Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S010827010000278X/ln1098sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S010827010000278X/ln1098Isup2.hkl | |
Structure factor file (CIF format) https://doi.org/10.1107/S010827010000278X/ln1098IIsup3.hkl | |
Structure factor file (CIF format) https://doi.org/10.1107/S010827010000278X/ln1098IIIsup4.hkl | |
Structure factor file (CIF format) https://doi.org/10.1107/S010827010000278X/ln1098IVsup5.hkl | |
Structure factor file (CIF format) https://doi.org/10.1107/S010827010000278X/ln1098Vsup6.hkl | |
Portable Document Format (PDF) file https://doi.org/10.1107/S010827010000278X/ln1098sup7.pdf |
CCDC references: 145555; 145556; 145557; 145558; 145559
To the respective silicon halide (5 mmol) in chloroform (25 ml) 4-picoline was added and the reaction was monitored by measuring the temperature. After approximately 3 h, the precipitated solid was isolated, washed and dried. Crystals of (V) were obtained by heating the powder in an evacuated glas ampul for 2 h to 500 K, then for 5 h to 445 K and cooling down the sample to room temperature within 4 h. (I) to (IV) were dissolved in hot chloroform and crystals appeared within 10 to 15 h at room temperature. Elemental analyses: (II), C12H14BrCl3Si: calculated: C 36.0, H 3.5, Br 19.9, Cl 26.5, N 7.0%; found: C 36.3, H 3.7, Br 18.9, Cl 25.7, N 7.0%; (III), C12H14Br2Cl2Si: calculated: C 32.4, H 3.2, Br 35.9, Cl 15.9, N 6.3%; found: C 33.0, H 3.3, Br 36.3, Cl 16.1, N 6.3%; (IV), C12H14Br3ClSi: calculated: C 30.9, H 3.4, Br 47.5, Cl 7.0, N 5.6%; found: C 30.1, H 3.4, Br 48.8, Cl 6.1, N 5.8%.
All H atoms were initially located by difference Fourier synthesis. Subsequently their positions were idealized and constrained to ride on their parent atoms with C—H(aromatic) = 0.95 and C—H(methyl = 0.98 Å, and fixed individual displacement parameters [U(H) = 1.2Ueq(Caromatic) or U(H) = 1.5Ueq(Cmethyl)]. The hydrogen atoms of the methyl groups are disordered. Two orientations differing by a 60° rotation about the Caromatic—Cmethyl bond could be identified.
Due to the crystallographic symmetry of these structures, the halogen atoms of (II), (III) and (IV) are disordered. The resolution of the data did not allow for distinguishing two distinct positions for Cl and Br. Only one peak was found in the respective difference maps. Thus, Br and Cl were refined with a site occupation factor fixed to the appropriate value (according to the elemental analyses) and a restrained bond length of 2.383 (1) Å and 2.203 (1) Å for Si—Br and Si—Cl, respectively. A search in the Cambridge Crystallographic Database (Version 5.18, October 1999; Allen & Kennard, 1993) for the fragment SiN2X4 (X = any group 7 A element) yielded only one comparable structure: tetrachlorodipyridylsilane (Bechstein et al., 1990) which was measured at room temperature. Thus, we employed the values found in (I) and (V) as restraints for the Si—Cl and Si—Br lengths. For (II) the anisotropic displacement parameters of Cl and Br were restrained to have the same Uij components with an effective standard deviation of 0.001.
For all compounds, data collection: SMART (Siemens, 1995); cell refinement: SMART; data reduction: SAINT (Siemens, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP (in SHELXTL-Plus, 1991).
C12H14Cl4N2Si | F(000) = 364 |
Mr = 356.14 | Dx = 1.524 Mg m−3 |
Orthorhombic, Pmna | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ac 2 | Cell parameters from 8192 reflections |
a = 7.1766 (1) Å | θ = 1–25° |
b = 7.8911 (1) Å | µ = 0.83 mm−1 |
c = 13.7036 (1) Å | T = 173 K |
V = 776.05 (2) Å3 | Block, colourless |
Z = 2 | 0.60 × 0.40 × 0.40 mm |
Siemens CCD three-circle diffractometer | 853 independent reflections |
Radiation source: fine-focus sealed tube | 815 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.019 |
ω scans | θmax = 26.3°, θmin = 2.6° |
Absorption correction: empirical (SADABS; Sheldrick, 1996) | h = −8→8 |
Tmin = 0.637, Tmax = 0.733 | k = −9→9 |
10172 measured reflections | l = −16→16 |
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)] = 0.020 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.058 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.15 | w = 1/[σ2(Fo2) + (0.0314P)2 + 0.2249P] where P = (Fo2 + 2Fc2)/3 |
853 reflections | (Δ/σ)max < 0.001 |
56 parameters | Δρmax = 0.26 e Å−3 |
0 restraints | Δρmin = −0.18 e Å−3 |
C12H14Cl4N2Si | V = 776.05 (2) Å3 |
Mr = 356.14 | Z = 2 |
Orthorhombic, Pmna | Mo Kα radiation |
a = 7.1766 (1) Å | µ = 0.83 mm−1 |
b = 7.8911 (1) Å | T = 173 K |
c = 13.7036 (1) Å | 0.60 × 0.40 × 0.40 mm |
Siemens CCD three-circle diffractometer | 853 independent reflections |
Absorption correction: empirical (SADABS; Sheldrick, 1996) | 815 reflections with I > 2σ(I) |
Tmin = 0.637, Tmax = 0.733 | Rint = 0.019 |
10172 measured reflections |
R[F2 > 2σ(F2)] = 0.020 | 0 restraints |
wR(F2) = 0.058 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.15 | Δρmax = 0.26 e Å−3 |
853 reflections | Δρmin = −0.18 e Å−3 |
56 parameters |
Experimental. The data collection nominally covered a sphere of reciprocal space, by a combination of seven, for (I), (III), (IV) and (V), and eight, for (II), sets of exposures; each set had a different ϕ angle for the crystal and each exposure covered 0.3° in ω. The crystal-to-detector distance was 4 cm for (II) and (IV), 5 cm for (III) and 6 cm for (I) and (V). Coverage of the unique set for all structures is 100% complete to at least 25.0° in θ. Crystal decay was monitored by repeating the initial frames at the end of data collection and analyzing the duplicate reflections. |
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. |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
Si1 | 0.0000 | 0.5000 | 0.5000 | 0.01946 (16) | |
Cl1 | 0.21877 (5) | 0.33821 (4) | 0.43645 (2) | 0.03014 (14) | |
N1 | 0.0000 | 0.64104 (17) | 0.38019 (10) | 0.0208 (3) | |
C2 | 0.0000 | 0.8127 (2) | 0.38592 (13) | 0.0245 (4) | |
H2 | 0.0000 | 0.8642 | 0.4486 | 0.029* | |
C3 | 0.0000 | 0.9155 (2) | 0.30441 (13) | 0.0263 (4) | |
H3 | 0.0000 | 1.0352 | 0.3118 | 0.032* | |
C4 | 0.0000 | 0.8439 (2) | 0.21074 (13) | 0.0237 (4) | |
C41 | 0.0000 | 0.9519 (2) | 0.11990 (13) | 0.0313 (4) | |
H41A | 0.0000 | 0.8795 | 0.0618 | 0.047* | 0.50 |
H41B | 0.1106 | 1.0248 | 0.1195 | 0.047* | 0.50 |
H41C | 0.0000 | 1.0722 | 0.1377 | 0.047* | 0.50 |
H41D | 0.1083 | 0.9268 | 0.0814 | 0.047* | 0.50 |
C5 | 0.0000 | 0.6671 (2) | 0.20496 (13) | 0.0251 (4) | |
H5 | 0.0000 | 0.6129 | 0.1430 | 0.030* | |
C6 | 0.0000 | 0.5706 (2) | 0.28969 (12) | 0.0249 (4) | |
H6 | 0.0000 | 0.4506 | 0.2842 | 0.030* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Si1 | 0.0231 (3) | 0.0158 (3) | 0.0195 (3) | 0.000 | 0.000 | 0.0019 (2) |
Cl1 | 0.0340 (2) | 0.0270 (2) | 0.0295 (2) | 0.01011 (12) | 0.00782 (12) | 0.00549 (11) |
N1 | 0.0242 (7) | 0.0178 (6) | 0.0205 (7) | 0.000 | 0.000 | 0.0023 (5) |
C2 | 0.0307 (9) | 0.0193 (8) | 0.0234 (8) | 0.000 | 0.000 | −0.0003 (6) |
C3 | 0.0312 (9) | 0.0185 (8) | 0.0292 (9) | 0.000 | 0.000 | 0.0040 (7) |
C4 | 0.0196 (8) | 0.0263 (9) | 0.0253 (9) | 0.000 | 0.000 | 0.0076 (7) |
C41 | 0.0337 (10) | 0.0325 (9) | 0.0275 (9) | 0.000 | 0.000 | 0.0114 (8) |
C5 | 0.0282 (9) | 0.0264 (9) | 0.0206 (8) | 0.000 | 0.000 | 0.0006 (6) |
C6 | 0.0309 (9) | 0.0196 (8) | 0.0242 (8) | 0.000 | 0.000 | 0.0006 (7) |
Si1—N1i | 1.9835 (13) | C3—H3 | 0.9500 |
Si1—N1 | 1.9835 (13) | C4—C5 | 1.397 (2) |
Si1—Cl1ii | 2.2030 (3) | C4—C41 | 1.509 (2) |
Si1—Cl1iii | 2.2030 (3) | C41—H41A | 0.9800 |
Si1—Cl1i | 2.2030 (3) | C41—H41B | 0.9800 |
Si1—Cl1 | 2.2030 (3) | C41—H41C | 0.9800 |
N1—C2 | 1.357 (2) | C41—H41D | 0.9600 |
N1—C6 | 1.359 (2) | C5—C6 | 1.389 (2) |
C2—C3 | 1.381 (2) | C5—H5 | 0.9500 |
C2—H2 | 0.9500 | C6—H6 | 0.9500 |
C3—C4 | 1.403 (3) | ||
N1i—Si1—N1 | 180.000 (1) | C2—C3—H3 | 119.9 |
N1i—Si1—Cl1ii | 90.12 (3) | C4—C3—H3 | 119.9 |
N1—Si1—Cl1ii | 89.88 (3) | C5—C4—C3 | 117.03 (16) |
N1i—Si1—Cl1iii | 89.88 (3) | C5—C4—C41 | 121.17 (17) |
N1—Si1—Cl1iii | 90.12 (3) | C3—C4—C41 | 121.80 (15) |
Cl1ii—Si1—Cl1iii | 180.0 | C4—C41—H41A | 109.9 |
N1i—Si1—Cl1i | 89.88 (3) | C4—C41—H41B | 109.7 |
N1—Si1—Cl1i | 90.12 (3) | H41A—C41—H41B | 109.7 |
Cl1ii—Si1—Cl1i | 89.098 (18) | C4—C41—H41C | 110.0 |
Cl1iii—Si1—Cl1i | 90.902 (18) | H41A—C41—H41C | 140.1 |
N1i—Si1—Cl1 | 90.12 (3) | H41B—C41—H41C | 55.5 |
N1—Si1—Cl1 | 89.88 (3) | C4—C41—H41D | 109.7 |
Cl1ii—Si1—Cl1 | 90.902 (18) | H41A—C41—H41D | 55.5 |
Cl1iii—Si1—Cl1 | 89.098 (18) | H41B—C41—H41D | 57.4 |
Cl1i—Si1—Cl1 | 179.999 (12) | H41C—C41—H41D | 109.7 |
C2—N1—C6 | 117.47 (14) | C6—C5—C4 | 120.01 (17) |
C2—N1—Si1 | 120.81 (12) | C6—C5—H5 | 120.0 |
C6—N1—Si1 | 121.72 (11) | C4—C5—H5 | 120.0 |
N1—C2—C3 | 122.68 (16) | N1—C6—C5 | 122.59 (15) |
N1—C2—H2 | 118.7 | N1—C6—H6 | 118.7 |
C3—C2—H2 | 118.7 | C5—C6—H6 | 118.7 |
C2—C3—C4 | 120.22 (15) | ||
N1i—Si1—N1—C2 | 0.0 (2) | C6—N1—C2—C3 | 0.0 |
Cl1ii—Si1—N1—C2 | 134.549 (9) | Si1—N1—C2—C3 | 180.0 |
Cl1iii—Si1—N1—C2 | −45.451 (9) | N1—C2—C3—C4 | 0.0 |
Cl1i—Si1—N1—C2 | 45.451 (9) | C2—C3—C4—C5 | 0.0 |
Cl1—Si1—N1—C2 | −134.548 (9) | C2—C3—C4—C41 | 180.0 |
N1i—Si1—N1—C6 | 180.0 (2) | C3—C4—C5—C6 | 0.0 |
Cl1ii—Si1—N1—C6 | −45.451 (9) | C41—C4—C5—C6 | 180.0 |
Cl1iii—Si1—N1—C6 | 134.549 (9) | C2—N1—C6—C5 | 0.0 |
Cl1i—Si1—N1—C6 | −134.549 (9) | Si1—N1—C6—C5 | 180.0 |
Cl1—Si1—N1—C6 | 45.452 (9) | C4—C5—C6—N1 | 0.0 |
Symmetry codes: (i) −x, −y+1, −z+1; (ii) −x, y, z; (iii) x, −y+1, −z+1. |
C12H14BrCl3N2Si | F(000) = 400 |
Mr = 400.60 | Dx = 1.717 Mg m−3 |
Orthorhombic, Pmna | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ac 2 | Cell parameters from 8192 reflections |
a = 7.177 (1) Å | θ = 1–25° |
b = 7.962 (1) Å | µ = 3.24 mm−1 |
c = 13.557 (1) Å | T = 173 K |
V = 774.69 (16) Å3 | Plate, colourless |
Z = 2 | 0.40 × 0.30 × 0.10 mm |
Siemens CCD three-circle diffractometer | 1278 independent reflections |
Radiation source: fine-focus sealed tube | 1051 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.057 |
ω scans | θmax = 30.5°, θmin = 2.6° |
Absorption correction: empirical (SADABS; Sheldrick, 1996) | h = −10→10 |
Tmin = 0.358, Tmax = 0.738 | k = −11→11 |
24114 measured reflections | l = −19→19 |
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)] = 0.040 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.111 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.12 | w = 1/[σ2(Fo2) + (0.0576P)2 + 0.7835P] where P = (Fo2 + 2Fc2)/3 |
1278 reflections | (Δ/σ)max < 0.001 |
65 parameters | Δρmax = 0.65 e Å−3 |
8 restraints | Δρmin = −1.14 e Å−3 |
C12H14BrCl3N2Si | V = 774.69 (16) Å3 |
Mr = 400.60 | Z = 2 |
Orthorhombic, Pmna | Mo Kα radiation |
a = 7.177 (1) Å | µ = 3.24 mm−1 |
b = 7.962 (1) Å | T = 173 K |
c = 13.557 (1) Å | 0.40 × 0.30 × 0.10 mm |
Siemens CCD three-circle diffractometer | 1278 independent reflections |
Absorption correction: empirical (SADABS; Sheldrick, 1996) | 1051 reflections with I > 2σ(I) |
Tmin = 0.358, Tmax = 0.738 | Rint = 0.057 |
24114 measured reflections |
R[F2 > 2σ(F2)] = 0.040 | 8 restraints |
wR(F2) = 0.111 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.12 | Δρmax = 0.65 e Å−3 |
1278 reflections | Δρmin = −1.14 e Å−3 |
65 parameters |
Experimental. ; |
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. |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
Br1 | 0.7267 (10) | 0.1751 (10) | 0.4254 (6) | 0.0279 (7) | 0.25 |
Cl1 | 0.7230 (7) | 0.1548 (8) | 0.4385 (5) | 0.0236 (5) | 0.75 |
Si1 | 0.5000 | 0.0000 | 0.5000 | 0.0172 (3) | |
N1 | 0.5000 | 0.1414 (4) | 0.6195 (2) | 0.0185 (6) | |
C2 | 0.5000 | 0.3104 (5) | 0.6123 (3) | 0.0219 (7) | |
H2 | 0.5000 | 0.3600 | 0.5486 | 0.026* | |
C3 | 0.5000 | 0.4138 (5) | 0.6940 (3) | 0.0234 (8) | |
H3 | 0.5000 | 0.5323 | 0.6857 | 0.028* | |
C4 | 0.5000 | 0.3448 (5) | 0.7886 (3) | 0.0202 (7) | |
C41 | 0.5000 | 0.4528 (6) | 0.8791 (3) | 0.0291 (9) | |
H41A | 0.5000 | 0.5667 | 0.8613 | 0.044* | 0.50 |
H41B | 0.3975 | 0.4223 | 0.9200 | 0.044* | 0.50 |
H41C | 0.5000 | 0.3880 | 0.9384 | 0.044* | 0.50 |
H41D | 0.3929 | 0.5222 | 0.8774 | 0.044* | 0.50 |
C5 | 0.5000 | 0.1699 (5) | 0.7956 (3) | 0.0228 (8) | |
H5 | 0.5000 | 0.1174 | 0.8585 | 0.027* | |
C6 | 0.5000 | 0.0735 (5) | 0.7111 (3) | 0.0220 (7) | |
H6 | 0.5000 | −0.0454 | 0.7173 | 0.026* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Br1 | 0.0369 (7) | 0.0240 (16) | 0.0227 (19) | −0.0067 (7) | 0.0049 (8) | 0.0017 (11) |
Cl1 | 0.0324 (5) | 0.0195 (12) | 0.0190 (14) | −0.0103 (6) | 0.0087 (6) | 0.0009 (8) |
Si1 | 0.0221 (7) | 0.0139 (6) | 0.0156 (6) | 0.000 | 0.000 | −0.0020 (5) |
N1 | 0.0233 (14) | 0.0164 (13) | 0.0157 (14) | 0.000 | 0.000 | −0.0025 (11) |
C2 | 0.0284 (19) | 0.0187 (16) | 0.0187 (17) | 0.000 | 0.000 | 0.0001 (13) |
C3 | 0.0308 (19) | 0.0177 (16) | 0.0215 (18) | 0.000 | 0.000 | −0.0038 (14) |
C4 | 0.0192 (16) | 0.0222 (17) | 0.0191 (17) | 0.000 | 0.000 | −0.0067 (14) |
C41 | 0.032 (2) | 0.033 (2) | 0.0217 (19) | 0.000 | 0.000 | −0.0109 (16) |
C5 | 0.0268 (18) | 0.0249 (18) | 0.0168 (17) | 0.000 | 0.000 | −0.0014 (14) |
C6 | 0.0292 (18) | 0.0181 (16) | 0.0187 (17) | 0.000 | 0.000 | 0.0003 (13) |
Br1—Si1 | 2.3695 (11) | C2—H2 | 0.9500 |
Cl1—Si1 | 2.1856 (10) | C3—C4 | 1.396 (5) |
Si1—N1 | 1.973 (3) | C3—H3 | 0.9500 |
Si1—N1i | 1.973 (3) | C4—C5 | 1.396 (5) |
Si1—Cl1i | 2.1855 (10) | C4—C41 | 1.498 (5) |
Si1—Cl1ii | 2.1855 (10) | C41—H41A | 0.9381 |
Si1—Cl1iii | 2.1856 (10) | C41—H41B | 0.9532 |
Si1—Br1i | 2.3695 (11) | C41—H41C | 0.9553 |
Si1—Br1ii | 2.3695 (11) | C41—H41D | 0.9471 |
Si1—Br1iii | 2.3695 (11) | C5—C6 | 1.380 (5) |
N1—C2 | 1.349 (5) | C5—H5 | 0.9500 |
N1—C6 | 1.354 (5) | C6—H6 | 0.9500 |
C2—C3 | 1.380 (5) | ||
N1—Si1—N1i | 180.0 | N1i—Si1—Br1iii | 89.1 (2) |
N1—Si1—Cl1i | 90.5 (2) | Cl1i—Si1—Br1iii | 89.52 (6) |
N1i—Si1—Cl1i | 89.5 (2) | Cl1ii—Si1—Br1iii | 176.1 (4) |
N1—Si1—Cl1ii | 90.5 (2) | Cl1—Si1—Br1iii | 90.48 (6) |
N1i—Si1—Cl1ii | 89.5 (2) | Cl1iii—Si1—Br1iii | 3.9 (4) |
Cl1i—Si1—Cl1ii | 94.2 (4) | Br1i—Si1—Br1iii | 93.2 (5) |
N1—Si1—Cl1 | 89.5 (2) | Br1ii—Si1—Br1iii | 179.999 (1) |
N1i—Si1—Cl1 | 90.5 (2) | Br1—Si1—Br1iii | 86.8 (5) |
Cl1i—Si1—Cl1 | 180.0 | C2—N1—C6 | 117.7 (3) |
Cl1ii—Si1—Cl1 | 85.8 (4) | C2—N1—Si1 | 120.7 (3) |
N1—Si1—Cl1iii | 89.5 (2) | C6—N1—Si1 | 121.6 (2) |
N1i—Si1—Cl1iii | 90.5 (2) | N1—C2—C3 | 122.5 (4) |
Cl1i—Si1—Cl1iii | 85.8 (4) | N1—C2—H2 | 118.7 |
Cl1ii—Si1—Cl1iii | 180.0 (3) | C3—C2—H2 | 118.7 |
Cl1—Si1—Cl1iii | 94.2 (4) | C2—C3—C4 | 120.2 (3) |
N1—Si1—Br1i | 89.1 (2) | C2—C3—H3 | 119.9 |
N1i—Si1—Br1i | 90.9 (2) | C4—C3—H3 | 119.9 |
Cl1i—Si1—Br1i | 3.9 (4) | C3—C4—C5 | 117.1 (3) |
Cl1ii—Si1—Br1i | 90.48 (6) | C3—C4—C41 | 121.8 (3) |
Cl1—Si1—Br1i | 176.1 (4) | C5—C4—C41 | 121.1 (4) |
Cl1iii—Si1—Br1i | 89.52 (6) | C4—C41—H41A | 110.2 |
N1—Si1—Br1ii | 89.1 (2) | C4—C41—H41B | 109.3 |
N1i—Si1—Br1ii | 90.9 (2) | H41A—C41—H41B | 113.3 |
Cl1i—Si1—Br1ii | 90.48 (6) | C4—C41—H41C | 112.3 |
Cl1ii—Si1—Br1ii | 3.9 (4) | H41A—C41—H41C | 137.6 |
Cl1—Si1—Br1ii | 89.52 (6) | H41B—C41—H41C | 51.1 |
Cl1iii—Si1—Br1ii | 176.1 (4) | C4—C41—H41D | 108.4 |
Br1i—Si1—Br1ii | 86.8 (5) | H41A—C41—H41D | 55.2 |
N1—Si1—Br1 | 90.9 (2) | H41B—C41—H41D | 62.3 |
N1i—Si1—Br1 | 89.1 (2) | H41C—C41—H41D | 109.6 |
Cl1i—Si1—Br1 | 176.1 (4) | C6—C5—C4 | 119.9 (4) |
Cl1ii—Si1—Br1 | 89.52 (6) | C6—C5—H5 | 120.0 |
Cl1—Si1—Br1 | 3.9 (4) | C4—C5—H5 | 120.0 |
Cl1iii—Si1—Br1 | 90.48 (6) | N1—C6—C5 | 122.6 (3) |
Br1i—Si1—Br1 | 180.0 | N1—C6—H6 | 118.7 |
Br1ii—Si1—Br1 | 93.2 (5) | C5—C6—H6 | 118.7 |
N1—Si1—Br1iii | 90.9 (2) | ||
N1i—Si1—N1—C2 | −1 (100) | Br1i—Si1—N1—C6 | 43.4 (2) |
Cl1i—Si1—N1—C2 | −132.91 (19) | Br1ii—Si1—N1—C6 | −43.4 (2) |
Cl1ii—Si1—N1—C2 | 132.91 (19) | Br1—Si1—N1—C6 | −136.6 (2) |
Cl1—Si1—N1—C2 | 47.09 (19) | Br1iii—Si1—N1—C6 | 136.6 (2) |
Cl1iii—Si1—N1—C2 | −47.09 (19) | C6—N1—C2—C3 | 0.000 (2) |
Br1i—Si1—N1—C2 | −136.6 (2) | Si1—N1—C2—C3 | 180.000 (1) |
Br1ii—Si1—N1—C2 | 136.6 (2) | N1—C2—C3—C4 | 0.000 (2) |
Br1—Si1—N1—C2 | 43.4 (2) | C2—C3—C4—C5 | 0.000 (2) |
Br1iii—Si1—N1—C2 | −43.4 (2) | C2—C3—C4—C41 | 180.000 (2) |
N1i—Si1—N1—C6 | 179.4 (5) | C3—C4—C5—C6 | 0.000 (2) |
Cl1i—Si1—N1—C6 | 47.09 (19) | C41—C4—C5—C6 | 180.000 (2) |
Cl1ii—Si1—N1—C6 | −47.09 (19) | C2—N1—C6—C5 | 0.000 (2) |
Cl1—Si1—N1—C6 | −132.91 (19) | Si1—N1—C6—C5 | 180.000 (1) |
Cl1iii—Si1—N1—C6 | 132.91 (19) | C4—C5—C6—N1 | 0.000 (2) |
Symmetry codes: (i) −x+1, −y, −z+1; (ii) x, −y, −z+1; (iii) −x+1, y, z. |
C12H14Br2Cl2N2Si | F(000) = 436 |
Mr = 445.06 | Dx = 1.854 Mg m−3 |
Orthorhombic, Pmna | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ac 2 | Cell parameters from 7725 reflections |
a = 7.252 (2) Å | θ = 1–25° |
b = 8.120 (2) Å | µ = 5.48 mm−1 |
c = 13.540 (3) Å | T = 173 K |
V = 797.3 (3) Å3 | Block, colourless |
Z = 2 | 0.35 × 0.30 × 0.12 mm |
Siemens CCD three-circle diffractometer | 1110 independent reflections |
Radiation source: fine-focus sealed tube | 969 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.042 |
ω scans | θmax = 28.7°, θmin = 2.5° |
Absorption correction: empirical (SADABS; Sheldrick, 1996) | h = −9→9 |
Tmin = 0.162, Tmax = 0.520 | k = −10→10 |
14499 measured reflections | l = −16→18 |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.027 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.063 | w = 1/[σ2(Fo2) + (0.0269P)2 + 0.6549P] where P = (Fo2 + 2Fc2)/3 |
S = 1.12 | (Δ/σ)max = 0.005 |
1110 reflections | Δρmax = 0.38 e Å−3 |
66 parameters | Δρmin = −0.37 e Å−3 |
2 restraints | Extinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.0048 (9) |
C12H14Br2Cl2N2Si | V = 797.3 (3) Å3 |
Mr = 445.06 | Z = 2 |
Orthorhombic, Pmna | Mo Kα radiation |
a = 7.252 (2) Å | µ = 5.48 mm−1 |
b = 8.120 (2) Å | T = 173 K |
c = 13.540 (3) Å | 0.35 × 0.30 × 0.12 mm |
Siemens CCD three-circle diffractometer | 1110 independent reflections |
Absorption correction: empirical (SADABS; Sheldrick, 1996) | 969 reflections with I > 2σ(I) |
Tmin = 0.162, Tmax = 0.520 | Rint = 0.042 |
14499 measured reflections |
R[F2 > 2σ(F2)] = 0.027 | 2 restraints |
wR(F2) = 0.063 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.12 | Δρmax = 0.38 e Å−3 |
1110 reflections | Δρmin = −0.37 e Å−3 |
66 parameters |
Experimental. ; |
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. |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
Br1 | 0.2298 (6) | 0.1680 (6) | 0.4263 (4) | 0.0274 (4) | 0.50 |
Cl1 | 0.2237 (13) | 0.1512 (14) | 0.4383 (9) | 0.0247 (8) | 0.50 |
Si1 | 0.0000 | 0.0000 | 0.5000 | 0.0185 (2) | |
N1 | 0.0000 | 0.1419 (3) | 0.61919 (17) | 0.0194 (5) | |
C2 | 0.0000 | 0.3083 (4) | 0.6110 (2) | 0.0234 (6) | |
H2 | 0.0000 | 0.3559 | 0.5469 | 0.028* | |
C3 | 0.0000 | 0.4114 (4) | 0.6923 (2) | 0.0239 (6) | |
H3 | 0.0000 | 0.5274 | 0.6833 | 0.029* | |
C4 | 0.0000 | 0.3450 (4) | 0.7877 (2) | 0.0223 (6) | |
C41 | 0.0000 | 0.4530 (4) | 0.8779 (2) | 0.0308 (7) | |
H41A | 0.0000 | 0.5669 | 0.8602 | 0.046* | 0.50 |
H41B | −0.1025 | 0.4225 | 0.9189 | 0.046* | 0.50 |
H41C | 0.0000 | 0.3882 | 0.9372 | 0.046* | 0.50 |
H41D | −0.1071 | 0.5224 | 0.8763 | 0.046* | 0.50 |
C5 | 0.0000 | 0.1736 (4) | 0.7959 (2) | 0.0236 (6) | |
H5 | 0.0000 | 0.1234 | 0.8593 | 0.028* | |
C6 | 0.0000 | 0.0765 (4) | 0.7116 (2) | 0.0224 (6) | |
H6 | 0.0000 | −0.0399 | 0.7187 | 0.027* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Br1 | 0.0322 (6) | 0.0237 (9) | 0.0263 (12) | −0.0079 (3) | 0.0068 (5) | −0.0018 (6) |
Cl1 | 0.0340 (11) | 0.0212 (18) | 0.0189 (18) | −0.0115 (10) | 0.0101 (9) | −0.0018 (13) |
Si1 | 0.0243 (5) | 0.0139 (5) | 0.0173 (5) | 0.000 | 0.000 | −0.0025 (4) |
N1 | 0.0248 (12) | 0.0164 (11) | 0.0170 (11) | 0.000 | 0.000 | −0.0023 (9) |
C2 | 0.0319 (16) | 0.0171 (13) | 0.0212 (14) | 0.000 | 0.000 | −0.0003 (11) |
C3 | 0.0290 (15) | 0.0165 (13) | 0.0263 (15) | 0.000 | 0.000 | −0.0061 (11) |
C4 | 0.0205 (13) | 0.0240 (14) | 0.0224 (13) | 0.000 | 0.000 | −0.0073 (12) |
C41 | 0.0367 (18) | 0.0312 (17) | 0.0246 (16) | 0.000 | 0.000 | −0.0134 (13) |
C5 | 0.0282 (15) | 0.0251 (14) | 0.0176 (14) | 0.000 | 0.000 | −0.0011 (11) |
C6 | 0.0303 (15) | 0.0165 (13) | 0.0205 (13) | 0.000 | 0.000 | −0.0008 (11) |
Br1—Si1 | 2.3734 (8) | C2—H2 | 0.9500 |
Cl1—Si1 | 2.1994 (11) | C3—C4 | 1.399 (4) |
Si1—N1 | 1.983 (2) | C3—H3 | 0.9500 |
Si1—N1i | 1.983 (2) | C4—C5 | 1.397 (4) |
Si1—Cl1i | 2.1993 (11) | C4—C41 | 1.504 (4) |
Si1—Cl1ii | 2.1993 (11) | C41—H41A | 0.9555 |
Si1—Cl1iii | 2.1994 (11) | C41—H41B | 0.9600 |
Si1—Br1i | 2.3734 (8) | C41—H41C | 0.9600 |
Si1—Br1ii | 2.3734 (8) | C41—H41D | 0.9600 |
Si1—Br1iii | 2.3734 (8) | C5—C6 | 1.388 (4) |
N1—C2 | 1.355 (4) | C5—H5 | 0.9500 |
N1—C6 | 1.359 (4) | C6—H6 | 0.9500 |
C2—C3 | 1.382 (4) | ||
N1—Si1—N1i | 180.0 | N1i—Si1—Br1iii | 89.54 (15) |
N1—Si1—Cl1i | 90.9 (3) | Cl1i—Si1—Br1iii | 87.8 (2) |
N1i—Si1—Cl1i | 89.1 (3) | Cl1ii—Si1—Br1iii | 176.8 (5) |
N1—Si1—Cl1ii | 90.9 (3) | Cl1iii—Si1—Br1iii | 3.2 (5) |
N1i—Si1—Cl1ii | 89.1 (3) | Cl1—Si1—Br1iii | 92.2 (2) |
Cl1i—Si1—Cl1ii | 95.1 (7) | Br1i—Si1—Br1iii | 90.8 (3) |
N1—Si1—Cl1iii | 89.1 (3) | Br1ii—Si1—Br1iii | 179.999 (1) |
N1i—Si1—Cl1iii | 90.9 (3) | Br1—Si1—Br1iii | 89.2 (3) |
Cl1i—Si1—Cl1iii | 84.9 (7) | C2—N1—C6 | 117.7 (2) |
Cl1ii—Si1—Cl1iii | 179.998 (2) | C2—N1—Si1 | 120.8 (2) |
N1—Si1—Cl1 | 89.1 (3) | C6—N1—Si1 | 121.47 (19) |
N1i—Si1—Cl1 | 90.9 (3) | N1—C2—C3 | 122.6 (3) |
Cl1i—Si1—Cl1 | 179.998 (1) | N1—C2—H2 | 118.7 |
Cl1ii—Si1—Cl1 | 84.9 (7) | C3—C2—H2 | 118.7 |
Cl1iii—Si1—Cl1 | 95.1 (7) | C2—C3—C4 | 120.1 (3) |
N1—Si1—Br1i | 89.54 (15) | C2—C3—H3 | 120.0 |
N1i—Si1—Br1i | 90.46 (15) | C4—C3—H3 | 120.0 |
Cl1i—Si1—Br1i | 3.2 (5) | C5—C4—C3 | 117.2 (3) |
Cl1ii—Si1—Br1i | 92.2 (2) | C5—C4—C41 | 121.1 (3) |
Cl1iii—Si1—Br1i | 87.8 (2) | C3—C4—C41 | 121.7 (3) |
Cl1—Si1—Br1i | 176.8 (5) | C4—C41—H41A | 111.1 |
N1—Si1—Br1ii | 89.54 (14) | C4—C41—H41B | 108.6 |
N1i—Si1—Br1ii | 90.46 (14) | H41A—C41—H41B | 113.3 |
Cl1i—Si1—Br1ii | 92.2 (2) | C4—C41—H41C | 111.1 |
Cl1ii—Si1—Br1ii | 3.2 (5) | H41A—C41—H41C | 137.8 |
Cl1iii—Si1—Br1ii | 176.8 (5) | H41B—C41—H41C | 51.4 |
Cl1—Si1—Br1ii | 87.8 (2) | C4—C41—H41D | 108.9 |
Br1i—Si1—Br1ii | 89.2 (3) | H41A—C41—H41D | 55.0 |
N1—Si1—Br1 | 90.46 (15) | H41B—C41—H41D | 62.5 |
N1i—Si1—Br1 | 89.54 (14) | H41C—C41—H41D | 110.0 |
Cl1i—Si1—Br1 | 176.8 (5) | C6—C5—C4 | 120.0 (3) |
Cl1ii—Si1—Br1 | 87.8 (2) | C6—C5—H5 | 120.0 |
Cl1iii—Si1—Br1 | 92.2 (2) | C4—C5—H5 | 120.0 |
Cl1—Si1—Br1 | 3.2 (5) | N1—C6—C5 | 122.4 (3) |
Br1i—Si1—Br1 | 180.0 | N1—C6—H6 | 118.8 |
Br1ii—Si1—Br1 | 90.8 (3) | C5—C6—H6 | 118.8 |
N1—Si1—Br1iii | 90.46 (14) | ||
N1i—Si1—N1—C2 | 0 (100) | Br1i—Si1—N1—C6 | 44.60 (14) |
Cl1i—Si1—N1—C2 | −132.5 (4) | Br1ii—Si1—N1—C6 | −44.60 (14) |
Cl1ii—Si1—N1—C2 | 132.5 (4) | Br1—Si1—N1—C6 | −135.40 (14) |
Cl1iii—Si1—N1—C2 | −47.5 (4) | Br1iii—Si1—N1—C6 | 135.40 (14) |
Cl1—Si1—N1—C2 | 47.5 (4) | C6—N1—C2—C3 | 0.000 (1) |
Br1i—Si1—N1—C2 | −135.40 (14) | Si1—N1—C2—C3 | 180.0 |
Br1ii—Si1—N1—C2 | 135.40 (14) | N1—C2—C3—C4 | 0.000 (1) |
Br1—Si1—N1—C2 | 44.60 (14) | C2—C3—C4—C5 | 0.000 (1) |
Br1iii—Si1—N1—C2 | −44.60 (14) | C2—C3—C4—C41 | 180.000 (1) |
N1i—Si1—N1—C6 | 180.0 (4) | C3—C4—C5—C6 | 0.000 (1) |
Cl1i—Si1—N1—C6 | 47.5 (4) | C41—C4—C5—C6 | 180.000 (1) |
Cl1ii—Si1—N1—C6 | −47.5 (4) | C2—N1—C6—C5 | 0.000 (1) |
Cl1iii—Si1—N1—C6 | 132.5 (4) | Si1—N1—C6—C5 | 180.0 |
Cl1—Si1—N1—C6 | −132.5 (4) | C4—C5—C6—N1 | 0.000 (1) |
Symmetry codes: (i) −x, −y, −z+1; (ii) x, −y, −z+1; (iii) −x, y, z. |
C12H14Br3ClN2Si | F(000) = 472 |
Mr = 489.52 | Dx = 2.014 Mg m−3 |
Orthorhombic, Pmna | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ac 2 | Cell parameters from 4418 reflections |
a = 7.296 (1) Å | θ = 1–25° |
b = 8.211 (1) Å | µ = 7.73 mm−1 |
c = 13.472 (1) Å | T = 173 K |
V = 807.07 (16) Å3 | Block, colourless |
Z = 2 | 0.25 × 0.15 × 0.10 mm |
Siemens CCD three-circle diffractometer | 1005 independent reflections |
Radiation source: fine-focus sealed tube | 823 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.048 |
ω scans | θmax = 27.5°, θmin = 2.5° |
Absorption correction: empirical (SADABS; Sheldrick, 1996) | h = −9→9 |
Tmin = 0.224, Tmax = 0.462 | k = −10→10 |
11697 measured reflections | l = −17→17 |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.024 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.052 | w = 1/[σ2(Fo2) + (0.0222P)2 + 0.3546P] where P = (Fo2 + 2Fc2)/3 |
S = 1.16 | (Δ/σ)max = 0.001 |
1005 reflections | Δρmax = 0.35 e Å−3 |
66 parameters | Δρmin = −0.35 e Å−3 |
2 restraints | Extinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.0044 (6) |
C12H14Br3ClN2Si | V = 807.07 (16) Å3 |
Mr = 489.52 | Z = 2 |
Orthorhombic, Pmna | Mo Kα radiation |
a = 7.296 (1) Å | µ = 7.73 mm−1 |
b = 8.211 (1) Å | T = 173 K |
c = 13.472 (1) Å | 0.25 × 0.15 × 0.10 mm |
Siemens CCD three-circle diffractometer | 1005 independent reflections |
Absorption correction: empirical (SADABS; Sheldrick, 1996) | 823 reflections with I > 2σ(I) |
Tmin = 0.224, Tmax = 0.462 | Rint = 0.048 |
11697 measured reflections |
R[F2 > 2σ(F2)] = 0.024 | 2 restraints |
wR(F2) = 0.052 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.16 | Δρmax = 0.35 e Å−3 |
1005 reflections | Δρmin = −0.35 e Å−3 |
66 parameters |
Experimental. ; |
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. |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
Br1 | 0.7312 (2) | 0.1639 (3) | 0.4262 (2) | 0.0262 (3) | 0.75 |
Cl1 | 0.7222 (18) | 0.151 (2) | 0.4391 (15) | 0.0301 (19) | 0.25 |
Si1 | 0.5000 | 0.0000 | 0.5000 | 0.0167 (3) | |
N1 | 0.5000 | 0.1418 (3) | 0.61899 (19) | 0.0175 (6) | |
C2 | 0.5000 | 0.3059 (4) | 0.6099 (2) | 0.0213 (7) | |
H2 | 0.5000 | 0.3521 | 0.5452 | 0.026* | |
C3 | 0.5000 | 0.4091 (4) | 0.6909 (2) | 0.0226 (7) | |
H3 | 0.5000 | 0.5237 | 0.6813 | 0.027* | |
C4 | 0.5000 | 0.3451 (4) | 0.7868 (3) | 0.0205 (7) | |
C41 | 0.5000 | 0.4524 (4) | 0.8769 (3) | 0.0293 (8) | |
H41A | 0.5000 | 0.5660 | 0.8608 | 0.044* | 0.50 |
H41B | 0.3975 | 0.4217 | 0.9195 | 0.044* | 0.50 |
H41C | 0.5000 | 0.3873 | 0.9378 | 0.044* | 0.50 |
H41D | 0.3929 | 0.5216 | 0.8769 | 0.044* | 0.50 |
C5 | 0.5000 | 0.1763 (4) | 0.7955 (2) | 0.0219 (7) | |
H5 | 0.5000 | 0.1276 | 0.8595 | 0.026* | |
C6 | 0.5000 | 0.0793 (4) | 0.7124 (2) | 0.0202 (7) | |
H6 | 0.5000 | −0.0356 | 0.7205 | 0.024* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Br1 | 0.0282 (4) | 0.0239 (4) | 0.0266 (8) | −0.0081 (3) | 0.0074 (3) | −0.0045 (3) |
Cl1 | 0.044 (3) | 0.032 (3) | 0.014 (3) | −0.017 (2) | 0.0137 (17) | −0.004 (2) |
Si1 | 0.0211 (6) | 0.0135 (6) | 0.0154 (5) | 0.000 | 0.000 | −0.0028 (5) |
N1 | 0.0212 (13) | 0.0152 (14) | 0.0161 (12) | 0.000 | 0.000 | −0.0035 (11) |
C2 | 0.0299 (18) | 0.0155 (16) | 0.0184 (15) | 0.000 | 0.000 | 0.0005 (13) |
C3 | 0.0286 (18) | 0.0132 (15) | 0.0260 (18) | 0.000 | 0.000 | −0.0044 (14) |
C4 | 0.0158 (15) | 0.0222 (17) | 0.0235 (15) | 0.000 | 0.000 | −0.0088 (14) |
C41 | 0.035 (2) | 0.027 (2) | 0.0262 (18) | 0.000 | 0.000 | −0.0124 (15) |
C5 | 0.0266 (17) | 0.0229 (17) | 0.0163 (15) | 0.000 | 0.000 | −0.0015 (14) |
C6 | 0.0262 (17) | 0.0128 (16) | 0.0218 (15) | 0.000 | 0.000 | 0.0000 (14) |
Br1—Si1 | 2.3758 (6) | C2—H2 | 0.9500 |
Cl1—Si1 | 2.2021 (11) | C3—C4 | 1.394 (5) |
Si1—N1i | 1.981 (2) | C3—H3 | 0.9500 |
Si1—N1 | 1.981 (2) | C4—C5 | 1.391 (4) |
Si1—Cl1ii | 2.2021 (11) | C4—C41 | 1.500 (5) |
Si1—Cl1i | 2.2022 (11) | C41—H41A | 0.9578 |
Si1—Cl1iii | 2.2022 (11) | C41—H41B | 0.9759 |
Si1—Br1ii | 2.3758 (6) | C41—H41C | 0.9794 |
Si1—Br1i | 2.3758 (6) | C41—H41D | 0.9659 |
Si1—Br1iii | 2.3758 (6) | C5—C6 | 1.374 (5) |
N1—C2 | 1.353 (4) | C5—H5 | 0.9500 |
N1—C6 | 1.359 (4) | C6—H6 | 0.9500 |
C2—C3 | 1.382 (4) | ||
N1i—Si1—N1 | 180.0 | N1—Si1—Br1iii | 89.68 (9) |
N1i—Si1—Cl1 | 91.7 (6) | Cl1—Si1—Br1iii | 87.3 (4) |
N1—Si1—Cl1 | 88.3 (6) | Cl1ii—Si1—Br1iii | 177.0 (6) |
N1i—Si1—Cl1ii | 91.7 (6) | Cl1i—Si1—Br1iii | 92.7 (4) |
N1—Si1—Cl1ii | 88.3 (6) | Cl1iii—Si1—Br1iii | 3.0 (6) |
Cl1—Si1—Cl1ii | 94.8 (10) | Br1ii—Si1—Br1iii | 180.0 |
N1i—Si1—Cl1i | 88.3 (6) | Br1—Si1—Br1iii | 89.53 (11) |
N1—Si1—Cl1i | 91.7 (6) | Br1i—Si1—Br1iii | 90.47 (11) |
Cl1—Si1—Cl1i | 180.0 | C2—N1—C6 | 117.4 (3) |
Cl1ii—Si1—Cl1i | 85.2 (10) | C2—N1—Si1 | 120.8 (2) |
N1i—Si1—Cl1iii | 88.3 (6) | C6—N1—Si1 | 121.8 (2) |
N1—Si1—Cl1iii | 91.7 (6) | N1—C2—C3 | 122.6 (3) |
Cl1—Si1—Cl1iii | 85.2 (10) | N1—C2—H2 | 118.7 |
Cl1ii—Si1—Cl1iii | 179.998 (3) | C3—C2—H2 | 118.7 |
Cl1i—Si1—Cl1iii | 94.8 (10) | C2—C3—C4 | 120.1 (3) |
N1i—Si1—Br1ii | 89.68 (9) | C2—C3—H3 | 120.0 |
N1—Si1—Br1ii | 90.32 (9) | C4—C3—H3 | 120.0 |
Cl1—Si1—Br1ii | 92.7 (4) | C5—C4—C3 | 117.0 (3) |
Cl1ii—Si1—Br1ii | 3.0 (6) | C5—C4—C41 | 121.1 (3) |
Cl1i—Si1—Br1ii | 87.3 (4) | C3—C4—C41 | 121.9 (3) |
Cl1iii—Si1—Br1ii | 177.0 (6) | C4—C41—H41A | 112.8 |
N1i—Si1—Br1 | 89.68 (9) | C4—C41—H41B | 108.9 |
N1—Si1—Br1 | 90.32 (9) | H41A—C41—H41B | 112.7 |
Cl1—Si1—Br1 | 3.0 (6) | C4—C41—H41C | 111.0 |
Cl1ii—Si1—Br1 | 92.7 (4) | H41A—C41—H41C | 136.2 |
Cl1i—Si1—Br1 | 177.0 (6) | H41B—C41—H41C | 50.7 |
Cl1iii—Si1—Br1 | 87.3 (4) | C4—C41—H41D | 110.2 |
Br1ii—Si1—Br1 | 90.47 (11) | H41A—C41—H41D | 55.1 |
N1i—Si1—Br1i | 90.32 (9) | H41B—C41—H41D | 62.1 |
N1—Si1—Br1i | 89.68 (9) | H41C—C41—H41D | 108.7 |
Cl1—Si1—Br1i | 177.0 (6) | C6—C5—C4 | 120.6 (3) |
Cl1ii—Si1—Br1i | 87.3 (4) | C6—C5—H5 | 119.7 |
Cl1i—Si1—Br1i | 3.0 (6) | C4—C5—H5 | 119.7 |
Cl1iii—Si1—Br1i | 92.7 (4) | N1—C6—C5 | 122.4 (3) |
Br1ii—Si1—Br1i | 89.53 (11) | N1—C6—H6 | 118.8 |
Br1—Si1—Br1i | 180.0 | C5—C6—H6 | 118.8 |
N1i—Si1—Br1iii | 90.32 (9) | ||
N1i—Si1—N1—C2 | −179.7 (7) | Br1ii—Si1—N1—C6 | 134.76 (5) |
Cl1—Si1—N1—C2 | 47.4 (5) | Br1—Si1—N1—C6 | −134.76 (5) |
Cl1ii—Si1—N1—C2 | −47.4 (5) | Br1i—Si1—N1—C6 | 45.24 (5) |
Cl1i—Si1—N1—C2 | −132.6 (5) | Br1iii—Si1—N1—C6 | −45.24 (5) |
Cl1iii—Si1—N1—C2 | 132.6 (5) | C6—N1—C2—C3 | 0.000 (1) |
Br1ii—Si1—N1—C2 | −45.24 (5) | Si1—N1—C2—C3 | 180.000 (1) |
Br1—Si1—N1—C2 | 45.24 (5) | N1—C2—C3—C4 | 0.000 (2) |
Br1i—Si1—N1—C2 | −134.76 (5) | C2—C3—C4—C5 | 0.000 (2) |
Br1iii—Si1—N1—C2 | 134.76 (5) | C2—C3—C4—C41 | 180.000 (1) |
N1i—Si1—N1—C6 | 0 (100) | C3—C4—C5—C6 | 0.000 (2) |
Cl1—Si1—N1—C6 | −132.6 (5) | C41—C4—C5—C6 | 180.000 (1) |
Cl1ii—Si1—N1—C6 | 132.6 (5) | C2—N1—C6—C5 | 0.000 (1) |
Cl1i—Si1—N1—C6 | 47.4 (5) | Si1—N1—C6—C5 | 180.0 |
Cl1iii—Si1—N1—C6 | −47.4 (5) | C4—C5—C6—N1 | 0.000 (2) |
Symmetry codes: (i) −x+1, −y, −z+1; (ii) −x+1, y, z; (iii) x, −y, −z+1. |
C12H14Br4N2Si | F(000) = 508 |
Mr = 533.98 | Dx = 2.178 Mg m−3 |
Orthorhombic, Pmna | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ac 2 | Cell parameters from 7725 reflections |
a = 7.3298 (2) Å | θ = 1–25° |
b = 8.2819 (3) Å | µ = 9.95 mm−1 |
c = 13.4126 (3) Å | T = 143 K |
V = 814.21 (4) Å3 | Block, colourless |
Z = 2 | 0.30 × 0.20 × 0.05 mm |
Siemens CCD three-circle diffractometer | 907 independent reflections |
Radiation source: fine-focus sealed tube | 728 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.045 |
ω scans | θmax = 26.4°, θmin = 2.9° |
Absorption correction: empirical (SADABS; Sheldrick, 1996) | h = −9→9 |
Tmin = 0.105, Tmax = 0.609 | k = −10→10 |
7079 measured reflections | l = −14→16 |
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)] = 0.028 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.065 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.04 | w = 1/[σ2(Fo2) + (0.0342P)2 + 0.9192P] where P = (Fo2 + 2Fc2)/3 |
907 reflections | (Δ/σ)max = 0.001 |
56 parameters | Δρmax = 0.63 e Å−3 |
0 restraints | Δρmin = −0.48 e Å−3 |
C12H14Br4N2Si | V = 814.21 (4) Å3 |
Mr = 533.98 | Z = 2 |
Orthorhombic, Pmna | Mo Kα radiation |
a = 7.3298 (2) Å | µ = 9.95 mm−1 |
b = 8.2819 (3) Å | T = 143 K |
c = 13.4126 (3) Å | 0.30 × 0.20 × 0.05 mm |
Siemens CCD three-circle diffractometer | 907 independent reflections |
Absorption correction: empirical (SADABS; Sheldrick, 1996) | 728 reflections with I > 2σ(I) |
Tmin = 0.105, Tmax = 0.609 | Rint = 0.045 |
7079 measured reflections |
R[F2 > 2σ(F2)] = 0.028 | 0 restraints |
wR(F2) = 0.065 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.04 | Δρmax = 0.63 e Å−3 |
907 reflections | Δρmin = −0.48 e Å−3 |
56 parameters |
Experimental. ; |
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. |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
Br1 | 0.23257 (4) | 0.16177 (4) | 0.42619 (3) | 0.02330 (15) | |
Si1 | 0.0000 | 0.0000 | 0.5000 | 0.0150 (4) | |
N1 | 0.0000 | 0.1415 (5) | 0.6189 (3) | 0.0168 (9) | |
C2 | 0.0000 | 0.3052 (6) | 0.6088 (4) | 0.0176 (10) | |
H2 | 0.0000 | 0.3504 | 0.5437 | 0.021* | |
C3 | 0.0000 | 0.4080 (6) | 0.6901 (4) | 0.0204 (11) | |
H3 | 0.0000 | 0.5215 | 0.6800 | 0.024* | |
C4 | 0.0000 | 0.3460 (6) | 0.7870 (4) | 0.0197 (10) | |
C41 | 0.0000 | 0.4520 (6) | 0.8766 (4) | 0.0264 (12) | |
H41A | 0.0000 | 0.5668 | 0.8598 | 0.040* | 0.50 |
H41B | −0.1025 | 0.4225 | 0.9185 | 0.040* | 0.50 |
H41C | 0.0000 | 0.3881 | 0.9369 | 0.040* | 0.50 |
H41D | −0.1071 | 0.5224 | 0.8759 | 0.040* | 0.50 |
C5 | 0.0000 | 0.1782 (6) | 0.7964 (4) | 0.0199 (10) | |
H5 | 0.0000 | 0.1307 | 0.8608 | 0.024* | |
C6 | 0.0000 | 0.0803 (6) | 0.7130 (4) | 0.0191 (10) | |
H6 | 0.0000 | −0.0335 | 0.7217 | 0.023* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Br1 | 0.0237 (2) | 0.0194 (2) | 0.0268 (2) | −0.00750 (14) | 0.00648 (14) | −0.00455 (15) |
Si1 | 0.0161 (8) | 0.0109 (9) | 0.0181 (9) | 0.000 | 0.000 | −0.0023 (8) |
N1 | 0.0179 (19) | 0.014 (2) | 0.018 (2) | 0.000 | 0.000 | −0.0035 (17) |
C2 | 0.020 (2) | 0.010 (2) | 0.022 (3) | 0.000 | 0.000 | 0.0035 (19) |
C3 | 0.026 (3) | 0.010 (2) | 0.025 (3) | 0.000 | 0.000 | −0.002 (2) |
C4 | 0.013 (2) | 0.020 (3) | 0.026 (2) | 0.000 | 0.000 | −0.008 (2) |
C41 | 0.027 (3) | 0.026 (3) | 0.026 (3) | 0.000 | 0.000 | −0.010 (2) |
C5 | 0.020 (2) | 0.023 (3) | 0.017 (3) | 0.000 | 0.000 | −0.004 (2) |
C6 | 0.026 (2) | 0.012 (2) | 0.019 (2) | 0.000 | 0.000 | 0.000 (2) |
Br1—Si1 | 2.3835 (3) | C3—H3 | 0.9500 |
Si1—N1 | 1.979 (4) | C4—C5 | 1.396 (7) |
Si1—N1i | 1.979 (4) | C4—C41 | 1.488 (7) |
Si1—Br1i | 2.3835 (3) | C41—H41A | 0.9777 |
Si1—Br1ii | 2.3835 (3) | C41—H41B | 0.9698 |
Si1—Br1iii | 2.3835 (3) | C41—H41C | 0.9657 |
N1—C6 | 1.360 (6) | C41—H41D | 0.9781 |
N1—C2 | 1.363 (6) | C5—C6 | 1.381 (7) |
C2—C3 | 1.384 (7) | C5—H5 | 0.9500 |
C2—H2 | 0.9500 | C6—H6 | 0.9500 |
C3—C4 | 1.397 (7) | ||
N1—Si1—N1i | 180.0 | C2—C3—H3 | 119.8 |
N1—Si1—Br1i | 89.89 (8) | C4—C3—H3 | 119.8 |
N1i—Si1—Br1i | 90.11 (8) | C5—C4—C3 | 116.7 (5) |
N1—Si1—Br1ii | 89.89 (8) | C5—C4—C41 | 121.0 (5) |
N1i—Si1—Br1ii | 90.11 (8) | C3—C4—C41 | 122.3 (5) |
Br1i—Si1—Br1ii | 91.320 (17) | C4—C41—H41A | 112.8 |
N1—Si1—Br1iii | 90.11 (8) | C4—C41—H41B | 108.6 |
N1i—Si1—Br1iii | 89.89 (8) | H41A—C41—H41B | 112.2 |
Br1i—Si1—Br1iii | 88.680 (17) | C4—C41—H41C | 110.7 |
Br1ii—Si1—Br1iii | 180.0 | H41A—C41—H41C | 136.5 |
N1—Si1—Br1 | 90.11 (8) | H41B—C41—H41C | 51.5 |
N1i—Si1—Br1 | 89.89 (8) | C4—C41—H41D | 110.1 |
Br1i—Si1—Br1 | 180.0 | H41A—C41—H41D | 54.4 |
Br1ii—Si1—Br1 | 88.680 (17) | H41B—C41—H41D | 62.2 |
Br1iii—Si1—Br1 | 91.320 (17) | H41C—C41—H41D | 109.5 |
C6—N1—C2 | 117.6 (4) | C6—C5—C4 | 120.8 (5) |
C6—N1—Si1 | 121.8 (3) | C6—C5—H5 | 119.6 |
C2—N1—Si1 | 120.6 (3) | C4—C5—H5 | 119.6 |
N1—C2—C3 | 122.2 (5) | N1—C6—C5 | 122.2 (4) |
N1—C2—H2 | 118.9 | N1—C6—H6 | 118.9 |
C3—C2—H2 | 118.9 | C5—C6—H6 | 118.9 |
C2—C3—C4 | 120.5 (5) | ||
N1i—Si1—N1—C6 | 180.0 (6) | C6—N1—C2—C3 | 0.000 (2) |
Br1i—Si1—N1—C6 | 45.660 (9) | Si1—N1—C2—C3 | 180.000 (2) |
Br1ii—Si1—N1—C6 | −45.660 (9) | N1—C2—C3—C4 | 0.000 (2) |
Br1iii—Si1—N1—C6 | 134.340 (9) | C2—C3—C4—C5 | 0.000 (2) |
Br1—Si1—N1—C6 | −134.340 (9) | C2—C3—C4—C41 | 180.000 (2) |
N1i—Si1—N1—C2 | 0 (100) | C3—C4—C5—C6 | 0.000 (2) |
Br1i—Si1—N1—C2 | −134.340 (9) | C41—C4—C5—C6 | 180.000 (2) |
Br1ii—Si1—N1—C2 | 134.340 (9) | C2—N1—C6—C5 | 0.000 (2) |
Br1iii—Si1—N1—C2 | −45.660 (9) | Si1—N1—C6—C5 | 180.000 (1) |
Br1—Si1—N1—C2 | 45.660 (9) | C4—C5—C6—N1 | 0.000 (2) |
Symmetry codes: (i) −x, −y, −z+1; (ii) x, −y, −z+1; (iii) −x, y, z. |
Experimental details
(I) | (II) | (III) | (IV) | |
Crystal data | ||||
Chemical formula | C12H14Cl4N2Si | C12H14BrCl3N2Si | C12H14Br2Cl2N2Si | C12H14Br3ClN2Si |
Mr | 356.14 | 400.60 | 445.06 | 489.52 |
Crystal system, space group | Orthorhombic, Pmna | Orthorhombic, Pmna | Orthorhombic, Pmna | Orthorhombic, Pmna |
Temperature (K) | 173 | 173 | 173 | 173 |
a, b, c (Å) | 7.1766 (1), 7.8911 (1), 13.7036 (1) | 7.177 (1), 7.962 (1), 13.557 (1) | 7.252 (2), 8.120 (2), 13.540 (3) | 7.296 (1), 8.211 (1), 13.472 (1) |
V (Å3) | 776.05 (2) | 774.69 (16) | 797.3 (3) | 807.07 (16) |
Z | 2 | 2 | 2 | 2 |
Radiation type | Mo Kα | Mo Kα | Mo Kα | Mo Kα |
µ (mm−1) | 0.83 | 3.24 | 5.48 | 7.73 |
Crystal size (mm) | 0.60 × 0.40 × 0.40 | 0.40 × 0.30 × 0.10 | 0.35 × 0.30 × 0.12 | 0.25 × 0.15 × 0.10 |
Data collection | ||||
Diffractometer | Siemens CCD three-circle diffractometer | Siemens CCD three-circle diffractometer | Siemens CCD three-circle diffractometer | Siemens CCD three-circle diffractometer |
Absorption correction | Empirical (SADABS; Sheldrick, 1996) | Empirical (SADABS; Sheldrick, 1996) | Empirical (SADABS; Sheldrick, 1996) | Empirical (SADABS; Sheldrick, 1996) |
Tmin, Tmax | 0.637, 0.733 | 0.358, 0.738 | 0.162, 0.520 | 0.224, 0.462 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 10172, 853, 815 | 24114, 1278, 1051 | 14499, 1110, 969 | 11697, 1005, 823 |
Rint | 0.019 | 0.057 | 0.042 | 0.048 |
(sin θ/λ)max (Å−1) | 0.623 | 0.714 | 0.675 | 0.649 |
Refinement | ||||
R[F2 > 2σ(F2)], wR(F2), S | 0.020, 0.058, 1.15 | 0.040, 0.111, 1.12 | 0.027, 0.063, 1.12 | 0.024, 0.052, 1.16 |
No. of reflections | 853 | 1278 | 1110 | 1005 |
No. of parameters | 56 | 65 | 66 | 66 |
No. of restraints | 0 | 8 | 2 | 2 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement | H atoms treated by a mixture of independent and constrained refinement | H atoms treated by a mixture of independent and constrained refinement | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.26, −0.18 | 0.65, −1.14 | 0.38, −0.37 | 0.35, −0.35 |
(V) | |
Crystal data | |
Chemical formula | C12H14Br4N2Si |
Mr | 533.98 |
Crystal system, space group | Orthorhombic, Pmna |
Temperature (K) | 143 |
a, b, c (Å) | 7.3298 (2), 8.2819 (3), 13.4126 (3) |
V (Å3) | 814.21 (4) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 9.95 |
Crystal size (mm) | 0.30 × 0.20 × 0.05 |
Data collection | |
Diffractometer | Siemens CCD three-circle diffractometer |
Absorption correction | Empirical (SADABS; Sheldrick, 1996) |
Tmin, Tmax | 0.105, 0.609 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 7079, 907, 728 |
Rint | 0.045 |
(sin θ/λ)max (Å−1) | 0.625 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.028, 0.065, 1.04 |
No. of reflections | 907 |
No. of parameters | 56 |
No. of restraints | 0 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.63, −0.48 |
Computer programs: SMART (Siemens, 1995), SMART, SAINT (Siemens, 1995), SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), XP (in SHELXTL-Plus, 1991).
Si1—N1 | 1.9835 (13) | N1—C2 | 1.357 (2) |
Si1—Cl1 | 2.2030 (3) | N1—C6 | 1.359 (2) |
N1—Si1—Cl1 | 89.88 (3) | C2—N1—C6 | 117.47 (14) |
Cl1—Si1—N1—C6 | 45.452 (9) |
Br1—Si1 | 2.3695 (11) | Si1—N1 | 1.973 (3) |
Cl1—Si1 | 2.1856 (10) | ||
N1—Si1—Cl1 | 89.5 (2) | C2—N1—C6 | 117.7 (3) |
N1—Si1—Br1 | 90.9 (2) | ||
Cl1—Si1—N1—C2 | 47.09 (19) | Br1—Si1—N1—C2 | 43.4 (2) |
Br1—Si1 | 2.3734 (8) | Si1—N1 | 1.983 (2) |
Cl1—Si1 | 2.1994 (11) | ||
N1—Si1—Cl1 | 89.1 (3) | C2—N1—C6 | 117.7 (2) |
N1—Si1—Br1 | 90.46 (15) | ||
Cl1—Si1—N1—C2 | 47.5 (4) | Br1—Si1—N1—C2 | 44.60 (14) |
Br1—Si1 | 2.3758 (6) | Si1—N1 | 1.981 (2) |
Cl1—Si1 | 2.2021 (11) | ||
N1—Si1—Cl1 | 88.3 (6) | C2—N1—C6 | 117.4 (3) |
N1—Si1—Br1 | 90.32 (9) | ||
Cl1—Si1—N1—C2 | 47.4 (5) | Br1—Si1—N1—C2 | 45.24 (5) |
Br1—Si1 | 2.3835 (3) | Si1—N1 | 1.979 (4) |
N1—Si1—Br1 | 90.11 (8) | C6—N1—C2 | 117.6 (4) |
Br1—Si1—N1—C2 | 45.660 (9) |
In recent years the extension of the coordination sphere of silicon in complexes with organic nitrogen bases has been the subject of numerous studies (Bechstein et al., 1990; Chuit et al., 1993; Kane et al., 1998; Hensen et al., 1998; Hensen et al. 2000). Several complexes of silicon halides are already known, but only little is known about adducts of mixed silicon halides, because exchange reactions have to be taken into account. This kind of exchange reaction between silicon tetrahalides at high temperatures and pressures have been described by Forbes & Anderson (1944) and were recently proved (Hensen et al., 2000) at ambient conditions. Furthermore, it was presumed (Wannagat et al., 1954) that pyridine or comparable ligands catalyze halogen exchange reactions of silicon halides. This would mean that during the reaction of mixed silicon halides with nitrogen bases not only the Lewis acid-base reaction, but also base-catalyzed dismutations have to be taken into account (Hass & Bechstein, 1981; Bassindale et al., 1995; Kost et al., 1995; Herzog et al., 1996; Boudjouk et al., 1998). We present in this work the first crystal structures of complexes in which the silicon centre carries different halogen ligands. \sch
All five compounds form isomorphous crystals and the cell parameters show only minor differences. However, the following trends are noticeable: in the line from SiCl4 to SiBr4 the c axis is shorter, whereas the a and the b axis are longer.
Compounds (I) and (V) belong to the symmetry point group C2 h (deviating only slightly from molecular D2 h symmetry). (II), (III) and (IV) are of lower molecular symmetry, but as a result of the disorder of the halogen ligands, they display the same crystallographic symmetry as (I) and (V). The Si atom is located on a special position of site symmetry 2/m and the picoline moieties lie on a crystallographic mirror plane. Only the halogen ligands and two H atoms of each methyl group occupy a general position. The silicon centre appears in a nearly ideal octahedral environment, where the two picoline ligands occupy axial positions and the four halogen ligands lie in the equatorial plane. There are only minor deviations from the perfect octahedral coordination. The planes of the methylpyridine rings bisect the Hal-Si-Hal angle almost exactly. As a result of the crystallographic symmetry the N—Si—N bond angles and the Hal-Si-Hal bond angles of opposite halogen atoms are exactly 180°. The remaining bond angles at Si differ only insignificantly from 90°. In spite of the different substitution pattern of the silicon centre, comparable geometric parameters are nearly identical in all five structures: the mean value of the Si—N bond length is 1.980 (4) Å. The C—N—C angle [mean value is 117.6 (1)°] is not affected by the different substitution pattern of the silicon centre, either. The crystallographic symmetry requires that there is only a quarter of the molecule in the asymmetric unit. As a result of that, the halogen atoms in (II), (III) and (IV) are disordered and they cannot be distinguished (see experimental section).
The molecules crystallize in planes perpendicular to the crystallographic a axis. The distance between these planes is a/2. A view onto these planes demonstrates (Fig. 4), that the aromatic residues are nearly perfectly stacked and the Si-Hal4 moieties fill the remaining gaps.
The structures presented in this paper are isostructural with trans-tetrachlorobis(4-methylpyridine)titanium (Hensen et al., 1999). The presence of an aromatic base during the reaction to synthesize these compounds did not considerably stimulate the halogen exchange, a fact that has already been observed (Hensen et al., 2000). As a result of that, no dismutation could be detected and each of the reaction products could be recrystallized. This result could also be attributed to the high dilution of the substance in the solvent and the fact that the complexes are extremely poorly soluble.