摘要:
1973 2069Lewis Acid-promoted Vinyl Rearrangement and Halogen Exchange ofPlatinum-f luoro-olef in ComplexesBy Peter K. Maples, MichaelUniversity, Bristol BS8 1 TSGreen, and F. Gordon A. Stone," Department of Inorganic Chemistry, TheTreatment of the complexes Pt[CF,:CF(CF,)] L, [L = PPh,, PPh,Me, (Ph,PCH,),, or AsPh,] with stannic chlorideyields products dependent on the nature of L. With PPh,Me or AsPh,, perfluoropropene is displaced, but with PPhsor diphos the vinylplatinum compounds trans-PtCI[CCI:CF(CF,)] (PPh,), and PtCI[CF:CF(CF,)] (diphos) areformed, respectively. Reaction of SnCI, with Pt(C,F,)L, (L = PPh,, PPh,Me, or AsPh,) or with Pt[trans(CF,)-CF:CF(CF,)] (AsPh,), leads to displacement of the fluoro-olefin and formation of PtCI,L,. In contrast, the tinhalide reacts with Pt[trans(CF,)CF:CF(CF,)] L, [L = PPh,, PPh,Me, or (Ph,PCH,),] to yield vinylplatinum com-pounds cis-PtCI [transC(CF,) :CF(CF,)] L,.A mechanism for the C-F bond cleavage and stereospecific natureof the reactions is proposed.ALTHOUGH numerous transition-metal fluoro-olefin com-plexes l y 2 have been prepared little work has been re-ported on the reactivity of the co-ordinated fluoro-olefinmoiety. Aside from simple displacement reactions,only three types of reaction involving co-ordinatedfluoro-olefins have been reported.Certain platinum(0) and rhodium(1) fluoro-olefincomplexes undergo electrophilic addition by trifluoro-acetic acid or hydrogen chloride respectively, to yieldthe corresponding platinum(1r) or rhodium(rI1) fluoro-ethyl complexes.Platinum(0) species containing co-ordinated halo-genofluoro-olefins (e.g.CF,:CFCl) undergo readily amolecular rearrangement affording a-bonded vinylmetalcomplexes [e.g. PtCl(CF:CF,) (PPh,)J. Similarly, theformation of nickel(r1) ' y 8 and palladium(r1) fluorovinylcompounds is thought to involve rapid molecularrearrangement of an initially co-ordinated halogen-substituted fluoro-olefin.A number of low-valent iron,l0Y1l cobalt,12 rhodium,13nickel,14 and platinum l5 complexes are known to reactwith an excess of fluoro-olefin to form complexescontaining the h*CF2(CF,),hF2 ring system. In at leastone instance l4 the intermediary of a metallocyclopropanecomplex PV'I*CF,dF, has been demonstrated. Such ring-expansion processes represent the most thoroughlystudied reaction of co-ordinated fluoro-olefins.2In all the above cases, carbon-fluorine bondintegrity is maintained with the final product containingeither the original number, or an exact multiple of theoriginal number, of fluorine atoms present in the startingcomplex. In contrast, we now report a new class ofI-M.I. Bruce and I?. G. A. Stone, Preparative Inorganic2 F. G. A. Stone, Pure and Applied Chem., 1972, 30, 551.3 D. M. Barlex, R. D. W. Kemmitt, and G. W. Littlecott,4 R. D. W. Kemmitt, B. Y. Kiniura, G. W. Littlecott, andR. D. W. Kemmitt and D. I. Nichols, J . Chem. SOC. ( A ) ,6 M. Green, R. B. L. Osborn. A. T. Rest, and F. G. A. Stone.Reactions, 1968, 4, 177.Chew Comnz., 1969, 613.R.D. Moore, J . Organometallic Chem., 1972, 44, 403.1969, 1577.I " J . Chem. SOC. ( A ) , 1968, 2525.SOC. ( A ) , 1969, 3019.' J. Ashley-Smith, M. Green, and F. G. A. Stone, J . Chem.Jane Browning, M. Green, and F. G. A. Stone, J . Chem.SOG. ( A ) , 1971, 453. 533.reaction of co-ordinated fluoro-olefins in which carbon-fluorine bond cleavage occurs under mild conditions.During the course of our work Kemmitt et aZ.16 describeda reaction in which treatment of Pt-CF,*kF,(PPh,), withlithium iodide at 95" afforded PtI(CF:CF,) (PPh,),.The identity of the new compounds described hereinwas established by elemental analysis, and i.r. and lH and19F n.m.r. spectroscopy (see Table).Treatment of perfluoropropene complexesPt*CF,*h(CF,)L, (L = PPh,, PPh,Me, Ph,PCH2CH,-PPh,, or AsPh,) with stannic chloride gave severalproducts which were dependent upon the nature of Lbut were independent of Sn : Pt ratios greater than one(Scheme 1).With PPh,Me or AsPh, as ligands, perfluoropropenewas recovered quantitatively.Similar displacement ofthe fluoro-olefin by stannic chloride was observed for thethree tetrafluoroethylene Complexes Pt*CF,-kF2L, (L =PPh,, PPh,Me, and AsPh,), C,F, being recoveredIn contrast, the reaction of Pt*CF,*kF(CF,)(PPh,),with stannic chloride gave a white crystalline, non-tin-containing platinum species (I), containing four fluorineand two chlorine atoms. The i.r. spectrum of (I)exhibited a weak absorbance at 1638 cm-l (vGo), andabsorbances in the 800-1400 cm-l region characteristicof fluorovinyl metal c o m p l e x e ~ .~ ~ ~ ~ ~ The replacement9 A. J. Mukhedkar, M. G-reen, and I?. G. A. Stone, J . Chem.SOC. ( A ) , 1969, 3023.10 R. Fields, M. M. Germain, R. N. Haszeldine, and P. W.Wiggans, J . Chem. SOC. ( A ) , 1970, 1969.11 R. Burt, M. Cooke, and M. Green, J . Chem. SOG. ( A ) , 1970,2975 and references cited therein.15! T. D. Coyle, R. B. King, E. Pitcher, S. L. Stafford, P. M.Treichel, and F. G. A. Stone, J . Inorg. Nuclear Chem., 1961, 20,172.13 A. J. Mukhedkar, V. A. Mukhedkar, M. Green, and F. G. A.Stone, J . Chem. SOG. ( A ) , 1970, 3166.14 I?. K. Maples, M. Green, and F. G. A. Stone, J.C.S. Dalton,1973, 388 and references cited therein.l5 J. Browning, H. D. Empsall, M.Green, and F. G. A. Stone,J.C.S. Dalton, 1973, 381.16 hI. J. Hacker, G. W. Littlecott, and R. D. W. Kemmitt,J . Orgnnometallic Chem., 1973, 47, 189.l7 E. Pitcher and I?. G. A. Stone, Spectrochirn. Arta, 1961, 17,1244.18 H. C. Clark and W. S. Tsang, J . Amer. Chem. SOC., 1967, 89,I-I-I-quantitatively. 12070 J.C.S. Daltonof two fluorine atoms by chlorine with formation of afiuorovinyl group implies the presence of a Pt-Cl bondand incorporation of a chlorine atom in the vinyl moiety.Support for such a structure was obtained from the 19Fn.m.r. of (I) which showed only two multiplets (rel.CCI,F, 0.0 p.p.m.) centred at 66.2 [3F, JPtF 28-1 Hz] andtriplet by coupling with 3lP nuclei, suggesting thepresence of stereochemically equivalent tram-PPh,groups.Confirmation of the presence oi trans phosphineligands was achieved by preparing the PPh,Me analogueof (I) through a phosphine ligand-exchange reactioil.It should be noted that Pt(Cl)[C(Cl):CF(CF,)](PPh,Me),Analytical, spectral, and other physical data for the fluoroca,rbon complexesAnalyses *Yield AConipound Mp. (%) c H I; CI P or A: AIPt(Cl)LCCl:CF(CF,)](PPh,), 170-174 $ 63 51.7(52*0) 3*4(3-6) 8.2(8*4) 7*8(7.9) 6*7(6.9) 882(902)Pt(C1) [CCl:CF(CF,)] (PPh,Me) , 173 57 43.6(43.3) 3*4(3*4) 9-9(10*2) 9.3(9.7)E't(C1) [CF:CF(CF,)] (diphos) 295-300 : 43 45*5(45*8) 3*3(3.8) 11.9(12.5) 5.1(4.7) 6 1 5 (760)Pt(C1) [C(CF,) :CF(CF,)] (PPh,), 2 90--2 9 1 76 50.9(51.3) 3*3(3*2) 14*4(14-2) 4*0(3.8) 6.7(6*6) 935(935)Pt (Cl) [C( CF,) :CF( CF,)l (PPh,Me) , 195-1 96 41 44*0(44*3) 3.3(3-2) 16.6(16-4) 4*4(4*4) 7*6(7*6) 776(812)Pt(C1) [C(CF,) :CF(CF,)](diphos) 221-222 44 44*6(44-5) 3*1(3*0) 16*2(16-4) 4*5(4*4)Pt (C!) [CCl :CF,] (PPh,) 267-259 : 67 53*5(53.2) 3.6(3.4) 4*5(4*0) 8.3(8*7)19F Chemical shifts (p.p.m.) and coupling constants (Hz)XW, -,X(2)ptc 4),c=c,x( 3)Com-Compounds X(1) X(2) X(3) 6X(1) SX(3) J(1-2) J ( 1 - 3 ) J ( 2 - 3 ) J ( 4 - l ) J(4-2) J(4-3) mentsPt(CI)[CCl:CF(CF,)](PPh,), c1 CF, F 66.2 115-7 14.0 28.1 136.8 b25.0 134.0 c Pt(Cl)[CCl:CF(CF,)] (PPh,Me), C1 CF, F 65.8 116.3 13.6Pt(C1) [CF:CF(CF,) J (diphos) F I; CF, 99.0 153.2 66.4 35.3 9.1 16.0 352.3Pt(Cl)[C(CF,):CF(CF,)](PPhJ, CF, F CF, 50.7 102.3 66.9 18.4 1.5 11.2 124.0 278 19.0 dPt(C1)[C(CF3):CF(CF,)](PPh~Me), CF, F CF, 49.6 102.2 66.9 15.0 2.0 12.1 87.0 200 17.8 PPt(Cl)[C(CF,):CF(CF,)](diphos) CF, F CF, 50.4 100.1 68.0 18.0 2.1 12-2 80.1 208 18.1 f* Calculated values given i n parentheses.a Measured in dichloromethane solution, relative t o CC1,F (0.0 pup.".) internal standard.With decomposition.Jp,g(l) 3.4, Jp,g(3) 5-3.Jp,x(l)3.0, JP,X(3) 5.3, lJPR +.TPHI 7.4, ./PtH 15.0. JP,X(I) 3.0. .Jp.X(1) 6.4, .TPH 4.6, 5.0, JPtIX 10.4, 21.2. J P , X ( l ) 6-20L,P t /;: -' c -'FF3FF+ S n C l ,L = P P h ,1 L = d i p h o s-_____)115.7 [lF, Jptp 136.8 Hz] p.p.m. The I95Pt-F couplingconstants of both multiplets were much less than thosecommonly found in Pt*C(CF,):C (JptcruY3 120-150 Hz)or Pt-CFX (JptctCF 450-500 Hz) substituted PtIIfluorovinyl conipounds.18 Thus the vinyl function mustcontain both a fluorine atom and CF, group substitutedon the P-carbon with a chlorine atom occupying the=-carbon site.In addition, the lg5Pt-Fp couplingconstant recorded is in the range (80-180 Hz) of thosereported 18919 for vinyl systems containing p-fluorineatoms cis to platinum. Each line of the basic p-CF3and (3-CF resonance pattern was further split into al@ A. J. Rest, D. T. Rosevear, and F. G. A. Stone, J . Chem.2o J. M. Jenkins and B. L. Shaw, J . Chem. SOC. [ A ) , 1966, 770.SOC. ( A ) , 1967, 66,(11) was not formed in the direct reaction ofPt*CF,*kF(CF,) (PPh,Me), with stannic chloride. TheI9F n.m.r. spectrum of (11) was virtually identical tothat of (I), while the IH phosphine methyl resonancepattern showed a sharp 1 : 2 : 1 triplet at 7 7-90 character-istic of methyl groups coupled to two trans 31P nuclei.20Further reaction of either (I) or (11) with stannicchloride did not occur even after a prolonged periodunder reflux (48 11) in benzene.The reaction of Pt*CF,-CF(CF,) (diphos) with stannicchloride resulted in the loss of a single fluorine atom andthe isolation of the platinum-perfluoropropenyl complex(111). The i.r.spectrum of (111) showed a band at1650 cm-l indicating the presence of a vinyl group.I-I- 1973 207 1The 19F n.m.r. spectrum consisted of three multipletscentred at 66.4 (3F), 99.0 [lF, Jptp 353 Hz], and 153[IF, J P t p 72.0 Hz] p.p.m. The large lg5Pt-F couplingconstant recorded for the 99.0 p.p.m.signal is goodevidence for a fluorine atom attached to a carbonbonded to platinum, while the JFclpp (Table, 38.2 Hz)coupling value is in the range of those reported for cisvinyl fluorine atoms and is much less than that expectedfor trans fluorine n u ~ l e i . ~ ~ J ~ These facts together withthe nearly identical chemical shift values of (111) com-pared with Pt (Cl) [cis-CF:CF(CF,)] (PEt,), l8 confirm thestructure proposed (Scheme 1). Compound (111) wascompletely inert to further reaction with stannic chloride.Reaction of stannic chloride with perfluoropropene inbenzene under vigorous conditions (100 O C , two weeks)led to quantitative recovery of unchanged fluoro-olefin.No evidence of chlorination was observed.I ‘A.uI I198 5 201.0 p p mI196.1I194.1FIGURE 19F N.m.r. spectrum (CF region) of an equirnolarmixture of $t*CF(CF,)*&(CF,) (AsPh,), and PPh, in di-chlorometiiane solutionTo test the generality and stereochemical courseof the above reactions, compounds of the typePt*CF(CF,)dF(CF,)L, (L = PPh,, PPh,Me, diphos,and AsPh,) were prepared and treated with stannicchloride. Reaction of an excess of a cisltrans mixture(1 : 4) of perfluorobut-2-ene with trans-stilbene-bis(tri-pheny1phosphine)platinum yielded a single isomer ofPt*CF(CF,)*kF(CF,) (PPh,), (IV). The 19F n.m.r.showed a doublet at 68-2 [3F, JpF 9.0, JptP 78 Hz] anda triplet at 201 [lF, J p t p 68 Hz] p.p.m. The tripletpattern is typical of an X resonance of an AA’XX’system (IJpF + J P p I 52-4 Hz), arising from strong J F Fcoupling.Such a resonance pattern may result fromeither a cis or a tram arrangement of the substituentson the co-ordinated fluoro-olefin, and has been observedin the spectra of both isomers of Pt*CFC1*&FCl(PPh3)2.21The reaction of an excess of perfluorobut-2-ene withtetrakis(tripheny1arsine)platinum also afforded a singleisomer PkF(CF,)*&F(CF,) (AsPh,), (V). The 19F n.m.r.spectrum of (V) showed two singlets a t 68-3 [3F, Jptp92 Hz] and 194-1 [lF, Jptp 95 Hz] p.p.m. (see Figure).That (IV) and (V) have the same stereochemistry for the21 J. Ashley-Smith, M. Green, and D. C . Wood, J . Chem. SOC.( A 4 ) , 1970, 1847.II1-co-ordinated olefin was demonstrated by the directconversion of (V) into (IV) by reaction with 2 mol.equiv.of triphenylphosphine, followed by examination of thei.r. spectrum. Similar ligand-exchange reactions of (V)with diphenylmetliylphosphine and bisdiphenylphos-phinoethane gave P’t*CF(CF,)dF(CFJ (PPh,Me), (VI 11 Iand Pt*CF(CF,)*CF(CF,)(diphos) (VIII) respectively.The l9F spectrum of (VI) was similar to (IV) and ex+hibited an AA’XX’ pattern in the CF spectral region.Compound (VII) was too insoluble for n.m.r. measure-ment. Thus all perfluorobut-2-ene complexes preparedhave an identical olefin stereochemistry but one whichcould not be established directly from their 19F n.m.r.spectra.In an effort to measure directlyJFF, and thus establishthe stereochemistry of compounds (1V)-(VII) anattempt was made to prepare an unsymmetrical ligand-substituted perfluorobut-2-ene complex.Reaction of1 mol. equiv. of triphenylphosphine with (V) yieldedan equilibrium mixture in solution of (IV), (V), andPt*CF(CF,)dF(CF,)(PPh,)(AsPh,) (1 : 1 : 4). An accu-mulated 19F n.m.r. spectrum in the C F region is shown inthe Figure. The resonance pattern of the environ-mentally different fluorine atoms F(trans to AsPh,) andF(trauts to PPh,) are clearly resolved, and JFapb can bemeasured directly from the F, pattern or from the 31Pdecoupled F b pattern. The measured JFaPb coupling of60 Hz is close to that reported for J I r a n s - p ~ ( 3 9 4 4 Hz)in a number of fluoro-olefin Pt, Ru,ll and 0 s 22 com-plexes, and is much larger than the correspondingJeis-pF (7-10 Hz) values reported. From the abovedata, compounds (1V)-(VII) must contain the ligandCF,CF:CFCF, in the tram-configuration.IC F F ( Y l I f ) L = P P h ,1 \;=c’ (EX) L = PPh,Me\ /- - P t 7 CLL \ /L P tL/ ‘CI+F cFJ\ /’CF,c=cL = AsPh,CF3 ‘ F’SCHEME 2Stannic chloride reacted with the perfluorobut-2-eneplatinum compounds according to Scheme 2.Theformation of vinyl species from compounds (IV), (VI),and (VII) was evidenced by the presence of a weak vcZaabsorbance at 1630-1640 cm-l in the i.r. spectra of the22 M. Cooke, M. Green, andT. A. Kuc, J . Chem. SOC. ( A ) , 1971,12002072 J.C.S. Daltonproducts (VII1)-(X). The 19F n.m.r. spectra of(VII1)-(X) were similar, so a detailed discussion islimited to the diphenylmethylphosphine species (IX) .Data are presented in the Table for the three isostructuralcompounds.Three widely separated resonance patterns (area ratio3 : 3 : I) were recorded in the 19F spectrum of (IX).The multiplet at 49-6 p.p.m.( J B ~ 87 Hz) was assignedto a Pt*C(CF,):CX, group, based on the large lg5Pt-Fcoupling constant, while the equally intense multiplet at66.9 p.p.ni. (JFtF 17 Hz) was assigned to a Pt*CX*C(CF,)XI 1or Lewis acid attack by the tin(rv) chloride on one ormore of the fluorine atoms of the co-ordinated fluoro-olefin with subsequent formation of perfluoro- or chloro-fluoro-vinyl species. Both the initial site of attack andthe subsequent formation of vinyl compounds appearsto be highly stereospecific.A mechanistic pathway isproposed in Scheme 3, illustrated by the reactions ofperfluoropropene complexes but consistent with theresults found for the other fluoro-olefins.Initial attack on co-ordinated perfluoropropene mayoccur at any of three sites FA4, FB, or F,. Attack andCB DSCHEME 3Egroup. The remaining signal at 102-2 p.p.ni. arisesfrom a fluorine atom Pt*CX:CXF. The stereochemistryof the perfluorobut-2-en-2-y1 group Pt*C(CF,):CF(CF,)was determined on the basis of the JcF,-cF, couplingconstants. In previous work on various C(CFJCR(CF,)[R = H or Me] 1*923-25 and C(CF,):CF(CF,) 26 derivatives,compounds with tmns-CF, groups showed couplingconstants of 1-3 Hz in their 19F spectra whereas thecorresponding coupling between cis-CF, groups was12-15 Hz.The Jc$,-c~, values for complexes (VII1)-(X) ranged from 1-5 to 2.1 Hz, indicating a trans-stereo-chemistry for the CF, groups about the carbon-carbonbonds. The lH n.m.r. spectrum of (IX) confirmed arelative cis-configuration for the pliosphine ligands.The methyl signal consisted of two doublets at T 8.10and 8.08, characteristic of environmentally non-equivalent cis diphenylmethylphosphine ligands.Treatment of (V) with stannic chloride displaced theperfluorobut-2-ene, with no evidence for formation ofany perfluorobutenyl platinum complex ; a result similarto that described above for the bis(tripheny1arsine)-platinum tetrafluoroethylene or perfluoropropene com-plexes.DISCUSSIONReaction of stannic chloride with the fluoro-olefin-platinum compounds either involved olefin displacement,23 J.B. TVilford and F. G. A. Stone, Inorg. Chem., 1965, 4, 93.24 W. R. Cullen, D. S. Dawson, and G. E. Styan, Canad. J .Chem., 1966, 43, 3392.carbon-fluorine bond fission a t Fc were eliminated by thefact that the CF, group in the vinyl product was alwaysobserved in the p-position. If the carbon atom of thecationic species A formed by attack at F A or FB effec-tively becomes sjb2 hybridized then a loss of stereo-specificity would be expected in the vinyl products. Onthe other hand, retention of configuration about thecarbon atom prior to rearrangement would result ineither a cis or a trans arrangement of the fluorine atomsin the products dependent on whether attack occurred ateither F A or FB.Non-selective attack at F A and Fsunder the same stereochemical constant would againlead to an isomeric mixture of vinyl compounds.Stereochemical retention about the cationic carboncentre in the proposed intermediate A was stronglysuggested by the observation that a single vinyl isomercontaining two trans CF, groups was formed in everycase from the reaction of stannic chloride with trans-perfluorobut-Zene complexes. Retention may resultfrom formation of a ‘ tight ’ ion-pair as has been pro-posed 27 to account for the retention of stereochemistryin the thermal vinyl rearrangement of co-ordinatedchlorofluoro-olefins.Based on the above, and on the fact that a singlez5 H. C. Clark and R. J. Puddephatt, Inovg.Chela., 1970, 9,26 R. B. King and W. C. Zipperer, Inorg. Chem., 1972, 11,27 M. Green and G. Parker, J.C.S. Dalton, 1973, 2099.2670.21191973 2073cis-vinyl isomer C was isolated in the reaction ofPt*CF,*CF(CF,) (diphos), selective attack must occurat F A .While participation of an intermediate of type Adirectly accounts for the stereospecific formation ofperfluorovinyl compounds from Pt*CF,*CF(CF,) (diphos)and dt-CF(CF,)*kF(CF,)L, it does not immediatelyaccount for the formation of a chlorofluorovinyl speciesfroni Pt*CF,*kF(CF,)(PPh,),. However, this result canbe rationalised on the basis of an internal return reactioninvolving attack of one of the chlorine atoms of theintimately associated anionic tin species a t the originalsite of carbon-fluorine fission.Subsequent fluorineabstraction could yield an intermediate D analogous toA which would undergo rearrangement to a chlorine-containing vinyl group. In order to test the ability ofan intermediate such as B to undergo the necessaryreaction with stannic chloride, the reaction ofPt-CFClkF,(PPh,), was studied. A single vinyl productwas obtained in high yield and shown to be Pt(C1)-(CCKCF,) (PPh,), by independent synthesis by thermalrearrangement of PtCCl,-(b,(PPh,),. This result notonly confirms the reactivity of species such as B towardattack by tin(1v) chloride but indicates that such attackoccurs selectively at the fluorine atom bound to thechlorine substituted carbon. Thus attack a t FB in €3is expected with subsequent formation of intermediateD which stereospecifically rearranges to the product E,observed, The possibility that E might be formed bysecondary attack of SnCl, on the a fluorine atom of anyperfluorovinyl compound present was eliminated by theobservation that both Pt (Cl) [tram-CF:CF(CF,)] (diphos)and PtCl(CF:CF,) (PPh,), were inert toward reactionwith stannic chloride even under the most stringentconditions (80 "C, 3 days).The relative rate of tin(rv) chloride reaction atplatinum leading to fluoro-olefin displacement, as com-pared with attack on the co-ordinated fluoro-olefin, isdependent on the nature of both the fluoro-olefin andthe appended ligands.Quantitative fluoro-olefin dis-placement occurred with all tetrafluoroethylene com-plexes, and with the triphenylarsine perfluoropropene orperfluorobut-2-ene platinum compounds.In contrastonly a small or often undetectable amount of displace-ment was observed with the PPh, and diphos-substitutedperfluoropropene, perfluorobut-2-ene, and chlorotri-fluoroethylene compounds. These results parallel quali-tatively the rate of displacement of co-ordinatedfluoro-olefin by iodine, tetrafluoroethylene being rapidlyliberated, perfluoropropene being slowly displaced, andthe perfluorobut-2-ene platinum complexes being inerttowards reaction with iodine.The reactivity of Pt*CFX* toward Lewis acid attackI 1I-I-I-I-s J. J. Lagowski, Quart. Rev., 1959, 13, 233.29 P. K. Maples, M. Green, and F. G. A. Stone, unpublishedwork.is a function of the geminal substituent (X) and varies inthe order C1 > F > CF,.The least electronegativegerminal substituent would be expected, on the basis ofsimple inductive effects, to have the greater activatinginfluence. However, steric factors may influence re-activity as suggested by the lower activating effectcompared with chlorine of the equally electronegative 28but more bulky CF, group.The broad scope and high stereoselectivity of thesereactions offers a synthetic route to a wide range ofvinyl platinum complexes unobtainable by conventionalprocedures. Results 29 on hexafluoro-butadiene systemsindicate that a wide range of perfluorobutadienylnietalcomplexes may be generated by Lewis acid attack byboth stannic chloride or bromide.EXPERIMENTALlH and 19F N.m.r.spectra were recorded on a VarianAssociates HA100 spectrometer at 100 and 94-1 MHz,respectively. 1.r. spectra were recorded with a Perkin-Elmer 457 spectrophotometer using Nujol and hexachloro-butadiene mulls. Solvents were dried and distilled undernitrogen, and all operations were conducted in an atmo-sphere of dry oxygen-free nitrogen. Stannic chloride wasdistilled under nitrogen immediately prior to use. Tetra-fluoroethylene, PtCF,CF,L, and perfluoropropenePtCI;,.CF(CF,)L2 complexes were prepared by publishedprocedures .6p 3oReaction between PtCF,&,(PPh,) , and SnCl,.-A stirred - Ibenzene (30 ml) solution of Pt*CF',*CF,(PPh,)2 (0.90 g,1.1 mmol) in a sealed evacuated flask was treated withstannic chloride (0.36 g, 1.4 mmol).Volatile products werefractionated in a vacuum system giving 0.92 mmol oftetrafluoroethylene (identified by its i.r. spectrum). Thewhite precipitate remaining was filtered off, giving cis-PtC12(PPh3), (0-78 g, 90%). Similar results were obtainedI- Ifor all PtCF,*CF,I,, complexes (L = PPh,Me, AsPh,,or diphos). ,-Reaction of Pt-CF,*&(CF,) (PPhJ, with SnCl,.-Stannicchloride (0.42 g, 1.6 mmol) was added dropwise to a stirredsolution of Pt*CF,*CF(CF,)(PPh,), (0.87 g, 1.0 mmol) inbenzene (40 ml). A red oil was precipitated during theaddition. Thc mixture was allowed to react for 8 h andsolvent was removed in vacuo. The residue was washedwith n-hexane and then extracted with benzene.Additionof n-hexane and cooling to 0" afforded white crystals of (I)(0.57 g, 63%) from dichloromethane-ethanol; v(C=C)1638 cm-l. The red oil was dissolved in dichloromethane.Addition of ethanol gave cis-PtCl,(PPh,), (0.15 g) whichWEE identified by its i.r. spectrum.Synthesis of Pt(C1) [CCl:CF(CF,)] (PPh,Me),.-A mixtureof PtCl[CCI:CF(CF,)](PPh,), (0.45 g, 0.5 mmol) and di-phenylmethylphosphine (0.20 g, 1 mmol) in benzene (20 ml)was refluxed for 12 h. The light yellow solution wasfiltered and solvent was removed in vucuo. Crystallisation- II- II-I I30 R. D. W. Kemmitt and R. D. Moore, J . Chem. SOC. (A),1971, 24722074 J.C.S. Daltonfrom dichloromethane-n-hexane gave white crystals of (11)(0.22 g, 57%); v(C=C) 1632 cni-l.Reaction of Pt*CF,CF(CF,) (diphos) with SnCl,.-Stannicchloride (0.26 g, 1.0 mmol) was added dropwise to a stirredsuspension of PtCF,*CF(CF,) (diphos) (0.74 g, 1.0 mmol).The platinum compound rapidly dissolved to yield a redoily precipitate and a clear pale yellow solution.Themixture was allowed to react for 4 h and solvent wasremoved in vacuo. The residue was washed with n-hexaneand extracted with benzene. Solvent was removed invacuo and the residue crystallised from dichloroniethane-n-hexane to give crystals of (111) (0.32 g, 43%) from di-chloromethane-methanol; v(C=C) 1650 cm-1.Synthesis of Pt-CF(CF,)*dF(CF,) (PPh,)2.-A solution ofstilbenebis(tripheny1phosphine)platinum (0.90 g, 1.0 mmol)in benzene (30 ml) in a Carius tube was treated with anexcess of perfluorobut-2-ene (4 nimol) a t - 196" and thesolution was allowed to react in the sealed tube a t roomtemperature for 48 h.Solvent was removed in vacuo andthe residue crystallised from dichloromethane-n-hexane togive white crystals (0.73 g, 79%) or (IV), m.p. 224-255'(Found: C, 52-0; H, 3.4; F, 16.6; PI 6.4%; M , 823(CGHG). C,,H,,F,P2Pt requires C, 52.2; H, 3.3; F, 16.6;I, 6.7%; JI, 919). 19F n.m.r.: 68-2 (d, 6F, CF,, Jpp 9.0,Jptp 78.1 Hz) and 201 (t, 2F, CF, ]Jpp -t- JppI 52-4, Jptp68.0 Hz) p.p.m.; I H n.ni.1.: 7 2.41 (m, 30H, C,H,).Synthesis of PtCF(CF,)*CF(CF,) (-4sPh,) ,.-A suspensionin benzene (50 ml) of tetrakistriphenylarsineplatinum (3.0 g,-2.1 mrnol) was placed into a Carius tube, and treated withan excess of perfluorobut-2-ene (5 mmol) .The solution washeated a t 60" for 18 h. The yellow solution was filteredoff and the solvent removed in vacuo. Cryatallisation ofthe residue from dichloromethane-n-hexane gave whitecrystals of (V) (1.2 g, 57%), m.p. 199-201" (Found: C,47-4; H, 3.1; I;, 14-9. C4,H,,F,As,Pt requires C, 47-6;H, 3.0; F, 15.1%); 19F n.m.r.: 68.3 (s, 6F, CF,, Jptp 92.2Hz) and 194.1 (s, 2F, CF, Jptp 95.0 Hz) p.p.m.; lH n.ni.r.:T 2-36 (m, 30H, C,H,).I- II- II1 II ISy.tzthesis of PtCF( CF,) CF(CF,) (PPh,Me) ,.-A solutionof PtCF(CF,)*CF(CF,) (AsPh,), (1.0 g, 1.0 mniol) anddiphenylmethylphosphine (0.40 g , 2.0 mmol) was refluxedin benzene (20 ml) for 24 h. The solution was filtered andI Ithe solvent ' removed in vacuo. The yellow oil remainingwas crystallised from dichloromethane-ethanol to givewhite crystals of (VI) (0.65 g, 82%), m.p.161-162' (Found:C, 45.0; H, 3.3; F, 19-2; P, 7.7%; M , 718 (C,H,).C,,H,,F,P,Pt requires C, 45.3; H, 3-5; F, 19-2; P, 7.8%;M , 795) ; 19F n.m.r. 68.0 (d, 6F, CF,, Jpp 9.8, Jptp 80-0 Hz)and 200.9 (t, 3F, CF, ~ J P F + J p ~ l 54.8, Jptp 66-2 H z )p.p.m.; IH n.m.r.: 7 8-10 (d, 12H, CH,, Jpg 3.8, Jptlr14.0 Hz) and 2.43 (m, 20H, C,H,).Synthesis of PtCF(CF,) *CF(CF,) (diphos) .-A solution ofPt*CF(CF,)*CF(CF,) (AsPh,), (0.8 g, 0.8 mmol) and 1,2-bis(dipheny1phosphino)ethane (0.32 g, 0.8 mmol) wasrefluxed in benzene (50 nil) for 6 h. Solvent was removedin vacua and the residue was crystallised from dichloro-methane-methanol to give white crystals of (VII) (0-55 g,87%), m.p.262-263' (Found: C, 45.3; H, 3.3; F, 19.0;P, 7.8. C,,H,,F,P,Pt requires C, 45.4; H, 3-1; F, 19.7;P, 7.8%). The compound was too insoluble for l9F n.m.r.measurements. IReaction of Pt*CF(CF,)*CF(CF,) (PPh,), with SnCl,.-Stannic chloride (0-39 g, 1.5 mmol) was added slowly to abenzene (50 nil) solution of lkF(CF,).dF(CF,) (PPh,),(0-91 g, 1.0 mmol). The mixture was stirred for 12 hduring which time a light yellow oil was precipitated fromthe colourless solution. The solution was decanted ,filtered, and the solvent removed in zracuo. The residuewas washed with n-hexane and crystallised from dichloro-methane-ethanol. Recrystallisation gave white crystals of(VIII) (0.71 g), v(C'c) 1651 cni-l.Reaction of &.*CF(CF,).dF(CF,) (PPh,Mej, with SnC14.-As above, reaction of stannic chloride (0-26 g, 1.0 mmol) andPt*CF(CF,)*CF(CF,) (PPh,Me), (0.48 g , 0.6 mmol) affordedwhite crystals of (IX) (0.20 g) from dichloromethane-ethanol v(C=C) 1659 cm-l.Reaction of Pt CF(CF,)*dF(CF,) (diphos) with SnCl,.-Asabove, reaction of stannic chloride (0.31 g, 1.2 mmol) andPt*CF(CF,)CF(CF,) (diphos) (0.80 g, 1.0 mmol) gave whitecvystals of (X) (0.36 g ) from dichloromethane-ethanolv(C=C) 1663 cm-l.Reaction of Pt*CFCl*CF,(PPh,), with SnCl,.-To a stirredsolution of Pt*CFCl*CF,(PPh,), (0-87 g, 1.0 mmol) inbenzene (60 ml) was slowly added stannic chloride (0.52 g,2.0 mmol). The mixture was allowed to react for 2 h.Solvent was removed in vacuo and the resulting solid waswashed with n-hexane. Crystallisation from dichloro-methane-ethanol gave white crystals of (XI) (0-57 g);vu=c 1689 cm-l. The compound was too insoluble for 19Fn.m.r. measurements.We thank the U.S.A.F. Office of Scientific Research forI I1 IiI III 1I- I- Isupport.[3/378 Received, 19th February, 1973
ISSN:1477-9226
DOI:10.1039/DT9730002069
出版商:RSC
年代:1973
数据来源: RSC