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In the title compound, C8H22Cl2N2Si3, the central Si atom is tetra­hedrally coordinated by two Cl and two N atoms in a mol­ecule that has crystallographically imposed C2 symmetry. Comparison is made with the isomorphous structure having titanium instead of silicon at the central position in the diaza­cyclo­pentane ring [Tinkler, Deeth, Duncalf & McCamley (1996). Chem. Commun. pp. 2623-2624].

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270107045969/ga3074sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270107045969/ga3074Isup2.hkl
Contains datablock I

CCDC reference: 669180

Comment top

Chlorine-containing silicon compounds are useful synthons for the preparation of a variety of organosilanes, higher coordinated silicon derivatives and organopolysilanes (Pawlenko, 1980; Corriu & Young, 1989; West, 1995; Herzog, 2001). Crystallization of the title compound, (I), occurs from a saturated solution in pentane at 248 K. The crystals redissolve when the temperature in the Schlenk tube rises above 273 K.

Fig. 1 shows the molecular structure of (I) and the atomic labelling scheme. Selected bond lengths and angles are listed in Table 1. Only half of the molecule is in the asymmetric unit. There is a twofold rotation axis passing through the Si atom and the middle of the C—C bond in the backbone of the diamide substituent. The central Si atom (Si1) is tetrahedrally coordinated by two Cl and two N atoms. Atom Si2 is also tetrahedrally coordinated, by three methyl groups and the N atom. Atom N1 has trigonal planar geometry coordinated by the two Si atoms and atom C1 (the sum of the bond angles at N is 359.25°). The five-membered ring is in a half chair conformation, in accordance with the crystallographic C2 symmetry.

There are few reports of compounds containing the 1,3-diaza-2,2-dichloro-2-silacyclopentane fragment (e.g. Schlosser et al., 1994) but surprisingly there exists an isomorphous structure with titanium instead of silicon at the central position in the diazacyclopentane ring (Tinkler et al., 1996). Comparison with the titanium compound, (II), shows that the molecular geometry is very similar (Fig. 2). Differences between the two molecules arise from the different atomic radii of silicon and titanium. We observed differences of 0.204 (1) (for M—Cl) and 0.157 (2) Å (for M—N) compared with the usual radii difference value (Pauling, 1962) of 0.19 Å. Thus the Ti—Cl1 [2.2603 (6) Å] and Ti—N1 [1.844 (2) Å] bonds are longer than the Si1—Cl1 and Si1—N1 bonds by 9.9 and 9.4%, respectively. These different bond lengths also lead to different bond angles at the central atom. The N—M—N angle is 91.0 (1)° in (II) compared with the larger value here (Table 1). This deformation allows the diamide ligand to retain its geometric features. The deformation of the five-membered ring from the titanium to the isomorphous silicon compound is shown in Fig. 2 in a superposition plot of both molecules. By contrast the other angle in the coordination tetrahedron is compressed here from 110.73 (4)° (Cl1—Ti—Cl1A) by 8.86 (4)°. The molecules of the titanium and silicon compounds are arranged in the cell in an antiparallel orientation along the b axis. There are no intermolecular interactions within the sum of the van der Waals radii.

The structure of (I) is an example that titanium can be replaced by silicon with formation of isomorphous compounds. Compound (I) might serve as a useful synthon for the preparation of organosilanes.

Related literature top

For related literature, see: Corriu & Young (1989); Herzog (2001); Pawlenko (1980); Tinkler et al. (1996); West (1995).

Experimental top

Triethylamine (5 ml, 0.036 mol) was added to a solution of silicon tetrachloride (2 ml, 0.017 mol) in 100 ml of tetrahydrofuran. 1,3-Bis(trimethylsilyl)ethylenediamine (3.27 g, 0.016 mol) was dissolved in tetrahydrofuran and added dropwise to the reaction mixture. A white precipitate of triethylammonium chloride was formed. The suspension was stirred for 6 h at reflux temperature. The solid triethylammonium chloride was removed by filtration. Afterwards the solvent and the excess of triethylamine were distilled off at reduced pressure. The product was distilled at 0.013 Torr and 303–323 K. The viscous liquid that was obtained after distillation solidified on standing overnight at room temperature (3.3 g, 68% yield, m.p. 356 K). Suitable crystals for X-ray structure analysis were obtained by recrystallization from pentane and storage in a freezer at 248 K for several weeks. NMR (CDCl3, 298 K, TMS): 1H δ 0.19 (s, SiMe3), 3.16 (s, –CH2–); 13C δ −0.5 (SiMe3), 45.2 (–CH2); 29Si δ −18.6 (SiCl2), 6.2 (SiMe3).

Refinement top

Atoms H1 and H2 at C1 were located by difference Fourier synthesis and refined without constraints. The positions of the H atoms of the methyl groups were idealized and constrained to ride on their parent atoms with Uiso(H) = 1.5Ueq(C).

Computing details top

Data collection: SMART (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP in SHELXTL-Plus (Sheldrick, 1991); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).

Figures top
[Figure 1] Fig. 1. The molecular structure of (I), drawn with 50% probability displacement ellipsoids. Symmetry equivalent atoms with label `A' are generated by twofold rotation (−x, y, −z + 1/2).
[Figure 2] Fig. 2. uperposition plot of (I) and the isomorphous titanium compound (II) [XP in SHELXTL-Plus (Sheldrick, 1991)]. The solid line is for (I), the broken line for (II).
2,2-Dichloro-1,3-bis(trimethylsilyl)-1,3-diaza-2-silacyclopentane top
Crystal data top
C8H22Cl2N2Si3Dx = 1.247 Mg m3
Mr = 301.45Melting point: 356 K
Orthorhombic, PbcnMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2n 2abCell parameters from 6642 reflections
a = 6.8227 (2) Åθ = 2.3–29.9°
b = 13.4226 (4) ŵ = 0.61 mm1
c = 17.5317 (5) ÅT = 153 K
V = 1605.52 (8) Å3Prism, colourless
Z = 40.50 × 0.45 × 0.35 mm
F(000) = 640
Data collection top
Bruker SMART CCD area-detector
diffractometer
2488 independent reflections
Radiation source: sealed tube2143 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.027
ϕ and ω scansθmax = 30.7°, θmin = 2.3°
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
h = 99
Tmin = 0.752, Tmax = 0.816k = 1919
18751 measured reflectionsl = 2525
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)] = 0.025Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.068H atoms treated by a mixture of independent and constrained refinement
S = 0.97 w = 1/[σ2(Fo2) + (0.0371P)2 + 0.5172P]
where P = (Fo2 + 2Fc2)/3
2488 reflections(Δ/σ)max = 0.001
80 parametersΔρmax = 0.38 e Å3
0 restraintsΔρmin = 0.18 e Å3
Crystal data top
C8H22Cl2N2Si3V = 1605.52 (8) Å3
Mr = 301.45Z = 4
Orthorhombic, PbcnMo Kα radiation
a = 6.8227 (2) ŵ = 0.61 mm1
b = 13.4226 (4) ÅT = 153 K
c = 17.5317 (5) Å0.50 × 0.45 × 0.35 mm
Data collection top
Bruker SMART CCD area-detector
diffractometer
2488 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
2143 reflections with I > 2σ(I)
Tmin = 0.752, Tmax = 0.816Rint = 0.027
18751 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0250 restraints
wR(F2) = 0.068H atoms treated by a mixture of independent and constrained refinement
S = 0.97Δρmax = 0.38 e Å3
2488 reflectionsΔρmin = 0.18 e Å3
80 parameters
Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Si10.00000.47382 (3)0.25000.02097 (9)
Si20.27136 (5)0.40677 (2)0.113829 (16)0.02537 (8)
Cl10.18785 (5)0.57036 (2)0.304291 (18)0.03464 (9)
N10.11682 (14)0.39286 (6)0.19215 (5)0.02460 (18)
H10.137 (2)0.2441 (11)0.2031 (8)0.033 (4)*
H20.070 (2)0.2735 (10)0.1735 (8)0.032 (4)*
C10.03830 (19)0.29159 (8)0.20917 (7)0.0306 (2)
C20.3154 (2)0.54219 (9)0.09897 (8)0.0354 (3)
H2A0.18980.57630.09180.053*
H2B0.39730.55170.05360.053*
H2C0.38240.56980.14370.053*
C30.50677 (19)0.34119 (9)0.13255 (8)0.0369 (3)
H3A0.56860.36930.17820.055*
H3B0.59440.34960.08870.055*
H3C0.48140.27010.14060.055*
C40.1510 (3)0.35033 (13)0.02898 (8)0.0504 (4)
H4A0.13020.27900.03790.076*
H4B0.23490.35930.01590.076*
H4C0.02450.38290.02020.076*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Si10.02333 (19)0.01455 (16)0.02502 (19)0.0000.00037 (14)0.000
Si20.02933 (16)0.02430 (14)0.02246 (14)0.00195 (11)0.00060 (11)0.00170 (10)
Cl10.03630 (16)0.02733 (14)0.04030 (16)0.00977 (11)0.00224 (12)0.00768 (10)
N10.0290 (5)0.0161 (3)0.0286 (4)0.0008 (3)0.0024 (3)0.0011 (3)
C10.0386 (6)0.0163 (4)0.0368 (6)0.0002 (4)0.0038 (5)0.0028 (4)
C20.0380 (6)0.0289 (5)0.0394 (6)0.0018 (5)0.0065 (5)0.0071 (5)
C30.0343 (6)0.0349 (6)0.0415 (7)0.0092 (5)0.0038 (5)0.0033 (5)
C40.0610 (9)0.0616 (9)0.0286 (6)0.0121 (7)0.0087 (6)0.0063 (6)
Geometric parameters (Å, º) top
Si1—N11.6866 (9)C2—H2A0.9800
Si1—Cl12.0562 (3)C2—H2B0.9800
Si2—N11.7413 (10)C2—H2C0.9800
Si2—C41.8605 (14)C3—H3A0.9800
Si2—C31.8607 (13)C3—H3B0.9800
Si2—C21.8606 (13)C3—H3C0.9800
N1—C11.4912 (14)C4—H4A0.9800
C1—C1i1.524 (2)C4—H4B0.9800
C1—H10.933 (16)C4—H4C0.9800
C1—H21.000 (15)
N1i—Si1—N199.77 (6)H1—C1—H2107.3 (12)
N1i—Si1—Cl1114.98 (3)Si2—C2—H2A109.5
N1—Si1—Cl1112.94 (3)Si2—C2—H2B109.5
N1i—Si1—Cl1i112.94 (3)H2A—C2—H2B109.5
N1—Si1—Cl1i114.98 (3)Si2—C2—H2C109.5
Cl1—Si1—Cl1i101.87 (2)H2A—C2—H2C109.5
N1—Si2—C4108.64 (6)H2B—C2—H2C109.5
N1—Si2—C3109.44 (6)Si2—C3—H3A109.5
C4—Si2—C3109.23 (7)Si2—C3—H3B109.5
N1—Si2—C2108.24 (5)H3A—C3—H3B109.5
C4—Si2—C2110.93 (7)Si2—C3—H3C109.5
C3—Si2—C2110.33 (6)H3A—C3—H3C109.5
C1—N1—Si1107.29 (7)H3B—C3—H3C109.5
C1—N1—Si2118.23 (7)Si2—C4—H4A109.5
Si1—N1—Si2133.73 (5)Si2—C4—H4B109.5
N1—C1—C1i108.12 (6)H4A—C4—H4B109.5
N1—C1—H1109.9 (9)Si2—C4—H4C109.5
C1i—C1—H1110.7 (9)H4A—C4—H4C109.5
N1—C1—H2111.3 (8)H4B—C4—H4C109.5
C1i—C1—H2109.5 (8)
N1i—Si1—N1—C19.58 (6)C3—Si2—N1—C167.80 (10)
Cl1—Si1—N1—C1132.14 (7)C2—Si2—N1—C1171.92 (9)
Cl1i—Si1—N1—C1111.53 (7)C4—Si2—N1—Si1117.26 (10)
N1i—Si1—N1—Si2179.11 (10)C3—Si2—N1—Si1123.55 (8)
Cl1—Si1—N1—Si258.33 (8)C2—Si2—N1—Si13.27 (10)
Cl1i—Si1—N1—Si258.00 (9)Si1—N1—C1—C1i25.45 (14)
C4—Si2—N1—C151.39 (11)Si2—N1—C1—C1i163.12 (10)
Symmetry code: (i) x, y, z+1/2.

Experimental details

Crystal data
Chemical formulaC8H22Cl2N2Si3
Mr301.45
Crystal system, space groupOrthorhombic, Pbcn
Temperature (K)153
a, b, c (Å)6.8227 (2), 13.4226 (4), 17.5317 (5)
V3)1605.52 (8)
Z4
Radiation typeMo Kα
µ (mm1)0.61
Crystal size (mm)0.50 × 0.45 × 0.35
Data collection
DiffractometerBruker SMART CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Sheldrick, 1996)
Tmin, Tmax0.752, 0.816
No. of measured, independent and
observed [I > 2σ(I)] reflections
18751, 2488, 2143
Rint0.027
(sin θ/λ)max1)0.718
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.025, 0.068, 0.97
No. of reflections2488
No. of parameters80
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.38, 0.18

Computer programs: SMART (Bruker, 2004), SAINT (Bruker, 2004), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), XP in SHELXTL-Plus (Sheldrick, 1991).

Selected geometric parameters (Å, º) top
Si1—N11.6866 (9)N1—C11.4912 (14)
Si1—Cl12.0562 (3)C1—C1i1.524 (2)
Si2—N11.7413 (10)
N1i—Si1—N199.77 (6)C1—N1—Si2118.23 (7)
Cl1—Si1—Cl1i101.87 (2)Si1—N1—Si2133.73 (5)
C1—N1—Si1107.29 (7)
Symmetry code: (i) x, y, z+1/2.
 

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