Isolation of a sulphur-rich indium polysulphide complex containing two different Sx2- ligands. Synthesis and structure of [InS10Br]2−

Polyhedron Vol. IO, No. IO, pp. 1069-1073, Printed in Great Britain

1991 0

0277-5387/91 %3.00+.00 199 1 Pergamon Press plc

ISOLATION OF A SULPHUR-RICH INDIUM POLYSULPHIDE COMPLEX CONTAINING TWO DIFFERENT S,*- LIGANDS. SYNTHESIS AND STRUCTURE OF [In&,Br]*SANDEEP

DHINGRA

and MERCOURI

G. KANATZIDIS*

Department of Chemistry, Michigan State University, East Lansing, MI 48824, U.S.A. (Received 15 November 1990 ; accepted 2i January 1991) Abstract-The reaction of InBr, with KzSs (or K2S4 and K,S6) and Ph,PBr afforded yellow (Ph,P),[In(S,)(!$,)Br] (I). Complex I crystallizes in the monoclinic space group P2,/c with a = 14.355(7), b = 17.723(4), c = 20.974(7) A, /? = 108.5(l)“, V = 5060.6(4) A’ (at 23”C), Z = 4. The [In(S,)(S6)Br]2- anion features a trigonal bipyramidal indium centre coordinated by four sulphur atoms and one bromine atom. The latter occupies an axial position. The In3+ centre is chelated by two bidentate polysulphide Sd2- and Sh2- ligands. The Se2ligand occupies two equatorial positions. The remaining one equatorial and one axial positions are occupied by the S42- ligand. The average In-S distance is 2.535(35) A. The In-Br distance is 2.615(3) A. Complex I shows no absorptions in the UV-vis spectrum. Two strong absorptions at 490 and 457 cm-’ in the IR spectrum are attributed to S-S vibrations.

Soluble transition-metal polychalcogenides constitute an important class of compounds with unusual structures and stoichiometries. They are useful as model compounds for sulphided hettransport erogeneous catalysts, ’ metal/sulphur agents in geochemistry’ and precursors to chalcogenide semiconductors.3 To date, a number of polysulphide, and to a lesser extent, polyselenide and polytelluride complexes with transition metals have been synthesized and structurally characterized. I-8 In some cases, polysulphides behave differently than their heavier congeners, while in others they behave similarly. It would be important to understand the role of the metal ion in determining similarities and differences in the chemistry of the various polychalcogenide ligands. To date, mostly transition metals have been investigated with respect to coordination to polychalcogenide ligands. On the contrary, the preparation of soluble polychalcogenide compounds containing maingroup elements has not been pursued to the same degree. The few existing examples are, [Bi2

In, Tl). As part of our systematic investigation of polychalcogenide chemistry of the late transition and main group metals’1-‘4 and in an attempt to prepare the sulphur analogue of the indium-polyselenide [In,Se, ,I”- we investigated the corresponding polysulphide chemistry. We have isolated and structurally characterized a new unexpected complex [InS,oBr]2-, which possesses an unusual structure. EXPERIMENTAL

All work was carried out in a glove box (Vacuum Atmospheres, Inc.) under a nitrogen atmosphere. Dimethylformamide (DMF) was stored over 4 A Linde molecular sieves for several days and distilled in vucuo. Ether was distilled over sodium (or potassium)/benzophenone under a nitrogen blanket. InCl, (anhydrous) was purchased from Alpha Products Inc. Satisfactory elemental analyses were obtained. Potassium polysulphides (K,S,, x = 46) were prepared in liquid ammonia from potassium metal and elemental sulphur in the appropriate s3414-yy [sn(s4)2(s6)0.6(s4)0.412-~‘o [1n2Se2114-?” [SnSe,2]2~,‘2 [PbSe812- I3 and [M3Se,,13- I4 (M = ratio. The X-ray powder diffraction patterns were recorded either with a standard Debye-Scherrer powder camera mounted on a Phillips Norelco *Author to whom correspondence should be addressed. XRG-5000 X-ray generator operating at 40 kV/20

1070

S. DHINGRA

and M. G. KANATZIDIS

mA, or a Phillips XRG-3000 computer controlled powder diffractometer. Ni filtered, Cu radiation was used. Thermal gravimetric analyses were performed on a Cahn TG System 121 under flowing nitrogen. A typical heating rate of 5°C min- ’ was used. IR spectra were recorded as KBr and CsI pellets on a Nicolet 740 FT-IR spectrometer. Elemental analyses were performed on a JEOL JSM-35C scanning electron microscope equipped with an Energy Dispersive Spectroscopy detector. Synthesis of I

A 20 cm3 DMF solution of InBr, (0.200 g, -0.564 mmol) was added to a 80 cm3 DMF solution of K2S4 (0.117 g, -0.568 mmol), K& (0.153 g, 0.565 mmol) in the presence of Ph4PBr (0.470 g, 1.12 1 mmol). The mixture was stirred for - 20 min.

Filtration of the pale yellow solution to remove the KBr precipitate, followed by slow addition of ca 60 cm3 of ether, and storage at room temperature for 2 days, afforded 0.41 g of analytically pure, yellow, chunky crystals (61% yield). The synthesis also can be carried out with KZSS (39% yield). The X-ray diffraction (XRD) powder pattern obtained from this material matches extremely well that calculated from the single crystal coordinates, connrrning the purity of the compound. A comparison between the calculated and observed dhk, spacings for this material is shown in Table 1.

X-ray crystallographic studies

The crystallographic data were collected on a Enraf-Nonius diffractometer using an ~20 scan

Table 1. Observed and calculated X-ray powder pattern of I

h

k

1

&,c

1

1 1 1 1 2

0

1 1 2 1

10.796 10.682 8.622 8.4506 8.0946

2 0 1 3 1 2 0 1 0 3 3 2 4 1 1 3 2 2 3 3 1 1 3 3 2 2 2

0 2 2 0 4 3 4 2 2 3 2 4 1 1 4 4 1 3 2 0 2 4 3 4 1 4 4

7.4268 6.6935 6.5406 5.4194 5.0222 4.8221 4.8069 4.7539 4.7345 4.4826 4.4293 4.3366 4.2064 4.0390 3.9508 3.8044 3.7569 3.7497 3.6945 3.5988 3.5163 3.4513 3.3895 3.3420 3.2930 3.2076 3.1309

-1 1 -1 0 1 -2 1 1 -1 -2 -2 2 -3 -1 -2 0 -1 3 -3 0 3 2 -3 3 -4 2 2 -3 -4 -2 -4

D ok%

I otls

h -4

10.660 8.554

4 4 2

9.09 16.4

8.0956 7.9486 7.4093 6.6918 6.5368 5.4163 5.0301 4.8218

36.6 100.0 4.2 21.6 13.8 26.1 49.2 60.1

4.7394

37.1

4.4927 4.4239 4.3289 4.1905 4.0271 3.9445 3.8022 3.7515

80.1 44.6 31.9 37.1 73.1 31.7 27.4 26.7

3.6936 3.5979 3.5099 3.4547 3.3875 3.3438 3.2940 3.2142 3.1302

25.0 24.1 25.9 27.1 36.4 43.0 94.2 25.0 19.5

-3 -3 -5 -2 -4 0 -5 -4 1 -5 -4 -3 -3 2 -6 -3 0 -4 -4 -6 6 6 -6 -7 -5 -7 2 -6

k

1

1 2 0 2 5 5 1 4 4 4 3 5 7 3 4 5 3 2 2 7 4 6 4 2 0 1 0 1 3 3 8 4

5 1 2 5 2 3 4 6 4 6 3 3 1 5 6 6 8 7 1 1 8 5 8 7 2 2 8 1 9 5 4 8

Dca,c 3.0738 3.0020 2.9465 2.8756 2.8375 2.7755 2.7560 2.7177 2.6705 2.6544 2.5722 2.4957 2.4525 2.4386 2.4110 2.3771 2.3393 2.2883 2.2619 2.2357 2.1618 2.1454 2.1126 2.0743 2.0741 2.0599 2.0264 1.9854 1.9506 1.9097 1.8748 1.8428

D ohs

I ohs

3.0750 3.0173 2.9410 2.8725 2.8372 2.7794 2.7515 2.7150 2.6699 2.6584 2.5700 2.4953 2.4588 2.4345 2.4129 2.3772 2.3312 2.2854 2.2582 2.2287 2.1707 2.1478 2.1085 2.0697

18.5 27.1 28.3 22.3 27.1 24.4 18.6 28.3 20.4 22.2 22.2 19.8 21.2 23.4 24.4 35.9 71.3 23.8 29.8 20.4 22.2 21.2 26.1 36.6

2.0545 2.0206 1.9816 1.9573 1.9028 1.8762 1.8458

32.4 22.7 45.8 18.9 33.9 18.2 16.1

Synthesis and structure of [Ins, oBr]Zmode and Mo-K, radiation. The crystals were mounted inside glass capillaries and sealed. Crystal data and details for data collection and refinement are shown in Table 2. The intensities of three check reflections were monitored every 100 reflections and did not show any appreciable decay during the data collection period. An empirical absorption correction was applied to all data based on $ scans for several reflections. The structure was solved with direct methods using SHELXS-86’ 5and was refined with the SDP16 package of crystallographic programs, using a VAXstation 2000 computer. All non-carbon and non-hydrogen atoms were refined anisotropically. The carbon atoms were refined isotropically. The hydrogen atom positions were calculated and included in the structure factor calculation but were not refined. The final coordinates of all atoms, thermal parameters of all non-hydrogen atoms, tables of least-squares planes and a listing of calculated and observed ( 1OF,/ 1OF,) structure factors (total of 32 pages) have been deposited with the Director, Cambridge Crystallographic Data Centre. There were no significant residual peaks in the final electron density different map. The XRD powder pattern was calculated using the atom coordinates determined from the single crystal data using the program POWD 10.17

Table 2. Data for crystal structure Formula FW a (A) b (A) c (A) fx (“) B(“) Y (“) V(A’) Z Space group h, (g cm- ‘) ~(Mo-K,) (cm- ‘) 26 range (“) Data collected Number of data unique Data used [F,’ > 3a(F,*)J Min. max. absorbance correction Number of variables Number of atoms per asymmetric unit Final R/Rw (%) “At 23°C.

analysis” of

1194.17 14.355(7) 17.723(4) 20.974(7) 90.0 108.50 90.00 5060.6 4 P2,lc 1.57 17.3 4-40 5288 4577

0.823/0.999

319 102 6.619.6

I

1071

RESULTS AND DISCUSSION Synthesis

Our original aim was to prepare In3+/Sx2- complexes structurally and compositionally analogous to the selenium analogues, [In2Se2,14- ” and [In3Se,,]3-,‘4 by reacting InCl,, K2SS and Ph,PBr in DMF. As it often happens with polychalcogenide ligands, a different complex than anticipated was obtained. The rational preparation of I was subsequently carried out by reacting InBr3 with K2SS (or a mixture of K2S4 and K2S6) in DMF in the presence of Ph,P+ according to eq. (1) :I8 InBr3 + 2K2S 5+ 2Ph4PBr (Ph4P)JInS,,Br]

+4KBr.

(1)

(I) The UV-vis spectrum of I in DMF solution has no characteristic absorption bands (30&800 nm) and features a rising absorbance at higher energies. The absence of an absorption band around 650 nm suggests that the complex does not dissociate in this solvent to form S,- radical anions which are responsible for this absorption. ” In the IR region of the spectrum we observe strong absorptions at 490 and 457 cm-’ and a weak absorption at 470 cm-’ . These are most likely due to S-S vibrations. A medium intensity absorption is also observed at 352 cm-’ which currently is not assigned with certainty. Thermal gravimetric analysis examination of the thermolysis of I under flowing nitrogen shows that the compound begins to lose weight at -335°C. This onset temperature of initial weight loss is shared by other Ph4P+ salts of polyselenide complexes. It represents the thermal stability of the Ph,Ph+ ion with respect to nucleophilic attack from the Sx2- ligands.3 The weight loss curve is complicated lacking any well-defined plateaux. At lOOO”C, the highest temperature studied, the material continues to lose weight. The grey-black residue obtained contains In, S and P in the 2 : 2 : 1 ratio. Its X-ray powder pattern does not show the presence of known In/S, In/P or In/S/P phases.

Description

of the structure of I

The monoclinic unit cell contains well separated [InS,,Br]‘- anions and Ph4P+ cations. The latter have the usual tetrahedral structure and will not be discussed further. The structure of the [InS,,Br]‘anion is shown in Fig. 1. In view of the structure of [In2Sez114-, and that described here, it appears that five coordination in indium polychalcogenide chem-

S. DHINGRA

1072

and M. G. KANATZIDIS

Br

Fig.

Br

1. Two views of the [In(S,)(S,)Br]*-

anion

istry is readily accessible. The coordination of indium is best described as a trigonal bipyramid with three equatorial sulphur ligands and two axial (a sulphur and a bromide) ligands. It is somewhat surprising that the bromide ligand occupies an axial site in the molecule since an equatorial position is predicted based on VSEPR arguments. The indium atom is chelated by a Sd2- and a Se2- ligand. The latter occupies two equatorial positions. The occurrence of Se2- ligands is rather rare. Another example of a polysulphide complex in which both S4’- and Se’- ligands are present is found in It should be noted, however, LW%>@4)212-.‘o that while in the latter complex the Sd2- and

Table 3. Selected

2.526(4) 2.596(5) 2.506(5) 2.514(5) 2.535(35)

In-Br

2.615(3)

10)

SC2- ligands are disordered about the same crystallographic site, in I they are ordered and occupy distinct sites. The average In-S bond distance is 2.535(35) A. The equatorial In-S bonds are shorter than the axial In-S(4) bond as expected. A listing of selected bond distances and angles for [InS,,Br12- is given in Table 3. The observed S-S bonds are in the normal range of single S-S bond distances reported for other metal polysulphide compounds.” It is interesting to note that in the seven-membered In& ring the In, S(5), S(7), S(8) and S(10) atoms lie very close to a plane with S(6) and S(9) positioned, respectively, I. 16 and 1.19 A above and below it. The same con-

distances (A) and angles (“) in the [In(S,)(S,)Br]‘Standard deviations are given in parentheses”

In-S( 1) In-S(4) In-S(5) In-S( 10) In-S(mean)

S( l)-In-S(4) S( 1)-In-S(5) S(4)-In-S(5) S(4tIn-S( S(S)-In-S(l0) S( I)-In-Br S(4)--In-Br S(S)-In-Br S( lo)--In-Br

with labelling scheme, as drawn by ORTEP.

91.0(2) 125.2(2) 85.4(2) 97.2(2) 115.7(2) 80.8( 1) 170.3( 1) 95.2(2) 91.4(2)

S(l)-S(2) S(2)-S(3) S(3)-S(4) S(5)_S(6) S(6)_S(7) S(7tS(8) S(8)--S(9) S(9)_S(lO) S-S(mean) In-S( 1)-S(2) In-S(5)-S(6) In-S(4)-S(3) In-S( 10)-S(9) S(l)-S(2)-S(3) S(2)_S(3)_S(4) S(5)-S(6)-S(7) S(6)_S(7)-S(8) S(7)_S(8t-S(9) S(8)---S(9)---S(l0)

anion.

2.061(8) 2.045(7) 2.035(6) 2.017(8) 2.060(8) 2.080( 10) 2.029(8) 2.048(6) 2.046(19) 106.3(2) 107.1(3) 98.8(2) 105.0(3) 103.5(3) 103.7(3) 107.2(4) 107.4(4) 107.9(4) 107.0(3)

a The estimated standard deviations in the mean bond lengths and the mean bond angles are calculated by the equations C, = {&(I, - 1)*/n@- 1)} ‘I*. Where I, is the length (or angle) of the nth bond, I is the mean length (or angle) and n is the number of bonds.

1073

Synthesis and structure of [Ins, oBr]2m formation has also been observed in the seven-membered HgSs ring of the [Hg(S,),]*- complex.*’ The equatorial position of the S6*- ligand in I is rationalized by its ability to provide a wide enough “bite” to span the 4.25 A needed between equatorial ligands. The smaller S4*- ligand cannot offer such a large bite (3.7 8, max.) and thus is better stabilized in the fashion in which it is found in [In(S,)(S,)Br]*-. The position of the S(9) atom in the Se2- ligand affects the S(4)-In-S(l0) angle which becomes 12” larger than the S(4)-In-S(5) angle, suggesting that the S(9) atom exerts a significant steric repulsion on S(4). The flexibility of the Se2- ligand to tune its “bite” size is evident by the fact that it has now been found to participate in chelating fashion in tetrahedral, trigonal bipyramidal and octahedral coordination. The five-membered Ins, ring adopts an envelope conformation with S(3) lying 1.1 A above the In( l)S(2) S(4) plane. To the best of our knowledge, [In(S,)(S6)Br]*is the first molecular example of an In3+ polysulphide complex. The In-Br bond length in [In(S,)(S&Br]‘is 2.615(3) & in the correct range for axial binding,

five-coordinate indium, being 0.055 8, shorter than the In-Br bond in the six-coordinate [InBr,13-,*’ and longer than the same bond in the tetrahedral [InBr,]-. *’ When the bromide is equatorially bound to five-coordinate indium such as in InBr,(Me,AsS),, it forms a shorter In-Br distance in the range of 2.53-2.55 A.** Work is continuing to isolate homoleptic indium polysulphide complexes. Acknowledgements-Financial support from the Donors of the Petroleum Research Fund, administered by the American Chemical Society, is gratefully acknowledged. We thank Drs Grahame Williams, Kay Fair and James Phillips of Enraf-Nonius Corp. for the kind collection of X-ray crystallographic data for I. REFERENCES (a) A. Miiller, Polyhedron 1986, 5, 323 ; (b) M. Draganjac and T. B. Rauchfuss, Angew. Chem., Int. Edn Engl. 1985,24, 742.

K. B. Krauskopf, Introduction to Geochemistry, 2nd edn. McGraw-Hill, New York (1979). (a) S. Dhingra and M. G. Kanatzidis, MRS Symp. Proc. 1990, 180, 825; (b) K.-W. Kim, S. Dhingra and M. G. Kanatzidis, 199th American Chemical Society Meeting, Boston MA (1990) INOR 141; (c) S. Dhingra, K.-W. Kim and M. G. Kanatzidis, MRS Symp. Proc., in press.

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W. T. Pennington, D. Jeter, A. W. Cordes and J. W. Kolis, Angew. Chem., Int. Edn Engl. 1988, 27, 1702; (c) S. C. O’Neal and J. W. Kolis, J. Am. Chem. Sot. 1988,110, 1971. 7. R. D. Adams, T. A. Wolfe, B. W. Eichhorn and R. C. Haushalter, Polyhedron 1989,8, 701. 8. (a) M. A. Ansari and J. A. Ibers, Coord. Chem. Rev. 1990,101, 223; (b) M. G. Kanatzidis, Comm. Znorg. Chem. 1990,10, 161. 9. A. Miiller, M. Zimmermann and H. Biigge, Angew. Chem., Int. Edn Engl. 1986,25,273.

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13. R. M. H. Banda, J. Cusick, M. L. Scudder, D. C. Craig and I. G. Dance, Polyhedron 1989, 8, 1995. 14. M. G. Kanatzidis and S. Dhingra, submitted. 15 G. M. Sheldrick, in Crystallographic Computing 3 (Edited by G. M. Sheldrick, C. Kruger and R. Goddard), pp. 175-189. Oxford University Press, Oxford (1985). CAD4 SDP 16. B. A. Frenz, The Enraf-Nonius System, in Computing in Crystallography, pp. 6471. Delft University Press, Delft, Holland (1978). 17. D. K. Smith, M. C. Nichols and M. E. Zolensky, POWD 10 : A FORTRAN Program for Calculating X-ray Powder Diffraction Patterns, Version 10. Pennsylvania State University (1983). 18. The isostructural (Ph,P),[InS, &I] has been synthesized in DMF by the reaction of InCl, and K,S, in the presence of Ph,PCl. It shows an identical X-ray powder diffraction pattern with that of I and its unit cell is a = 14.314(7), b = 17.623(8), c = 20.861(15) A, b = 108.28(5)“, l’= 5022 A3. 19. (a) D. Coucouvanis, P. R. Patil, M. G. Kanatzidis, B. Detering and N. C. Baenziger, Znorg. Chem. 1985, 24, 24; (b) A. Miiller, E. Krickemeyer and H. Bogge, Z. Anorg. Allg. Chem. 1987,554,61. 20. A. Miiller, J. Schimanski and U. Schimanski, Angew. Chem., Znt. Edn Engl. 1984,23,

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