Dihydridotetrakis(4-picoline-N)­silicon dichloride chloro­form hexasolvate

The title compound, [SiH₂(C₆H₇N)₄]Cl₂·6CHCl₃ or C₂₄H₃₀N₄Si²⁺·2Cl^-·6CHCl₃, 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 4-picoline ligands in the equatorial plane and the two H atoms occupying axial positions. The title compound is isomorphous with its analogue where the Cl ions are substituted by Br ions.

Key indicators

• Single-crystal X-ray study
• T = 150 K
• Mean [sigma](C-C) = 0.009 Å
• R factor = 0.069
• wR factor = 0.181
• Data-to-parameter ratio = 17.6

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level C:



PLAT_420  Alert C D-H Without Acceptor       Si1    -   H1SI              ?


 0 Alert Level A = Potentially serious problem

 0 Alert Level B = Potential problem

 1 Alert Level C = Please check

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S1. Comment

Lewis acid–base complexes between silicon compounds and nitrogen bases have in recent years been the subject of many structural studies (Hensen et al., 1988, 1997; Chuit et al. 1993). In addition to [H₂Si(3-picoline)₄]Cl₂^.4CHCl₃ (Fleischer et al., 1996), [H₂Si(pyridine)₄]Cl₂^.4CHCl₃ (Hensen et al., 1998), [H₂Si(N-methylimidazole)₄]Cl₂^.3CHCl₃ (Hensen, Mayr-Stein et al., 2000), [H₂Si(3,4-lutidine)₄]Cl₂^.6CHCl₃ (Hensen, Kettner et al., 2000) and [H₂Si(3,5-lutidine)₄]Br₂^.2CH₃CN (Bolte et al., 2000), the crystal structure of the title compound, (I), is a further example with the structural element SiH₂. The title compound is an ionic complex with the Si atom located on a crystallographic centre of inversion and with half a molecule in the asymmetric unit. The coordination of the Si atom can be described as a slightly distorted octahedron, with the picoline ligands in the equatorial plane and the two H atoms occupying axial positions. Two Cl^- ions are displaced from the first sphere of coordination. The title compound is isomorphous with its analogue where the Cl ions are substituted by Br ions (Bolte & Faber, 2001).

The title compound was prepared in two different ways. Firstly, the reaction of 4-picoline with bis(dichlorosilyl)methylamine affords directly the crystals of the title compound. A second way to synthesize (I) is the reaction of liquid dichlorosilane with 4-picoline to form H₂SiCl₂(4-picoline)₂. With an excess of base in chloroform this adduct forms again the title compound.

S2. Experimental

The title compound was prepared in two different ways: (i) 0.60 ml (3.46 mmol) bis(dichlorosilyl)methylamine, prepared and purified according to Fleischer et al. (1995), was dissolved in 5.0 ml chloroform. Then 1.0 ml (10.24 mmol) 4-picoline was added in portions of 0.2 ml. After several days, colourless crystals had formed. They were isolated, washed with n-hexane, and a single-crystal was selected for the diffraction experiment. (ii) 1.0 ml (13.9 mmol) H₂SiCl₂ (liquid) was condensed into 50 ml n-hexane and 6.0 ml (66.4 mmol) 4-picoline was added within 30 min whilst the solution was stirred and kept at 213 K. The solution was then allowed to warm to room temperature. The formation of a white precipitate was observed. This precipitate was washed with n-hexane and dried in vacuo. Yield: 100%; C₁₂H₁₆Cl₂N₂Si (287.3), calculated: C 50.2, H 5.6, Cl 24.7, N 9.8%; found: C 48.3, H 5.7, Cl 25.4, N9.0%; IR (Nujol, NaCl, cm^-1): 2922.1 (versus), 2855.3 (versus), 2165.5 (br,s), 1626.8 (s), 1581.1 (s), 1459.6 (versus), 1376.2 (versus), 1315.0 (m), 1203.7 (m), 997.8 (s), 992.6 (s), 825.4 (m). Single crystals were grown from a solution of 150 mg (0.52 mmol) H₂SiCl₂(4-picoline)₂ and 0.2 ml (2.0 mmol) 4-picoline in 3.0 ml CHCl₃ at 277 K within 5 d. After cell determination, the selected crystal turned out to contain the identical structure as the former crystal, which was used for data collection. All procedures were carried out under argon (dried with 4 Å molecular sieves and Sicapent) either on a vacuum line or in a glove-box. 4-Picoline was distilled from CaH₂ and sealed in ampules. H₂SiCl₂ (Aldrich, 99.99%) was used without further purification.

S3. Refinement

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

Computing details

Data collection: DIF4 (Stoe & Cie, 1992); cell refinement: DIF4; data reduction: REDU4 (Stoe & Cie, 1992); 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); software used to prepare material for publication: CIFTAB in SHELXL97.

Figures

	Fig. 1. A perspective view of the cation 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.
	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)

Crystal data

C24H30N4Si^2+·2Cl^−·6CHCl3	Z = 1
Mr = 1189.72	F(000) = 598
Triclinic, P1	Dx = 1.534 Mg m^−3
a = 9.3854 (8) Å	Mo Kα radiation, λ = 0.71073 Å
b = 11.0958 (9) Å	Cell parameters from 35 reflections
c = 12.7495 (11) Å	θ = 2.3–15.2°
α = 93.018 (5)°	µ = 1.11 mm^−1
β = 101.092 (5)°	T = 150 K
γ = 97.548 (4)°	Plate, colourless
V = 1287.47 (19) Å^3	0.4 × 0.3 × 0.2 mm

Data collection

Stoe four-circle diffractometer	3349 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.017
Graphite monochromator	θmax = 25.0°, θmin = 1.9°
ω/θ scans	h = −11→10
Absorption correction: ψ scan (North et al., 1968)	k = −13→13
Tmin = 0.665, Tmax = 0.808	l = −14→15
4775 measured reflections	3 standard reflections every 120 min
4518 independent reflections	intensity decay: 3%

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.069	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.181	H atoms treated by a mixture of independent and constrained refinement
S = 1.19	w = 1/[σ^2(Fo^2) + (0.0575P)^2 + 3.942P] where P = (Fo^2 + 2Fc^2)/3
4518 reflections	(Δ/σ)max < 0.001
256 parameters	Δρmax = 0.81 e Å^−3
0 restraints	Δρmin = −0.56 e Å^−3

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
Si1	0.0000	0.5000	0.0000	0.0296 (4)
H1SI	0.108 (5)	0.476 (4)	−0.053 (3)	0.016 (11)*
N1	0.1178 (4)	0.6531 (4)	0.0666 (3)	0.0294 (9)
C1	0.2401 (6)	0.6974 (5)	0.0340 (4)	0.0344 (12)
H1	0.2671	0.6554	−0.0243	0.041*
C2	0.3278 (6)	0.8019 (5)	0.0825 (5)	0.0390 (13)
H2	0.4132	0.8316	0.0567	0.047*
C3	0.2930 (6)	0.8639 (5)	0.1680 (4)	0.0399 (13)
C4	0.1651 (6)	0.8182 (5)	0.1995 (4)	0.0404 (13)
H4	0.1361	0.8590	0.2577	0.048*
C5	0.0805 (6)	0.7155 (5)	0.1481 (4)	0.0383 (12)
H5	−0.0080	0.6868	0.1704	0.046*
C6	0.3894 (8)	0.9760 (6)	0.2251 (6)	0.0604 (18)
H6A	0.4658	0.9522	0.2807	0.091*
H6B	0.3302	1.0273	0.2583	0.091*
H6C	0.4353	1.0218	0.1736	0.091*
N2	0.0881 (4)	0.4163 (3)	0.1220 (3)	0.0308 (9)
C11	0.0297 (6)	0.4069 (5)	0.2096 (4)	0.0374 (12)
H11	−0.0609	0.4363	0.2096	0.045*
C12	0.0944 (7)	0.3571 (5)	0.2986 (5)	0.0440 (14)
H12	0.0505	0.3546	0.3598	0.053*
C13	0.2251 (7)	0.3098 (5)	0.2999 (5)	0.0460 (14)
C14	0.2827 (6)	0.3168 (5)	0.2080 (5)	0.0407 (13)
H14	0.3707	0.2846	0.2044	0.049*
C15	0.2130 (6)	0.3701 (5)	0.1226 (5)	0.0361 (12)
H15	0.2550	0.3746	0.0606	0.043*
C16	0.3002 (9)	0.2539 (8)	0.3958 (6)	0.077 (2)
H16A	0.2438	0.1750	0.4029	0.115*
H16B	0.3071	0.3082	0.4603	0.115*
H16C	0.3990	0.2420	0.3870	0.115*
Cl1	0.65044 (15)	0.25888 (12)	0.20878 (11)	0.0386 (3)
C31	0.6162 (7)	0.5510 (5)	0.2619 (5)	0.0461 (14)
H31	0.6061	0.4606	0.2657	0.055*
Cl2	0.4844 (2)	0.60734 (17)	0.32400 (16)	0.0677 (5)
Cl3	0.5845 (2)	0.58228 (18)	0.12667 (14)	0.0658 (5)
Cl4	0.79421 (19)	0.61549 (16)	0.32824 (14)	0.0595 (4)
C41	0.7794 (7)	0.2108 (6)	0.4661 (5)	0.0507 (15)
H41	0.7577	0.2131	0.3864	0.061*
Cl5	0.7986 (3)	0.35853 (18)	0.52606 (19)	0.0896 (7)
Cl6	0.9442 (2)	0.1520 (2)	0.50568 (17)	0.0782 (6)
Cl7	0.6361 (2)	0.1190 (2)	0.50503 (17)	0.0835 (7)
C51	0.8032 (7)	0.0146 (6)	0.1422 (5)	0.0530 (16)
H51	0.7404	0.0800	0.1468	0.064*
Cl8	0.8189 (3)	−0.0590 (3)	0.26041 (18)	0.1050 (9)
Cl9	0.9733 (2)	0.08113 (16)	0.1209 (2)	0.0804 (7)
Cl10	0.7172 (2)	−0.09081 (15)	0.03440 (15)	0.0651 (5)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Si1	0.0297 (10)	0.0215 (9)	0.0399 (11)	0.0038 (8)	0.0129 (9)	0.0007 (8)
N1	0.029 (2)	0.024 (2)	0.037 (2)	0.0056 (17)	0.0119 (18)	0.0019 (17)
C1	0.034 (3)	0.030 (3)	0.042 (3)	0.004 (2)	0.013 (2)	0.004 (2)
C2	0.039 (3)	0.028 (3)	0.049 (3)	−0.006 (2)	0.013 (3)	0.000 (2)
C3	0.044 (3)	0.030 (3)	0.040 (3)	0.001 (2)	−0.003 (2)	0.007 (2)
C4	0.054 (4)	0.028 (3)	0.037 (3)	0.000 (2)	0.011 (3)	−0.006 (2)
C5	0.040 (3)	0.034 (3)	0.046 (3)	0.005 (2)	0.019 (3)	0.002 (2)
C6	0.068 (4)	0.047 (4)	0.055 (4)	−0.016 (3)	0.004 (3)	−0.006 (3)
N2	0.029 (2)	0.021 (2)	0.043 (2)	0.0026 (16)	0.0105 (19)	−0.0021 (17)
C11	0.038 (3)	0.035 (3)	0.042 (3)	0.009 (2)	0.014 (2)	−0.001 (2)
C12	0.051 (4)	0.048 (3)	0.039 (3)	0.018 (3)	0.016 (3)	0.003 (3)
C13	0.051 (4)	0.042 (3)	0.040 (3)	0.009 (3)	−0.001 (3)	−0.005 (3)
C14	0.035 (3)	0.035 (3)	0.051 (3)	0.009 (2)	0.005 (3)	−0.002 (3)
C15	0.032 (3)	0.031 (3)	0.048 (3)	0.007 (2)	0.013 (2)	0.000 (2)
C16	0.089 (6)	0.094 (6)	0.050 (4)	0.047 (5)	−0.001 (4)	0.008 (4)
Cl1	0.0443 (8)	0.0312 (7)	0.0456 (8)	0.0125 (6)	0.0167 (6)	0.0045 (5)
C31	0.059 (4)	0.034 (3)	0.049 (3)	0.010 (3)	0.019 (3)	−0.006 (3)
Cl2	0.0625 (11)	0.0692 (11)	0.0752 (12)	0.0079 (9)	0.0315 (9)	−0.0199 (9)
Cl3	0.0739 (12)	0.0751 (12)	0.0571 (10)	0.0287 (10)	0.0201 (9)	0.0154 (9)
Cl4	0.0527 (9)	0.0559 (10)	0.0682 (11)	0.0030 (7)	0.0148 (8)	−0.0083 (8)
C41	0.059 (4)	0.050 (4)	0.042 (3)	0.009 (3)	0.005 (3)	0.006 (3)
Cl5	0.127 (2)	0.0533 (11)	0.0940 (16)	0.0193 (12)	0.0350 (14)	−0.0049 (10)
Cl6	0.0658 (12)	0.0859 (14)	0.0810 (13)	0.0267 (10)	0.0005 (10)	0.0026 (11)
Cl7	0.0661 (12)	0.0966 (15)	0.0763 (13)	−0.0176 (11)	−0.0010 (10)	0.0323 (11)
C51	0.061 (4)	0.041 (3)	0.058 (4)	0.021 (3)	0.009 (3)	−0.003 (3)
Cl8	0.148 (2)	0.126 (2)	0.0620 (13)	0.0764 (18)	0.0263 (14)	0.0311 (13)
Cl9	0.0526 (10)	0.0450 (10)	0.1359 (19)	0.0031 (8)	0.0062 (11)	−0.0060 (11)
Cl10	0.0751 (12)	0.0440 (9)	0.0730 (12)	−0.0101 (8)	0.0236 (9)	−0.0102 (8)

Geometric parameters (Å, º)

Si1—N2^i	1.955 (4)	C12—C13	1.394 (8)
Si1—N2	1.955 (4)	C12—H12	0.950
Si1—N1	1.955 (4)	C13—C14	1.383 (8)
Si1—N1^i	1.955 (4)	C13—C16	1.497 (9)
Si1—H1SI	1.37 (4)	C14—C15	1.363 (8)
N1—C1	1.338 (6)	C14—H14	0.950
N1—C5	1.345 (6)	C15—H15	0.950
C1—C2	1.371 (7)	C16—H16A	0.980
C1—H1	0.950	C16—H16B	0.980
C2—C3	1.373 (8)	C16—H16C	0.980
C2—H2	0.950	C31—Cl3	1.753 (6)
C3—C4	1.381 (8)	C31—Cl2	1.754 (6)
C3—C6	1.501 (8)	C31—Cl4	1.760 (6)
C4—C5	1.357 (8)	C31—H31	1.000
C4—H4	0.950	C41—Cl5	1.744 (7)
C5—H5	0.950	C41—Cl7	1.744 (7)
C6—H6A	0.980	C41—Cl6	1.753 (7)
C6—H6B	0.980	C41—H41	1.000
C6—H6C	0.980	C51—Cl8	1.742 (7)
N2—C11	1.339 (7)	C51—Cl9	1.746 (7)
N2—C15	1.339 (6)	C51—Cl10	1.751 (6)
C11—C12	1.360 (8)	C51—H51	1.000
C11—H11	0.950
N2^i—Si1—N2	180.0	N2—C11—H11	118.5
N2^i—Si1—N1	90.66 (17)	C12—C11—H11	118.5
N2—Si1—N1	89.34 (17)	C11—C12—C13	119.9 (5)
N2^i—Si1—N1^i	89.34 (17)	C11—C12—H12	120.0
N2—Si1—N1^i	90.66 (17)	C13—C12—H12	120.0
N1—Si1—N1^i	180.0	C14—C13—C12	116.9 (5)
N2^i—Si1—H1SI	89.6 (18)	C14—C13—C16	121.2 (6)
N2—Si1—H1SI	90.4 (18)	C12—C13—C16	121.9 (6)
N1—Si1—H1SI	90.8 (18)	C15—C14—C13	119.9 (5)
N1^i—Si1—H1SI	89.2 (18)	C15—C14—H14	120.1
C1—N1—C5	117.9 (4)	C13—C14—H14	120.1
C1—N1—Si1	120.9 (3)	N2—C15—C14	123.1 (5)
C5—N1—Si1	121.2 (3)	N2—C15—H15	118.4
N1—C1—C2	121.9 (5)	C14—C15—H15	118.4
N1—C1—H1	119.0	C13—C16—H16A	109.5
C2—C1—H1	119.0	C13—C16—H16B	109.5
C1—C2—C3	120.4 (5)	H16A—C16—H16B	109.5
C1—C2—H2	119.8	C13—C16—H16C	109.5
C3—C2—H2	119.8	H16A—C16—H16C	109.5
C2—C3—C4	117.0 (5)	H16B—C16—H16C	109.5
C2—C3—C6	121.7 (5)	Cl3—C31—Cl2	109.4 (3)
C4—C3—C6	121.3 (5)	Cl3—C31—Cl4	110.9 (3)
C5—C4—C3	120.5 (5)	Cl2—C31—Cl4	110.5 (3)
C5—C4—H4	119.8	Cl3—C31—H31	108.6
C3—C4—H4	119.8	Cl2—C31—H31	108.6
N1—C5—C4	122.2 (5)	Cl4—C31—H31	108.6
N1—C5—H5	118.9	Cl5—C41—Cl7	110.0 (4)
C4—C5—H5	118.9	Cl5—C41—Cl6	108.8 (4)
C3—C6—H6A	109.5	Cl7—C41—Cl6	110.0 (4)
C3—C6—H6B	109.5	Cl5—C41—H41	109.3
H6A—C6—H6B	109.5	Cl7—C41—H41	109.3
C3—C6—H6C	109.5	Cl6—C41—H41	109.3
H6A—C6—H6C	109.5	Cl8—C51—Cl9	112.2 (4)
H6B—C6—H6C	109.5	Cl8—C51—Cl10	109.0 (4)
C11—N2—C15	117.3 (5)	Cl9—C51—Cl10	109.8 (4)
C11—N2—Si1	121.7 (3)	Cl8—C51—H51	108.6
C15—N2—Si1	121.0 (4)	Cl9—C51—H51	108.6
N2—C11—C12	122.9 (5)	Cl10—C51—H51	108.6
N2^i—Si1—N1—C1	−79.2 (4)	N1—Si1—N2—C11	88.9 (4)
N2—Si1—N1—C1	100.8 (4)	N1^i—Si1—N2—C11	−91.1 (4)
N2^i—Si1—N1—C5	102.4 (4)	N1—Si1—N2—C15	−88.5 (4)
N2—Si1—N1—C5	−77.6 (4)	N1^i—Si1—N2—C15	91.5 (4)
C5—N1—C1—C2	1.2 (8)	C15—N2—C11—C12	2.4 (8)
Si1—N1—C1—C2	−177.2 (4)	Si1—N2—C11—C12	−175.1 (4)
N1—C1—C2—C3	1.0 (8)	N2—C11—C12—C13	−1.9 (9)
C1—C2—C3—C4	−2.0 (8)	C11—C12—C13—C14	0.1 (9)
C1—C2—C3—C6	177.9 (6)	C11—C12—C13—C16	−179.9 (6)
C2—C3—C4—C5	1.0 (8)	C12—C13—C14—C15	1.1 (8)
C6—C3—C4—C5	−178.9 (6)	C16—C13—C14—C15	−178.9 (6)
C1—N1—C5—C4	−2.3 (8)	C11—N2—C15—C14	−1.2 (7)
Si1—N1—C5—C4	176.1 (4)	Si1—N2—C15—C14	176.4 (4)
C3—C4—C5—N1	1.2 (9)	C13—C14—C15—N2	−0.6 (8)

Symmetry code: (i) −x, −y+1, −z.