The reactions of sulphuryl chloride with metals—II

.I. inorg,nucl.Chem., 1969,Vol. 31, pp. 2427 to 2430. PergamonPress. Printedin Great Britain

THE

REACTIONS OF SULPHURYL CHLORIDE WITH METALS-II THE PLATINUM METALS[I] i. M. D I L L A M O R E

and D. A. E D W A R D S

School of Chemistry and Chemical Engineering, Bath University of Technology, Bath BA2 7AY (Received 15 November 1968)

Abstract-The Platinum metals are converted into chlorides by reaction with sulphuryl chloride, in some cases the chloride isolated being dependent on reaction temperature./3-PtCI2, PtC14,/3-PdCI., lrCl3, c~-RuC13./3-RuCI3 and OsCI4 have all been prepared in virtually quantitative yields within a reasonable reaction time, but rhodium (111/chloride is only formed extremely slowly from the metal by this method.

MANY metals react with sulphuryl chloride[l, 2] to produce chlorides, although molybdenum, tungsten and rhenium[l] are converted into oxidetetrachlorides. the necessary oxygen being derived from the sulphur dioxide formed in the dissociation of the sulphuryl chloride. We have now examined the usefulness of the reagent in its reactions with the platinum metals and find that in sealed reaction tubes, suitable conditions can easily be found (Table 1) for virtually quantitative conversion of the metals, other than rhodium, into chlorides. Table 1

Metal

SO~CI.,/M ratio

Ru Ru Os Rh h Pd Pt Pt

6" 1 6-9 8.1 7.5 7.7 7.9 8.5 6.3

Temp. 300-350 450-500 450-500 350-400 450 400 450-500 350

Time

Product

1 day 4 days 10 days 40 days 6 days 3 days 7 days 7 days

/3- RuCI,s a - RuCl,s OsCl4 RhCI~ + Rh IrCla /3-PdClz /3-PtCI~ PtCI 4

Metal (%1 Found Calcd. 48.4 48.6 57.1 79.7 63.9 60.0 73.5 57-7

48.7 48.7 57.3 49.2* 64.4 60.0 73.3 57.9

Chlorine % Found Calcd. 51. I 51.2 42.7 20-0 35.2 40.0 26.2 42.2

51.3 51.3 42.7 50,8* 35,6 40-0 26,7 42.1

* For RhCI:~.

The reaction between ruthenium and an excess of sulphuryl chloride in the temperature range 300-350 ° gives a dark brown powder of low density as the only product, an X-ray powder pattern of which was in excellent agreement with published data[3] for/3-RuCI3. The i.r. spectrum (Table 2) showed only minor 1. Part 1 is considered to be D. A. Edwards and A. A. Woolf, J. chem. Soc. (A), 91 (1966). 2. "Gmelins Handbuch der anorg. Chemie", 8th Edn, Sulphur. Pt, B. 3 (1963). 3. J. M. Fletcher, W. E. Gardner. A. C. Fox and G. Topping, J. chem. Soc. (A), 1038 (I 967). 2427

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DILLAMORE

and D. A. E D W A R D S

Table 2. Infrared absorption bands Chloride

Frequency (cm -1) and intensity*

Previous work

a-RuCI3 /3-RuC13

322 sh; 306 s 380 m; 370 sh; 330 sh; 317 m,b; 285 s 381 s: 368 sh; 305 sh; 285 sh 318 s; 296 m 331 s 340 sh; 329 s 317 s 365 s; 340 s; 325 m; 289 w; 273 w; 235 w, b

[3] [3]

OsCI4 lrCl3 RhCI3 /3-PdC12 /3-PtCI2 PtCI4

[15]

*s = strong; m = medium; w = weak; b = broad; sh = shoulder.

differences in band maxima from previous results[3] for B-RuCI3. Reaction temperatures between 450 and 500 °, however, lead to the isolation of a black solid in the form of platelets, X-ray and infrared data being in good agreement with previous results[3] for a-RuCI3. The /3--->a irreversible transformation has previously been studied[4, 5]. There was no evidence of the formation of the dioxide or oxidechlorides[4, 6], such as RuzOCI~, which have been formed in low yields by reaction of metal with chlorine in silica apparatus. Thus, sulphur dioxide derived from the dissociation of the sulphuryl chloride, at the reaction temperature, appears to be unable to provide the necessary oxygen for ruthenium oxychioride formation, but is able to do so with molybdenum, tungsten and rhenium [ 1]. The reaction of sulphuryl chloride with rhodium powder at temperatures up to 400 ° was very slow and even after 40 days reaction time a considerable portion of the metal was recovered unchanged, with only a small amount of the trichloride being formed. This result is not unexpected since the metal does not react completely with chlorine to produce the trichloride unless temperatures of 800-900 ° are employed. This chloride is iso-structural with aluminium trichloride, having a pseudohexagonal layer lattice with defect stacking of layers[7] but our i.r. spectrum shows only one strong, sharp, rhodium-chlorine stretch at 331 cm -1. The sole product of the reaction between sulphuryl chloride and osmium is the tetrachloride, although reaction is slow even in the temperature range 450500 °, the metal being incompletely converted to the tetrachloride even after fourteen days at 380°. The tetrachloride has previously been prepared by direct chlorination[8] and a partial X-ray powder pattern recorded. The X-ray pattern of our product is in reasonable agreement with these previous results but some 4. K. R. Hyde, E. W. HoopeL J. Waters and J. M. Fletcher, J. less-common Metals 8 , 4 2 8 (1965). 5. N. I. Kolbin and A. N. Ryabov, Vest. Leningr. gos. Univ. 22, 121 (1959). 6. J. M. Fletcher, W. E. Gardner, E. W. Hooper, K. R. Hyde, F. H. Moore and J. L. Woodhead. Nature, Lond. 199, 1089 (1963). 7, H. Biirnighausen and B. K. H a n d a , J . less-common Metals, 6,225 (1964). 8, N. I. Kolbin. 1. N. Semenov and Yu. M. Shutov, Russ. J, inorg. Chem. 8.1270 (1963).

The reactions of sulphuryl chloride with m e t a l s - 11

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extra lines have been found so our results (see Experimental) are given in full. Osmium (IV) chloride has also been prepared[9] by reaction of the tetroxide with carbon tetrachloride at 470 ° and the X-ray powder pattern of this product tentatively indexed on the basis of an orthorhombic unit cell. A second, possibly cubic, form results from the reaction of the tetroxide with thionyl chloride at lower temperatures[9, 10]. The i.r. spectrum of our high-temperature form is complex in the osmium-chlorine stretching region. The wide separation of the bands is somewhat reminiscent of that for complexes such as [Pd2C1612-[11] in which there are both terminal (v(Pd-Cl) 336 and 339 cm -~) and bridging (u(Pd-C1) 305 and 263 cm -1) palladium-chlorine bonds. Evidence is becoming available[11, 12] to suggest that terminal modes generally appear above the corresponding bridging modes, although it must be remembered that coupling between these modes could be significant. Such coupling would, however, occur to a greater extent in the second Transition series iruthenium, rhodium, palladium) than in the third series iosmium, iridium, platinum) due to the greater mass of the latter metals. The reaction of iridium with sulphuryl chloride at 450 ° was slow but finally gave good samples of iridium (11I) chloride as an olive-green micro-crystalline powder. Neither the yellow a-modification [ 13] nor the black/3-modification [ 14] were prepared by our method. The product of the reaction of platinum with sulphuryl chloride is dependent on the temperature of reaction. Reaction at 350 ° gives platinum (IV) chloride, the structure of which has not been determined. The i.r. spectrum of this chloride is, like osmium (IV) chloride, complex in the platinum-chlorine stretching region, probably indicating a low symmetry with both bridging and terminal platinum-chlorine bonds. Above 450 ° the product is, however, platinum (il) chloride, the infrared spectrum of which agrees with previous results[15]. The X-ray powder pattern obtained agrees with the full crystal structure previously reported[16] for hexameric/3-platinum (II) chloride, which has the structural unit of an octahedron of platinum atoms with bridging chlorines along each edge. The corresponding reaction with palladium at 400 ° gives palladium ill) chloride. Unlike platinum ill) chloride, where only one modification q3) is known, palladium ill) chloride is known in two forms. An a-form[17], with endless chains of planar PdC14/2 units, can be prepared by reaction of the metal with chlorine at 550 °. Vacuum sublimation of this modification yields the/3-form[18]. The X-ray powder pattern of our product is not in agreement with previous data[17] on the a-modification, so presumably/3-palladium Ill) chloride has been formed. this being isotypic with B-platinum (11) chloride[18]. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18.

P. Machmer. Chem. Comm. 610(1967). R. Colton and R. H. Farthing, A ust. J. Chem. 21, 589 (1968). D. M. Adams, P. J. Chandler and R. G. Churchill,J. chem. Soc. CA). 1272 ( 1967), D. M. Adams and R. G. Churchill,J. chem. Soc. CA), 2141 (1968). K. Brodersen, F. Moers and H. G. Schnering, Naturwissenschaften 52,205 C19651. D. Babel and P, Deigner, Z. anorg, allg. Chem. 339~ 57 (1965). D. M. Adams, M. Goldstein and E. F. Mooney, Trans. Faraday Soc. $9,2228 (1963), K. Brodersen. G. Thiele and H. G. Schnering, Z. anorg, allg. Chem. 337.120 {1965). A. F. Wells, Z. Kristallogr. Kristallgeom. I00, 189 (1938). N. Schafer, U. Weise, K. Rinke and K. Brende[,Angew. Chem. lnternat. Edn. 6, 253 (1967).

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D I L L A M O R E and D. A. E D W A R D S EXPERIMENTAL

Samples of the metal powder were weighed into Pyrex glass tubes (1.6 cm bore, 0"2 cm wall, 25 cm length) outgassed at 25-30 mtorr., an excess (see Table 1) of sulphuryl chloride distilled on to the metal and the tube sealed in vacuo. The tubes were heated at the temperatures shown in Table 1 until all the metal had reacted (except rhodium), cooled, then opened and the excess sulphuryl chloride and decomposition products removed at the above pressure. For analysis, the products were generally reduced in a current of hydrogen, the resulting metal being weighed and the hydrogen chloride evolved being trapped in sodium hydroxide solution, the chloride being finally estimated, after acidification, as silver chloride. l.r. spectra were obtained for Nujol mulls using a Grubb-Parsons DM4 spectrophotometer. X-ray powder photographs were obtained with a Debye-Scherrer focusing camera of 11.46cm diameter using nickel-filtered Cu Ka radiation. Line intensities were judged visually. The interplanar spacings (,~) for osmium (IV) chloride, together with intensities on a ten-point scale, are: 5'735, (10); 4-171, (3); 3.943 (3); 3.558, (2); 2.983, (4); 2.700, (4); 2.515, (2); 2.454, (5); 2.239, (2); 2.107, (3); 2.047, (2); 1-975, (2); 1.902, (3); 1.790, (1); 1.741, (4); 1"687, (2); 1.660, (2); 1.629, (2); 1.596, (2). Typical analytical results and reaction conditions are shown in Table 1. The i.r. results, together with keference to previous investigations, are given in Table 2.

Acknowledgement- We thank Dr. R. A. Walton for some i.r. measurements.