organic compounds
(3,5-Dimethyl-1H-pyrazol-1-yl)trimethylsilane
aInstitut für Anorganische Chemie, Technische Universität Bergakademie Freiberg, Leipziger Str. 29, 09599 Freiberg, Germany
*Correspondence e-mail: uwe.boehme@chemie.tu-freiberg.de
The title compound, C8H16N2Si, crystallizes in the the orthorhombic P212121 with one molecule in the The Si—N bond is 1.782 (2) Å, which is substantially longer than is found in comparable (3,5-dimethylpyrazolyl)silanes. The trimethylsilyl group adopts a with respect to the planar 3,5-dimethylpyrazolyl unit. C—H⋯N hydrogen bonds between neighboring molecules form a strand of molecules along the b-axis direction.
Keywords: crystal structure; in situ crystallization; organosilane.
CCDC reference: 2041610
Structure description
et al., 2000; Kuzu et al., 2008; Armbruster et al. 2009). Such (3,5-dimethylpyrazolyl)silanes form potent multidentate ligands with a `podand topology' (Gade 2002a,b,c).
substituted with 3,5-dimethylpyrazolyl units have been investigated over the last twenty years as an alternative to the long-known pyrazolylborates (PullenThe title compound (3,5-dimethyl-1H-pyrazol-1-yl)trimethylsilane is a key compound in the preparation of different (3,5-dimethylpyrazolyl)silanes by transsilylation (Armbruster et al., 2009; Bitto et al., 2012, 2013, 2016a). The solid-state structure of this compound has never been determined, since it is a liquid at room temperature. In situ cryo-crystallization of low-melting compounds has been practiced for many years (Atoji et al., 1955; Smith & Lipscomb, 1965; Brodalla et al., 1985). Different in situ cryo-crystallization techniques have been described in a review (Boese & Nussbaumer, 1994). State of the art of in situ crystallization is summarized recently in a special issue of Zeitschrift für Kristallographie (Boese, 2014). We have performed several single-crystal structure determinations of pyrophoric liquids by in situ crystallization on the diffractometer (Schmidt et al., 2013; Gerwig et al. 2020). With the experience gained in these processes, we were able to crystallize the title compound on the diffractometer and we report its here.
The title compound crystallizes in the orthorhombic P212121 with one molecule in the (Fig. 1). The Si1—N1 bond is 1.782 (2) Å long. This is substantially longer than comparable bonds in tris(3,5-dimethylpyrazolyl)methylsilane [1.745 (5) Å; Vepachedu et al., 1995] and tetrakis(3,5-dimethylpyrazolyl)silane [from 1.712 (3) to 1.725 (3) Å; Armbruster et al. 2009). The pyrazol ring is planar with an r.m.s. deviation of 0.003 Å from the ring plane. The trimethylsilyl group adopts a with respect to the plane of the 3,5-dimethylpyrazolyl unit. This can be seen in the torsion angles C8—Si1—N1—N2 with −35.1 (2)° and C6—Si1—N1—C2 with 36.3 (2)°. The methyl group C7 is orientated perpendicular to the 3,5-dimethylpyrazolyl unit. There is a hydrogen bond between the hydrogen atom at C6 and the nitrogen atom N2 from a neighboring molecule (see Table 1). These hydrogen bonds form a strand of molecules generated by a twofold screw axis (21) along the crystallographic b axis (see Fig. 2).
Synthesis and crystallization
The title compound was prepared from 3,5-dimethylpyrazol (19.23 g, 0.2 mol) and chlorotrimethylsilane (22.81 g, 0.21 mol). The reaction was performed in 300 ml THF as solvent and in the presence of triethylamine (21.25 g, 0.21 mol). Triethylamine hydrochloride is formed during the reaction as a voluminous white precipitate. This precipitate is filtered off. After that the solvent is distilled off in vacuo. The title compound is isolated by vacuum distillation at 107°C and 1.3 kPa. It is a colourless liquid (26.97 g, 0.16 mol, 80% yield) (Bitto 2016b).
The compound was filled as liquid with 10% n-pentane in a glass capillary with 0.5 mm diameter. A single crystal was grown on the diffractometer at 255 K. The data collection was perfomed at a slightly lower temperature in order to have a stable crystal on the diffractometer.
Refinement
Crystal data, data collection and structure .
details are summarized in Table 2Structural data
CCDC reference: 2041610
https://doi.org/10.1107/S2414314620014443/sj4215sup1.cif
contains datablock I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314620014443/sj4215Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S2414314620014443/sj4215Isup3.cml
Data collection: X-AREA (Stoe, 2009); cell
X-AREA (Stoe, 2009); data reduction: X-RED (Stoe, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014/7 (Sheldrick 2015); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: SHELXL2014/7 (Sheldrick 2015).C8H16N2Si | Dx = 1.087 Mg m−3 |
Mr = 168.32 | Melting point: 260 K |
Orthorhombic, P212121 | Mo Kα radiation, λ = 0.71073 Å |
a = 6.1056 (3) Å | Cell parameters from 32385 reflections |
b = 10.8114 (7) Å | θ = 2.3–29.7° |
c = 15.5867 (9) Å | µ = 0.18 mm−1 |
V = 1028.88 (10) Å3 | T = 250 K |
Z = 4 | Capillary, colourless |
F(000) = 368 | 0.50 × 0.40 × 0.40 mm |
STOE IPDS 2 diffractometer | 2346 independent reflections |
Radiation source: sealed X-ray tube, 12 x 0.4 mm long-fine focus | 2258 reflections with I > 2σ(I) |
Plane graphite monochromator | Rint = 0.048 |
Detector resolution: 6.67 pixels mm-1 | θmax = 27.5°, θmin = 2.3° |
rotation method scans | h = −7→6 |
Absorption correction: integration (X-RED; Stoe, 2009) | k = −14→14 |
Tmin = 0.708, Tmax = 0.932 | l = −19→20 |
8249 measured reflections |
Refinement on F2 | H-atom parameters constrained |
Least-squares matrix: full | w = 1/[σ2(Fo2) + (0.0384P)2 + 0.1226P] where P = (Fo2 + 2Fc2)/3 |
R[F2 > 2σ(F2)] = 0.030 | (Δ/σ)max < 0.001 |
wR(F2) = 0.080 | Δρmax = 0.12 e Å−3 |
S = 1.09 | Δρmin = −0.15 e Å−3 |
2346 reflections | Extinction correction: SHELXL-2014/7 (Sheldrick 2015, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
106 parameters | Extinction coefficient: 0.038 (8) |
0 restraints | Absolute structure: Flack x determined using 896 quotients [(I+)-(I-)]/[(I+)+(I-)] (Parsons et al., 2013) |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: 0.07 (9) |
Hydrogen site location: inferred from neighbouring sites |
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. |
x | y | z | Uiso*/Ueq | ||
Si1 | 1.09038 (8) | 0.83129 (5) | 0.28856 (3) | 0.03560 (16) | |
N1 | 0.9829 (3) | 0.91025 (15) | 0.37963 (9) | 0.0371 (3) | |
N2 | 0.8044 (3) | 0.98582 (17) | 0.36345 (11) | 0.0449 (4) | |
C1 | 1.2467 (4) | 0.8620 (3) | 0.49915 (16) | 0.0604 (6) | |
H1A | 1.2704 | 0.8905 | 0.5574 | 0.091* | |
H1B | 1.3765 | 0.8782 | 0.4651 | 0.091* | |
H1C | 1.2171 | 0.7738 | 0.4996 | 0.091* | |
C2 | 1.0558 (3) | 0.92883 (18) | 0.46120 (11) | 0.0390 (4) | |
C3 | 0.9227 (4) | 1.01575 (19) | 0.49782 (12) | 0.0443 (4) | |
H3 | 0.9317 | 1.0469 | 0.5540 | 0.053* | |
C4 | 0.7709 (4) | 1.04880 (18) | 0.43507 (13) | 0.0422 (4) | |
C5 | 0.5894 (5) | 1.1411 (2) | 0.44085 (18) | 0.0670 (7) | |
H5A | 0.6504 | 1.2230 | 0.4493 | 0.100* | |
H5B | 0.4951 | 1.1204 | 0.4888 | 0.100* | |
H5C | 0.5049 | 1.1397 | 0.3882 | 0.100* | |
C6 | 1.2361 (4) | 0.6905 (2) | 0.32373 (15) | 0.0544 (6) | |
H6A | 1.3721 | 0.7136 | 0.3516 | 0.082* | |
H6B | 1.2677 | 0.6390 | 0.2743 | 0.082* | |
H6C | 1.1450 | 0.6449 | 0.3637 | 0.082* | |
C7 | 1.2781 (5) | 0.9387 (2) | 0.23290 (16) | 0.0593 (6) | |
H7A | 1.1987 | 1.0127 | 0.2163 | 0.089* | |
H7B | 1.3368 | 0.8989 | 0.1821 | 0.089* | |
H7C | 1.3972 | 0.9610 | 0.2711 | 0.089* | |
C8 | 0.8569 (4) | 0.7920 (3) | 0.21896 (16) | 0.0589 (6) | |
H8A | 0.7518 | 0.7433 | 0.2511 | 0.088* | |
H8B | 0.9084 | 0.7447 | 0.1701 | 0.088* | |
H8C | 0.7875 | 0.8675 | 0.1990 | 0.088* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Si1 | 0.0353 (2) | 0.0376 (3) | 0.0339 (2) | 0.0038 (2) | 0.0023 (2) | 0.00083 (19) |
N1 | 0.0377 (8) | 0.0398 (8) | 0.0338 (7) | 0.0062 (7) | 0.0010 (6) | 0.0016 (6) |
N2 | 0.0477 (10) | 0.0474 (9) | 0.0395 (8) | 0.0141 (8) | −0.0014 (7) | 0.0014 (7) |
C1 | 0.0550 (13) | 0.0720 (16) | 0.0541 (13) | 0.0143 (12) | −0.0176 (10) | −0.0073 (11) |
C2 | 0.0396 (10) | 0.0414 (9) | 0.0361 (8) | −0.0028 (8) | −0.0016 (8) | 0.0000 (7) |
C3 | 0.0515 (11) | 0.0435 (10) | 0.0380 (8) | −0.0020 (10) | 0.0016 (9) | −0.0049 (8) |
C4 | 0.0452 (11) | 0.0375 (10) | 0.0438 (10) | 0.0042 (8) | 0.0072 (8) | −0.0007 (7) |
C5 | 0.0701 (16) | 0.0590 (14) | 0.0718 (16) | 0.0264 (14) | 0.0064 (14) | −0.0074 (11) |
C6 | 0.0651 (14) | 0.0476 (12) | 0.0506 (12) | 0.0175 (11) | 0.0024 (11) | 0.0007 (9) |
C7 | 0.0599 (14) | 0.0557 (13) | 0.0623 (14) | −0.0014 (12) | 0.0219 (12) | 0.0060 (10) |
C8 | 0.0500 (12) | 0.0713 (15) | 0.0554 (13) | 0.0044 (11) | −0.0075 (10) | −0.0176 (12) |
Si1—N1 | 1.7816 (15) | C4—C5 | 1.494 (3) |
Si1—C8 | 1.841 (2) | C5—H5A | 0.9700 |
Si1—C6 | 1.847 (2) | C5—H5B | 0.9700 |
Si1—C7 | 1.848 (2) | C5—H5C | 0.9700 |
N1—C2 | 1.362 (2) | C6—H6A | 0.9700 |
N1—N2 | 1.385 (2) | C6—H6B | 0.9700 |
N2—C4 | 1.324 (3) | C6—H6C | 0.9700 |
C1—C2 | 1.494 (3) | C7—H7A | 0.9700 |
C1—H1A | 0.9700 | C7—H7B | 0.9700 |
C1—H1B | 0.9700 | C7—H7C | 0.9700 |
C1—H1C | 0.9700 | C8—H8A | 0.9700 |
C2—C3 | 1.367 (3) | C8—H8B | 0.9700 |
C3—C4 | 1.394 (3) | C8—H8C | 0.9700 |
C3—H3 | 0.9400 | ||
N1—Si1—C8 | 107.15 (10) | C4—C5—H5A | 109.5 |
N1—Si1—C6 | 109.63 (9) | C4—C5—H5B | 109.5 |
C8—Si1—C6 | 110.98 (13) | H5A—C5—H5B | 109.5 |
N1—Si1—C7 | 107.53 (10) | C4—C5—H5C | 109.5 |
C8—Si1—C7 | 110.39 (13) | H5A—C5—H5C | 109.5 |
C6—Si1—C7 | 111.02 (13) | H5B—C5—H5C | 109.5 |
C2—N1—N2 | 109.87 (15) | Si1—C6—H6A | 109.5 |
C2—N1—Si1 | 133.98 (14) | Si1—C6—H6B | 109.5 |
N2—N1—Si1 | 115.29 (11) | H6A—C6—H6B | 109.5 |
C4—N2—N1 | 105.74 (16) | Si1—C6—H6C | 109.5 |
C2—C1—H1A | 109.5 | H6A—C6—H6C | 109.5 |
C2—C1—H1B | 109.5 | H6B—C6—H6C | 109.5 |
H1A—C1—H1B | 109.5 | Si1—C7—H7A | 109.5 |
C2—C1—H1C | 109.5 | Si1—C7—H7B | 109.5 |
H1A—C1—H1C | 109.5 | H7A—C7—H7B | 109.5 |
H1B—C1—H1C | 109.5 | Si1—C7—H7C | 109.5 |
N1—C2—C3 | 107.29 (18) | H7A—C7—H7C | 109.5 |
N1—C2—C1 | 123.58 (18) | H7B—C7—H7C | 109.5 |
C3—C2—C1 | 129.12 (19) | Si1—C8—H8A | 109.5 |
C2—C3—C4 | 106.16 (17) | Si1—C8—H8B | 109.5 |
C2—C3—H3 | 126.9 | H8A—C8—H8B | 109.5 |
C4—C3—H3 | 126.9 | Si1—C8—H8C | 109.5 |
N2—C4—C3 | 110.94 (18) | H8A—C8—H8C | 109.5 |
N2—C4—C5 | 120.6 (2) | H8B—C8—H8C | 109.5 |
C3—C4—C5 | 128.5 (2) | ||
C8—Si1—N1—C2 | 156.8 (2) | Si1—N1—C2—C3 | 169.00 (16) |
C6—Si1—N1—C2 | 36.3 (2) | N2—N1—C2—C1 | −179.88 (19) |
C7—Si1—N1—C2 | −84.5 (2) | Si1—N1—C2—C1 | −11.4 (3) |
C8—Si1—N1—N2 | −35.13 (18) | N1—C2—C3—C4 | −0.7 (2) |
C6—Si1—N1—N2 | −155.65 (15) | C1—C2—C3—C4 | 179.8 (2) |
C7—Si1—N1—N2 | 83.55 (17) | N1—N2—C4—C3 | −0.3 (2) |
C2—N1—N2—C4 | −0.1 (2) | N1—N2—C4—C5 | 179.69 (19) |
Si1—N1—N2—C4 | −171.00 (14) | C2—C3—C4—N2 | 0.6 (3) |
N2—N1—C2—C3 | 0.5 (2) | C2—C3—C4—C5 | −179.4 (2) |
D—H···A | D—H | H···A | D···A | D—H···A |
C6—H6B···N2i | 0.97 | 2.75 | 3.670 (3) | 159 |
Symmetry code: (i) −x+2, y−1/2, −z+1/2. |
Funding information
Funding for this research was provided by: Open Access Funding by the Publication Fund of the TU Bergakademie Freiberg.
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