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The title compound, catena-poly[[μ2-bis­(trimethyl­silyl)amido-κ2N:N]-lithium(I)-[μ2-bis­(trimethyl­silyl)amido-κ2N:N]potassium], [LiK(C6H18NSi2)2]n or [{(Me3Si)2NLi}{(Me3Si)2NK}], is a polymeric one-dimensional chain composed of alternating lithium and potassium centers bridged through the amide N atoms of the hexa­methyl­disilazide anions. The repeat unit is centrosymmetric, with K on a center of symmetry, Li on a twofold rotation axis, and the complete hexa­methydisilazide anion in the asymmetric unit. All of the methyl C atoms in the hexa­methyl­disilazide anion are disordered over two sites, with the site occupancies refined to 0.63 (2) for the major component of one trimethyl­silyl group and 0.54 (3) for the major component of the second trimethyl­silyl group.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807033922/zl2045sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536807033922/zl2045Isup2.hkl
Contains datablock I

CCDC reference: 663564

Key indicators

  • Single-crystal X-ray study
  • T = 100 K
  • Mean [sigma](N-Li) = 0.001 Å
  • Disorder in main residue
  • R factor = 0.029
  • wR factor = 0.083
  • Data-to-parameter ratio = 14.1

checkCIF/PLATON results

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Alert level B PLAT241_ALERT_2_B Check High Ueq as Compared to Neighbors for K1 PLAT301_ALERT_3_B Main Residue Disorder ......................... 37.00 Perc.
Alert level C PLAT242_ALERT_2_C Check Low Ueq as Compared to Neighbors for Si1 PLAT242_ALERT_2_C Check Low Ueq as Compared to Neighbors for Si2 PLAT242_ALERT_2_C Check Low Ueq as Compared to Neighbors for N1 PLAT764_ALERT_4_C Overcomplete CIF Bond List Detected (Rep/Expd) . 1.33 Ratio
Alert level G PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints ....... 30
0 ALERT level A = In general: serious problem 2 ALERT level B = Potentially serious problem 4 ALERT level C = Check and explain 1 ALERT level G = General alerts; check 0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 4 ALERT type 2 Indicator that the structure model may be wrong or deficient 2 ALERT type 3 Indicator that the structure quality may be low 1 ALERT type 4 Improvement, methodology, query or suggestion 0 ALERT type 5 Informative message, check

Comment top

The title complex was synthesized during the attempted synthesis of mixed alkali metal hexamethyldisilazide complexes coordinated by ferrocene (Morris et al., 2007). The asymmetric unit contains a hexamethyldisilazide (HMDS) anion that coordinates to both a lithium and potassium through the nitrogen center (Fig. 1). The nitrogen has an approximately tetrahedral coordination geometry, bonding to two silicons, a potassium and a lithium. Symmetry expansion gives a polymeric one-dimensional chain composed of alternating lithium and potassium cations, each coordinated to two bridging HMDS anions (Fig. 2). The one-dimensional chain polymer adopts a zigzag conformation with a K—N—Li angle of 107.80 (9)°, which is slightly larger than the Na—N—Na angle of 102.0° seen in the isostructural sodium hexamethyldisilazide complex (Grüning & Atwood, 1977). The potassium has a crystallographically required linear N—K—N coordination environment with a K—N distance of 2.861 (1) Å, while the lithium has a near linear N—Li—N angle of 176.4 (2)° and a Li—N distance of 1.935 (1). In addition, the potassium has short K—C agostic interactions of 3.136 (13) Å for K1—C4 and 3.336 (13) Å for K1—C2. The structure is notable in forming a chain polymer rather than a LiN2K heterodimeric ring, as found for the THF solvate [{(Me3Si)2N}2LiK}(THF)3] (Williard & Nichols, 1991).

Related literature top

The isostructural one-dimensional chain polymer sodium hexamethyldisilazide (Grüning & Atwood, 1977), the dimeric mixed lithium–potassium hexamethyldisilazide solvated by THF (Williard & Nichols, 1991), and the related homometallic ferrocene solvates (Morris et al., 2007) have been reported.

Experimental top

All experimental manipulations were performed under a purified nitrogen atmosphere using standard Schlenk techniques. n-Butyllithium was purchased from Aldrich and standardized prior to use. KHMDS was purchased from Aldrich and used as received. Toluene was dried immediately before use by passage through columns of copper-based catalyst and alumina and stored over 4 Å molecular sieves. Ferrocene was purchased from Aldrich and dried by sublimation. Hexamethyldisilazane was purchased from Fluka and distilled over CaH2 prior to use. NMR spectroscopy data were recorded on a Varian Unity Plus 300 spectrometer at 298 K. For the synthesis of the title compound, n-BuLi (2.5 mmol of a 1.6 M solution in hexane) was added to a stirred solution of hexamethyldisilazane (2.5 mmol) in toluene (6.0 ml) at 273 K. KHMDS (2.5 mmol) and ferrocene (2.5 mmol) were added to give an orange solution. The solution was then cooled to 263 K, which gave colourless crystals within 24 h. 1H NMR (300 MHz, Toluene-d8, 298 K): δ 0.15 (s, Si(CH3)3).

Refinement top

H atoms were placed in calculated positions and allowed to ride on their respective parent atom. The isotropic methyl hydrogen thermal parameters were set to 1.5Ueq(C). All of the methyl carbons in the hexamethyldisilazide anion are disordered over two sites, with the site occupancy refined to 0.63 (2) for the major component of the first trimethylsilyl group (C1—C3) and 0.54 (3) for the major component of the second trimethylsilyl group (C4—C6). In addition, all Si—C bonds were restrained to be equal using the SADI restraint (30 total restraints).

Structure description top

The title complex was synthesized during the attempted synthesis of mixed alkali metal hexamethyldisilazide complexes coordinated by ferrocene (Morris et al., 2007). The asymmetric unit contains a hexamethyldisilazide (HMDS) anion that coordinates to both a lithium and potassium through the nitrogen center (Fig. 1). The nitrogen has an approximately tetrahedral coordination geometry, bonding to two silicons, a potassium and a lithium. Symmetry expansion gives a polymeric one-dimensional chain composed of alternating lithium and potassium cations, each coordinated to two bridging HMDS anions (Fig. 2). The one-dimensional chain polymer adopts a zigzag conformation with a K—N—Li angle of 107.80 (9)°, which is slightly larger than the Na—N—Na angle of 102.0° seen in the isostructural sodium hexamethyldisilazide complex (Grüning & Atwood, 1977). The potassium has a crystallographically required linear N—K—N coordination environment with a K—N distance of 2.861 (1) Å, while the lithium has a near linear N—Li—N angle of 176.4 (2)° and a Li—N distance of 1.935 (1). In addition, the potassium has short K—C agostic interactions of 3.136 (13) Å for K1—C4 and 3.336 (13) Å for K1—C2. The structure is notable in forming a chain polymer rather than a LiN2K heterodimeric ring, as found for the THF solvate [{(Me3Si)2N}2LiK}(THF)3] (Williard & Nichols, 1991).

The isostructural one-dimensional chain polymer sodium hexamethyldisilazide (Grüning & Atwood, 1977), the dimeric mixed lithium–potassium hexamethyldisilazide solvated by THF (Williard & Nichols, 1991), and the related homometallic ferrocene solvates (Morris et al., 2007) have been reported.

Computing details top

Data collection: APEX2 (Bruker, 2006); cell refinement: APEX2 and SAINT (Bruker, 2006); data reduction: SAINT and XPREP (Sheldrick, 2003); program(s) used to solve structure: XS in SHELXTL (Sheldrick, 2001); program(s) used to refine structure: XL in SHELXTL; molecular graphics: XP in SHELXTL; software used to prepare material for publication: XCIF in SHELXTL.

Figures top
[Figure 1] Fig. 1. Asymmetric unit showing 50% probability displacement ellipsoids. Only the the methyl groups of the major component of the disordered hexamethyldisilazide anion are shown for clarity.
[Figure 2] Fig. 2. Section of the polymeric zigzag chain of the title compound highlighting the alternating lithium and potassium metal sites.
catena-poly[[µ2-bis(trimethylsilyl)amido-κ2N:N]-lithium(I)-[µ2-bis(trimethylsilyl)amido-κ2N:N]-potassium] top
Crystal data top
[LiK(C6H18NSi2)2]F(000) = 800
Mr = 366.83Dx = 1.030 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2ycCell parameters from 5346 reflections
a = 11.3154 (3) Åθ = 2.4–25.6°
b = 17.5465 (5) ŵ = 0.42 mm1
c = 12.6528 (5) ÅT = 100 K
β = 109.657 (1)°Parallelepiped, colourless
V = 2365.76 (13) Å30.32 × 0.30 × 0.24 mm
Z = 4
Data collection top
Bruker SMART APEX II CCD
diffractometer
2265 independent reflections
Radiation source: fine-focus sealed tube1943 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.029
Detector resolution: 8.33 pixels mm-1θmax = 25.8°, θmin = 2.2°
ω and φ scansh = 1313
Absorption correction: multi-scan
(SADABS; Sheldrick, 2004)
k = 2116
Tmin = 0.86, Tmax = 0.90l = 1515
24282 measured reflections
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)] = 0.029Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.083H-atom parameters constrained
S = 1.08 w = 1/[σ2(Fo2) + (0.0436P)2 + 0.9001P]
where P = (Fo2 + 2Fc2)/3
2265 reflections(Δ/σ)max < 0.001
161 parametersΔρmax = 0.23 e Å3
30 restraintsΔρmin = 0.23 e Å3
Crystal data top
[LiK(C6H18NSi2)2]V = 2365.76 (13) Å3
Mr = 366.83Z = 4
Monoclinic, C2/cMo Kα radiation
a = 11.3154 (3) ŵ = 0.42 mm1
b = 17.5465 (5) ÅT = 100 K
c = 12.6528 (5) Å0.32 × 0.30 × 0.24 mm
β = 109.657 (1)°
Data collection top
Bruker SMART APEX II CCD
diffractometer
2265 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 2004)
1943 reflections with I > 2σ(I)
Tmin = 0.86, Tmax = 0.90Rint = 0.029
24282 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.02930 restraints
wR(F2) = 0.083H-atom parameters constrained
S = 1.08Δρmax = 0.23 e Å3
2265 reflectionsΔρmin = 0.23 e Å3
161 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*/UeqOcc. (<1)
Li10.00000.1461 (2)0.25000.0508 (9)
K10.25000.25000.50000.0795 (2)
N10.18132 (10)0.14957 (6)0.31084 (9)0.0352 (3)
Si10.23253 (4)0.06732 (2)0.37876 (4)0.04687 (15)
Si20.22947 (4)0.20084 (3)0.22140 (4)0.04769 (15)
C10.1043 (5)0.0361 (7)0.4356 (9)0.075 (2)0.64 (2)
H1A0.08750.07720.48110.112*0.64 (2)
H1B0.13190.00950.48220.112*0.64 (2)
H1C0.02770.02460.37290.112*0.64 (2)
C1'0.1023 (8)0.0058 (10)0.3916 (18)0.077 (4)0.36 (2)
H1D0.05140.03510.42640.115*0.36 (2)
H1E0.13800.03870.43840.115*0.36 (2)
H1F0.04950.01130.31690.115*0.36 (2)
C20.3699 (8)0.0751 (7)0.5133 (5)0.061 (2)0.64 (2)
H2A0.43640.10540.50010.092*0.64 (2)
H2B0.40190.02400.53890.092*0.64 (2)
H2C0.34280.09990.57070.092*0.64 (2)
C2'0.3637 (17)0.0856 (15)0.5143 (13)0.092 (7)0.36 (2)
H2D0.43610.10670.49820.138*0.36 (2)
H2E0.38780.03760.55570.138*0.36 (2)
H2F0.33570.12200.55970.138*0.36 (2)
C30.2750 (14)0.0137 (6)0.3029 (11)0.098 (3)0.64 (2)
H3A0.20430.02510.23470.147*0.64 (2)
H3B0.29450.05870.35160.147*0.64 (2)
H3C0.34850.00020.28260.147*0.64 (2)
C3'0.303 (2)0.0040 (10)0.2957 (15)0.082 (4)0.36 (2)
H3D0.24570.00060.21810.124*0.36 (2)
H3E0.31680.04700.32930.124*0.36 (2)
H3F0.38330.02540.29660.124*0.36 (2)
C40.3468 (10)0.2758 (6)0.2978 (11)0.059 (2)0.54 (3)
H4A0.30650.31210.33380.088*0.54 (3)
H4B0.37720.30290.24420.088*0.54 (3)
H4C0.41770.25140.35500.088*0.54 (3)
C4'0.3276 (17)0.2872 (8)0.2749 (16)0.089 (5)0.46 (3)
H4D0.28080.32340.30470.133*0.46 (3)
H4E0.34860.31110.21350.133*0.46 (3)
H4F0.40500.27240.33470.133*0.46 (3)
C50.0906 (7)0.2606 (5)0.1331 (9)0.071 (2)0.54 (3)
H5A0.05270.28650.18240.107*0.54 (3)
H5B0.02820.22740.08090.107*0.54 (3)
H5C0.11960.29850.09050.107*0.54 (3)
C5'0.0863 (8)0.2267 (16)0.0976 (14)0.111 (6)0.46 (3)
H5D0.04030.18020.06530.167*0.46 (3)
H5E0.11260.25280.04080.167*0.46 (3)
H5F0.03190.26030.12260.167*0.46 (3)
C60.3043 (16)0.1554 (8)0.1259 (12)0.078 (3)0.54 (3)
H6A0.38300.13090.17080.117*0.54 (3)
H6B0.32170.19440.07770.117*0.54 (3)
H6C0.24740.11700.07920.117*0.54 (3)
C6'0.3196 (17)0.1392 (10)0.1535 (16)0.092 (4)0.46 (3)
H6D0.40020.12500.20940.138*0.46 (3)
H6E0.33440.16740.09230.138*0.46 (3)
H6F0.27110.09300.12350.138*0.46 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Li10.0303 (17)0.063 (2)0.057 (2)0.0000.0117 (15)0.000
K10.0700 (4)0.0934 (5)0.0703 (4)0.0042 (3)0.0174 (3)0.0453 (4)
N10.0298 (6)0.0391 (6)0.0357 (6)0.0020 (5)0.0099 (5)0.0012 (5)
Si10.0353 (2)0.0437 (3)0.0515 (3)0.00070 (17)0.00125 (18)0.01018 (18)
Si20.0339 (2)0.0634 (3)0.0458 (3)0.00183 (18)0.01350 (18)0.0130 (2)
C10.057 (2)0.066 (4)0.092 (4)0.008 (2)0.012 (2)0.037 (3)
C1'0.060 (4)0.051 (6)0.106 (8)0.014 (4)0.011 (4)0.028 (5)
C20.053 (3)0.070 (4)0.041 (3)0.010 (3)0.010 (2)0.001 (3)
C2'0.080 (9)0.085 (9)0.095 (11)0.045 (7)0.009 (7)0.042 (7)
C30.103 (5)0.045 (5)0.114 (5)0.018 (4)0.006 (3)0.022 (4)
C3'0.107 (10)0.030 (6)0.077 (5)0.022 (6)0.013 (5)0.007 (4)
C40.052 (3)0.044 (3)0.085 (4)0.014 (3)0.030 (2)0.005 (3)
C4'0.107 (9)0.056 (5)0.124 (9)0.008 (4)0.068 (8)0.025 (5)
C50.046 (2)0.082 (4)0.076 (4)0.001 (2)0.006 (2)0.043 (3)
C5'0.068 (4)0.170 (13)0.089 (7)0.001 (6)0.017 (4)0.085 (8)
C60.106 (5)0.095 (5)0.052 (5)0.018 (4)0.053 (4)0.009 (4)
C6'0.101 (7)0.134 (9)0.065 (7)0.046 (6)0.060 (6)0.021 (6)
Geometric parameters (Å, º) top
Li1—N11.9348 (11)C1'—H1E0.9800
Li1—N1i1.9348 (11)C1'—H1F0.9800
Li1—Si2i2.9032 (14)C2—H2A0.9800
Li1—Si1i2.933 (2)C2—H2B0.9800
Li1—K1i3.9133 (19)C2—H2C0.9800
K1—N12.8612 (11)C2'—H2D0.9800
K1—N1ii2.8612 (11)C2'—H2E0.9800
K1—C4ii3.136 (13)C2'—H2F0.9800
K1—C2'ii3.14 (3)C3—H3A0.9800
K1—C4'ii3.315 (19)C3—H3B0.9800
K1—C2ii3.336 (13)C3—H3C0.9800
K1—Si1ii3.5303 (5)C3'—H3D0.9800
K1—Si2ii3.5599 (5)C3'—H3E0.9800
K1—Li1ii3.9133 (19)C3'—H3F0.9800
N1—Si21.6738 (12)C4—H4A0.9800
N1—Si11.6798 (12)C4—H4B0.9800
Si1—C31.866 (5)C4—H4C0.9800
Si1—C1'1.878 (6)C4'—H4D0.9800
Si1—C2'1.880 (7)C4'—H4E0.9800
Si1—C3'1.881 (7)C4'—H4F0.9800
Si1—C21.884 (3)C5—H5A0.9800
Si1—C11.904 (4)C5—H5B0.9800
Si2—C4'1.866 (7)C5—H5C0.9800
Si2—C61.872 (5)C5'—H5D0.9800
Si2—C6'1.881 (6)C5'—H5E0.9800
Si2—C41.888 (5)C5'—H5F0.9800
Si2—C5'1.891 (6)C6—H6A0.9800
Si2—C51.907 (5)C6—H6B0.9800
C1—H1A0.9800C6—H6C0.9800
C1—H1B0.9800C6'—H6D0.9800
C1—H1C0.9800C6'—H6E0.9800
C1'—H1D0.9800C6'—H6F0.9800
N1—Li1—N1i176.4 (3)N1—Si2—C4111.2 (4)
N1—Li1—Si2i144.40 (12)C6—Si2—C4103.6 (7)
N1i—Li1—Si2i33.48 (5)N1—Si2—C5'107.8 (3)
N1—Li1—Si1i150.35 (18)C4'—Si2—C5'110.2 (7)
N1i—Li1—Si1i32.95 (6)C6'—Si2—C5'101.8 (8)
Si2i—Li1—Si1i63.407 (14)N1—Si2—C5107.5 (3)
N1—Li1—K1i133.50 (12)C6—Si2—C5108.6 (5)
N1i—Li1—K1i44.12 (6)C4—Si2—C5102.5 (5)
Si2i—Li1—K1i60.84 (4)Si1—C1—H1A109.5
Si1i—Li1—K1i60.069 (19)Si1—C1—H1B109.5
N1—K1—N1ii180.0Si1—C1—H1C109.5
N1—K1—C4ii121.49 (9)Si1—C1'—H1D109.5
N1ii—K1—C4ii58.51 (9)Si1—C1'—H1E109.5
N1—K1—C2'ii121.81 (18)H1D—C1'—H1E109.5
N1ii—K1—C2'ii58.19 (18)Si1—C1'—H1F109.5
N1—K1—C4'ii121.43 (13)H1D—C1'—H1F109.5
N1ii—K1—C4'ii58.57 (13)H1E—C1'—H1F109.5
N1—K1—C2ii122.21 (8)Si1—C2—H2A109.5
N1ii—K1—C2ii57.79 (8)Si1—C2—H2B109.5
C4ii—K1—C2ii85.8 (3)Si1—C2—H2C109.5
N1—K1—Si1ii151.94 (2)Si1—C2'—H2D109.5
N1ii—K1—Si1ii28.06 (2)Si1—C2'—H2E109.5
C4ii—K1—Si1ii76.14 (15)H2D—C2'—H2E109.5
C2'ii—K1—Si1ii32.07 (14)Si1—C2'—H2F109.5
C4'ii—K1—Si1ii78.3 (2)H2D—C2'—H2F109.5
C2ii—K1—Si1ii31.69 (6)H2E—C2'—H2F109.5
N1—K1—Si2ii152.43 (2)Si1—C3—H3A109.5
N1ii—K1—Si2ii27.57 (2)Si1—C3—H3B109.5
C4ii—K1—Si2ii31.96 (9)Si1—C3—H3C109.5
C2'ii—K1—Si2ii73.9 (3)Si1—C3'—H3D109.5
C4'ii—K1—Si2ii31.23 (12)Si1—C3'—H3E109.5
C2ii—K1—Si2ii73.56 (13)H3D—C3'—H3E109.5
Si1ii—K1—Si2ii51.263 (10)Si1—C3'—H3F109.5
N1—K1—Li1ii151.92 (3)H3D—C3'—H3F109.5
N1ii—K1—Li1ii28.08 (3)H3E—C3'—H3F109.5
C4ii—K1—Li1ii76.34 (11)Si2—C4—H4A109.5
C2'ii—K1—Li1ii77.83 (16)Si2—C4—H4B109.5
C4'ii—K1—Li1ii74.08 (18)Si2—C4—H4C109.5
C2ii—K1—Li1ii77.48 (8)Si2—C4'—H4D109.5
Si1ii—K1—Li1ii46.06 (5)Si2—C4'—H4E109.5
Si2ii—K1—Li1ii45.415 (10)H4D—C4'—H4E109.5
Si2—N1—Si1132.29 (7)Si2—C4'—H4F109.5
Si2—N1—Li1106.91 (9)H4D—C4'—H4F109.5
Si1—N1—Li1108.27 (13)H4E—C4'—H4F109.5
Si2—N1—K1100.13 (5)Si2—C5—H5A109.5
Si1—N1—K198.70 (5)Si2—C5—H5B109.5
Li1—N1—K1107.80 (9)Si2—C5—H5C109.5
N1—Si1—C3119.7 (5)Si2—C5'—H5D109.5
N1—Si1—C1'113.1 (4)Si2—C5'—H5E109.5
N1—Si1—C2'110.5 (8)H5D—C5'—H5E109.5
C1'—Si1—C2'114.9 (10)Si2—C5'—H5F109.5
N1—Si1—C3'111.1 (7)H5D—C5'—H5F109.5
C1'—Si1—C3'101.6 (8)H5E—C5'—H5F109.5
C2'—Si1—C3'104.9 (10)Si2—C6—H6A109.5
N1—Si1—C2115.9 (4)Si2—C6—H6B109.5
C3—Si1—C2104.1 (6)Si2—C6—H6C109.5
N1—Si1—C1105.4 (2)Si2—C6'—H6D109.5
C3—Si1—C1109.6 (4)Si2—C6'—H6E109.5
C2—Si1—C1100.4 (5)H6D—C6'—H6E109.5
N1—Si2—C4'118.7 (6)Si2—C6'—H6F109.5
N1—Si2—C6121.9 (5)H6D—C6'—H6F109.5
N1—Si2—C6'110.4 (6)H6E—C6'—H6F109.5
C4'—Si2—C6'106.6 (9)
Symmetry codes: (i) x, y, z+1/2; (ii) x+1/2, y+1/2, z+1.

Experimental details

Crystal data
Chemical formula[LiK(C6H18NSi2)2]
Mr366.83
Crystal system, space groupMonoclinic, C2/c
Temperature (K)100
a, b, c (Å)11.3154 (3), 17.5465 (5), 12.6528 (5)
β (°) 109.657 (1)
V3)2365.76 (13)
Z4
Radiation typeMo Kα
µ (mm1)0.42
Crystal size (mm)0.32 × 0.30 × 0.24
Data collection
DiffractometerBruker SMART APEX II CCD
Absorption correctionMulti-scan
(SADABS; Sheldrick, 2004)
Tmin, Tmax0.86, 0.90
No. of measured, independent and
observed [I > 2σ(I)] reflections
24282, 2265, 1943
Rint0.029
(sin θ/λ)max1)0.611
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.029, 0.083, 1.08
No. of reflections2265
No. of parameters161
No. of restraints30
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.23, 0.23

Computer programs: APEX2 (Bruker, 2006), APEX2 and SAINT (Bruker, 2006), SAINT and XPREP (Sheldrick, 2003), XS in SHELXTL (Sheldrick, 2001), XL in SHELXTL, XP in SHELXTL, XCIF in SHELXTL.

Selected geometric parameters (Å, º) top
Li1—N11.9348 (11)N1—Si21.6738 (12)
K1—N12.8612 (11)N1—Si11.6798 (12)
N1—Li1—N1i176.4 (3)Si2—N1—Si1132.29 (7)
N1—K1—N1ii180.0Li1—N1—K1107.80 (9)
Symmetry codes: (i) x, y, z+1/2; (ii) x+1/2, y+1/2, z+1.
 

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