摘要:

J. CHEM. SOC. DALTON TRANS. 1982 1881The Preparation, Variable-temperature Nuclear Magnetic ResonanceSpectra, and Behaviour under Reflux Conditions of [OS,(CO),,(~-ER)~](E = S, R = Me, Ph, or CH,Ph; E = Se, R = Ph)By Peter V. Broadhurst, Brian F. G. Johnson, and Jack Lewis," University Chemical Laboratory, LensfieldRoad, Cambridge CB2 1 EWThe cluster [OS,(CO)~,(NCM~)] reacts with the compounds R2E2 (E = S, R = Me, Ph, or CH2Ph; E = Se,R = Ph) to give the clusters [OS,(CO),~(~-ER)~] which have been fully characterised on the basis of their spectro-scopic properties. In each case, only one of the three possible isomers of these compounds is produced. Onheating, [ O S ~ ( C O ) , ~ ( ~ - S M ~ ) ~ ] converts to a second isomeric form which is isostructural with the known com-pound [0s3(C0),,(p-0Me),], whereas the compounds [ O S ~ ( C O ) ~ ~ ( ~ - E R ) ~ ] (E = S, R = Ph or CH2Ph;E = Se, R = Ph) give small yields of [ O S ~ ( C O ) ~ E ~ ] (E = S or Se) and [Os,(CO),(SR),] (E = S or Se, R = Ph).THE trimetallic cluster carbonyls [M3(C0),,] (M = Ru or0 s ) have been reported to undergo reaction with eitherR,S, or R,Se, (R = alkyl or aryl) to produce the dimericcompounds [M,(CO),(p-ER)& (E = S or Se) 1-8 and insome cases ,-* the related polymeric compounds [M,(CO),-(ER),],. Single-crystal X-ray crystallographic studies ofcompounds containing M,(p-SR), cores, for example[Rh2(?5-C5H5) 2 (p-SPh)A or [Fez (?'-C5H5),(CO),(p-SPh),] ,lo have revealed a puckered arrangement (Figure1).It has also been established that, depending on theRFIGURE I Representations of the puckered Ma(p-SR)a corestereochemistry about the bridging sulphur ligand, up tothree isomers of these compounds [Figure 2, (A)-(C)]are possible; however only isomers (A) and (B) havebeen observed to date.Various isomer interconversionand fluxional processes have also been e~tablished.@~~~-~~( A ) (B) ( C )FIGURE 2 The isomers of the Ma(p-ER)a core, as a viewalong the M - * - M axisIn this paper, we report the synthesis and study of thecluster compounds [Os,(CO),,(p-ER)J (E = S, R = Me,Ph, or CH2Ph; E = Se, R = Ph), in which the Os, hasbeen retained and the new isomeric form (C) established.RESULTS AND DISCUSSIONThe cluster [Os,(CO),,(NCMe)J reacts with thecompounds &E2 in dichloromethane to produce thetrimetallic compound [Os,(CO),(p-ER),] [E = S, R =Me (la), Ph (lb), or CH,Ph (lc) ; E = Se, R = Ph (Z)] inyields of ca.50% [except for (PhCH,),S, where yieldsare closer to 2070]. The i.r. spectra of these compoundsin the v(C0) region are similar to those of [OsJCO),,(p-X),j (X = C1, Br, or I) l4 indicating a related moleculargeometry, i.e. a triangle of three osmium atoms with onelong (non-bonded) edge which is spanned by two REbridging groups.In addition to these products, for the reaction whenE = S, small yields of the hydrido-compounds [Os,-(CO),,H(ER)] were also obtained. These compoundswere readily identified on the basis of their mass spectra(Tables 1 and 2) and by a comparison of their i.r.spectrawith those previously reported for these corn pound^.^^Yields of the new compounds were highest whenbetween a five- and ten-fold excess of &E2 was employed.I t has been proposed previously9J1-13 that under thereaction conditions employed to produce the dimers[M,(CO),(p-ER),] (i.e. heat or photolysis) the compoundsR2E, unflergo homolytic cleavage to produce the radicalspecies ER and that it is these radicals which are thereactive species. In the reactions reported here, webelieve that a different mechanism operates. In thisalternative mechanism, we consider that the donor R2E2molecule initially displaces the MeCN from [Os,(CO),,-(NCMe)] to produce [Os,(CO),,(E,R2)] which thenundergoes rearrangement and CO loss to form theobserved product. The observation that the yield of theproduct is increased in the presence of excess R2E, tendsto support our view that the addition of R,E, is rever-sible.With But,S2 reaction does not take place to yield thedesired trimetallic product.Presumably the large bulkof the Buts ligand encourages further fragmentation ofthe Os, cluster. In support of this view, it is worthnoting that the large PhCH,S ligand only gives rela-tively poor yields of the trimeric product.As observed with the bimetallic compounds discussedabove, the compounds [Os,(CO),,(p-ER),] may existin three different isomeric forms depending on the stereo-chemistry about the ER bridging groups. Theseisomeric possibilities are shown in Figure 3, where arepresentative view of the molecule along the non-bonded osmium-osmium edge supported by the two ERligands is given.In all cases the lH n.m.r. spectra of thecompounds [Os,(CO),,(p-ER),] are consistent with thepresence of only one isomer, namely isomer (B), with twodifferent R environments. For compounds (la) and(lc) the spectra at 30 "C exhibited two sets of signals i1882 J. CHEM. SOC. DALTON TRANS. 1982each case 7 7.00 (1) and 7.55 (1) for (la) and at T 5.81 (1)and 6.41 (1) for (lc) (relative intensities are in parentheses).Compounds (lb) and (2) exhibited a complex spectrum inthe phenyl region. However, a comparison of thesespectra with that of free Ph,E, revealed that they re-sembled two superimposed pat terns of the organic ligandconsistent with the idea that there are two differentphenyl environments.( A ) (6) (C)plane of the Os, triangleFIGURE 3 The isomers of the OS,(p;ER), core, showing theThese spectra show little or no change over the temper-ature range 30-100 "C indicating that no fluxionalprocess or isomer interconversion occurs.However,with [Oq(CO)lo(pSMe)2] (la) the spectrum shows tworesonances at T 7.00 and 7.55 of relative intensities 1 : 1at 30 "C but as the temperature is raised, line broadeningand coalescence occurs until at 95 "C a single resonanceat T 6.92 is observed. This change is not reversible andis time dependent suggesting that isomer interconversionis taking place. In agreement, the i.r. spectrum [v(CO)]of the final solution is different to that of the original(Table 1).Isolation of the final product shows, on thebasis of its mass spectrum, that it has the same com-position as (la). From this information, together withthe fact that the i.r. spectrum of the new compound (3) isclosely related to that of [Os3(CO)lo(p-OMe)2] which isknown l6 to possess the geometry given for isomer (C), webelieve (3) also to possess the isomer structure (C). Theformation of isomer (C) rather than the alternative (A),which is favoured for [M,(CO)&ER),], presumablyresults from the unfavourable steric interactions betweenthe SMe bridging group and the CO ligands of the thirdosmium atom expected for isomer (A). The compound[Oq(CO)lo( pSCH,Ph),] also undergoes reaction onheating (in octane).However, in this case, simpleisomerisation was not observed ; instead small amountsof [Os,(CO),S,] l7 and a large amount of intractablepolymer were obtained. Similar behaviour was alsoMe 1'KO), cco,,FIGURE 4 The thermal isomerisation of [Os,(CO),,(p-SMe),]noted for [Os,(CO),(pSPh)J except in this case asmall amount (- 6%) of [Os,(CO),(p-SPh)J (4) was alsoproduced. Spectroscopic data did not permit the mole-cular structure of this compound to be deduced butthree possible structures may be proposed (Figure 4).Structure type (111) has been postulated previously for[Fe,(CO),(SBut),] ,13 and triply bridging SR groups havebeen observed elsewhere as, for example, in [Co,H(CO),-(k-SR)] (R = Me or Et).18=Ph(III)FIGURE 6 Possible structures of [Os,(CO),(SPh),]The compound [Os,(CO)l,,(p-SePh),] (2) behavessimilarly, undergoing thermal decomposition in hot n-octane to give low yields of [Os,(CO),Se,] l7 and a secondisomeric form (C) of [ O S ~ ( C O ) ~ ~ ( ~ S ~ P ~ ) , ] which exhibitedan i.r.spectrum closely related to that of [Os,(CO),,(p-OMe),] with structure (C).EXPERIMENTALReactions were performed under N,. Solvents forreactions or crystallisations were dried and deoxygenated bydistillation under N, over CaH,, except benzene whenAnalaR grade was used. Prior to distillation, unsaturatedimpurities in the saturated hydrocarbons were removed bystirring over concentrated H,SO,.A literature preparation was used for [Os,(CO),,-(NCMe)], l9 and other reagents were obtained commerciallyand used without further treatment.Product separation was achieved using thin layer chrom-atography (t.1.c.) with plates precoated to 0.25 mm thicknesswith Merck Kieselgel 6OF,,,, supplied by Merck.Infrared spectra were recorded on a Perkin-Elmer 257spectrophotometer using the 2 143 cm-l absorption of CO(g)as calibrant.Mass spectra were recorded with an A.E.I.MS 12 spectrometer. Microanalyses were performed by theUniversity Chemical Laboratory microanalytical depart-ment.Proton n.m.r. spectra were recorded on Varian AssociatesCFT 20 or XL-100-12 spectrometers at 80 and 100 MHzrespectively. The latter was used for elevated temperaturework. Spectra were recorded in CD,C1, solution or, atelevated temperature, in [2HJ toluene (for [Os,(CO)(pSCH,PB),]} or in CD,NO,.given in Tables 1 and 2.Spectroscopic and analytical data for new compounds arJ.CHEM. soc. DALTON TRANS. 1982 1883Reaction of [Os,(CO),,(NCMe)] with R,E,.-(a) R = Me,E = S. The compound [Os,(CO),,(NCMe)] (211 mg, 0.23mmol) and Me,S, (ca. 200 mg, 2.1 mmol, 0.2 cm3) in CH,Cl,(30 cm3) were stirred overnight. T.l.c., eluting with CH,-C1,-hexane (2 : 8), gave a trace of [Os3(CO),,H(p-SMe)](yellow, Rf = 0.75) and [Os3(CO),,(~-SMe),] (yellow, Rf =0.55) (la) which gave yellow crystals on cooling in hexanesolution (106 mg, 49%).benzene-hexane (1 : 1) solution by cooling to give yellowcrystals (55 mg, 19%).(d) R = Ph, E = Se. The compound [OS,(CO),,-(NCMe)] (246 mg, 0.27 mmol) and Ph2Se, (500 mg, 1.60mmol) in CH,Cl, (40 cm3) were stirred overnight at roomtemperature. T.l.c., eluting with CH,Cl,-hexane (2 : 8)gave excess Ph,Se, (yellow, Rf = 0.8) and [Os3(CO),,-(y-SePh),] (yellow, Rf = 0.6) (2) which crystallised byTABLE 1Infrared, 1H n.m.r., and melting point data for new compoundsCompound v(C0) (cm-l) lH n.m.r.(7) M.p. ("C)2 116mw, 2 066s, 2 046ms, 2 042 (sh), 2 037ms,2 032vs, 2 014w, 1 991m, 1 988 (sh), 1 980m,1969mw2 116mw, 2 069s, 2 046ms. 2 036vs, 2 016w,1 996m. 1986mw, 1 978w, 1 966w, 1 959mw2 112m, 2 062s, 2 044ms, 2 039 (sh), 2 031vs,1988ms, 1977m, 1 9 6 1 ~ . 1966w2 113m, 2 066s, 2 044ms, 2 033vs, 2 014w,1992m, 1977m, 1966w, 1 968w2 106ms, 2 066s, 2 056m, 2 022vs, 2 018 (sh),1 996vw, 1988s, 1978mw2 102ms, 2 039ms, 2 036s, 2 026vs, 2 OOlmw,1974vs, 1 966ms2 104m, 2 064s, 2 065w, 2 060w, 2 019vs,2 OOOw, 1988m, 198Ow7.00 (s, Me), 7.66 (s, Me)Integrate 1 : 12.39 (m, Ph), 2.62 (m, Ph),2.68 (m, Ph), 2.74 (m, Ph) 150-1632.65 (m, Ph) Integrate 144-1466.81 (s, CH,) } 10 : 2 : 26.41 (s, CH,)2.41 (m, Ph), 2.69 (m, Ph) 141-1436.92 (s, Me) decomp .ca.1902.04 (m, Ph), 2.21 (m, Ph) decomp.2.39 (m, Ph), 2.42 (m, Ph) ca. 200decomp.ca. 140 (la) [0s3(c0)10(Y-sMe)Zl(1b) [ o ~ ~ ( ~ ~ ) i o ( Y - ~ ~ h ) ~ l(Ic) ~0s3(C0)10(~-SCH!4Ph)~(2) [Os3(CO)io(Y-SePh) a1(3) [Os3(CO)io(~-SMe),l(4) [0~3(CO)v(SPh)al(6) [Os3(CO)io(P-SePh)ala m = Medium, s = strong, w = weak, (sh) = shoulder; cyclohexane solution. (s) = Singlet, (m) = multiplet.(b) R = Ph, E = S.The complex [Os,(CO),,(NCMe)](250 mg, 0.27 mmol) and Ph,S, (250 mg, 1.15 mmol) in CH,-C1, (20 cm3) were stirred at room temperature for 6 h.T.l.c., eluting with hexane, gave a yellow band (Rf = 0.7)at the head of a broad band visible under U.V. light and ayellow band (Rf = 0.2). These were [Os3(CO),,H(p-SPh)](trace), excess Ph,S,, and [OS~(CO),~(~-SP~),] (lb) whichcrystallised by cooling a benzene-hexane ( 1 : 1) solution togive yellow crystals (150 mg, 52%).TABLE 2Microanalytica1,a mass spectral, and yield data for newproductsAnalysis (%)16.36 0.80(14.96) (0.66)24.85 1.20(24.70) (0.96)26.60 1.36(26.80) (1.25)22.76 0.90(22.36) (0.85)16.06 0.90(14.96) (0.66)24.40 1.10(23.76) (0.96)t AC H ' mJe9601074110211689601 0461168a Calculated values in parentheses.1s40s, '5'Se.(c) R = CH,Ph, E = S. The cluster [Os,(CO),,(NCMe)](247 mg, 0.27 mmol) and (PhCH,),S, (500 mg, 2.03 mmol) inCH,Cl, (40 cm3) were stirred overnight. T.l.c., with hexaneeluant gave two yellow bands (Rf = 0.55 and 0.25) and aheavy band (u.v. visible) in between. Repeated t.1.c. maybe needed to separate the central band of excess (PhCH,),S,.The yellow bands are a trace of [Os3(CO),,H(y-SCH,Ph)]and [OS~(CO),~(~-SCH,P~),] (lc) which crystallised fromcooling a benzene-hexane (1 : 1) solution to give yellowcrystals (156 mg, 50%).RefEclx Reactions of [Os3(CO),,(p-ER),], Isomer (B).-(a) R = Me, E = S. The complex [Os3(CO),,(p-SMe),] (la)(70 mg, 7.3 x 10-2 mmol) was refluxed in n-octane (30 cm3)for 30 min; t.l.c., eluting with CH2C1,-hexane (1 : 9),gave [Os3(CO),,(p-SMe),] (yellow, Iif = 0.6) (3) which provedto be another isomer, (C). Crystallisation by cooling ahexane solution yielded 37 mg, 53%.(b) R = Ph, E = S.Compound (lb), [Os,(CO),,(p-SPh),] (141 mg, 0.13 mmol), was refluxed in n-octane (40cm3) for 25 min. After t.l.c., eluting with CH,Cl,-hexane(15 : 85), the first yellow band (Rf = 0.9) was identified as[OS,(CO)~S,] and the third yellow band as [Os,(CO),(SPh),](4). Crystallisation from benzene-hexane (1 : 1) solutionsby cooling yielded 1.8 mg (1.5%) and 8.0 mg (6.0%) respec-tively.(c) R = CH,Ph, E = S. Compound (lc) [Os,(CO),,,-(p-SCH,Ph),] (20 mg, 1.8 x lo-, mmol) was treated asabove.The first yellow band on t.1.c. was identified as[0~3(cO)esz1 (ca. 5%).( d ) R = Ph, E = Se. Compound (2), [Os,(CO),,(p-SePh),] (93 mg, 8.0 x lo-, mmol), was refluxed in n-octane(30 cm3) for 15 min. After t.l.c., eluting with CH,Cl,-hexane (1 : 9), the first yellow band (Rf = 0.75) wasidentified as [Os,(CO),Se,] and was crystallised by cooling ahexane solution (10 mg, 13%). The fourth band, visibleunder U.V. light, was identified spectroscopically as [Os,-(CO),,(p-SePh),] ( 5 ) , isomer (C) (ca. 3%).VariabZe-temfieratwe lH N . M . R. Exfieriments.-Sampleswere sealed under N,. Spectra were run at 30, 50, 70, and90 "C for all samples, and at 100 "C for [Os,(CO) lo(p-SCH,Ph),](lc) but showed no indication of any fluxional behaviour.Some coalescence of peaks occurred for [Os3(CO),,(p-SePh),]due to increased thermal motion.For [Os3(CO),,(p-SMe),] (la), a series of spectra at 95 "Cover 2.5 h showed an isomerisation to [Os,(CO),,(p-SMe),1884 J.CHEM. soc. DALTON TRANS. 1982(3), which was followed by the decay of the two methylsignals of (la) and concurrent growth of the one methylsignal of (3).[1/1920 Received, 11th December, 19811REFERENCESG. Bor, J. Ovganomet. Chem., 1968, 11, 196.R. B. King, J. Am. Chem. SOC., 1962, 84, 2460.a G. Cetini, 0. Gambino, E. Sappa, and M . Valle, J. Ovgano-4 R. B. King and M. B. Bisnette, Inmg. Chem., 1966, 4, 1663.5 R. B. King and M. B. Bisnette, Inorg. Chem., 1966.4, 482.6 E. Kostiner, M. L. N. Reddy, D. S. Urch, and A. G. Massey,7 J . Cooke, M. Green, and F. G. A. Stone, J. Chem. SOC. A ,8 E. D. Schermer and W. H. Baddley, J . Organomet. Chem.,* N. G. Connelly, G. A. Johnson, B. A. Kelly, and P. Wood-met. Chem., 1968, 15, P4.J . Organomet. Chem., 1968, IS, 383.1968, 170.1971, 80, 67.ward, J . Chem. SOC., Chem. Commun., 1977, 436.lo G. Ferguson, C. Hannaway, and M. S. Islam, Chem. Commun.,1968, 1165.l1 S. D. Killopsand S. A. R. Knox, J. Chem. SOC., Dalton Trans.,1978, 1260 and refs. therein.R. Hill, B. A. Kelly, F. G. Kennedy, S. A. R. Knox, and P.Woodward, J. Chem. SOC., Chew Commun., 1977, 434.la J. A. DeBeer and R. J. Haines, J . Organornet. Chem., 1970,24, 757 and refs. therein.l4 A. J. Deeming, B. F. G. Johnson, and J. Lewis, J. Chem.SOC. A , 1970, 897.16 G. R. Crooks, B. F. G. Johnson, J . Lewis, and I. G. Williams,J. Chem. SOC. A , 1969, 797.V. F. Allen, R. Mason, and P. B. Hitchcock, J. Organomet.Chem., 1977, 140, 297.l7 B. F. G. Johnson, J. Lewis, P. G. Lodge, P. R. Raithby, K.Hendrick, and M. McPartlin, J. Chem. SOC., Chem. Commun.,1979, 719.18 B. F. G. Johnson, J. Lewis, and D. A. Pippard, J. 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ISSN:1477-9226    

DOI:10.1039/DT9820001881

出版商:RSC    

年代:1982

数据来源: RSC