Tri­methyl­arsonium iodide

organic papers

Acta Cryst.(2005). E61, o4229–o4230 doi:10.1107/S160053680503792X Tobias van Almsick _C

3H10As+I

o4229

Acta Crystallographica Section E

Structure Reports Online

ISSN 1600-5368

Trimethylarsonium iodide

Tobias van Almsick

Lehrstuhl fu¨r Analytische Chemie, Ruhr-Universita¨t Bochum, Universita¨tsstrasse 150, 44780 Bochum, Germany

Correspondence e-mail: [email protected]

Key indicators

Single-crystal X-ray study

T= 292 K

Mean(s–C) = 0.007 A˚

Rfactor = 0.029

wRfactor = 0.078

Data-to-parameter ratio = 22.4

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

#2005 International Union of Crystallography Printed in Great Britain – all rights reserved

The title compound, C3H10As +

I, contains discrete [(CH3)3AsH]

+

cations with a distorted tetrahedral geometry for the central As atom, which lies on a mirror plane. Weak van der Waals contacts are observed between the I atom and the H atoms in the range 3.15 (1)–3.25 (1) A˚ .

Comment

[(CH3)4As]+ cations have been reported with a variety of different counteranions. Tetramethylarsonium halides, for example, have been characterized by X-ray structural analysis for the heavier halides bromide (Collinset al., 1963) and iodide (Assenmacher & Jansen, 1995), whereas the chloride compound has not yet been characterized by single-crystal structure analysis, although Debye–Scherrer investigations have revealed that it is isostructural with (CH3)4AsBr (Ang & Dunell, 1976). In contrast, the trimethylarsonium cation has been characterized only twice. In both [(CH3)3AsH][As2F11] and [(CH3)3AsH][SbF6] (Minkwitz et al., 1999), relatively large counteranions are needed to stabilize the [(CH3)3AsH]

+ cations in the solid state.

The title compound, (CH3)3AsHI, (I), is the first example of a discrete trimethylarsonium cation crystallizing with a halide counteranion. The As atom, which lies on a mirror plane, exhibits a distorted tetrahedral environment, with As—C distances of 1.923 (5) and 1.927 (8) A˚ , which are similar to those observed in [(CH3)3AsH][As2F11] [1.894 (5)– 1.908 (5) A˚ ].

The I counteranion exhibits long-range van der Waals interactions with its surrounding H atoms [I H 3.15 (1)– 3.25 (1) A˚ ]; these stabilize the arrangement of (I) in the crystal packing (Fig. 2).

Experimental

GeI4(580.19, 1.0 mmol), As2Se3(193.4 mg, 0.5 mmol), Se (79.0 mg,

1.0 mmol) and K2CO3(138.2 mg, 1.0 mmol) were heated to 433 K in

CH3OH (0.8 ml) in a sealed glass tube. After 2 d, the contents were

cooled to room temperature to afford colourless crystals of (I) in 52% yield.

Crystal data

C3H10As+I

Mr= 247.93

Orthorhombic,Pnma a= 14.174 (3) A˚

b= 8.0458 (16) A˚

c= 6.2037 (12) A˚

V= 707.5 (2) A˚3

Z= 4

Dx= 2.328 Mg m

3

MoKradiation Cell parameters from 21

reflections = 6.2–15.0

= 9.04 mm1

T= 292 (2) K Block, colourless 0.410.330.21 mm

Data collection

SiemensP4 four-circle diffractometer !scans

Absorption correction: scan (XPREPinSHELXTL; Sheldrick, 1995)

Tmin= 0.040,Tmax= 0.152

671 measured reflections 671 independent reflections

576 reflections withI> 2(I) max= 25.0

h= 0!16

k=9!0

l= 0!7

3 standard reflections every 97 reflections intensity decay: none

Refinement

Refinement onF2

R[F2_{> 2(F}2_{)] = 0.029}

wR(F2_{) = 0.078}

S= 1.16 671 reflections 30 parameters

H-atom parameters constrained

w= 1/[2_(F

o2) + (0.0439P)2]

whereP= (Fo2+ 2Fc2)/3

(/)max< 0.001 max= 0.82 e A˚

3 min=0.73 e A˚

3

Extinction correction:SHELXL97

(Sheldrick, 1997)

Extinction coefficient: 0.0286 (17)

Table 1

Selected geometric parameters (A˚ ,_).

As—C1 1.923 (6) As—C2 1.927 (8)

C1i—As—C1 98.9 (3) C1—As—C2 97.8 (2)

Symmetry code: (i)x;yþ1 2;z.

H atoms were located in a difference electron-density map but were refined with fixed individual displacement parameters [Uiso(H) =

1.5Ueq(C)] using a riding model, with C—H = 0.96 A˚ . The idealized

As—H bond length is 1.40 A˚ .

Data collection:R3m/V(Siemens, 1989); cell refinement:R3m/V; data reduction: XDISK(Siemens, 1989); program(s) used to solve structure: SHELXS97(Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL(Sheldrick, 1995); software used to prepare material for publication:SHELXL97.

References

Ang, T. T. & Dunell, B. A. (1976).Can. J. Chem.54, 1985–1990.

Assenmacher, W. & Jansen, M. (1995).Z. Anorg. Allg. Chem.621, 143–148.

Collins, E., Sutor, D. J. & Mann, F. G. (1963).J. Chem. Soc.pp. 4051–4055. Minkwitz, R., Hirsch, C. & Berends, T. (1999).Eur. J. Inorg. Chem.12, 2249–

2254.

Sheldrick, G. M. (1995).SHELXTL. Release 5.03 for Siemens R3. Siemens Analytical X-ray Instruments Inc., Madison, USA.

Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Go¨ttingen, Germany.

Siemens (1989).R3m/V(Version 3.2) and XDISK(Version 3.11). Siemens Analytical X-ray Instruments Inc., Madison, Wisconsin, USA.

Figure 1

The structure of (I). Displacement ellipsiods are drawn at the 50% probability level. [Symmetry code: (i)x,1

2y,z.]

Figure 2

supporting information

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Acta Cryst. (2005). E61, o4229–o4230

supporting information

Acta Cryst. (2005). E61, o4229–o4230 [https://doi.org/10.1107/S160053680503792X]

Trimethylarsonium iodide

Tobias Van Almsick

Trimethylarsonium iodide

Crystal data C3H10As+·I−

Mr = 247.93

Orthorhombic, Pnma Hall symbol: -P 2ac 2n a = 14.174 (3) Å b = 8.0458 (16) Å c = 6.2037 (12) Å V = 707.5 (2) Å3

Z = 4 F(000) = 456

Dx = 2.328 Mg m−3

Melting point: not measured K Mo Kα radiation, λ = 0.71073 Å Cell parameters from 21 reflections θ = 6.2–15.0°

µ = 9.04 mm−1

T = 292 K Block, colourless 0.41 × 0.33 × 0.21 mm

Data collection Siemens P4 four-circle

diffractometer

Radiation source: fine-focus sealed tube Graphite monochromator

ω scans

Absorption correction: ψ scan

(XPREP in SHELXTL; Sheldrick, 1995) Tmin = 0.040, Tmax = 0.152

671 measured reflections

671 independent reflections 576 reflections with I > 2σ(I) Rint = 0.000

θmax = 25.0°, θmin = 2.9°

h = 0→16 k = −9→0 l = 0→7

3 standard reflections every 97 reflections intensity decay: none

Refinement Refinement on F2

Least-squares matrix: full R[F2 _{> 2σ(F}2_{)] = 0.029}

wR(F2_{) = 0.078}

S = 1.16 671 reflections 30 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) + (0.0439P)2]

where P = (Fo2 + 2Fc2)/3

(Δ/σ)max < 0.001

Δρmax = 0.82 e Å−3

Δρmin = −0.73 e Å−3

Extinction correction: SHELXL97 (Sheldrick, 1997), Fc*_{=kFc[1+0.001xFc}2_λ3_/sin(2θ)]-1/4

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

I 0.40703 (3) 0.2500 0.09746 (9) 0.0509 (3)

As 0.08001 (5) 0.2500 −0.06698 (14) 0.0482 (3)

H3 −0.0166 0.2500 −0.1138 0.072*

C1 0.1327 (4) 0.0683 (7) 0.0946 (9) 0.0565 (14)

H1A 0.1985 0.0885 0.1196 0.085*

H1B 0.1253 −0.0329 0.0146 0.085*

H1C 0.1005 0.0588 0.2302 0.085*

C2 0.1695 (6) 0.2500 −0.3007 (13) 0.056 (2)

H2A 0.1538 0.3465 −0.3792 0.084*

H2B 0.2316 0.2500 −0.2407 0.084*

Atomic displacement parameters (Å2₎

U11 _U22 _U33 _U12 _U13 _U23

I 0.0487 (4) 0.0535 (4) 0.0505 (4) 0.000 −0.0053 (2) 0.000

As 0.0374 (4) 0.0659 (5) 0.0412 (5) 0.000 −0.0046 (3) 0.000

C1 0.066 (3) 0.048 (3) 0.055 (3) −0.007 (3) 0.001 (3) −0.002 (3)

C2 0.065 (5) 0.057 (5) 0.046 (4) 0.000 0.006 (4) 0.000

Geometric parameters (Å, º)

As—C1i _{1.923 (6) C1—H1B 0.9600}

As—C1 1.923 (6) C1—H1C 0.9600

As—C2 1.927 (8) C2—H2A 0.9432

As—H3 1.4000 C2—H2B 0.9557

C1—H1A 0.9600

C1i_{—As—C1 98.9 (3) H1A—C1—H1B 109.5}

C1i_{—As—C2 97.8 (2) As—C1—H1C 109.5}

C1—As—C2 97.8 (2) H1A—C1—H1C 109.5

supporting information

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Acta Cryst. (2005). E61, o4229–o4230

As—C1—H1A 109.5 H2A—C2—H2B 114.7

As—C1—H1B 109.5