It crystallizes in the monoclinic space group C2/c with a b c A, ß

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Notizen 695

The Crystal Structure of [Et4N ]22+[TeI6]2- , a Tetraalkyl Ammonium Salt Containing a Discrete Octahedral [Tel6]2~ Anion P. C. Srivastava3, H.-G. Schmidtb, H. W. Roeskyb *

a D epartm ent of Chemistry Lucknow University, Lucknow 226007, India

b Institut für Anorganische Chemie

der Universität Göttingen, Tam m annstraße 4, D-37077 Göttingen

Z. Naturforsch. 50b, 695-696 (1995);

received Septem ber 1, 1994 Hexacoordinate Tellurium(IV),

Tellurium (IV)-Iodine Com pound, X-Ray

The structure of [Et4N]22+[TeI6]2~, the first tetraalkyl am monium salt to contain the almost regular octahedron of a discrete [TeI6Jz_ anion, has been determ ined by single crystal X-ray dif

fraction studies. It crystallizes in the monoclinic space group C2/c with a = 18.757(3), b = 11.578(2), c = 15.447(2) A, ß = 109.380(10)°. The [Tel6]2~ anion has T e - I bond distances in the range of 2.845 to 2.948 Ä and I - T e - I bond angles in the range of 89(1) to 90.1(1)°.

Introduction

Kiriyama et al. [1] tried to prepare [Me4N]22+[TeI6]2- and ended up with [Me4N]2TeI8.

Pohl et al. [2] reported that they could not obtain [Et4N]22+[TeI6]2~.

In our attem pt to prepare butyltin cations in the solid state by the reactions of Bu2SnCl2 or

R eprint requests to Prof. Dr. H. W. Roesky.

Bu3SnCl with [Et4N]22+[TeI4]2_ in acetonitrile, we obtained crystals of [Et4N]22+[TeI6]2~. Its structure has been determ ined by single crystal X-ray dif

fraction studies which show it to contain discrete octahedral [Tel6]2~ anions and thus account for the first example of tetraalkylam m onium salt con

taining a regular octahedron of a discrete [Tel6]2- anion.

Experimental

[Et4N]22+[TeI4]2_ (1.0 g, 1.1 mmol) was dis

solved in (20 ml) dry acetonitrile. To this light brown solution, Bu2SnCl2 (0.34 g, 1.1 mmol) was given. It was stirred for 6 h at room tem perature and refluxed for additional 5 h. The solution was concentrated (to 5 ml) and left overnight when black crystals of [Et4N j221 [Tel6]?~ appeared (yield 0.60 g).

The reaction of [Et4N]22+[TeI4]2 (1.0 g, 1.1 mmol) with Bu3SnCl (0.73 g, 2.2 mmol) in ace

tonitrile (20 ml) under similar experim ental con

ditions also yielded crystals of [Et4N]22+[TeI6]2~

(yield 0.74 g). The crystals obtained from both the experiments have the same cell constants.

In a separate experim ent, the attem pt to synthe

size [Et4N]22+[TeI6]2~ directly from excess E t4NI [2] (1.78 g, 6.9 mmol), Te (0.32 g, 2.5 mmol) and I2 (1.28 g, 5.0 mmol) by refluxing in dry acetonitrile (50 ml) with stirring for 4 h, filtering hot to get rid of unreacted tellurium, reducing the volume (20 ml) and keeping it at 4 °C was not successful.

It resulted in the synthesis of brown crystals of [Et4N]22+[TeI4]2_ in almost quantitative yield.

Analysis for C 16H 40N 2TeI4

Found C 21.8 N 3.4 H 4 .6 % , Calcd C 21.43 N 3.12 H 4.46% .

C 16H 40N2TeI6, M = 1148.5; monoclinic, space group C2/c; a = 18.757(3), b = 11.578(2), c = 15.447(2) Ä, ß = 109.380(10)°, V = 3164.2(9) A 3, D^caiccn = 2.413 Mg/m3, absorption coefficient = 6.743 mm->, F(000) = 2080.

2274 reflections were collected on a STOE four circle diffractom eter (Rev: 6.2). 2056 thereof were independent and 1961 observed with F > 3 a(F).

A bsorption corrections were applied by azimuthal scans. Refinem ent converged at R = 0.037 (wR = 0.051, w -1 = ct2(F) + 0.0004 F 2).

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696 Notizen

Description of the Structure

[Et4N]22+[TeI6]2~ consists of N E t4+ cations and regular discrete Tel62~ anion octahedra, in con

trast to the tetram ethyl ammonium salts and their analogues [Me4N]2TeI8 [1] which possess consider

ably distorted Tel6 octahedra owing to different interactions with surrounding I2 molecules.

[Me3NH]2TeI7 [4] has an elongated Tel6 octa

hedron and [Me3NH]2TeI6 [4] consists of Tel6 octahedron with weak hydrogen iodine inter

actions [5].

The [Tel6]2~ anion is centrosymm etric with Te on special position 1/4, 1/4, 1/2; [1].

The lengths of the three independent T e - I bonds are in the range of 2.945 to 2.948 A and the I - T e - I bond angles are in the range of 89.9(1) to 90.1(1)° indicating that the coordination octahedra of Te(IV) atoms are practically regular. The T e - I bond lengths might be com pared with that in K2TeI6 [3], The [Et4N]+ cations have C (2 )-N (l), C (3 )- N (l), C (4 )- N (l) and C (5 )- N (l) as 1.500, 1.545, 1.539, and 1.531 A, respectively, whereas C ( 2 ) - N ( l) - C ( 4 ) , C (3 ) - N ( l) - C ( 3 ) , C ( 2 ) - N ( l ) - C(5), C (3 ) - N ( l) - C ( 5 ) , C ( 4 ) - N ( l) - C ( 5 ) and N ( l) -C (2 )-C (2 1 ) , N (l) -C (3 )-C (3 1 ) , N ( l ) - C (4 )-C (4 1 ), and N ( l) -C (5 )-C (5 1 ) are 109.2(6)°, 109.5(6)°, 112.8(6)°, 107.9(6), 108.2(6)°, 115.7(7)°, 115.9(7)°, 118.1(7)°, and 113.7(7)°, respectively.

Table I. Atomic coordinates (xlO4) and equivalent iso

tropic displacement coefficients (pm2x l 0 _1).

Atom ^X _y z u eq

Te 2500 2500 5000 36(1)

1(1) 1940(1) 361(1) 3962(1) 49(1)

1(2) 3728(1) 1192(1) 6331(1) 48(1)

1(3) 1517(1) 2067(1) 6108(1) 49(1)

N (l) 1111(3) -2400(5) 5726(4) 41(2)

C(2) 1824(4) -2344(8) 6538(6) 53(3)

C(21) 2344(4) -1323(8) 6553(6) 59(3)

C(3) 599(4) -3365(7) 5883(6) 49(3)

C(31) 915(6) -4563(8) 5969(7) 66(4)

C(4) 1311(4) -2671(8) 4858(6) 55(4)

C(41) 693(5) -2784(10) 3987(6) 69(4)

C(5) 663(4) -1269(7) 5565(6) 49(3)

C(51) 443(5) - 885(8) 6383(6) 61(4)

* Equivalent isotropic U defined as one third of the trace of the orthogonalized U;j tensor.

Table I contains atomic coordinates (xlO4) and equivalent isotropic displacement coefficients (pm2x l 0 _1).

A cknow ledgem ent

Financial support of the Deutsche Forschungs

gemeinschaft and the Fonds der Chemischen Indu

strie is highly acknowledged.

[1] H. Kiriyama, K. Nishizaki, Bull. Chem. Soc. Jpn. 59, 2415 (1986).

[2] S. Pohl, W. Saak. B. Krebs, Z. Naturforsch. 40b, 251 (1985).

[3] S. Syoyama, K. Osaki, S. Kusanagi, Inorg. Nucl.

Chem. Lett. 8, 181 (1972).

[4] H. Kiriyama, Y. Mizuhashi, J. Ootani. Bull. Chem.

Soc. Jpn. 59, 581 (1986).

[5] Further details of the crystal structure investigation may be obtained from the Fachinformationszentrum Karlsruhe, Gesellschaft für wissenschaftlich-tech

nische Information mbH. D-76344 Eggenstein-Leo- poldshafen (Germ any), on quoting the deposit num ber CSD 58478, the nam es of the authors, and the journal citation.