Bhattacharya, S. N.

Raj, Prem

English

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Indian Journal of ChemistryVol. IliA, September 1977, pp. 802-804Cleavage of Triaryltin Halides with Iodine Halides & Halogens:A Novel Route to Mixed Diaryltin DihalidesS. N. BHATTACHARYA & PREM RAJChemistry Department, Lucknow University, Lucknow 226007Received 27 January 1977; accepted 6 April 1977Electrophilic tin-carbon bond cleavage reactions employing iodine halides IY (Y =" CI andBr) and bromine have been used to synthesize mixed diaryltin dihalides (Ar,SnXY; Ar = phenyland p-tolyl; XY '~-'CIBr). Reactions of Ph"SnI with iodine halides to prepare Ph,SnCII orPh,SnBrI are also discussed. The mixed halides also form 1: 2 dimethyl sulphoxide additioncomplexes similar to other organorin halides.As compared to extensively reported diorgano- tindihalides R2SnXz (ref. 1), compounds containingtwo different halogens X and Y attachedto tin, e.g. RzSnXY, are rare. Aronhcim- reportedtwo such compounds PhzSnClBr and Ph2SnCII.Redistrihution or exchange methods have beenemployed to synthesize Bu2SnClBr (ref. 3,4) orR2SnFCl (rd. 5, 6) (R=Ml~, z-Bu). A recent note?on mixed dialkvlt in dihalidcs (RzSnXY; R=Me,Et or n-Bu; XY=ClBr, ell or BrI) prompted usto present our results on the preparation of diaryltindihalides through elcctrophilic cleavage of tin-aryl bond with halogen and iodine monohalides.Iodine mono halide (ICl) has also been previously"used to prepare PhBiClBr from PhzBiBr. Theconditions for the cleavage reactions described inthis paper are uniform and mild and thus are advan-tageous over redistribution reactions which needvarying specific conditions--s. The newly synthe-sized compounds were converted into their 1:2DMSO adducts (ArzSnXY: 2DMSO) and a tentativestructure assigned.Materials and MethodsTriarvltin chlorides and bromides were svnthesiz-ed by 'the redistribution reaction of tctraarylt insand the corresponding stannic halides". Triphcnyl-tin iodide was prepared bv the previously reportedmethod".Iodine monochloride (Flub grade) was distilledbefore use. Iodine mono bromide was preparedby dissolving iodine in an excess of bromine andpurified bv the published rnethod!''.Anhydrous CCI4 was used as a solvent and mois-ture was excluded dnring the reactions and theirwork up.Reactions of Ar3SnX compounds teiili IY and Br2-Typical experiments arc given here. Furtherdetails are given in Table 1.Reaction of Ph3SnCl and 12 (1 :1) -' Thereaction did not take place at room temperature.EVen rofluxing a mixture containing cquimolarsolution of the reactants in CCl4 for 7 hr gave the802TABLE 1 - REACTIONS OF Ar"SnX (X = Cl.: Br, I) WITHTCI, IBr AND Br2.Ph"SIlIMole Rc- Prof\ucts(a,h) m.p.ratio action °C(e)time(hr)andtemp.(0C)REACTION WITI! ICII :2 2 (30) Ph,SnCl. 41-42(42-44)REACTION WITH IEr: 1 6 (30) Ph3SnBr 120(120-21):2 4 (77) Ph.SnBr2 37-38(38): 1 4 (77) Ph2SnCIBr 38(39): 1 4 (77) (p-Tol),SnCIBr 59RE,\CTION wrr n TCl1 : 1 1 (30) (p- Tol)2SnClBr 59REACTION WITI! Dr,1 : 1 1 (-5) Ph,SnCIBr 38-39(39)1 : 1 1 (-5) (p- Tol).SnClBr 58-59doPh3SnCI(P-Tol)3SnCl(p- Tol)3SnCIPh3SnCI(p-Tol)3SnCI(a) Corresponding amounts of arvl halides arc also obtained.(b) Products arc obtained in 60-75 % yields.(c) Literature melting points (ref. 1) are given in parentheses.starting PhaSnCI aft cr evaporation of the solvent.No trace of iodobenzenc could he detected.Reaction of Ph.Sn] u·ith ICt (1 :1) - Gradualaddition of ICI (0'81 g, 0·005 mole) in CC14 (20 ml)to a solution of t riphonvlf in iodide (2·35 g, 0'005mole) in CC14 (100 ml) at room temperature produceda violet colour which persisted even after (10 hr)refluxing. The solvent was distilled off (whichremoved partially the violet colour) and the distillategave test for free iodine. The residue was dissolvedin pet. ether (4 ml) which on cooling affordedBHATTACHARYA & RAJ: A KOVEL IWUTE TO 1UXED DIARYLTIN DlHALlDESunreactcd triphenyltin iodide (1·10 g, 46%), m.p.120° (lit." m.p. 121°). After adding ether (10 ml)the filtrate was treated with O·IM KOH. Thewhite solid t hus separated was filtered, washedwith water, ethanol and petroleum ether. It wascharacterized (superimposable IH.) as diphcnyltinoxide (0·6 g, 83%) (Fonml: C, 49·28; H, 3·50; Sn, 40·08.Calc. for C12HlOOSn: C, 49'79; H, 3'46; Sn , 41'09%).The organic layer on concentration afforded phenyliodide (0·4 g, 78·4%), b.p. 182° (lit.ll b.p. 180-84°).Reaction of Ph3SnBr with lCl (1 :1): Formationof diphenyltin chloride bromide - rei (0·81 g, 0·005mole) in CCl4 (20 ml) was slowly added to a cons-tantly stirred solution of triphcnylt in bromide(2·15 g, 0'005 mole) in the same solvent (100 ml)at room temperature. The contents were stirredfor 30 min and then worked up. Phenyl iodide(0·7 g, 69%) was distilled off at 63-65°/10 mm .toafford crystals of diphenyHin chloride bromide(Found: C, 37·0; H, 2'48; Sn, 30·44. Calc. forC12H1oSnBrCI: C, 37·06; H, 2'57; Sn, 30'63%).It recrystallized with pet. ether (40-60°), m.p. 38°(Iit.! m.p. 39°); yield 1·5 g (70%); mol. wt 368 {calc.388·5).Similarly tri-p-tolyltin bromide and iodine mono-chloride gave di-p-tolyltin chloride bromide, m.p.59° (Found: C, 40·40; H, 3·27; Sn, 28·52. C14H14-BrCISn requires C, 40'33; H, 3'35; Sn , 28'57%);mol. wt 403 (calc. 416·5). .Reaction of Ph2SnCl2 and Ph2Snl2 -- Heating anequimolar mixture of the reactants for 2 ~lr at 12~0did not give any product except that diphcnyltindiiodide was recovered quantitatively.Complexes (1 :2) of Ar2SnXY with DMSO -. Arepresentative experiment is given below. Furtherdetails are given in Table 2.Diphenyltin chloride bromide (1·94 g, 0·005 mO.le)in pet. ether (60-80°, 40 ml) was rofluxed WIth(0·78 g, 0'011 mole) dimethyl sulphoxidc for 1 hr.Excess solvent was distilled off, chloroform addedand cooled to give a crystalline compound. Thiswas finally washed with ether and dried in vacuoTABLE 2 - ADDUCTS OF Ar2S11XY WITH DIMETHYLSULPIIOXIDEAdducts(a,b) m.p. Found (%) (Calc.)(0e) ------------C H Snl'h2S11CIBr.2L 144 35·30 4·04 21·90(35,26) (4'04) (21'85)l'h2SnCIl3r.2L 143-44 35'24 4·00 21·88(35'26) (4'04) (21'85)Ph2SnClBr.2L 144 35·42 3·96 21·94(35'26) (4-04) (21·85)(p- Tol)2SnCll3r.2L 164-65 37·42 4·44 20'72(37,72) (4'54) (20·78)(p-Tol)2SuClBr.2L 165 37·64 4·38 20·70(37,72) (4,54) (20·78)(p- Tol)2SnClI3r.2L 165 37·68 4·50 20·74(37-72) (4'54) (20·78)(a) L = dimethyl sulphoxide,yields.(b) Products are obtained in 80-90%(2·3 g, 74%), m.p. 144° (Found: C, 35·30; H, 4·04;Sn , 21·90. C16H22BrCI02S2~n requires C, 35'26; H,4·04; Sn , 21'85%).Results and DiscussionIodination of tetraaryltin compounds (Ar4Sn)by 12 have been reportedl~ to. cleave up to two t.in-aryl bonds successively yielding the correspondingdiarvltin diiodides (Ar2SnI2), through an isolableintermediate AraSnl. Attempts were made underidentical conditions to synthesize diaryltin chlorideiodide (Ar 2SnC11) by the reaction of 12 and PhaSnC1.No reaction was observed and the reactants wererecovered unchanged probably due to the reducednucle(,philic character of tin-aryl bonds in AraSnCIas compared to that in Ar4Sn or in AraSnI.In an earlier invcst.igat.ion-" on the reaction oftctraorganornctallics by lCl and ~B.r we have ob-served that both mono and di-tin-carbon bondcleavages occur. This prompted us to try this ~e-action on Ph3SnI (for Ph2SnClI or Ph2SnBrI) WIththese clcct rcphilcs. Unexpectedly, cleavage of bothtin-phenyl and tin-iodine bonds were observed.Thus the reaction of cquimolar quantities of ICIand Ph3SnI gave 0·5 mole of Ph2SnCl2 along with0·5 mole of unreacted PhaSnl, on doubling the molarratio of clectrophilcs (ICl and IBr) only the di-phenyltin dichlorides or dibromides were obtained(Eqs. 1 and 2~. .IBr which IS a weaker electrophile than ICI(ref. 10) when reacts with PhaSnI preferentiallycleaves the tin-iodine bond only giving PhaSnBrand 12,Ph3SnI+ICl-+~Ph2S11CI2+-~12+lPhl+iPh3Snl... (1)Ph3Snl+21(Cl or Br)-+Ph2SnCI2(or Br2)+Phl+12... (2)Cleavage of Sn-Ph and Sn-I bonds by ICI maybe due to the similar e1ectronegativity and electronwithdrawing capacity of the iodide and phenylgroups'". In this reaction the Sn-I b?n~ presum-ably is cleaved first as ~he. colou~ due to iodine m?no-chloride (blood red) IS immediately turned violetindicating the formation of molecular iodine.The reactions of Ar3SnBr with ICI or of AraSnCIwith IBr successfully yielded the mixed diaryltindihalides Ar2SnClBr and aryl iodide.The mixed diaryltin dihalidcs (Ar2SnClBr) werealso obtained through the reaction of Br2 withAr 3-SnC1. The other product obtained was arylbromide.It is thus evident that the replacement of I inAr3SnI with Cl or Br stabilizes the Sri-halogen bondtowards cleavage by ICI or IBr due to the greaterelectronegativity of Cl and Br and at the sametime decreases the nucleophilicity of the tin-arylbond through their electron withdrawing powerand only the Ar-Sn bond is cleaved. Similar re-actions of Ar3SnF in which there is a further decreasein nucleophilicity of Ar-Sn bonds and the effect ofchange in the metal, e.g. with AraGeX and AraPbXare currently being studied.In some preliminary experiments attempts weremade to synthesize diphenyltin chloride iodide by803INDIAN J. CHEM., VOL. 15A, SEPTEMBER 1977disproportionation of the corresponding dihalides.The reactants were recovered unchanged afterheating for 2 hr at 120°, suggesting for more drasticconditions.All the mixed dihalides prepared were convertedinto their corresponding 1:2 DMSO complexes(R2SnXY.2DMSO) which showed the characteristicshift in vS=O from 1045 cm-1 in DMSOto 945± 5crrr? in the tin complexes, indicating coordinationthrough oxygen of the DMSO molecule to tin. Thestructures of ~SnX2.2DMSO have been exhaustivelystudied earlier15-17 and an octahedral arrangementaround the tin atom has been suggested. Thepresence of different halides are expected to deformthe regular octahedron geometry, in the complexesof mixed dihalides.AcknowledgementOne of us (P.R.) is thankful to the CSIR, NewDelhi, for the award of a senior research fellowship.References1. INGHAM,R. K., ROSENBURG,S. K. & GILMAN,H., Chem,tu«. 60 (1960), 459.8042. ARONHEIM.B., Ann. Chem., 194 (1878), 145.3. HUGEL, G., Kolloid Z., 4 (1953), 131.4. ALLESTON,D. L. & DAVIjES,A. G., J. chem, Soc., (1962).2050.5. KANDlL, S. A. & ALLRED,A. L., J. chem, Soc., (A), (1970),2987.6. LEVCHUK,L. E., SAMS,J~R. & AUBKE, F., Inorg. Chem.,11 (1972), 43.7. ARMITAGE, D. A. & TJ\RASSOLI, A., Inorg, Chem., 14(1975), 1210. :8. CHALLENGER,F. & ALLl'RESS, C. F., Proc, chem, Soc.,30 (1914), 292.9. SRIVASTAVA,T. N. & BHATTACHARYA,S. N., J. inorg,nucl, css«, 28 (1966), 2445.10. FOLARANMI, A., MCLEAN, R. A. N. & WADIBIA, N.,J. organometal, Chern., 73 (1974), 59.11. VOGEL, A. I., Practical organic chemistry [Longrnans,Green, London), 1971. 538.12. SRIVASTAVA,T. N. & BHATTACHARYA,S. N., Z. anorg;aUg. Chem., 344 (1966), 102.13. BHATTACHARYA,S. N., PREM RAJ & SRIVASTAVA,R. C.,J. organometal. cu-«, 105 (1976), 45.14. FERGUSON,L. N., The modern structural theory of organicchemistry (Prentice-Hall, Englewood, New York), 1963,172.15. LANGER, H. G. & BLur, A. H., J. organometal. cs-«,S (1966), 288.16. TANAKA, T., Inorg. chim. Acta, 1 (1967), 217.17. KHURANA, M., Studies on aryltin. and aryllead complexesrbith some nitrogen and oxygen donors, Ph.D. Thesis,Lucknow University, 1976.

Cleavage of Triaryltin Halides with Iodine Halides & Halogens: A Novel Route to Mixed Diaryltin Dihalides

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Cleavage of Triaryltin Halides with Iodine Halides & Halogens: A Novel Route to Mixed Diaryltin Dihalides

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