Redetermination of tetra­kis(trimethyl­stann­yl)germane

Abstract

Redetermination of the structure of the title compound, [Ge(SnMe₃)₄] or [GeSn₄(CH₃)₁₂], previously refined from powder diffraction data only [Dinnebier, Bernatowicz, Helluy, Sebald, Wunschel, Fitch & van Smaalen et al. (2002 ▶). Acta Cryst. B58, 52–61], confirms that four bulky trimethyl­stannyl ligands surround the central Ge atom (site symmetry 1) in a tetra­hedral coordination.

Related literature

For related literature, see: Dinnebier et al. (2002 ▶); Wrackmeyer & Bernatowicz (1999 ▶); Chizmeshya et al. (2003 ▶).

Experimental

Crystal data

• [GeSn₄(CH₃)₁₂]

• M _r = 727.76

• Triclinic,

• a = 9.1666 (7) Å

• b = 9.9521 (7) Å

• c = 14.5400 (14) Å

• α = 90.033 (2)°

• β = 90.546 (1)°

• γ = 111.736 (1)°

• V = 1232.06 (17) ų

• Z = 2

• Mo Kα radiation

• μ = 5.19 mm⁻¹

• T = 298 (2) K

• 0.22 × 0.22 × 0.15 mm

Data collection

• Bruker SMART APEX diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 2002 ▶) T _min = 0.317, T _max = 0.460

• 12284 measured reflections

• 5646 independent reflections

• 4466 reflections with I > 2σ(I)

• R _int = 0.085

Refinement

• R[F ² > 2σ(F ²)] = 0.049

• wR(F ²) = 0.105

• S = 1.01

• 5646 reflections

• 154 parameters

• H-atom parameters constrained

• Δρ_max = 1.09 e Å⁻³

• Δρ_min = −1.01 e Å⁻³

Data collection: SMART (Bruker, 2002 ▶); cell refinement: SAINT (Bruker, 2002 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Bruker, 1997 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Supplementary Material

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

supplementary crystallographic information

Comment

The structure of the Ge[Sn(CH₃)₃]₄ cluster has been previously determined by powder X-ray diffraction and magic angle spinning NMR spectroscopy (Dinnebier et al., 2002). Here, we have developed a new synthetic route to form Ge[Sn(CH₃)₃]₄ in high yields (80–90%) and, for the first time, adequately sized crystals suitable for a single-crystal structure determination. The long-term objective is to use this bonding information to understand structural trends in recently developed Ge_{1 - x}Sn_x and Ge_{1 - x-y}Sn_xSi_y semiconductor alloys, including unusual deviations from Vegard's Law (Chizmeshya et al., 2003). Various tetrahedral cluster compounds with the general formula A(BH₃)₄ (where {A, B}= {Si, Ge, Sn}) are potentially viable low-temperature CVD precursors of Group IV alloys with highly metastable compositions and structures that cannot be obtained by conventional growth routes.

The central Ge atom is tetrahedrally coordinated with four Me₃Sn ligands. The average Ge—Sn distance of 2.5934 (8) Å agrees well with the predicted value of 2.5680 Å for a Ge(SnH₃)₄ analogue (Chizmeshya et al., 2003). In the previous structure determination using powder data, estimated standard deviations for bond lengths and angles are given as 0.04 Å and 0.1°, respectively. In the current determination, an improvement in precision for the structure can be seen in the Ge—Sn core bond lengths, which range from 2.5912 (7) to 2.5953 (8) Å, and bond angles, which range from 107.59 (3) to 111.09 (3) °.

Experimental

After addition of GeH₄ (0.1 g; 1.3 mmol) to Me₃SnNMe₂ (1.0 g; 5 mmol) at -196 °C, the mixture was warmed to room temperature and stirred for 24 h. The volatiles were identified as HNMe₂ and small amounts of GeH₄ by gas phase IR spectroscopy and were removed at room temperature in vacuo.

GeH₄ + 4 Me₃SnNMe₂ => Ge[Sn(CH₃)₃]₄ + 4 HNMe₂

The white solid was recrystallized from a saturated toluene solution at -20 °C and the purity was confirmed by matching the IR spectrum, powder XRD pattern, 1H NMR spectrum, and melting point with the published data (Dinnebier et al., 2002; Wrackmeyer & Bernatowicz, 1999). This represents a simpler alternative than the multistepped reaction, hydrolysis, and separation procedure required with the reaction of Me₃SnLi and GeCl₄ in tetrahydrofuran. Larger crystals, suitable for single-crystal XRD, were grown by subliming the pure powder in a sealed quartz tube held at 100 °C on one end and room temperature on the other. In contrast, sublimation at 135 °C in vacuo yields only microcrystalline powders.

Refinement

H atoms were positioned geometrically and refined using a riding model, with C–H = 0.96 Å and U_iso(H) = 1.5 times U_eq(C).

Figures

Fig. 1.

Structure of Ge[Sn(CH3)3]4. (Ellipsoids are drawn at the 50% probability level.)

Crystal data

[GeSn4(CH3)12]	Z = 2
Mr = 727.76	F000 = 680
Triclinic, P1	Dx = 1.962 Mg m−3
Hall symbol: -P 1	Mo Kα radiation λ = 0.71073 Å
a = 9.1666 (7) Å	Cell parameters from 6668 reflections
b = 9.9521 (7) Å	θ = 2.2–27.5º
c = 14.5400 (14) Å	µ = 5.19 mm−1
α = 90.033 (2)º	T = 298 (2) K
β = 90.546 (1)º	Block, colorless
γ = 111.736 (1)º	0.22 × 0.22 × 0.15 mm
V = 1232.06 (17) Å3

Data collection

Bruker SMART APEX diffractometer	5646 independent reflections
Radiation source: fine-focus sealed tube	4466 reflections with I > 2σ(I)
Monochromator: graphite	Rint = 0.085
T = 298(2) K	θmax = 27.6º
ω scan	θmin = 2.2º
Absorption correction: multi-scan(SADABS; Bruker, 2002)	h = −11→11
Tmin = 0.317, Tmax = 0.460	k = −12→12
12284 measured reflections	l = −18→18

Refinement

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)] = 0.049	H-atom parameters constrained
wR(F2) = 0.105	w = 1/[σ2(Fo2) + (0.0304P)2] where P = (Fo2 + 2Fc2)/3
S = 1.01	(Δ/σ)max = 0.001
5646 reflections	Δρmax = 1.09 e Å−3
154 parameters	Δρmin = −1.01 e Å−3
Primary atom site location: structure-invariant direct methods	Extinction correction: none

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
Ge1	0.75863 (7)	0.73542 (6)	0.75103 (5)	0.04589 (16)
Sn1	0.76633 (5)	0.47736 (5)	0.75113 (4)	0.05566 (14)
Sn2	0.67526 (5)	0.79813 (5)	0.91050 (3)	0.05480 (14)
Sn3	0.55868 (5)	0.75649 (5)	0.63013 (3)	0.05205 (13)
Sn4	1.03424 (5)	0.92048 (5)	0.70999 (3)	0.05197 (13)
C1A	0.5374 (9)	0.3234 (8)	0.7776 (6)	0.084 (2)
H1AA	0.5400	0.2278	0.7776	0.125*
H1AB	0.4659	0.3296	0.7306	0.125*
H1AC	0.5030	0.3432	0.8364	0.125*
C1B	0.9275 (9)	0.4584 (9)	0.8546 (7)	0.092 (3)
H1BA	0.9284	0.3623	0.8534	0.138*
H1BB	0.8949	0.4776	0.9141	0.138*
H1BC	1.0311	0.5270	0.8424	0.138*
C1C	0.8419 (9)	0.4301 (9)	0.6205 (6)	0.084 (2)
H1CA	0.8442	0.3344	0.6214	0.126*
H1CB	0.9451	0.4990	0.6080	0.126*
H1CC	0.7702	0.4355	0.5734	0.126*
C2A	0.8272 (9)	0.7754 (10)	1.0181 (6)	0.088 (3)
H2AA	0.7939	0.7992	1.0762	0.132*
H2AB	0.9332	0.8395	1.0067	0.132*
H2AC	0.8224	0.6774	1.0194	0.132*
C2B	0.6866 (10)	1.0148 (8)	0.9115 (6)	0.087 (2)
H2BA	0.6556	1.0371	0.9707	0.131*
H2BB	0.6172	1.0264	0.8651	0.131*
H2BC	0.7922	1.0790	0.8993	0.131*
C2C	0.4400 (9)	0.6608 (10)	0.9404 (6)	0.088 (3)
H2CA	0.4116	0.6858	0.9996	0.132*
H2CB	0.4321	0.5619	0.9409	0.132*
H2CC	0.3703	0.6730	0.8943	0.132*
C3A	0.6191 (9)	0.7151 (9)	0.4940 (5)	0.085 (2)
H3AA	0.5431	0.7236	0.4509	0.128*
H3AB	0.6202	0.6191	0.4909	0.128*
H3AC	0.7212	0.7840	0.4792	0.128*
C3B	0.3259 (8)	0.6064 (8)	0.6589 (6)	0.076 (2)
H3BA	0.2539	0.6160	0.6134	0.115*
H3BB	0.2952	0.6266	0.7187	0.115*
H3BC	0.3247	0.5095	0.6575	0.115*
C3C	0.5645 (8)	0.9736 (8)	0.6319 (6)	0.075 (2)
H3CA	0.4909	0.9828	0.5874	0.112*
H3CB	0.6683	1.0393	0.6172	0.112*
H3CC	0.5371	0.9959	0.6920	0.112*
C4A	1.2038 (8)	0.9083 (9)	0.8092 (6)	0.081 (2)
H4AA	1.3058	0.9769	0.7938	0.121*
H4AB	1.2058	0.8125	0.8088	0.121*
H4AC	1.1756	0.9299	0.8693	0.121*
C4B	1.0969 (8)	0.8697 (9)	0.5750 (5)	0.078 (2)
H4BA	1.1990	0.9379	0.5593	0.117*
H4BB	1.0210	0.8748	0.5306	0.117*
H4BC	1.0986	0.7738	0.5752	0.117*
C4C	1.0413 (9)	1.1383 (7)	0.7095 (6)	0.080 (2)
H4CA	1.1451	1.2033	0.6940	0.120*
H4CB	1.0148	1.1625	0.7693	0.120*
H4CC	0.9674	1.1468	0.6648	0.120*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
Ge1	0.0459 (3)	0.0435 (3)	0.0477 (4)	0.0158 (3)	0.0020 (3)	0.0011 (3)
Sn1	0.0596 (3)	0.0444 (2)	0.0628 (3)	0.0192 (2)	−0.0006 (2)	0.0007 (2)
Sn2	0.0586 (3)	0.0588 (3)	0.0469 (3)	0.0216 (2)	0.0030 (2)	0.0002 (2)
Sn3	0.0501 (2)	0.0549 (3)	0.0501 (3)	0.0183 (2)	−0.00229 (19)	−0.0012 (2)
Sn4	0.0469 (2)	0.0507 (3)	0.0549 (3)	0.01392 (19)	0.00327 (19)	0.0024 (2)
C1A	0.079 (5)	0.058 (4)	0.102 (7)	0.012 (4)	0.009 (5)	0.015 (4)
C1B	0.086 (6)	0.081 (6)	0.119 (8)	0.042 (5)	−0.015 (5)	0.022 (5)
C1C	0.098 (6)	0.080 (5)	0.080 (6)	0.039 (5)	0.011 (5)	−0.021 (4)
C2A	0.091 (6)	0.110 (7)	0.068 (6)	0.045 (5)	−0.023 (4)	−0.006 (5)
C2B	0.120 (7)	0.072 (5)	0.076 (6)	0.041 (5)	0.003 (5)	−0.012 (4)
C2C	0.071 (5)	0.105 (7)	0.082 (6)	0.025 (5)	0.022 (4)	0.018 (5)
C3A	0.102 (6)	0.091 (6)	0.051 (5)	0.022 (5)	0.010 (4)	−0.011 (4)
C3B	0.055 (4)	0.082 (5)	0.084 (6)	0.016 (4)	0.006 (4)	−0.003 (4)
C3C	0.080 (5)	0.060 (4)	0.086 (6)	0.028 (4)	0.000 (4)	0.009 (4)
C4A	0.063 (4)	0.102 (6)	0.080 (6)	0.035 (4)	−0.020 (4)	−0.016 (5)
C4B	0.079 (5)	0.084 (5)	0.069 (5)	0.026 (4)	0.029 (4)	0.006 (4)
C4C	0.094 (6)	0.049 (4)	0.094 (7)	0.022 (4)	0.009 (5)	0.009 (4)

Geometric parameters (Å, °)

Ge1—Sn4	2.5912 (7)	Sn2—C2C	2.132 (7)
Ge1—Sn3	2.5917 (8)	Sn2—C2A	2.152 (7)
Ge1—Sn1	2.5952 (7)	Sn3—C3A	2.141 (7)
Ge1—Sn2	2.5953 (8)	Sn3—C3C	2.141 (7)
Sn1—C1A	2.130 (7)	Sn3—C3B	2.148 (7)
Sn1—C1C	2.139 (8)	Sn4—C4C	2.145 (7)
Sn1—C1B	2.156 (7)	Sn4—C4A	2.147 (7)
Sn2—C2B	2.120 (8)	Sn4—C4B	2.162 (7)
Sn4—Ge1—Sn3	108.29 (3)	C2B—Sn2—Ge1	110.0 (2)
Sn4—Ge1—Sn1	109.08 (3)	C2C—Sn2—Ge1	110.9 (3)
Sn3—Ge1—Sn1	111.09 (3)	C2A—Sn2—Ge1	111.2 (2)
Sn4—Ge1—Sn2	109.91 (3)	C3A—Sn3—C3C	107.0 (3)
Sn3—Ge1—Sn2	107.59 (3)	C3A—Sn3—C3B	108.5 (3)
Sn1—Ge1—Sn2	110.83 (3)	C3C—Sn3—C3B	110.3 (3)
C1A—Sn1—C1C	108.9 (3)	C3A—Sn3—Ge1	111.5 (2)
C1A—Sn1—C1B	109.3 (3)	C3C—Sn3—Ge1	108.7 (2)
C1C—Sn1—C1B	108.0 (3)	C3B—Sn3—Ge1	110.9 (2)
C1A—Sn1—Ge1	109.4 (2)	C4C—Sn4—C4A	108.0 (3)
C1C—Sn1—Ge1	110.3 (2)	C4C—Sn4—C4B	108.7 (3)
C1B—Sn1—Ge1	111.0 (2)	C4A—Sn4—C4B	109.4 (3)
C2B—Sn2—C2C	107.9 (3)	C4C—Sn4—Ge1	112.1 (2)
C2B—Sn2—C2A	108.2 (3)	C4A—Sn4—Ge1	109.6 (2)
C2C—Sn2—C2A	108.6 (3)	C4B—Sn4—Ge1	109.0 (2)