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The title compound, C24H30N4Si2+·2Br-·4CHCl3, (I), contains a hexacoordinated Si atom located on a crystallographic centre of inversion. The coordination of the Si atom can be described as a slightly distorted octahedron, with the 3-picoline ligands in the equatorial plane and the two H atoms occupying axial positions. It is remarkable that (I) is not isomorphous with its analogue where the Br- ions are substituted by Cl- ions.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536801003415/wn6005sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536801003415/wn6005Isup2.hkl
Contains datablock I

CCDC reference: 159871

Key indicators

  • Single-crystal X-ray study
  • T = 173 K
  • Mean [sigma](C-C) = 0.013 Å
  • R factor = 0.093
  • wR factor = 0.268
  • Data-to-parameter ratio = 23.3

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


Amber Alert Alert Level B:
PLAT_731 Alert B Bond Calc 1.40(6), Rep 1.401(10) .... 6.00 s.u-Ratio SI1 -H1 1.555 1.555
Author response: The Si-H bond was refined applying a restraint of 1.40(1)\%A.
PLAT_731  Alert B Bond    Calc     1.40(6), Rep   1.401(10) ....       6.00 s.u-Ratio
                     SI1  -H1      1.555   1.555
Author response: The Si-H bond was refined applying a restraint of 1.40(1)\%A.

Yellow Alert Alert Level C:
RFACR_01 Alert C The value of the weighted R factor is > 0.25 Weighted R factor given 0.268 PLAT_420 Alert C D-H Without Acceptor Si(1) - H(1) ?
0 Alert Level A = Potentially serious problem
2 Alert Level B = Potential problem
2 Alert Level C = Please check

Comment top

Lewis acid–base complexes between silicon compounds and nitrogen bases have in recent years been the subject of many structural studies (Hensen et al., 1997, 1988; Chuit et al. 1993). Apart from [H2Si(3-picoline)4]2+.2Cl-.4CHCl3 (Fleischer et al., 1996), [H2Si(pyridine)4]2+.2Cl-.4CHCl3 (Hensen et al., 1998), [H2Si(3,4-lutidine)4]2+.2Cl-.6CHCl3 (Hensen et al., 2000), [H2Si(3,5-lutidine)4]2+.2Br-.2CH3CN (Bolte et al., 2000), [H2Si(4-picoline)4]2+.2Cl-.6CHCl3 (Stumpf & Bolte, 2001) and [H2Si(4-picoline)4]2+.2Br-.6CHCl3 (Bolte & Faber, 2001), the crystal structure of the title compound, (I), is a further example with the structural element H2Si(pyridine)4.

The coordination of the Si atom can be described as a slightly distorted octahedron, with the 3-picoline ligands in the equatorial plane and the two H atoms occupying axial positions. The two Br- ions are displaced from the first sphere of coordination. It is remarkable that (I) is not isomorphous with its analogue in which the Br- ions are substituted by Cl- ions (Fleischer et al., 1996). A least-squares fit of all non-H atoms of the cations of both structures (r.m.s. deviation 0.259 Å) shows that there are only minor differences between them, e.g. the angle between the aromatic rings is 90.0 (3)° in (I) and 96.9° in the structure containing the Cl- ions. However, the packing patterns of the two structures are completely different.

Experimental top

The title compound was prepared as described by Faber (2000).

Refinement top

All H atoms were located by difference Fourier synthesis and refined with fixed individual displacement parameters [U(H) = 1.5 Ueq[C(methyl)] or U(H) = 1.2Ueq(C)] using a riding model with C—H(aromatic) = 0.95, CH(methyl) = 0.98, or C—H(tertiary) = 1.00 Å. The H atom bonded to Si was refined isotropically applying a restraint of 1.40 (1) Å to the Si—H distance The methyl groups attached to the aromatic rings were allowed to rotate about their local threefold axis.

Computing details top

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 (Sheldrick, 1991).

Figures top
[Figure 1] Fig. 1. A perspective view of the cation of (I) with the atom-numbering scheme. Displacement ellipsoids are at the 50% probability level. H atoms, except those attached to Si, have been omitted for clarity.
[Figure 2] Fig. 2. A perspective view of the anion and the solvent molecules of (I) with the atom-numbering scheme. Displacement ellipsoids are at the 50% probability level and H atoms are drawn as small spheres of arbitrary radii.
(I) top
Crystal data top
C28H34Br2Cl12N4SiZ = 1
Mr = 1039.90F(000) = 518
Triclinic, P1Dx = 1.554 Mg m3
a = 8.840 (1) ÅMo Kα radiation, λ = 0.71073 Å
b = 10.059 (1) ÅCell parameters from 7621 reflections
c = 13.330 (1) Åθ = 1–25°
α = 97.65 (1)°µ = 2.60 mm1
β = 90.68 (1)°T = 173 K
γ = 108.63 (1)°Block, colourless
V = 1111.35 (19) Å30.40 × 0.35 × 0.20 mm
Data collection top
Siemens CCD three-circle
diffractometer
5095 independent reflections
Radiation source: fine-focus sealed tube3406 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.087
ω scansθmax = 27.5°, θmin = 1.5°
Absorption correction: empirical
(SADABS; Sheldrick, 1996)
h = 1111
Tmin = 0.37, Tmax = 0.60k = 1313
22862 measured reflectionsl = 1717
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)] = 0.093Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.268H atoms treated by a mixture of independent and constrained refinement
S = 1.11 w = 1/[σ2(Fo2) + (0.0856P)2 + 12.6187P]
where P = (Fo2 + 2Fc2)/3
5095 reflections(Δ/σ)max = 0.002
219 parametersΔρmax = 2.39 e Å3
1 restraintΔρmin = 0.85 e Å3
Crystal data top
C28H34Br2Cl12N4Siγ = 108.63 (1)°
Mr = 1039.90V = 1111.35 (19) Å3
Triclinic, P1Z = 1
a = 8.840 (1) ÅMo Kα radiation
b = 10.059 (1) ŵ = 2.60 mm1
c = 13.330 (1) ÅT = 173 K
α = 97.65 (1)°0.40 × 0.35 × 0.20 mm
β = 90.68 (1)°
Data collection top
Siemens CCD three-circle
diffractometer
5095 independent reflections
Absorption correction: empirical
(SADABS; Sheldrick, 1996)
3406 reflections with I > 2σ(I)
Tmin = 0.37, Tmax = 0.60Rint = 0.087
22862 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0931 restraint
wR(F2) = 0.268H atoms treated by a mixture of independent and constrained refinement
S = 1.11 w = 1/[σ2(Fo2) + (0.0856P)2 + 12.6187P]
where P = (Fo2 + 2Fc2)/3
5095 reflectionsΔρmax = 2.39 e Å3
219 parametersΔρmin = 0.85 e Å3
Special details top

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Si10.00000.50000.00000.0181 (6)
H10.095 (8)0.592 (6)0.062 (5)0.022*
N110.1233 (8)0.6138 (7)0.1258 (5)0.0245 (13)
C120.0870 (9)0.5698 (9)0.2165 (6)0.0279 (17)
H120.00240.48390.21900.034*
C130.1699 (10)0.6467 (10)0.3067 (7)0.0346 (19)
C1310.1271 (14)0.5955 (13)0.4048 (8)0.059 (3)
H13A0.01860.52720.39780.088*
H13B0.13170.67580.45650.088*
H13C0.20270.54950.42500.088*
C140.2969 (9)0.7754 (9)0.2986 (6)0.0306 (18)
H140.35560.83210.35810.037*
C150.3335 (10)0.8167 (9)0.2068 (6)0.0318 (18)
H150.41900.90090.20160.038*
C160.2460 (9)0.7358 (8)0.1209 (6)0.0278 (17)
H160.27180.76570.05680.033*
N210.1444 (8)0.3859 (7)0.0114 (5)0.0240 (13)
C220.1176 (10)0.2725 (8)0.0383 (6)0.0278 (17)
H220.02700.24900.07820.033*
C230.2159 (11)0.1886 (9)0.0340 (7)0.0350 (19)
C2310.1800 (14)0.0644 (11)0.0918 (8)0.050 (3)
H23A0.25410.08880.15170.075*
H23B0.19250.01750.04820.075*
H23C0.06990.04090.11310.075*
C240.3474 (11)0.2239 (10)0.0254 (8)0.040 (2)
H240.41750.16900.03080.048*
C250.3753 (11)0.3401 (10)0.0768 (7)0.040 (2)
H250.46430.36450.11790.048*
C260.2747 (10)0.4198 (9)0.0683 (6)0.0303 (18)
H260.29630.50010.10280.036*
C10.8545 (14)0.0240 (12)0.3371 (9)0.056 (3)
H110.80220.04650.27760.067*
Cl110.9042 (8)0.1295 (4)0.2984 (4)0.1131 (17)
Cl120.7192 (5)0.0003 (5)0.4349 (4)0.1039 (14)
Cl131.0267 (5)0.1644 (5)0.3757 (4)0.0996 (14)
C20.4663 (12)0.3654 (11)0.6797 (8)0.048 (2)
H210.43380.29740.72950.058*
Cl210.2981 (4)0.5164 (5)0.6433 (3)0.0908 (13)
Cl220.6144 (4)0.4136 (4)0.7382 (3)0.0755 (10)
Cl230.5386 (4)0.2817 (5)0.5741 (3)0.0904 (13)
Br10.32492 (12)0.85295 (10)0.14354 (7)0.0387 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Si10.0192 (13)0.0191 (13)0.0166 (13)0.0062 (11)0.0034 (10)0.0054 (10)
N110.025 (3)0.026 (3)0.027 (3)0.012 (3)0.002 (3)0.009 (3)
C120.026 (4)0.031 (4)0.027 (4)0.008 (3)0.007 (3)0.010 (3)
C130.029 (4)0.044 (5)0.031 (5)0.013 (4)0.001 (3)0.004 (4)
C1310.050 (6)0.064 (7)0.041 (6)0.004 (5)0.002 (5)0.008 (5)
C140.019 (4)0.045 (5)0.020 (4)0.003 (3)0.002 (3)0.006 (3)
C150.028 (4)0.029 (4)0.035 (5)0.006 (3)0.003 (3)0.002 (3)
C160.025 (4)0.030 (4)0.031 (4)0.010 (3)0.011 (3)0.011 (3)
N210.027 (3)0.024 (3)0.022 (3)0.010 (3)0.002 (3)0.002 (3)
C220.028 (4)0.031 (4)0.027 (4)0.013 (3)0.007 (3)0.007 (3)
C230.037 (5)0.033 (5)0.038 (5)0.018 (4)0.003 (4)0.001 (4)
C2310.067 (7)0.043 (6)0.055 (6)0.033 (5)0.008 (5)0.023 (5)
C240.039 (5)0.038 (5)0.049 (6)0.023 (4)0.003 (4)0.001 (4)
C250.035 (5)0.051 (6)0.043 (5)0.025 (4)0.014 (4)0.008 (4)
C260.029 (4)0.034 (4)0.031 (4)0.012 (3)0.008 (3)0.008 (3)
C10.058 (7)0.052 (6)0.059 (7)0.016 (5)0.002 (5)0.015 (5)
Cl110.186 (5)0.070 (2)0.090 (3)0.052 (3)0.002 (3)0.009 (2)
Cl120.077 (3)0.123 (4)0.098 (3)0.007 (2)0.028 (2)0.030 (3)
Cl130.064 (2)0.084 (3)0.122 (4)0.0043 (19)0.003 (2)0.013 (2)
C20.043 (6)0.050 (6)0.053 (6)0.018 (5)0.006 (5)0.010 (5)
Cl210.058 (2)0.114 (3)0.072 (2)0.0119 (19)0.0015 (17)0.014 (2)
Cl220.065 (2)0.091 (2)0.079 (2)0.0296 (18)0.0071 (16)0.0325 (19)
Cl230.065 (2)0.125 (3)0.092 (3)0.024 (2)0.0131 (18)0.068 (3)
Br10.0433 (5)0.0395 (5)0.0363 (5)0.0135 (4)0.0107 (4)0.0144 (4)
Geometric parameters (Å, º) top
Si1—H11.401 (10)N21—C261.363 (10)
Si1—N211.966 (6)C22—C231.388 (11)
Si1—N21i1.966 (6)C22—H220.9500
Si1—N11i1.990 (7)C23—C241.393 (13)
Si1—N111.990 (7)C23—C2311.505 (12)
Si1—H11.401 (10)C231—H23A0.9800
N11—C121.349 (10)C231—H23B0.9800
N11—C161.363 (10)C231—H23C0.9800
C12—C131.396 (12)C24—C251.389 (13)
C12—H120.9500C24—H240.9500
C13—C141.435 (12)C25—C261.371 (12)
C13—C1311.478 (14)C25—H250.9500
C131—H13A0.9800C26—H260.9500
C131—H13B0.9800C1—Cl131.729 (12)
C131—H13C0.9800C1—Cl111.752 (12)
C14—C151.354 (12)C1—Cl121.769 (12)
C14—H140.9500C1—H111.0000
C15—C161.378 (12)C2—Cl221.743 (11)
C15—H150.9500C2—Cl231.758 (11)
C16—H160.9500C2—Cl211.760 (11)
N21—C221.353 (10)C2—H211.0000
H1—Si1—N2190 (3)C15—C16—H16119.2
H1—Si1—N21i90 (3)C22—N21—C26118.3 (7)
N21—Si1—N21i179.999 (1)C22—N21—Si1120.6 (5)
H1—Si1—N11i88 (3)C26—N21—Si1121.1 (5)
N21—Si1—N11i90.2 (3)N21—C22—C23123.3 (7)
N21i—Si1—N11i89.8 (3)N21—C22—H22118.4
H1—Si1—N1192 (3)C23—C22—H22118.4
N21—Si1—N1189.8 (3)C22—C23—C24117.6 (8)
N21i—Si1—N1190.2 (3)C22—C23—C231120.6 (8)
N11i—Si1—N11179.999 (1)C24—C23—C231121.8 (8)
H1—Si1—H10 (3)C23—C231—H23A109.5
N21—Si1—H190 (3)C23—C231—H23B109.5
N21i—Si1—H190 (3)H23A—C231—H23B109.5
N11i—Si1—H188 (3)C23—C231—H23C109.5
N11—Si1—H192 (3)H23A—C231—H23C109.5
C12—N11—C16119.6 (7)H23B—C231—H23C109.5
C12—N11—Si1120.1 (5)C25—C24—C23119.4 (8)
C16—N11—Si1120.3 (5)C25—C24—H24120.3
N11—C12—C13122.0 (8)C23—C24—H24120.3
N11—C12—H12119.0C26—C25—C24120.2 (8)
C13—C12—H12119.0C26—C25—H25119.9
C12—C13—C14116.8 (8)C24—C25—H25119.9
C12—C13—C131120.6 (8)N21—C26—C25121.2 (8)
C14—C13—C131122.6 (8)N21—C26—H26119.4
C13—C131—H13A109.5C25—C26—H26119.4
C13—C131—H13B109.5Cl13—C1—Cl11109.6 (7)
H13A—C131—H13B109.5Cl13—C1—Cl12110.7 (7)
C13—C131—H13C109.5Cl11—C1—Cl12111.5 (7)
H13A—C131—H13C109.5Cl13—C1—H11108.3
H13B—C131—H13C109.5Cl11—C1—H11108.3
C15—C14—C13120.4 (8)Cl12—C1—H11108.3
C15—C14—H14119.8Cl22—C2—Cl23110.7 (6)
C13—C14—H14119.8Cl22—C2—Cl21109.7 (6)
C14—C15—C16119.7 (8)Cl23—C2—Cl21110.6 (6)
C14—C15—H15120.2Cl22—C2—H21108.6
C16—C15—H15120.2Cl23—C2—H21108.6
N11—C16—C15121.6 (7)Cl21—C2—H21108.6
N11—C16—H16119.2
H1—Si1—N11—C12177 (3)H1—Si1—N21—C22178 (3)
N21—Si1—N11—C1286.8 (6)N11i—Si1—N21—C2294.4 (6)
N21i—Si1—N11—C1293.2 (6)N11—Si1—N21—C2285.6 (6)
H1—Si1—N11—C162 (3)H1—Si1—N21—C261 (3)
N21—Si1—N11—C1692.5 (6)N11i—Si1—N21—C2686.5 (6)
N21i—Si1—N11—C1687.5 (6)N11—Si1—N21—C2693.5 (6)
C16—N11—C12—C131.0 (12)C26—N21—C22—C230.2 (12)
Si1—N11—C12—C13179.7 (6)Si1—N21—C22—C23179.4 (7)
N11—C12—C13—C140.2 (12)N21—C22—C23—C240.5 (13)
N11—C12—C13—C131180.0 (9)N21—C22—C23—C231179.6 (8)
C12—C13—C14—C151.0 (13)C22—C23—C24—C250.4 (14)
C131—C13—C14—C15178.8 (9)C231—C23—C24—C25179.7 (9)
C13—C14—C15—C161.3 (13)C23—C24—C25—C260.5 (15)
C12—N11—C16—C150.7 (11)C22—N21—C26—C251.1 (12)
Si1—N11—C16—C15180.0 (6)Si1—N21—C26—C25179.7 (7)
C14—C15—C16—N110.5 (12)C24—C25—C26—N211.3 (14)
Symmetry code: (i) x, y+1, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C1—H11···Br1ii1.002.583.565 (12)170
C2—H21···Br1iii1.002.523.519 (11)174
Symmetry codes: (ii) x+1, y+1, z; (iii) x, y1, z+1.

Experimental details

Crystal data
Chemical formulaC28H34Br2Cl12N4Si
Mr1039.90
Crystal system, space groupTriclinic, P1
Temperature (K)173
a, b, c (Å)8.840 (1), 10.059 (1), 13.330 (1)
α, β, γ (°)97.65 (1), 90.68 (1), 108.63 (1)
V3)1111.35 (19)
Z1
Radiation typeMo Kα
µ (mm1)2.60
Crystal size (mm)0.40 × 0.35 × 0.20
Data collection
DiffractometerSiemens CCD three-circle
diffractometer
Absorption correctionEmpirical
(SADABS; Sheldrick, 1996)
Tmin, Tmax0.37, 0.60
No. of measured, independent and
observed [I > 2σ(I)] reflections
22862, 5095, 3406
Rint0.087
(sin θ/λ)max1)0.649
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.093, 0.268, 1.11
No. of reflections5095
No. of parameters219
No. of restraints1
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
w = 1/[σ2(Fo2) + (0.0856P)2 + 12.6187P]
where P = (Fo2 + 2Fc2)/3
Δρmax, Δρmin (e Å3)2.39, 0.85

Computer programs: SMART (Siemens, 1995), SMART, SAINT (Siemens, 1995), SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), XP in SHELXTL-Plus (Sheldrick, 1991).

Selected geometric parameters (Å, º) top
Si1—N211.966 (6)
N21—Si1—N1189.8 (3)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C1—H11···Br1i1.002.583.565 (12)169.9
C2—H21···Br1ii1.002.523.519 (11)173.9
Symmetry codes: (i) x+1, y+1, z; (ii) x, y1, z+1.
 

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