 0.1374 (2) | 0.0226 (13) | |
H2A | 0.6879 | 0.3714 | 0.1553 | 0.034* | |
H2B | 0.6287 | 0.4935 | 0.1521 | 0.034* | |
H2C | 0.6576 | 0.4244 | 0.1033 | 0.034* | |
N2 | 0.6052 (3) | 0.1612 (4) | 0.14393 (15) | 0.0125 (9) | |
C3 | 0.6869 (4) | 0.1740 (5) | 0.1081 (2) | 0.0183 (12) | |
H3A | 0.6711 | 0.2385 | 0.0857 | 0.027* | |
H3B | 0.6942 | 0.1008 | 0.0896 | 0.027* | |
H3C | 0.7496 | 0.1914 | 0.1252 | 0.027* | |
C4 | 0.6060 (4) | 0.0462 (5) | 0.1683 (2) | 0.0194 (12) | |
H4A | 0.5545 | 0.0448 | 0.1938 | 0.029* | |
H4B | 0.6719 | 0.0328 | 0.1831 | 0.029* | |
H4C | 0.5922 | −0.0157 | 0.1444 | 0.029* | |
C5 | 0.5318 (3) | 0.2392 (4) | 0.15005 (16) | 0.0109 (10) | |
C6 | 0.4400 (4) | 0.1967 (4) | 0.17545 (17) | 0.0113 (10) | |
C7 | 0.3621 (3) | 0.1384 (4) | 0.15758 (18) | 0.0090 (10) | |
N3 | 0.2856 (3) | 0.0847 (4) | 0.18667 (15) | 0.0135 (10) | |
C8 | 0.2094 (4) | 0.1616 (5) | 0.2075 (2) | 0.0202 (13) | |
H8A | 0.2364 | 0.2005 | 0.2365 | 0.030* | |
H8B | 0.1506 | 0.1149 | 0.2166 | 0.030* | |
H8C | 0.1900 | 0.2209 | 0.1834 | 0.030* | |
C9 | 0.3192 (4) | −0.0079 (5) | 0.2199 (2) | 0.0206 (13) | |
H9A | 0.3710 | −0.0551 | 0.2039 | 0.031* | |
H9B | 0.2623 | −0.0583 | 0.2284 | 0.031* | |
H9C | 0.3466 | 0.0277 | 0.2496 | 0.031* | |
C10 | 0.3455 (4) | 0.1153 (4) | 0.10276 (18) | 0.0087 (10) | |
C11 | 0.3601 (4) | −0.0161 (4) | 0.09338 (19) | 0.0145 (11) | |
H11A | 0.3426 | −0.0341 | 0.0595 | 0.022* | |
H11B | 0.3168 | −0.0612 | 0.1154 | 0.022* | |
H11C | 0.4302 | −0.0372 | 0.0993 | 0.022* | |
C12 | 0.2409 (3) | 0.1539 (4) | 0.08853 (18) | 0.0112 (10) | |
H12A | 0.2334 | 0.2383 | 0.0947 | 0.017* | |
H12B | 0.1916 | 0.1103 | 0.1078 | 0.017* | |
H12C | 0.2301 | 0.1381 | 0.0538 | 0.017* | |
O1 | 0.4196 (2) | 0.1804 (3) | 0.07547 (12) | 0.0096 (7) | |
Si1 | 0.41809 (10) | 0.21877 (12) | 0.01674 (5) | 0.0103 (3) | |
C13 | 0.3405 (4) | 0.3517 (5) | 0.0054 (2) | 0.0169 (12) | |
H13A | 0.2698 | 0.3332 | 0.0113 | 0.025* | |
H13B | 0.3491 | 0.3772 | −0.0285 | 0.025* | |
H13C | 0.3616 | 0.4149 | 0.0274 | 0.025* | |
C14 | 0.3757 (4) | 0.0988 (5) | −0.02454 (19) | 0.0170 (12) | |
H14A | 0.4182 | 0.0295 | −0.0198 | 0.025* | |
H14B | 0.3804 | 0.1251 | −0.0585 | 0.025* | |
H14C | 0.3060 | 0.0785 | −0.0170 | 0.025* | |
C15 | 0.5486 (4) | 0.2599 (5) | 0.00131 (18) | 0.0196 (11) | |
H15A | 0.5687 | 0.3283 | 0.0207 | 0.029* | |
H15B | 0.5529 | 0.2791 | −0.0335 | 0.029* | |
H15C | 0.5934 | 0.1939 | 0.0086 | 0.029* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Br1 | 0.0172 (2) | 0.0146 (3) | 0.0128 (3) | −0.0002 (2) | 0.0014 (2) | 0.0024 (2) |
Br2 | 0.0157 (2) | 0.0198 (3) | 0.0097 (2) | 0.0007 (2) | −0.0020 (2) | −0.0043 (2) |
N1 | 0.010 (2) | 0.015 (2) | 0.019 (2) | −0.0006 (18) | −0.003 (2) | −0.0009 (18) |
C1 | 0.017 (3) | 0.014 (3) | 0.033 (3) | 0.006 (2) | −0.003 (3) | −0.002 (2) |
C2 | 0.013 (3) | 0.018 (3) | 0.036 (4) | −0.009 (2) | −0.004 (3) | −0.003 (3) |
N2 | 0.009 (2) | 0.013 (2) | 0.015 (2) | 0.0023 (16) | −0.0033 (18) | −0.0027 (18) |
C3 | 0.011 (3) | 0.024 (3) | 0.020 (3) | 0.002 (2) | 0.002 (2) | −0.009 (3) |
C4 | 0.017 (3) | 0.014 (3) | 0.027 (3) | 0.005 (2) | −0.002 (2) | −0.003 (2) |
C5 | 0.011 (2) | 0.013 (2) | 0.009 (2) | −0.002 (2) | −0.0038 (18) | −0.0037 (19) |
C6 | 0.017 (3) | 0.012 (2) | 0.005 (2) | 0.001 (2) | 0.002 (2) | −0.0028 (19) |
C7 | 0.009 (2) | 0.008 (2) | 0.011 (3) | 0.0018 (18) | 0.000 (2) | −0.0007 (19) |
N3 | 0.011 (2) | 0.017 (2) | 0.013 (2) | −0.0023 (17) | 0.0040 (17) | 0.0027 (18) |
C8 | 0.014 (3) | 0.029 (3) | 0.017 (3) | 0.001 (2) | 0.008 (2) | −0.004 (2) |
C9 | 0.026 (3) | 0.017 (3) | 0.019 (3) | −0.001 (2) | 0.005 (2) | 0.005 (2) |
C10 | 0.011 (2) | 0.004 (2) | 0.011 (3) | −0.0030 (18) | −0.002 (2) | 0.000 (2) |
C11 | 0.018 (3) | 0.013 (3) | 0.013 (3) | −0.001 (2) | −0.001 (2) | −0.004 (2) |
C12 | 0.009 (2) | 0.013 (3) | 0.012 (3) | −0.0002 (19) | 0.000 (2) | 0.001 (2) |
O1 | 0.0090 (16) | 0.0135 (18) | 0.0064 (17) | −0.0018 (13) | 0.0008 (14) | −0.0002 (14) |
Si1 | 0.0086 (6) | 0.0130 (7) | 0.0091 (7) | −0.0004 (5) | −0.0014 (5) | 0.0002 (6) |
C13 | 0.016 (3) | 0.018 (3) | 0.016 (3) | −0.001 (2) | −0.002 (2) | 0.005 (2) |
C14 | 0.020 (3) | 0.022 (3) | 0.010 (3) | −0.001 (2) | 0.001 (2) | 0.000 (2) |
C15 | 0.015 (2) | 0.028 (3) | 0.016 (3) | −0.004 (3) | 0.002 (2) | 0.003 (2) |
Br2—C6 | 1.926 (5) | C8—H8C | 0.9800 |
N1—C5 | 1.319 (6) | C9—H9A | 0.9800 |
N1—C1 | 1.475 (6) | C9—H9B | 0.9800 |
N1—C2 | 1.476 (6) | C9—H9C | 0.9800 |
C1—H1A | 0.9800 | C10—O1 | 1.445 (6) |
C1—H1B | 0.9800 | C10—C12 | 1.515 (7) |
C1—H1C | 0.9800 | C10—C11 | 1.530 (6) |
C2—H2A | 0.9800 | C11—H11A | 0.9800 |
C2—H2B | 0.9800 | C11—H11B | 0.9800 |
C2—H2C | 0.9800 | C11—H11C | 0.9800 |
N2—C5 | 1.333 (6) | C12—H12A | 0.9800 |
N2—C4 | 1.470 (6) | C12—H12B | 0.9800 |
N2—C3 | 1.475 (6) | C12—H12C | 0.9800 |
C3—H3A | 0.9800 | O1—Si1 | 1.669 (3) |
C3—H3B | 0.9800 | Si1—C15 | 1.854 (5) |
C3—H3C | 0.9800 | Si1—C13 | 1.860 (5) |
C4—H4A | 0.9800 | Si1—C14 | 1.862 (5) |
C4—H4B | 0.9800 | C13—H13A | 0.9800 |
C4—H4C | 0.9800 | C13—H13B | 0.9800 |
C5—C6 | 1.491 (7) | C13—H13C | 0.9800 |
C6—C7 | 1.327 (7) | C14—H14A | 0.9800 |
C7—N3 | 1.433 (6) | C14—H14B | 0.9800 |
C7—C10 | 1.542 (7) | C14—H14C | 0.9800 |
N3—C8 | 1.458 (6) | C15—H15A | 0.9800 |
N3—C9 | 1.464 (6) | C15—H15B | 0.9800 |
C8—H8A | 0.9800 | C15—H15C | 0.9800 |
C8—H8B | 0.9800 | ||
C5—N1—C1 | 120.3 (4) | N3—C9—H9B | 109.5 |
C5—N1—C2 | 124.4 (4) | H9A—C9—H9B | 109.5 |
C1—N1—C2 | 114.6 (4) | N3—C9—H9C | 109.5 |
N1—C1—H1A | 109.5 | H9A—C9—H9C | 109.5 |
N1—C1—H1B | 109.5 | H9B—C9—H9C | 109.5 |
H1A—C1—H1B | 109.5 | O1—C10—C12 | 110.4 (4) |
N1—C1—H1C | 109.5 | O1—C10—C11 | 109.1 (4) |
H1A—C1—H1C | 109.5 | C12—C10—C11 | 110.9 (4) |
H1B—C1—H1C | 109.5 | O1—C10—C7 | 108.6 (4) |
N1—C2—H2A | 109.5 | C12—C10—C7 | 109.5 (4) |
N1—C2—H2B | 109.5 | C11—C10—C7 | 108.2 (4) |
H2A—C2—H2B | 109.5 | C10—C11—H11A | 109.5 |
N1—C2—H2C | 109.5 | C10—C11—H11B | 109.5 |
H2A—C2—H2C | 109.5 | H11A—C11—H11B | 109.5 |
H2B—C2—H2C | 109.5 | C10—C11—H11C | 109.5 |
C5—N2—C4 | 122.8 (4) | H11A—C11—H11C | 109.5 |
C5—N2—C3 | 124.1 (4) | H11B—C11—H11C | 109.5 |
C4—N2—C3 | 112.7 (4) | C10—C12—H12A | 109.5 |
N2—C3—H3A | 109.5 | C10—C12—H12B | 109.5 |
N2—C3—H3B | 109.5 | H12A—C12—H12B | 109.5 |
H3A—C3—H3B | 109.5 | C10—C12—H12C | 109.5 |
N2—C3—H3C | 109.5 | H12A—C12—H12C | 109.5 |
H3A—C3—H3C | 109.5 | H12B—C12—H12C | 109.5 |
H3B—C3—H3C | 109.5 | C10—O1—Si1 | 128.7 (3) |
N2—C4—H4A | 109.5 | O1—Si1—C15 | 106.0 (2) |
N2—C4—H4B | 109.5 | O1—Si1—C13 | 112.4 (2) |
H4A—C4—H4B | 109.5 | C15—Si1—C13 | 106.3 (2) |
N2—C4—H4C | 109.5 | O1—Si1—C14 | 113.5 (2) |
H4A—C4—H4C | 109.5 | C15—Si1—C14 | 109.4 (2) |
H4B—C4—H4C | 109.5 | C13—Si1—C14 | 109.0 (2) |
N1—C5—N2 | 123.6 (4) | Si1—C13—H13A | 109.5 |
N1—C5—C6 | 119.4 (4) | Si1—C13—H13B | 109.5 |
N2—C5—C6 | 116.6 (4) | H13A—C13—H13B | 109.5 |
C7—C6—C5 | 129.3 (4) | Si1—C13—H13C | 109.5 |
C7—C6—Br2 | 121.8 (4) | H13A—C13—H13C | 109.5 |
C5—C6—Br2 | 108.8 (3) | H13B—C13—H13C | 109.5 |
C6—C7—N3 | 124.5 (5) | Si1—C14—H14A | 109.5 |
C6—C7—C10 | 123.9 (4) | Si1—C14—H14B | 109.5 |
N3—C7—C10 | 111.6 (4) | H14A—C14—H14B | 109.5 |
C7—N3—C8 | 117.4 (4) | Si1—C14—H14C | 109.5 |
C7—N3—C9 | 115.8 (4) | H14A—C14—H14C | 109.5 |
C8—N3—C9 | 113.7 (4) | H14B—C14—H14C | 109.5 |
N3—C8—H8A | 109.5 | Si1—C15—H15A | 109.5 |
N3—C8—H8B | 109.5 | Si1—C15—H15B | 109.5 |
H8A—C8—H8B | 109.5 | H15A—C15—H15B | 109.5 |
N3—C8—H8C | 109.5 | Si1—C15—H15C | 109.5 |
H8A—C8—H8C | 109.5 | H15A—C15—H15C | 109.5 |
H8B—C8—H8C | 109.5 | H15B—C15—H15C | 109.5 |
N3—C9—H9A | 109.5 | ||
C1—N1—C5—N2 | 167.2 (5) | C6—C7—N3—C8 | 77.4 (6) |
C2—N1—C5—N2 | −23.8 (8) | C10—C7—N3—C8 | −105.1 (5) |
C1—N1—C5—C6 | −20.1 (7) | C6—C7—N3—C9 | −61.4 (6) |
C2—N1—C5—C6 | 148.9 (5) | C10—C7—N3—C9 | 116.1 (5) |
C4—N2—C5—N1 | 161.7 (5) | C6—C7—C10—O1 | −7.7 (6) |
C3—N2—C5—N1 | −25.9 (7) | N3—C7—C10—O1 | 174.8 (4) |
C4—N2—C5—C6 | −11.3 (7) | C6—C7—C10—C12 | −128.4 (5) |
C3—N2—C5—C6 | 161.1 (4) | N3—C7—C10—C12 | 54.1 (5) |
N1—C5—C6—C7 | 104.0 (6) | C6—C7—C10—C11 | 110.6 (5) |
N2—C5—C6—C7 | −82.7 (6) | N3—C7—C10—C11 | −66.9 (5) |
N1—C5—C6—Br2 | −78.9 (5) | C12—C10—O1—Si1 | −40.7 (5) |
N2—C5—C6—Br2 | 94.4 (4) | C11—C10—O1—Si1 | 81.4 (5) |
C5—C6—C7—N3 | 169.1 (5) | C7—C10—O1—Si1 | −160.9 (3) |
Br2—C6—C7—N3 | −7.7 (7) | C10—O1—Si1—C15 | −163.6 (4) |
C5—C6—C7—C10 | −8.1 (8) | C10—O1—Si1—C13 | 80.7 (4) |
Br2—C6—C7—C10 | 175.1 (3) | C10—O1—Si1—C14 | −43.5 (4) |
D—H···A | D—H | H···A | D···A | D—H···A |
C3—H3C···Br1i | 0.98 | 2.81 | 3.742 (3) | 159 |
C14—H14B···Br1ii | 0.98 | 2.87 | 3.790 (3) | 156 |
Symmetry codes: (i) −x+3/2, y−1/2, z; (ii) −x+1, −y+1, −z. |
D—H···A | D—H | H···A | D···A | D—H···A |
C3—H3C···Br1i | 0.98 | 2.81 | 3.742 (3) | 159 |
C14—H14B···Br1ii | 0.98 | 2.87 | 3.790 (3) | 156 |
Symmetry codes: (i) −x+3/2, y−1/2, z; (ii) −x+1, −y+1, −z. |
Acknowledgements
The authors thank Dr W. Frey (Institut für Organische Chemie, Universität Stuttgart) for measuring the diffraction data.
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Orthoamide derivatives of alkynecarboxylic acids are prepared from N,N,N',N',N'',N''- hexaalkylguanidinium chlorides and terminal alkynes. Their conversion into propiolamidinium chlorides by reaction with benzoyl chloride and into propiolamidinium triflates by reaction with triethylsilyl trifluoromethanesulfonate is well known in literature (Weingärtner et al., 2011). Alkyne orthoamides are transformed by elemental iodine or bromine to vinylogous guanidinium iodides or bromides (Kantlehner et al., 2012a). Phenyl substituted alkyne orthoamides like 3,3,3-Tris(dimethylamino)-1-phenyl- prop-1-yne (Weingärtner et al., 2011) behave differently, it reacts with bromine to give 3-Phenyl-N,N,N',N''- tetramethyl-1-ethyne-1-carboximidamidium bromide (Tiritiris & Kantlehner, 2012b). According to the structure analysis of the title compound, the C–N bond lengths in the amidinium unit are 1.319 (6) and 1.333 (6) Å, indicating double bond character. The positive charge in the cation is distributed between both dimethylamino groups. The bromine atom Br2 and the 3-dimethylamino group are in cis position due to sterical reasons (Fig. 1). The angle between the planes N1/C5/N2 and C10/C7/N3 is 85.1 (1)°. Other prominent bond parameters in the cation are: C6–Br2 = 1.926 (5) Å and C6–C7 = 1.327 (7) Å, characteristic for a C–Br single and C–C double bond, respectively. Additionally, an bromine-bromine interaction [d(Br···Br) = 3.229 (3) Å] between the anion and cation has been determined, which is shorter than the sum of their van der Waals radii (Desiraju & Parthasarathy, 1989). Week C–H···Br interactions between the hydrogen atoms of –N(CH3)2 and –SiCH3 groups and the bromide ions are present (Fig. 2), ranging from 2.81 to 2.87 Å (Tab. 1). Typical values of Br···Br, C···Br and H···Br interactions in bromohydrocarbon crystals were considered by Desiraju and Parthasarathy having less than 3.72, 3.61 and 3.06 Å, respectively (Desiraju & Parthasarathy, 1989).