trans Tetra­bromo­bis­­(di­methyl­amine)­tin

metal-organic papers

m684

Structure Reports

Online ISSN 1600-5368

trans

-Tetrabromobis(dimethylamine)tin

Cole Ritter III, Thomas L. Groy and John Kouvetakis*

Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287-1604, USA

Correspondence e-mail: jkouvetakis@asu.edu

Key indicators

Single-crystal X-ray study

T= 298 K

Mean(N±C) = 0.005 AÊ

Rfactor = 0.025

wRfactor = 0.065

Data-to-parameter ratio = 21.9

For details of how these key indicators were automatically derived from the article, see http://journals.iucr.org/e.

#2002 International Union of Crystallography Printed in Great Britain ± all rights reserved

The title compound, [SnBr4(C2H7N)2], consists of separate

centrosymmetric molecules with nearly octahedral geometry, in which the central Sn metal is surrounded by four Br atoms and two dimethylamine ligands. The unique SnÐN bond length is 2.244 (3) AÊ and the two SnÐBr lengths are 2.5867 (11) and 2.5707 (12) AÊ. The CÐN bond lengths of the amine ligand are 1.482 (6) and 1.492 (6) AÊ. The unique angle in the SnBr4 plane is 90.82 (3), and the axial to

equatorial angles are 86.18 (10) and 85.46 (10)_.

Comment

Recently, we have utilized reactions between common

germanium hydrides and SnD4 to grow epitaxic layers of

Ge1ÿxSnxsemiconductors on Si(100) substrates. The bandgaps

of these materials are intermediate between those of Ge (Eg= 0.066 eV) and Sn (Eg= 0.1 eV), and decrease monotonically with increasing Sn concentration in the alloy, indicating that this material will have important application in Si-based devices, such as IR photodetectors. The application of pure SnD4is the essential component in the preparation of these

metastable and technologically important materials. SnD4 is

synthesized by reduction of SnBr4 with LiAlD4 and it is

typically isolated as a volatile liquid, which is unstable at room temperature with respect to Sn and D2. Nevertheless, mixtures

of the compound with high-purity H2 have the necessary

stability at 295 K to be used as viable CVD sources in deposition of Ge1ÿxSnx(Bauer, Taraciet al., 2002). Ongoing

efforts to further stabilize SnD4 by adduct formation with

simple Lewis bases, such as dimethylamine, have led to the

synthesis of the previously unknown complex

SnBr4[HN(CH3)2]2. This compound is currently utilized to

prepare the corresponding SnH4 and SnD4 derivatives as

viable low-temperature CVD precursors of Sn.

The central Sn metal of the title compound is sixfold coordinated, with four Br atoms arranged in square-planar fashion and the two amine ligands nearly perpendicular to the

SnBr4 plane (Fig. 1). The SnÐBr bond distances are

2.5867 (11) (Sn1ÐBr2) and 2.5707 (12) AÊ (Sn1ÐBr3). These values are signi®cantly longer than those reported for a related SnBr4(dioxane) complex (Bauer, Groy & Kouvetakis,

2002), which are in the range 2.5005 (7)±2.5045 (6) AÊ. The angles within the SnBr4square plane are nearly 90[90.82 (3)

for Br2ÐSn1ÐBr3] and the angles between the plane and the axis of the HN(CH3)2ligands are 86.18 (10) (N4ÐSn1ÐBr2)

and 85.46 (10)_{(N4ÐSn1ÐBr3).}

All H-atom positions were calculated based on idealized geometry. The H atoms were then allowed to ride on their bonding partners during the ®nal stages of re®nement. There is an indication of intermolecular interaction between one amine H atom and the nearest neighbor Br atom, since the Br2 H4Adistance is 2.63 AÊ and the N4ÐH4A Br2 angle is 150_.

Experimental

SnBr4[HN(CH3)2]2 is readily synthesized in toluene by direct

combination of SnBr4with puri®ed HN(CH3)2. This compound has

been characterized by spectroscopic methods and combustion analysis. Single crystals have been grown by slowly cooling concen-trated toluene solutions of the compound.

Crystal data [SnBr4(C2H7N)2]

Mr= 528.50 Monoclinic,P21=c

a= 6.592 (4) AÊ b= 12.029 (7) AÊ c= 8.326 (5) AÊ

= 96.114 (11) V= 656.5 (7) AÊ3

Z= 2

Dx= 2.674 Mg mÿ3 MoKradiation Cell parameters from 3041

re¯ections

= 3.0±25.1

= 14.08 mmÿ1

T= 298 (2) K Block, colorless 0.280.210.14 mm Data collection

Bruker SMART APEX diffractometer

!scans

Absorption correction: multi-scan (SADABS; Bruker, 2001) Tmin= 0.034,Tmax= 0.135

5130 measured re¯ections

1161 independent re¯ections 1028 re¯ections withI> 2(I) Rint= 0.042

max= 25.1

h=ÿ7!7 k=ÿ14!14 l=ÿ9!9 Re®nement

Re®nement onF2

R[F2_{> 2(F}2_{)] = 0.026}

wR(F2_{) = 0.065}

S= 1.05 1161 re¯ections 53 parameters

H-atom parameters constrained

w= 1/[2_(F

o2) + (0.0306P)2 + 0.2351P]

whereP= (Fo2+ 2Fc2)/3 (/)max< 0.001

max= 0.71 e AÊÿ3 min=ÿ0.73 e AÊÿ3

Extinction correction:SHELXTL Extinction coef®cient: 0.0021 (5)

Data collection:SMART(Bruker, 2002); cell re®nement:SAINT

(Bruker, 2002); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Bruker, 1997); program(s) used to re®ne structure:SHELXTL; molecular graphics:SHELXTL; software used to prepare material for publication:SHELXTL.

The authors thank the National Science Foundation for its contribution toward the purchase of the single-crystal diffraction instrument that was used in this study (CHE-9808440). JK acknowledges NSF support (DMR-0221993).

References

Bauer, M., Groy, T. L. & Kouvetakis, J. (2002).Z. Kristallogr. New Cryst. Struct.pp. 217±223.

Bauer, M., Taraci, J., Tolle, J., Chizmeshya, A. V. G., Zollner, S., Menendez, J., Smith, D. J. & Kouvetakis, J. (2002).Appl. Phys. Lett.81, 2992±2994. Bruker (1997). SHELXTL. Version 5.1. Bruker AXS Inc., Madison,

Wisconsin, USA.

Bruker (2001).SADABS. Version 2.03. Bruker AXS Inc., Madison, Wisconsin, USA.

Bruker (2002).SMART(Version 5.625) andSAINT(Version 6.28A). Bruker AXS Inc., Madison, Wisconsin, USA.

Figure 1

supporting information

sup-1 Acta Cryst. (2002). E58, m684–m685

supporting information

Acta Cryst. (2002). E58, m684–m685 [https://doi.org/10.1107/S160053680201927X]

trans-Tetrabromobis(dimethylamine)tin

Cole Ritter III, Thomas L. Groy and John Kouvetakis

(I)

Crystal data [SnBr4(C2H7N)2] Mr = 528.50 Monoclinic, P21/c Hall symbol: -P 2ybc a = 6.592 (4) Å b = 12.029 (7) Å c = 8.326 (5) Å β = 96.114 (11)° V = 656.5 (7) Å3 Z = 2

F(000) = 484 Dx = 2.674 Mg m−3

Mo Kα radiation, λ = 0.71073 Å Cell parameters from 3041 reflections θ = 3.0–25.1°

µ = 14.08 mm−1 T = 298 K Block, colorless 0.28 × 0.21 × 0.14 mm

Data collection Bruker SMART APEX

diffractometer

Radiation source: fine-focus sealed tube Graphite monochromator

ω scans

Absorption correction: empirical (using intensity measurements)

(SADABS; Bruker, 2001) Tmin = 0.034, Tmax = 0.135

5130 measured reflections 1161 independent reflections 1028 reflections with I > 2σ(I) Rint = 0.042

θmax = 25.1°, θmin = 3.0° h = −7→7

k = −14→14 l = −9→9

Refinement Refinement on F2 Least-squares matrix: full R[F2 _{> 2σ(F}2_{)] = 0.026} wR(F2_{) = 0.065} S = 1.05 1161 reflections 53 parameters 0 restraints

Primary atom site location: structure-invariant direct methods

Secondary atom site location: difference Fourier map

Hydrogen site location: inferred from neighbouring sites

H-atom parameters constrained w = 1/[σ2_(F

o2) + (0.0306P)2 + 0.2351P] where P = (Fo2 + 2Fc2)/3

(Δ/σ)max < 0.001 Δρmax = 0.71 e Å−3 Δρmin = −0.73 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 F}2_, conventional R-factors R are based on F, with F set to zero for negative F2_{. The threshold expression of F}2 _{> σ(F}2_{) 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₎

x y z Uiso*/Ueq

Sn1 0.0000 0.0000 0.0000 0.02403 (16)

Br2 −0.24796 (7) −0.01825 (4) 0.21934 (6) 0.04042 (18)

Br3 0.16035 (7) −0.18946 (4) 0.08034 (6) 0.0438 (2)

N4 0.2523 (5) 0.0720 (3) 0.1709 (4) 0.0365 (9)

H4A 0.3651 0.0337 0.1488 0.044*

C5 0.3060 (9) 0.1898 (4) 0.1449 (7) 0.0552 (15)

H5A 0.4155 0.2115 0.2240 0.083*

H5B 0.1892 0.2359 0.1551 0.083*

H5C 0.3480 0.1983 0.0387 0.083*

C6 0.2406 (8) 0.0515 (5) 0.3464 (5) 0.0542 (14)

H6A 0.3559 0.0851 0.4081 0.081*

H6B 0.2411 −0.0271 0.3665 0.081*

H6C 0.1171 0.0833 0.3776 0.081*

Atomic displacement parameters (Å2₎

U11 _U22 _U33 _U12 _U13 _U23

Sn1 0.0245 (3) 0.0287 (3) 0.0187 (2) 0.00402 (15) 0.00164 (16) 0.00229 (15)

Br2 0.0349 (3) 0.0584 (4) 0.0297 (3) 0.0060 (2) 0.0114 (2) 0.0074 (2)

Br3 0.0425 (3) 0.0368 (3) 0.0515 (3) 0.01180 (19) 0.0029 (2) 0.0108 (2)

N4 0.032 (2) 0.049 (2) 0.027 (2) 0.0048 (17) −0.0039 (16) −0.0008 (17)

C5 0.060 (4) 0.041 (3) 0.062 (4) −0.007 (2) −0.008 (3) −0.008 (3)

C6 0.046 (3) 0.088 (4) 0.026 (3) 0.001 (3) −0.004 (2) −0.005 (3)

Geometric parameters (Å, º)

Sn1—N4 2.244 (3) C5—H5A 0.9600

Sn1—Br3 2.5707 (12) C5—H5B 0.9600

Sn1—Br2 2.5867 (11) C5—H5C 0.9600

N4—C5 1.482 (6) C6—H6A 0.9600

supporting information

sup-3 Acta Cryst. (2002). E58, m684–m685

N4—Sn1—Br3 85.46 (10) Sn1—N4—H4A 104.0

N4i_{—Sn1—Br3 94.54 (10) N4—C5—H5A 109.5}

Br3i_{—Sn1—Br3 180.000 (10) N4—C5—H5B 109.5}

N4—Sn1—Br2 93.82 (10) H5A—C5—H5B 109.5

N4i_{—Sn1—Br2 86.18 (10) N4—C5—H5C 109.5}

Br3i_{—Sn1—Br2 89.18 (3) H5A—C5—H5C 109.5}

Br3—Sn1—Br2 90.82 (3) H5B—C5—H5C 109.5

N4—Sn1—Br2i _{86.18 (10) N4—C6—H6A 109.5}

N4i_—Sn1—Br2i _{93.82 (10) N4—C6—H6B 109.5}

Br3i_—Sn1—Br2i _{90.82 (3) H6A—C6—H6B 109.5}

Br3—Sn1—Br2i _{89.18 (3) N4—C6—H6C 109.5}

Br2—Sn1—Br2i _{180.00 (3) H6A—C6—H6C 109.5}

C5—N4—C6 109.8 (4) H6B—C6—H6C 109.5

C5—N4—Sn1 116.7 (3)