摘要:
1972 2319Some New Iridium Complexes Derived from ChlorotricarbonyliridiumBy P. Piraino, F. Faraone,' and R. Pietropaolo, lstituto di Chimica Generale ed lnorganica dell'Universit8,Reactions of [Ir(CO),CI], with chelating agents L-L (L-L = Ph,PCH,CH,PPh, or Ph,AsCH,CH,AsPh,) to giveIr(CO),(L-L)CI complexes are reported. Complexes of the type [Ir(CO),LCI], (L = SEt,, SeEt,, orTeEt,) have alsobeen isolated by making [Ir(CO),CI], react with ligands containing Group VIE donor atoms. Oxidative additionreactions on the cationic four-co-ordinated [Ir(CO),( Ph,AsCH,CH,AsPh,)] + are included and discussed accord-ing to the o-donor ability of the co-ordinated ligands and the positive charge of the complex. The i.r. spectralproperties of the complexes are discussed.981 00 Messina, ItalyINTEREST in the preparation of new d8 complexes isrelated to the ability of some of them to undergo oxid-ative additions 1 and to catalyse the homogeneoushydrogenation of olefins and acetylenes., Compoundsof the type M(CO)L,X, MLX, and [M(L-L)J+ (M = Rhor Ir; L = P, As, or Sb containing ligands; L-L =Ph2PCH2CH,PPh,; X = Cl, Br, or I) seem to have aparticular versatility for these reactions.In this paper we report on the preparation of newproducts obtained by reacting [Ir(CO),Cl].with chelat-ing agents L-L (L-L = Ph,PCH,CH,PPh, or Ph,As-CH,CH,AsPh,) and with monodentate ligands SEt,,SeEt,, and TeEt,. Oxidative addition reactions on thecationic f our-co-ordinated complex [ Ir(C0) ,( Ph,As-CH,CH,AsPh,)] + are also included.RESULTS AND DISCUSSIONReactions with Chelating Agents.-On refluxing, forseveral hours, a (1 : 1 molar) suspension of [Ir(CO),Cl],of the five-co-ordinated species as 1 : 1 electrolytesand an equilibrium of the type:Ir(CO),(L-L)Cl [Ir(CO),(L-L)]+ + C1- (1)could be operating.Moreover, equilibrium (1) is shiftedfurther to the right when L-L = Ph2AsCH,CH,AsPh2than when L-L = Ph,PCH,CH,PPh, and this may bedue to steric as well as to electronic effects.The i.r. spectrum (Nujol mull) in the CO stretchingregion of the compound formulated as Ir(CO),( Ph,-PCH2CH,PPh2)C1 is slightly different from that ofIr(CO),(Ph,AsCH2CH,AsPhJC1. In the latter case thereis a shoulder at 1934 cm-1 which appears as a sharp bandin the spectrum of [Ir(CO),(Ph,AsCH,CH,AsPh,)]+(see below).The far4.r. spectrum of Ir(CO),(Ph,-PC,H,PPh,)Cl shows a medium-weak band at 328 cm-lwhich can be assigned to the Ir-Cl stretching frequency;the assignment of this stretching frequency at 325 cm-lfor the analogous Ir(CO),(Ph,AsC,H,AsPhJ C1 is onlyComplex[ Ir (CO),( Ph,PCHaCHaPPha)Cl]Analytical dataFound yo Required %C H Halogen C H Halogen49.25 3.65 5.0 49-2 3.55 5.2[ 1 r (CO),( Ph,AsCH,CH,AsPh2)C1] 43.7 3.3 4.8 43-66 3.15 4.60[ Ir(CO),( Ph,AsCH,CHaAsPh,)]BPh4 59.2 4.45 0.0 58.9 4.25 0.0(Ir(CO)*( Ph&CHICH,AsPh.)C1,]BPh, 55.25 4-15 6-15 55.5 3.95 6.3[ Ir CO), ( PhsAsCH CH,AsPh,) 1 ,] BPh, 47.65 3.65 19.6 47.75 3.4 19.4[IrICO),(Ph,AsCH:CH,AsPh,)(MeCO)CI]BPh,[Ir(CO l(Ph,AsCHaCH,AsPhr)(PhSO,)Cl]BPh, c 56-25 4-25 2.95 56.6 4.0 2.9[Ir~COhSEtr)C1l~ d 19-15 2.81, 9.4 19.3 2.7 9-517.36 2.55 8.4 17.1 2.45 8.415.1 2.3 7.3 15.4 2.15 7.551.r.(Nujol mull, cm-l)M a Colour M.p.OC AM^ v(C0) vIr-CI699 o Pale yellow >170 dec. 16 2048vs, 1962vs 328m(683)Yellow-orange 120-140 60 2050vs, 1966vs, 326mdec. 1932sh,mPale yellow 215-219 96 2018w, 1932vsYellow-orange 128-132 94 2064vsYellowdec.Yellow 102-105 89 2132~, 2 0 3 8 ~ ~ 330s2130vs, 2040~s~1710sYellow 138-142 98 2 0 6 0 ~ ~ 299m1825 Dark violet 125-131 2060~s. 2021sdec.dec.2418 Brown >175 dec. 2050vs, 2018s2215 Brown 184-198 2018vs, 1969mIn CHCl,. a Molar conductivities for a. 5 x lPsr-solutions in acetone at 25'- in a-1 mol-' cm'. e S found 2*390/ required 2.60%.d 0 found 8.75%, requiredIn acetone solution; calculated valug'in parentheses. 8.56%. CI 0 found 7.43%, required 7.6176. f 0 found 6.54%, required 6.83%.and L-L in benzene, the colour of the reaction mixtureturns to orange-red. After filtering, evaporating thesolvent, and crystallization of the crude product fromCH,Cl,-ether, a yellow compound is obtained. On thebasis of the analytical data (Table) the complexes couldbe formulated as five-co-ordinated species Ir(L-L)-(CO),Cl. Conductivity data for acetone solutions ofthe complexes and the molecular weight in acetonesolution for the Ir(CO),(Ph,PC,H,PPh,)Cl are given inthe Table. No molecular weight measurement couldbe made for Ir(CO),(Ph2AsC,H,AsPh2)C1 because of itslimited solubility in acetone.The conductivity valuesare lower than those expected for a complete dissociationJ. P. Collman and W. R. Roper, A h . Organometallic Chem.,1968, 7, 64.tentative because there are other absorptions, due tothe chelating ligand, in this region of the spectrum.In conclusion, conductivity, i.r., and molecular weightdata suggest that the phosphine chelated compound ismainly a five-co-ordinated neutral species Ir(CO),-( Ph,PC2H,PPh,)C1 whereas the arsine chelated com-pound is a mixture of 1r(C0),(Ph,AsC2H,AsPh,)C1and [Ir(CO),(Ph,AsC,H,AsPh2)]C1. By adding Na-BPh, in methanol to a methanolic solution of Ir(CO),-(Ph,AsCH,CH,AsPh,)Cl, a pale yellow precipitate isobtained which can be formulated as [Ir(CO),(Ph,-AsCH,CH,AsPh,)]BPh, on the basis of elementalanalysis, i.r.spectrum, and conductivity measurements.2 'Aspects of Homogeneous Catalysis,' ed. R. Ugo, vol. 1,Manfredi, Ed., Milan, 19702320 J.C.S. DaltonA similar precipitate is formed, as the only product,when a methanolic suspension of [Ir(CO),Cl], reactswith Ph,AsCH,CH,AsPh, in the presence of NaBPh,.Iridium(1) complexes of the type [Ir(CO),L,-,]+,where x = 1-3, [Ir(L-L),CO]+ [L = phosphine orarsine ; L-L = bis( 1,2-&phenylphosphine)ethane] havebeen reported.,-’ Four-co-ordinated complexes such as[ Ir (L-LIJ + have also been prepared:, lo and complexesof the type [Ir(CO),LJ+ were postulated as intermediatesin the reductive elimination of hydrogen from [Ir(CO),-H,L,]+ and isolated when L = P(C,H,,), or P(Pri)3.6,8Very recently, cationic complexes of the type [Ir(CO)-L3]+ have been i s ~ l a t e d .~ ~ ~ Therefore, the complex[Ir (CO),( Ph,AsCH,CHBAsPh,)!+ can be considered thefirst example of four-co-ordmated cationic iridium(1)complex containing CO and bidentate ligands.In the CO stretching region, the four-co-ordinatecomplex [Ir(CO),(Ph,AsCH,CH,AsPh,)] + shows a weakband at 2018 cm-l and a strong one at 1932 cm-l, aswould be expected.Oxidative Addition Reactions of [Ir(CO),(Ph,AsCH,-CH,AsPh,)] +.-The ability of the complexes to undergooxidative addition reactions is related to the electrondensity on the metal, which in turn depends on thenature of the co-ordinated ligands. In consequence,cationic four co-ordinated iridium(1) complexes should beless effective in the oxidative additions than the neutralones.The only four-co-ordinated cationic complexwhich displays an aptitude for activating small mole-cules by oxidative addition, reminiscent of the Vaskacomplex, is [Ir( Ph,PCH,CH,PPh,)J +.4 Complexes ofthe types [Ir(CO)L,]+ and [IrLJ+ (L = PPh,, PPh,Me,and PPh,Et) react with hydrogen but only the compoundcontaining more basic phosphines adds ~ x y g e n . ~The complex [Ir(CO),(Ph,AsCH2CH,AsPh2)] + doesnot react with H,, O,, and CH,I in solution, but reactswith Cl,, I,, and PhS0,Cl very easily giving cationicsix-co-ordinated adducts of iridium(II1). In additionMeCOCl reacts with [Ir(CO),(Ph,AsCH,CH,AsPh,)]+ togive [Ir(CO),(Ph,AsCH,CH,AsPh,)(MeCO)C1]+ as isconfirmed by the i.r.spectrum, which shows two strongbands in the carbonyl stretching region at 2130 and2040 cm-1 and a band at 1710 cm-l due to the acylCO stretching. However, the addition is reversibleand we could not obtain the complex in a pure form.A different stereochemistry has been observed for thesix-co-ordinated cationic adducts of irridium( 111) herereported. In the i.r. spectrum the compound [Ir(CO),-(Ph,AsC,H,AsPh,) CLJ BPh, shows two strong v( CO)bands at 2132 and 2038 cm-l and a v(1r-C1) band atL. Malatesta, G. Caglio, and M. Angoletta, J . Chem. Soc.,1966, 6974.4 L. Vaska and D. L. Catone, J . Amer. Chem. Soc., 1966, 88,6324.5 A. J . Deeming and B. L. Shaw, J . Chem. SOC. ( A ) , 1970,2706.6 M. J . Church, M. J. Mays, R.N. F. Simpson, and F. P.Stefanini, J. Chem. SOC. (A). 1970, 2909.7 L. M. Haines and E. Singleton, J . Organometallic Chem.,1971, 30, C, 81.M. J . Mays, R. N. F. Simpson, and F. P. Stefanini, J.Chem. SOC. ( A ) , 1970, 3000.330 cm-1 due to two chlorine atoms in tram-positions.This suggests the structure (Ia) reported in the Figure.X coY( I 1(Ia; X = C1, Y = Cl) (IIa; X = I, Y = I)(Ib; X = C1, Y = CHSCO) (IIb; X = C1, Y = PhSO,)A similar structure (Ib) can be formulated for theacyl compound. The complexes [Ir(CO),(Ph,AsCH,-CH,AsPh,) Id+ and [Ir(CO),(Ph,AsCH,CH,AsPh,) (Ph-S02)C1]+ in the i.r. region give only a band v(C0) a t 2064and 2060 cm-l respectively. For the latter compounda band v(1r-C1) at 299 cm-l is indicative of a chlorineatom in trans-position to a bidentate ligand, as indicatedin the structure (IIb).A different stereochemistry inthe halogen addition was recently observed in the re-action of [RhL,]+ with Cl,, Br,, and 12.11 However thedifferent configuration of the adducts could be due to apossible isomerization in solution or to a differentpathway in the addition. In conclusion, the complex[Ir(CO),(Ph,AsCH,CH,AsPh,)]+ is less effective in theoxidative additions than the neutral complexes orother chelated compounds such as [Ir( Ph,PCH,CH2-PPh,),]+. Certainly the presence of two weak ts donorCO groups co-ordinated to the metal is a contributoryfactor in determining the observed behaviour.Reactions with Ligands Containing Group VIB DonorAtoms.-In previous papers 1 2 9 1 3 we reported on thepreparation of new complexes of the type tram-[Rh-(CO)L,Cl] (L = SEt,, SeEt,, TeEt,).Our aim has been,in part, the preparation of similar iridium(1) complexes.We recall, in this respect, that, inter alia, the com-pounds trans-[Ir(CO)L,Br] (L = PPh,, AsPh,) can beprepared by refluxing [Ir(CO),Br], with the appropriateligand in t01uene.l~When a suspension of [Ir(CO),Cl], is refluxed inbenzene with SEt,, SeEt,, or TeEt,, the compoundsobtained can be formulated, on the basis of elementalanalysis and molecular weight measurements, as[Ir(CO),LCl],. Metathetical reactions of these withLiBr or LiI, in acetone, give the corresponding bromo-and iodo-derivatives.The chlorocarbonyliridium [Ir( CO),Cl], is a compound* G.R. Clark, C. A. Reed, W. R. Roper, B. W. Skelton, andlo K. A. Taylor, Advances in Chemistry Series 70, 1968, 195.l1 L. M. Haines, Inorg. Chem., 1971, 10, 1693.l2 F. Faraone, R. Pietropaolo. and S. Sergi, J. Organometallic13 F. Faraone, R. Pietropaolo, S. Sergi, and P. Piraino,l4 F. Canziani, U. Sartorelli, and F. Zingales, Chim. e. Ind.T. N. Waters, Chem. Comm., 1971, 768.Chem., 1970, 24, 797.J . Organometallic Chem., 1970, 24, 805.(Milan), 1967, 49, 4691972 2321with linear chains of metal atoms.l5 We think thatthere are simiIar metal-metal linkages in the case ofthe complexes [Ir(CO),LCl],. By making [Ir(CO),-LCl], react with PPh,, using a 1 : 2 molar ratio, theVaska compound is obtained, while the reaction withPh,PCH,CH,PPh, in benzene gives Ir(CO),(Ph,PCH,-CH2PPh,)C1.As shown in the Table, two i.r. bands inthe CO stretching region are observed for [Ir(CO),-LCl], and their high values could be due to an increaseof the formal charge in the iridium atoms as a conse-quence of iridium-iridium bonds.When [Ir(CO),Br], reacts with PPh, or AsPh,, com-plexes analogous to the Vaska compounds are obtained.l*The different behaviour of the ligands containing phos-phorous or arsenic and SEt,, SeEt,, or TeEt, can beattributed to their different tram-activating ability.EXPERIMENTALChlorocarbonyliridium was a Strem product. Otherreagents were used without purification. 1.r. spectrawere recorded with a Perkin-Elmer 457 spectrometer.Molecular weights were determined with a Knauer vapourpressure osmometer.M.p.s were determined on a Fisher-Jones hot-stage apparatus. A conductivity meter WTWLBR was used for conductivity measurements. Elementalanalyses were by Bernhardt, Mulheim, Germany.All reactions were carried out under a nitrogen atmo-sphere.Chlmodicarbonyl [bis ( 1,2-diPhenylphosphino)ethane]irid-iurn(~), [Ir(CO) ,(Ph,PCH,CH,PPh,)Cl].-A suspension of[Ir(CO),Cl], (0.400 g; 1.28 mmol) and Ph,PCH2CH2-PPh, (0.51 g, 1.28 mmol) in anhydrous benzene (150 ml)was refluxed for ca. 3 h. The red solution was filteredand evaporated in vacuo. The crude product obtained wascrystallized from CHCl,-ether to give a yellow solid solublein CH,Cl,, CHCl,, or acetone, but insoluble in ether andhydrocarbons (yield 65%).Chlorodicarbonyl[bis (1,2-difihenylarsino)ethane]iridium (I),[Ir(CO),(Ph,AsCH,CH,AsPh,)Cl].-A suspension of [Ir-(CO),Cl], (0.40 g, 1.28 mmol) and Ph,AsCH,CH,AsPh,(0-62 g, 1-28 mmol) in benzene was refluxed for ca.4 h.The orange solution was then filtered and concentratedto a small volume (2 ml). By adding ether an orange solidwas obtained (yield 75%) soluble in chlorinated solventsor benzene.Dicarbonyl[bis( 1,2-diphenylarsino)ethane]iridium(1) Tetra -phenylborate, [Ir (CO) 2(Ph2AsCH2CH2AsPh2)]BPh4.-Method (a). NaBPh, was added to a solution of Ir(CO),-(Ph,AsCH,CH,AsPh,)Cl in methanol. The pale yellowprecipitate, immediately formed, was washed with methanoland dried.Method (b). To a suspension of [Ir(CO),Cl], (0.40 g,1.28 mmol) in ethanol, Ph,AsCH,CH,AsPh, (0-62 g, 1.28mmol) and NaBPh, (0.51 g, 1.5 mmol) were added and themixture was refluxed for ca.2 h. A mixture of yellowand dark compounds was formed; the yellow solid wasdissolved in CH,CI, and, after evaporation of the solvent,crystallized from CH,Cl,-ether (yield 55%).Bistbis ( 1,2-di~henyl~hos~hino)ethane]iridiurn(1) Tetra-phenylbornte, [Ir (Ph2PCH2CH,PPh,) JBPh,.-To a sus -pension of [Ir(CO),Cl], (0-40 g, 1.28 mmol) in ethanol,Ph,PCH,CH,PPh, (1.20 g, 2.56 mmol) and NaBPh, (0-52g, 1-5 mmol) were added and the mixture was refluxed for2 h. The red-orange precipitate formed was filtered off,then dissolved in CH,Cl, to separate i t from the startingmaterial. By adding pentane [Ir(Ph,PCH,CH,PPh,)cJ -BPh, was formed.Dichlorodicarbonyl[bis( 1,2-diPhenylarsino)ethane]iridium-(111) Tetraphenylborate, [Ir(CO) ,(Ph,AsCH,CH,AsPh,)Cl~ -BPh,.-A dichloromethane solution of C1, was added to[Ir(CO),(Ph,AsCH,CH,AsPh,)]BPh, dissolved in CH,Cl,.The progress of the reaction was followed by i.r.spectro-scopy. The solution was concentrated and by addingpentane a pale yellow solid was obtained. The compoundis soluble in chlorinated solvents but less soluble in methanoland acetone.Di-iododicarbonyl [bis ( 1,2-diphenyZarsino) ethane] iridium-(111) Tetraphenylbovate, [Ir(CO),(Ph,AsCH,CH,AsPh,)I,] -BPh,.-A dichloromethane solution of I, (0.12 g, 0.5 mmol)was added to [Ir(CO),(Ph,AsCH,CH,AsPh,)]BPh, (0-40 g,0-38 mmol) dissolved in the same solvent.After ca. 10min the reaction was complete and by adding pentane ayellow-orange compound was obtained. The compoundis soluble in chlorinated solvents and acetone.Chlorodicarbonyl[bis (1,2-diphenylarsino) ethane] (S-benzene-su2phinate)iridium (111) Tetraphenylborate, [Ir(CO) ,( Ph,As -CH,CH,AsPh,) (PhSO2)C1]BPh,.-PhSO,C1 in CH,Cl, wasadded dropwise to a solution of [Ir(CO),(Ph,AsCH,CH,-AsPh,)]BPh, in the same solvent. The reaction wasfollowed by i.r. spectroscopy until the band v(C0) at 1952cm-f disappeared. By adding light petroleum a yellowsolid was obtained.Chloro(acetyl)dicarbonyl[bis( 1,2-di~henylarsino)ethane]-iridiurn(II1) Tetraphenylborate, [Ir(CO),(Ph,AsCH,CH,As-Ph,) (CH,CO)Cl]BPh,.-MeCOC1 in dichloromethane wasadded dropwise to a solution of [Ir(CO),(Ph,AsCH,CH,As-Ph,)]BPh, in the same solvent. The i.r. spectrum showedthat the reaction was not complete. By concentratingthe solution and adding pentane a yellow precipitate wasformed, which still contained starting material. Attemptsto separate the mixture have been unsuccessful.Chlorodicarbonyl (diethyl sulphide) iridium, [Ir (CO) ,(SEt ,) -Cl],.-To [Ir(CO),Cl], dissolved in benzene (150 ml) anexcess of SEt, was added and the solution was refluxed for8 h. After filtration and evaporation an oil was obtained.By adding pentane a dark violet precipitate was formedwhich was crystallized from chloroform-light petroleum.Similarly chlorodicarbonyE(diethyE selenide)iridium, [Ir(CO) ,-(SeEt,) Cl], and chlorodicarbonyl (diethyl telluride) iridium,[Ir(CO) a (TeEt,) Cl], have been prepared.The compounds of the type [Ir(CO),LX], (L = SEt,, Se-Et,, or TeEt,; X = Br or I) have been prepared bymetathetical reactions of the chloro-derivatives with aslight excess of the corresponding halides in acetone.After ca. 12 h the solvent was evaporated and the residuewashed with water and dried. The compounds have beencry s t allized from chloroform-light petroleum .We thank C. N. R. for financial support.[1/2411 Received, 16th December, 19711l5 K. Krogmann, W. Binder, and H. D. Hansen, Angew Chem.Internat. Edn.. 1968, 7 , 812
ISSN:1477-9226
DOI:10.1039/DT9720002319
出版商:RSC
年代:1972
数据来源: RSC