6529

Synthesisand Reactions of Bis(cyclopentadienyl)titanium( IV ) tttetallocycles

JosephX. McDermott,r Michael E. Wilson,and GeorgeM. Whitesides* Contributionfromthe Deportment oJ'Chenti.strr', Massachusetts Institute oJ Techrutlogt', Cantbridge,Ma.ssachusett.s 02139. ReceiredJanuarr 16, 1976

Abstract: 1,4-Tctramethylenebis(cyclopentadienyl)titanium(lV)(l) was preparedbv rcactionbetween dichlorobis(cyclopen- tadicnyl)titanium(lV) and 1.4-dilithiobutane:it could be isolatedat low tcmperature.but its thermal lability was such that it could be characterizedonly through its reactions.Compound I and the analogoussix-membered metallocycle I .5-penta- methylcncbis(cvclopentadienyl)titanium(lV)(5) were much more stablethan an acyclictitanium alkyl. di-n-butylbis(cyclo- pentadienyl)titanium(lV)(3). Thermal decompositionsof 3 and 5 appearto take place by unexceptionalp-climination and reductionreactions involving titanium .These reactions yield, respectively'.u mixture of butenesand n-butaneand a mixture of pentenesand cyclopentane.By contrast,thermal decompositionof I (4 h,0'C) takesplace in part by a path that clcavesa carbon-carbon bond of the titanocyclopentanering and generatesethylene: I -butcnc is the secondmajor product of this decomposition.Carbonylation of I yieldscyclopcntanone; carbonylation of 3. 5. and dimethylbis(cyclopentadienyl)titanr- um(lV) takesplace less readily, if at all. Theseresults indicate that the high stabilit;-of the titanocyclopcntanering, presum- ably reflecting suppressionof the p-elimination of metal , is accompaniedbl abnormally high reactivity in carbonyla- tion and in thermal decompositionby carbon-carbon fragmentation. Several functional equivalentsof titanocene (CpzTi- N:TiCp:, [CplTiH].-, [Cp:Ti]:. Cp:TiCl: reducedwith lithium naphthalenide)react directll'with olefinsand form titanocy- cloDentanerings. The best vields in thesereactions are obtained usine benzonorbornadiene.norbornene. and .

A dominant decompositionreaction of transition metal SchemeI. hcparation and Reactionsof CprTi(CHr)o(l )

alkyls is the /3-eliminationof a metal hydride moiety.r Al- Li(cH2)1Li CO (l atm) though this reactionis fundamentalto much of transitionmetal ------:- Cpr'l'iCl t'p Ti | o-( | catalysis.its very facility limits the importanceof other. po- Et20, -?8 "C \--./ -4O to 23 C \--/ tentially valuable,types of reactions,particularly those in- 2O7o volving carbon-carbon bond formation and cleavage.We have co previouslysuggested that one way of suppressingthe (l-hydride Br, CFCITCFTCI -cc L eliminationreaction is to constrainthe M-C-C-H dihedral -40 0c TOVo angleto valuesfar from the optimal 0o. This suggestionwas 1('p-TiCl 1t'pTiI3r' o verilicd by preparingseveral platinum(ll) metalloc)'cles,and \_ establishingthat their thermal decompositionis dramatically 1- + /\ (-p- Ti ) Iessrapid than that of acyclicanalogues.r Here we describe llt\ B11 \-J --RrJI ') | dctailsof the preparation,characterization, and reactionsof "'n-.--J 2 bis(cyclopentadienyl)titanium(lV)metallocyclcs. and par- r t'r, ticularly of 1,4-tetramethylenebis(cyclopentadienyl)titani- *I um(lV). CpsTi(CH2)a (l) These studies reinforce the suggcstionthat the chemistryof metallocyclopentanesis sig- o<| \----l nificantly different from that of analogousacyclic organo- * Cp Ti{CO)- rnetalliccompounds, and that an important basisfor this dif- fercncc is suppressionof il-hydrideelimination.r yieldsarc basedon thc assumptionthat the reactionof I with bromineyields 1.4-dibromobutanequantitatively: viz., that Results this reactioncan be usedto assaysolutions for the quantity of Preparation and Characterizationof 1,4-Tetramethvlene- I thel' contain.The major part of the dcscriptivechemistry of bis(cyclopentadienyl)titanium(lV)(l ). Reactionof a suspension I was carried out by preparing I by reaction of 1,4-dili- ol'dichlorobis(cyclopentadienyl )titanium( I V ) (CplTiClz) with thiobutancwith CplTiCl:, isolatingI by low-temperature oC 1.4-dilithiobutanein diethylether at -78 yieldsa reaction chromatographyusing procedures outlined in the Experimental mixturecontaining I (SchemeI). Its isolationand purification Scction.and assayingan aliquotby brominationto determine can be accomplishedby chromatographyover alumina at -40 the quantitypresent. The conversionof Cp:TiCl: to a solution oC underargon using as elucnt;crystallization may be containingI was normally ca.20o/". oC. cffcctedby'cooling thc eluentto -78 Compound I is a dark Two linesof cvidenceargue that I is a monomer containing orangccrvstalline solid. readily soluble in pentaneand ethereal a five-memberedtitanocyclopentane moiety, rather than a solvents.whrch decomposesthermally in CFCI:CClF1 solution dimer or higheroligmer having the sameempirical composi- oC. with a half-liieof ca.0.5 h at 0 tion. First.its thermalstability is much greaterthan that of Sincc the thermal instabilityoi I precludedtraditional an- acyclicanalogues. For cxample,CpzTi(CHtCH2CHzCH r): ali,tical proccdures.it was characterizedby its reactions. (3, videinfra)dccomposes rapidly at -55 oC, while t hasap- Trcatment of chronratographedsamples of I with HCI (gas) preciablestability at 0 oC. If I werea dimer or oligmercon- in hexancor CFICICFCl2 yieldedCp2TiClz and butanein taining a ring having more than five members,its thermal rnolarratio l:1.0:treatment with brominein thesame solvents sterbilitlwould be expectedto be determinedby the rate of yieldedCpsTiBrz and 1,4-dibromobutanein molar ratio l:1.2. /J-h-v-drideelimination. and to be approximatelythe sameas Thc lact that the ratio of titanium-coniainingproducts to that ol3.r The observationthat the stabilityof I is qualitatively productsderived from the 1,4-tetramethylenemoiety is ap- much grcatcr than that of 3 arguesstrongly that the 1,4-te- proximately1.0 in bothof theseexperiments indicates that the tramethylenemoiety of I is part of a five-memberedring. compoundhas stoichiometry [CpzTi(CH:)+]u. In what follows, Second.carbonylation of I (CO, I atm, warming from -40

IReprinted from the Journal of the American Chemical Societr'.98, 6529 (1976).] ('opvright 1976bv the American Chemical Societr.'andreprinted bv permissiono1'the c'opr.'right owner 6530

TableI. Productsot'Thcrmal Decomposition o1 Two aspectsof thcscdata deservecompari\()rt I rr'1.the \{etallocy clopcntane sa muchenhanced thermal stabilitl'of I relatir.'clt,3 r:.ruut)lll- 1-Butenc/ paniedby a changein the t) pesof hydrocarbonprtrllii!1. i.\r'()- A Compound Temp ('C) Ct l)\ lL'nL"' duccd on decomposition:thc carbon-carbonl'nrenrcri.rtlr)n (csHs),Ti(cHr)o(l) 20 9 that convcrtsI to cthylenehas no counterpartin tll! (ir'!,\nt- A .e.rct (') a positionof 3. Second.this increased stltbility pcnr)n: I t,' 150c 0.05 with carbonnronoxidc and gencratecvclopentan()ite [)rl,cn- (C,NIc.)rTi(Cll,)4 0 (4.s) zvlbis(c)'clopcntadienl'l )titanium( I V ) and ntcthr Ii.r.r .', . i',- l5 0.' (0.4) pentadicnyl)titanium(lV)chloride . in whrch,J-hidrrtle e :;''- (Cql\'Iea I:t) rTi(CHr)4 0 (6) 250c (0.6) inationis nrttpossible. ulso carbonvlatc:'r dintcthrIl.r. .'.gI1r- CprZr(ClI,)o It) 6 pcntadienl'l)titaniunt(lV)reacts onll slowlr \\rtlr,,,r'rr)!r 250. l rnonoxidcat roor.t'ttenrpcraturc. The observationtir,ri I r\ a Thcrmaldecompositions rvcrc carricd out in CIrClrccllr, solu- significantll nrore reactive tor.lardcarbon nton()\itit I . tion at conccntrationsoriginalll' ca. 0.02 1\lin rlrganometalliccor.n- Cp.TiN{e1suggests that thc fivc-mcmbercdmetallocrclt. t.iirr pound. b The absolutcyit:lds o1'oletins u'crc not mcasurcdin in- ol'I servesboth to suppress,J-h1'drideelimination and lri .,r,'- stanccsrndtcated bl'parcntlrescs; in othcr cases,thc irroductbalancc vidca purticul;rrlrrcuclivc grouping. \\,asgrcatcr than 80%. l,.l-tctramethy'lenc Thc rcmaining rnoieties The factorsinfluencing the partitioningof the 1.4-tctrrr- appcared asa mirture ot'ethancand butanc.Sincc irredotninantll' of I betweenethl"lenc and l-buteneon therntul the ratio of cthancto \\'as approxinratcly tltc sanrcas that ot' methl'leneunit cth-'-lcncto butcne,thcsc tbrmer matcrialsu'cre- probabll lormcd b1 decompositionwcre cxploredbriefly (Table I). Also for conr- redrrcti,rrrol lllf llttt'r.8.l)ec()ln11()sili()n\\'a\carri.'d rrut hr irrjce- parison,thc rclatcdnrctrllocvclcs 4 and 5 *'crc prcparcd.pu- tion dircctlf into a GLC inlct port at 250'C. riiicd by chrornatographr.antl itllow'edto decomposcthcr- nrallr.The thcrmalstabilitics ol' thcse substunccs arc intcr- mediatebetwccn those ol-l and 3. The productso1'deconrpo- to 25 "C) yields cyclopentanone in 80-90o/oyield. If I were a sitionvaried slightll u ith tcntperaturc.but alr',ay'sconsistcd dimcr or oligmer, the carbonylgroups would be expectedto predominantll'of pcntcncs.No rnorethan trace propylcne join diliercnt tetramethylenemoieties. The productionof cy- a of or cth)'lene\\'as observcd ()n dccomposition of 4. clopentanonein good yield is consistentwith the existenceof a titanocyclopentanemoiety in l. cyclo- The Thermal Decompositionand Carbonylation Reactions I 250 C 1- + 2-pentene + pentane of I Produce Different Types of Products Than Do Analogous t'ofi 0.35 0.65 0.00 Reactionsof Di-n-butylbis(cyclopentadienyl)titanium(lV)(3). \--) (GL(l rntection) Reactionof n-butyllithiumand methyllithiumwith CplTiCll 4 at -78 oC is accompaniedby the samecolor changcs observed 250 C on reactionwith 1.4-dilithiobutane:CplTiMe2 is casilyisolated t'pr|-\ 0.30 (1.65 0.05 in 80o/nyield as a yellow-orangesolid which is moderatelystable \--l (GLC injection) at room temperature;r'6CpuTiBu: (3) decomposesrapidly at 5 -50 oC and has beenisolated only ar -18 oC. It has been Thesestudics do not providcsufficient evidcnce to indicate possibleto examinethe productsof thermal decompositionof the structuralfeatures that promotecurbttn carboncleavagc 3 and of the productsresulting from its treatment with bro- in thermaldecomposition of I a1tlrc cxpcnsc of the (presunt- minc, hydrochloricacid, and carbon monoxide.Comparison ablv 13-hydrideelimination-based) path that lcadsto butenes.r0 of these products with those obscrvedfollowing analogous The markedtemperature dependencc ol-thc ieldsof hydro- rcactionsof I is helpfulin identifyingreactivity characteristic f carbonsobscrvcd on decompositionol' I is crperimentally re- of the titanocyclopentanering. Thermal decompositionof 3 producible.but not easilf interprcted.Thc 1..1-tetramethl,'- o lenebis(pentaalkylcl'clopentadienl'l )t itrr n i u m ( | V ) spccieswere ll 2so"c preparedto test the hypothesisthat incrcuscdsteric bulk in the BuCBu *_//_"o CpsTiBu - ,/\./ + planeof the cvclopcntadien.v-lrings might inhibit both puck- 3 (GLC I ering of the metallocvclopentanering and transfcroi a p- injection) hydrogenfrom carbonto titaniurn(l .* 7) Thcscmatcrials + '\-- 0.,1 co25oc -/,L - A .* ) o1 I .- CpTi | ------__----,,"\'V + t'p Ti l-. \__, \).,-r_/ \__, lcI.c I lJ) rnJectron) I is completein minutesat -50 oC, or very rapidly in the in- jection port of the GLC at 250 oC. Either decomposition 4'^ generates,in greater than 80o/oyield, the I :l mixture of n- butane and butenesexpected2'7 for initial _-) i/-,A B-eliminationfollowed by reductiveelimination of butane.No I

Journalof theAmericanChemicol Society / 98:21f October13, 1976 653l fragmentation.perhaps due to a facilep-hydride elimination In principle.any two-electronreduction of Cp2TiCl2might involvingthe methyl group.The stabilityof the relatedplati- generatea titanium(ll) spcciesthat could act as an ethylene nocvcleis. however.relatively unaffected by the additional acceptor.6Although Cp2TiN2TiCp2 servesadequately as a rnethylgroup.r sourceof "titanocene". it is not easilyprepared. Accordingly, Cycloaddition Reactionsof Olefins with Functional Equir,- we spent some effort in trying to find aliernativeand more alents of Titanocene.Two compounds of empirical formula convenientprocedures for generatingthe functionalequivalent (CroH11;Ti)have been called "titanocens" 6.ll l8 (SchemeIl). o[ titanocenefrom CplTiCll by reduction.The development of a satisfactorvreducing agent is made difficult by the re- SchemeII. Routesto Titanocene quirementthat it work rapidlyat -30 oC. at whichtempera- --: ture I is moderatell'stable. The alkali metals,alkali metal [Cp,Ti]N, Cp,Ti lCp,Til, + amalgams.and Na K alloyreduce Cp2TiCl2 to CprTill slowlv -,|, evenat room tcmperaturc.Hydridic reducingagents (potas- r/ l\-r" sium hy'dride.Vitride. isobutylmagnesiumbromide) were /** l- \ sirnilarll'unsatisfactory. Solutions of aromaticanions proved TiHl.a Cp.'fiCl, [('p ] to be efficientreducing agents.6' |7' le Thus. reactionof a sus- pensionof CpzTiCll in toluenewith lithium naphthalenidc( 1.7 M in TH F) occurredreadily at -55 to -30 oC in the presence of ethylene( I atm). Carbonylationof the resultingreaction mixture yieldedcvclopentanonc in l7o/oyield: the resultsof sevcralrelated experiments are summarizedin Table II. These

1. 2Li+Np.- (THF) l"'b -. -=--+ 8 Cp,TiCl |'\--/ FO t1-fi %) The structureof the lessreactive. green. dimeric compoundl:.1 l i?,11';;l''' hasrecently been established as 8.la In this paperwe refer to 2. CO bis(cyclopentadienyl)titanium(lI), CplTi, as titanocene.This cxpcrimcnts.combined with resultsdescribed earlier, suggest r substancehas been well characterizedby Brintzinger.et al.l that the failurc of this procedureto providea generalroute In solution,titanocene is preponderantlydimeric and fairly from olefin to kctoneis due to poor yieldson trappingof tita- oC stableat room temperature.llHeating to 90 in toluene. noceneby olefin, rather than to a failure to producetitanocene | however.gives almost a quantitativeyield oi 8.1 Titanocene in the reductionor to unsatisfactorycarbonylation (Scheme may be generatedfrom its polymeric hydride (CpzTiH). or lV). Reactiveolefins (norborncne. benzonobornadiene) are its dimericdinitrogen complex (Cp:Ti):N:, but the prepara- ('onversion tions of thesecompounds are fairly difiicult and hazardous SchemelV. of Olefinsto C,vclopentanonesby' Reactionu'ith CprTi Equivalcnts sincethey arc pyrophoric.rrTwo-electron reduction of tita- nocenedichloride using Grignard rcagents,l5 sodium sand.i6 It'- I{ (r:('li. sodium naphthalenide,lTor electrochemicalreductionls ('p,Ti('l ------*"Cp.Ti" .------probably yieldstitanocene, but under the conditionsemployed it rearrangesto 8 or reactswith solvent.ll The most straightforward rationalizationfor production of cthylenefrom I is a pathway'of the type suggcstedby I - 6. It seemedpossible that this pathwav might be reversible-that ,ra): is. that ethylenemight react with titanoceneand form l. To test this possibility,a functional equivalentof titanocene, good Cp:TiN:TiCp,,lr was exposedto ethyleneat temperatures convertedin yieldsto ketones.based on titanium. Thus, between-78 and -30 oC (SchemeIII). Reactionof the re- the reductionof CplTiClz to CpzTi must proceedin satisfac- tory yields.Previous evidence indicated that carbonylationof SchemeIIl. Reactionof Ethyleneand "Titanocene" Generates I I to cyclopentanoncprocceded in goodyield, in agreementwith 1. CH3Li N2 the observationof high yieldsof ketonesfrom norborneneand (.p,TiCl, -_------) [Cp,TiHl, [CprTiN,TiCpr] benzonorbornadiene. Thus, carbonylationof the metallocycle, 2.H. onceformed, also takes place in goodyield. Hence,the yield- | determiningstep for product of ketonesis the reactionof ti- O I totuene"",-"", G tanocenewith olefinsand formation of metallocyclopentanes. \l-30"c The order oi yields-benzonorbornadiene) norbornene) Cn' .-1---tl ?l ethylene) 1.7-hexadiene-isthat expectedif coordinationof \-B' olefin to metal is important.l0 Y Although 1.7-octadienedoes not trap Cp2Ti generatedby 1\H reduction of CplTiCl2. it does react in low yield with \.t-,,H CplTiNlTiCp: (Scheme V). This observationprovides an sulting mixture with carbon monoxide,hydrochloric acid, or opportunityto checkon the rate at which metallocyclopentane bromineled to productscharacteristic of the I ,4-tetramethv- and diolefin-metalcomplex are in equilibrium.Both cis- and lenemoiety in yieldsof ca. l0 I 5olo.based on the [Cp2Ti]2N1 trans-1.2-di(lithiomethyl)cyclohexanereact with Cp2TiCl2 usedas a starting material.Although we were neversuccessful to givc (uncharacterized)metallocyclopentanes, which, in turn, in isolatinga pure sampleof I from the reactionof [Cp2Ti]:N: i'ield the corrcspondinghexahydroindanones in ca.20o/o yield with ethy'lene,the productionof moderateyields of products (basedon titanium) on carbonylation.The stereochemistryof characteristicof I stronglyimplicates it as an intermediatein the cyclohexanering is completelyretained in thesetransfor- thesereactions. It is, however,possible that other mono- or mations:no l4 is obtainedfrom I l, and no l2 is obtainedfrom dititanium organometallicspecies would showa similar pattern 13. Thus, ll and 13 do not equilibrateunder the reaction oC. of reactivty.and alternativestructures cannot presentlybe conditions(-20 I h). Reactionof 1,7-octadienewith excluded. CplTiNlTiCp3. followedby carbonylation,generates only 12,

McDermott, Wilson, Whitesides I Bis(ct'clopentadienvl)titanium(IV) Metallocvcles 6532

Table II. In Situ Fo rma tio n a nd C arb on vlat io n of \1 e t all o cv c lot.lt- It t ant- s{

RrTiCl. Olefin (equiv/eqtriv Ti) I)roducl \ ic.ldt1'l)b

Cp,TiCl, Irthl'lcnc (l) .i rl0; 1,1 ).1 Norbornene (t) ,-T 118),

rl0; 7-<

(:5 Bcnzonorbornadicnc ( I ) t6 )( \r,. j ' l-\ /- J/ (5) \ ., --r-- 9{) 1' ii 1l

( t\ 1.7-Octadienc 10) I Ftl

(C.Mc,)rTiCl. I.-th1'lcnc (l0) ( i clopctrIllrt()nr' rl 1l (CsN{c4l-t)rTiCl2 Fthl,lcnc (l0) ('l clopcntanotte B enzclnorbornadicrte (-5 ) l0 r) -f a All rcactionswcrc carriedout by rcducingthc titanium (lV) dichloridr'intolrrcrtr-u itlr a solrrtionot'Iithiurrt naphthalcnidc rrr Ill lt 't 40'C in tlre presenceof olet'in.l'All l'ieldsu'erc obtaincd b1'GL(- anall'sisusingilrtr' nra I stltntj ard tt-'clrnirlucs.ettcl arc bascdott ittttttttttt c Isolatcdyicld.

oC SchemeV. Reactionsot'\'letallon'cles Related to 1.7-Octadicne anglesto!'alucs far from the 0 that scenlsto be tlptimalfor metal hydrideelinrination decrcasss thermal dccomposition riites.Sccond. I is tnorc rcactivctoward carbon monoxidethan either diniethvlbis(clclopentadien)'l)titanium(lV)or 5: the thermalinstabiliti oi 3 precludesuscful direct comparison with l. The diff'ercncein rcactivit)'of I and 5 suggeststhat the five-mcmberedring lna\ be sufficicntlystrained to show cn- hancedrcactivitv in reactionsthat increasecoordinatittn of thc titanium centcr(e.g.. coordination of carbonmonoxide) and (presumabll')decrease the C Ti C angle.Third, thcrmal dcconrpositionol'l takcsplacc in part b-v"a rcactioninvolving curbon carbonbond clcavagc. This rcactionapparcntl) htts taY^r,r'p-l no unalogucin dccontpositionsof 3 or 5. Althoughthe oppor- L\-'V l tunitl lor thiscarbon carbonl'ragntcntation to compctc\\'ith 13 74('n%) 1i-hydrideclirnination undoubtcdly' arises in the cxceptional 1. Cp.TiN.TiCp, slorvncssol'thc lattcr.it is not clcarwhat l)ctors encouragcthc a" lirrnrcr.Thc tacitassur.nption that thc ntcchanisntsol-thesc t$o \-,-\ 2. CO Gor27r'r 12 rcactionslrre straightlbrw'ard docs not prcsentl\rcst in an\ (no detectable14 formed) dctailcdappreciation ol thcir course. Thus, although decont- positionol-l with fornrationof'l-butcne ntight take placcb1' y'ield(ca. 2ozn)following carbonylation. Thus how be it in low initial1l-hldridc clirlination. it rlight also.in principlc.occur the metallocycleforrned directly from olefin and titanoccne by initialrr-hldridc climination. I-oss ol'rr-hvdrogcn atotns t\ alsoshows no tendencyto equilibratecis and trans isomersof now wcll establishcdin organontctallicdcrivativcs tl1' ntetals the 1.2-disubstitutedcyclohcxane ring. Thermal decomposition on the lcft ol'thc transitionseries.ll and this tvpc of decttrtt- oi ll and l3 in the absenccof carbon monoxidedoes yield 1,7-octadienc()507o). The conclusionfrom theseexperiments HT T is that the carbon carbon bond breakingrequired to convcrt \A ('pri^ thesemetallocyclopentanc rings to 1,7-octadieneis a slow ('p.'fi. ('P ---+ l* Ti l- i \ -40 oC. \---l \v./ process,relative to carbonylationat HJ HJ Discussion positionmight ser\,'ct() crpllin the insensitivit\of'thc relltivc ratcsof produclionol-ethllcnc and butcncttl thc bulk oi sub- The reactivity of 1,4-tetramethylenebis(cyclopentadien- stituentson thc crclopcntadicnvlrings. Distinction bctrvccn yl)titanium( IV) (l ) differs in threecharacteristic ways from rv- rnd ^l-hldridcpaths ntust u'llit on furtlter cxpcritrlcntrtl that of di-n-butylbis(cyclopentadienyl)titanium(lV)(3). First. e','idcnce.frt'rrtlulatittn ol'thc productionof cthvlencfront I its I is much more stablethan 3 toward thermal decomposition. a straightforuurdrcductivc climinatit'rn reection is supported The observationthat 1,5-pentamethylenebis(cyclopentadi- b1't hc obscrvutit'rno1' thc rcversereactitln. ellsilv rat itlnaI i zcd enyl)titanium(lV) (5) sharessome of this stabilitywith I asun oridativclddition. This potentiallyuscf'ul rcactitln t1'pc suggeststhat the structuralfeatures that determinethe thernlal onl_vu'orks w'cll u'i1h rcltctivc olefins (ntlrborncne derivittivcs. stability of thesetitanium(lV) metallocyclesparallel those establishedfor related metallocyclicderivatives of bis(tri- IIC phenylphosphine)platinum(ll).3The high stabilityoi Pt(II) A ).t and Ti(lV) five- and six-memberedmetallocycles is compatiblc ('p,'fir : ['p,Ti'-'^\ \)) l-, cH with the hypothesisthat suppressionof the metal p-hydride v eliminationreaction on constrainingthe M-C-C-H dihedral H C'

JournaloJ'the American Chentical Societl' I 98:21f October13, 1976 6533

perature.the rcagenthad a uscfulliie of 3 -4 weeks.The concentration ethylene),and it is not evident how the system should be of "RLi" was I .2 N (90u/"vicld) with 0.02 N residualbase by dibro- nrodi[iedto increascits ratc. r0 moethancdoublc titration. (; LC analysisol'aliqutlts of the solution Theseresults possible establishthat it is to form titanocy- obtained from this organolithium reiigentfollowing reactionwith clopcntanesby oxidativecycloaddition of two olefinsand one dibromocthaneindicated that most of the Rt-i titer was presentas titaniumatom. lt remainsto beestablished whether this path dilirhium reagcnt.Cvclobutane was the principalby'-product of the is conrmonor extraordinaryin transitionmetal catalysis.Re- reaction.along with smalleramounts of butaneand butene.No eth- latedstoichiometric reactions have been observed previously r lcnc wusobscrvcd. Much lcsssatisfactory' results were obtirined using in reactionsbetrveen other metalsand reactiveolefins.rl but cithcr ltlrv-sodiurnlithium or 1.4-dibromobutane. the possibleintermediacy of metallocyclicspecies in useful l.-5-Dilithiopcnt:lnewas preparedin an analogousmanner in 8-5o/o catalytic proccsseshas not beeninvestigated. Three tlpes of r reld. 1.4-Tetramethvlenebis(cvclopentadienyl)titanium(lV)( l ). A sus- reactionsparticularll' w'arrant attention. First. the varietl'of pensionol'('p'Ti(-l- (0.50g: 2.0mmol)was rapidly'stirredin 20 ml reactionsin ivhich transitionmetals catalyzethe conversion ot'dicthrlcthcrlt -7lt oC \ solutionoi 1.4-dilithiobutane(2.1mmol) ol'cthi,leneto l-buteneare presently'believedto involvemetal in cthcr uus uddedrrrpidlr bl slringe.Thc solutionwas gradualll hydridesas intermcdiates.lrAlthough this formulation is urrrrncdwith rigorousstirring to -45 oC and maintainedat this HC tcnrpcralurcuntil all thc dichloridchad dissolved ( 1.5 h). Methanol \Et- (-s0gl) uus addcdto dcstrol cxccssalkvllithium reagent. Removal cH, (-].r --10 / /"' " _-H'"> /E ol'thcsolvent lt "('(0.05 Torr) lcft a red-brownresiduc which II -----) \l *>. uith hcxancat -40 oC to givean orange- u'rrstrituratcd l0 rnl of H brou'nsolution. Thc crtrlct u'asthcn lransfcrrcdby cannulato a dr\ HC 5-cnrcolumn ol'alumina (Woelm, activity grade l) which had bcen EtEt thoroughlr I'lushedrvith urgon. This coluntn wrls providedu'ith a ------) .=+l jackct. -.10 oC. wastrituratcd NI cooling and nraintainedat The residue --., uith two lurther -:-nrlaliquots of'hexane, and thescwere alst-r trans- I'errcdto thc column.Thc column lr'aselutcd with hcxane(pentanc. M-H oC) 1.2.'l-trinrethrlpcntane(isooctane). and CFCITCFTCI(mp -37 ccrtainlv correct in manv instances. formation and decompo- u cre alsosirtishctorl clutingsolvcnts for thc chromatography).and sition of a nietallocyclopentane may be involved in others. a brightonlngc bundwus collccted as it clutcd.Cooling the resulting -7lJ oC Second. the steps involved in initiation of olefin polymerization. dirrk orange-rcdsolution to gavedark orangcncedles which -30 oC. particularly with discolorcdif u'armcd ubo','c Thc solutionshowcd no dc- heterogeneous cat:rlysts. remain unclear.:a oC. compositionul'tcr,1l( h at -71{ (-ompclundI has a sharpsinglct Irormation and decomposition of a surface metallocl'clopen- oC) rn thc \MR spcclrum(60 \{Hz: 0 at 6 6.20when dissolved in tane rvould provide a method of generating either me tal h_v-- ('FC'lrCF.Cl. Thc nrcthvlcncregion was obscured b1' residual traces dride or mctal alkyl centers dircctly from olefins. Third, it is ol'ctherund hcrrrne.tithc slrmplcu'as allowcd tostand at 0'C.light possible to writc mechanisms for olefin metathesis that involve tun solrdsprccipitatcd from solutit'rnand the NMR singletdecrcased rnetallocyclic intermcdiatcs.l5 Although current attention is to hall'rtsoriginal valuc in 0.-5h. focused on the probablc intermediacy of metal-carbene The thcrmaland oxrdativeinstabilit,v- of I precludedmicroanalysis. complexes in these reactions.l6 at least onc reaction. probabll,' Instead.it was possiblcto cstimatc the ratio of Cp:Ti to 1.4-tetra- involving an internrediatetungsten metallocycle. has y'ielded nrcthylenemoietics b1 examining the products derivcd from l. results of the tvpe expected for metathesis.l5 In the work re- Treatnrentof a CI"('lrCFrCl solutionof I with bromine,followed b1 (il-C' anallsis.pcrmitted an cstimationof the quantit;"of 1,4-dibro- ported here, eramination of thc reactions of 1.7-octadienewith oC. mobutaneformed: cooling thc solutionto -20 separatingthe dark titanocenc showcd no suggcstion of metathesis-likc rear- red prccipitatcbv l'iltration.and washingit with cold hexaneisolated rangements of thc carbon skelcton.Titanium is not, however, thc CprTiBrl (characterizcdb.v decomposition temperaturc and N MR a component of activc mctathcsis catalysts.l' (CDCllr)D 6.70 (s). with no detectableimpurities). The molar ratitr ol'thcscnrute riuls w'as 1.,1-CallxBr,.:Cp.TiBrl = 1.2:1.0.Similarly. Experimental Section lirllouing trcirtnrcntrvith unhvdrousHCll. analvsislor butanc and (ieneral l\Iethods.AII rcactionsinvolving organonretalliccom- Cp.'Ii(-11(churitctcrizcd b1 decompositiontemperature and NMR poundswere carricd out under u'eldinggrade argon usingstandard (C DC'lr) 6 6.-i7(s) with no dclcctableimpurities) gavc the ratio tcchniqucsfirr handlingair-scnsrtivc compounds.ls':q Diethr I ether ('111111:('plTi('1.= L0:1.0. Carbonvlation of a solutionol I in wasdistilled from lithiumaluminum hydridc. Toluenc und 2.1,4-tri- C lr('l:('t'1Cl br allowingthc solutionto warm to ambicnt from -'10 mcthl lpentane\\,ere distille d f'romcalcium hrdride after rcl'luxing o('over scvcralhours undcr I atnt ol'CO y'ieldedcvclopcntanonc ior ll h. Pcntancand hcranc u'creu'ashed {'ree of'olel'ins with con- (0 8 0.9 cquir'.bascd tln thc rtssumptionthat thc reactionof I with centratedsull'uric acid and distillcd l'rom a suspensionol'sodium llr. r icldingI .-1-dibromr)butaneis quantitative). bcnzophcnoncketll. Tetrahvdrol'uranr,''as distillcd lronr a solution Di-n-butylbis{cyclopentadienyl)titanium(lV)(3). A suspcnsionol' ol-sodiumbenzophenonc diunion. .{ll distillationsuerc curricdout Cp.TiCll (0.50g: 1.0 mntol) u'asrapidh stirredin ,5nrl of dieth-v-lether undcrargon. CFTCIC-FCll was purged with argonor degasscdundcr at -7u oC. A solutionof n-butyllithium(2.0 mmol) in etherwas added oC high vacuum bef'orcuse. NMR spectrawcre run on Varian T-60 or rapidly by's1ringc.itnd stirringwas continuedat -78 for I h. t{itachi Perkin-[:lmerR20B (60 MHz) and R22 (90 MHz) spec- Methanol (,50gl) was in.iectedto destroyany unreactedlithium re- oC tr()meters.Inl'rared spcctra were nreasured u'ith a Perkin-ElmcrModcl agent.Removal of the solventat -7il (0.01 Torr) for 2 h lef'tan -167instrunlcnt. Standard. tightlv stoppcrcd.sodium chloridc solution ()rangesludgc. Thc product rvas chromatographed by a procedure ir cellsprovcd satisl'actorl lirr air-scnsitivccompounds rf thc spectra Irnulogous1o thrrl usedlitr I uith isottctaneas the elutingsolvent while oC. were taken pronrptlr. GLC'anall,scsvv'cre pcrformed on a Perkin- nrrrintrriningthc columnat -70 to -7lJ A clcarorange solution F:lnrcr\lodcl 990 instrunrcnt.equipped uith a flame ionizationde- urrsobtaincd. and rrlthoughit readilrdecontposed to a tan prccipitatc tector.Di*clopentadienr ltitaniunr dichloridc wasobtained front Alfa rrt --5()o(-. nt'rchrtngc in uppeantnce had occurredaf'ter standing for Inorgunicsand useduithout furtherpurification. F.thilene u'as ob- 1.1h at -7lJ o('. taincd tronr Mirthcson(C. P. gradc).Other chemicals\r'ere reagcnt l-hc lhcrnrrllnd oxidativcinstabilitl'of'3 necessitated its charac- grade and uscd u,ithoutl'urther purification. I iquid reagentsto be lcrizlrtionthrough its rertctittnproducts. Treatment of thc isooctanc addcdto air-sensitivcsolutitlns \\'ere l'i rst purgedrvith argon. :olutionol'3 with brorninc.follow'cd bl (it-C analvsis.pcrmittcd an 1.4-I)ilithiobutaneand 1,5-f)ilithiopentane.A solutittn ol' I ..1-di- cstirnrrliono1' thc quuntrtr ol' l-brttmobutltnelormcd: the dark rccl ehlonrbutanc(11.0 ml:0.10 nrol) in -i0ntl ot'dicthrlether was addcd prccipitltcol'( p.Tillr. u,tsscparatcd br'l'iltratittn and washedwith rndrops ovcr a pcriodof'I h to I00 nrlof'cthercontaining 3.8 g (0.,10 pcntanc:its \\'lR spcctrttm(CD( 1r)shtlwcda singlctat A 6.70.and ll()l)ol lithium (l()r,\ir) u'irelrt 0'('. Thc reactjonu,as stirrcd at 0 inrpuritics{-i l0'\') i 1.0 I 6. Thc tttolarratio of'lhcsc matcriills urtr o(- -Ihc lirr l-l h solutionwas I'rcedof'suspendcd solids br ccntrilu- (;ll,rBr.('plTrllr. - 1.9:1.0Similarlr. tbilowing trcatmcnt urlh qutronrlnd stored tn a Schlcnktube at -10 "C. lf keptitt this tcnr- ;rnhrdrousll('l.lnulrsis lur butuneand Cp.l-iCl. (\\{R (('l)('l'i

,llt'Derntott.LVil.son, Whiteside.\ f Bist('rclopentadienylttitanium(lV'tMetallo('l'r'/t'r 6534

6 6.-57(s). no detectableimpurities) yielded the ratio CqlJl6:CpzTiC ll Thc liclds of hrdrocarbonsfound in theseerpcriments are sum- = 2.0:1.0.Attempts to carbonylate3 gaveless than 0.01equiv of di- marizcdin Tablc I butyl ketoneby GLC analysisowing to thc rapid decompositionof 3 Reaction of ('p2-l'i\le2 with ('arhon \{onoxide. A 0.1 M solution oC). at normal carbonylationtemperatures (-50 of CplTiNlcl rn CI'.CICF('lr \\'irSstirrcd at l5 oC under l0 atnrof' 1,5-Pentamethylenebis(cyclopentadienyl)titanium(l\')(5) was pre- CO. At intcn'rrlsthc solutionu'as cranrincd b1' \ \{R. Thc spcctrunr parcd bv a procedurcanalogous to that usedfor l, substitutingl.-i- o1'Cp.Ti \{cr ((- F-('l(' [r('11). /t6. I 0 (s. I 0 H ). 0.0] (s.6 ll ). rvasob- dilithiopcntanefor 1.4-dilithiobutanc.Column chromatographrusrng servcdto dcclinconlr slightlr al'1erscvcnrl hours. \o cvidcncclor rn CFCITCFTCIor isooctaneas elutingsolvents gave a dark orangeso- acllcornplcxcould bc foundill an\ trnrc.,Atltlwcr tcmpcratures no oC lution.After standingfor 30 min at -45 a smallamountof yellou obscrvablcrclrc:tion took placc. prccipitatehad fbrmed.Bromine and HCI clucnchcsof thescsolutions Isolationof 2 in the ('arbonr'lationof l. ,,\ pcntancsolution ol'l (0.8 gavethc ratiosl.-5-CsH 168r1/CplTiBr. = 0.7and C.tl11/CplTi( l1 nrrnolbr Br-.qucnch) *as stirrcd lbr I h undcr I rrtrl ol'carbon = 1.5.Both of the isolatedtitanocene products had decomposition nronoxidcat -55 "C. ,\ rcllou-br,rwnsolid scparated lronr solution. pointsthat wcre lowerand broader than authcnticsamplcs. Clarbon- Thc solid \\'lrs\\lshcd ()nce\\'ith cold pentanc.thcn dissolvcdin a o('. 1'lationol'solutions of'5 gaveless than a l9oyicld of'cy"clohexanonc nrinimumunrount of ttllucncat 0 Pcntanculrs addcdsloulv until b1'Gt-C analysis. a slightcloudincss pcrsisted. A 1'cllorvsolid crrstallized w'hen the ro- I -Methyl- 1,4-tetramethvlenebis(cyclopentadienyl )titanium( I\' ) (4 ) lution u'ussloulv coolcdto -60 o('. Aftcr 2 h thc solutionu'as dis- was preparedby a procedureanalogous to that usedfor l, substituting cardedund thc solidu'ushcd riith pcntancund dricd undcr a strerlnr I .4-dilithiopentane for I .4-dilithiobutanc.Col u rnn chrornatographl of'argonat 0 o('. riclding0.16 g (7-5t',,'1ol2: NMR (('[).C1,)r)6.]5 using isooctaneas eluting solventgave an orange-brou'nsolution that (s.l0 H. Cp).1.5 1.0(nr.8 tJ. (( tl:)+).\n irspcctrunrof thcsanrc oC. slowly decomposedat -4,5 Brominc and HCI quenchcsol thc solutionhud it strongband at l7l0 cm-r rrhichgraduallr disappearcd solutiongave 1,4-dibromopentancand pentanc.respcctively. but thc at l-5"('to bc rcpluccclbr a broadband ccntcrcd ut 17.10crn-r.'I'hc reactionswere not cleanand the resultingtitanocene products were carbonrl bandol'cvclopentanonc is at l7;1-5cnr-'r. The Cp resonancc verv impure. et 6.15disappclrcd ut a similarratc and a half-lit'c ol'l5 min al J5 oC Carbonylationsof l, 3, and 5. Chromatographedsolutions of thesc can bc cstimrrted.,\nalrsis ol'the resullunt solution b1 Gt-C show'cd compounds(ca. 0.02 M) wcrc prcparedas described abovc. They,werc crclopcntunoneto bc prcscnt.Solid 2 decomposcdcomplctclv whcn oC stirredunder I atm o{'CO at -50 and allowedto warm to room lcl'tlrt l5 o( lirr l-1 h. In solution2 is crtrclnclr scnsilivcto ox\- temperatureover several hours rvith stirring.Yie ids of'ketone products 8cn were determinedby GI-C analysisusing intcrnal standardtechniques. l('p2TiH|. \4rrsprcparcd br thc proccdurcof Brintzingcrct al.r1 I yielded0.8 0.9 equivof cyclopentanone,while 3 and 5 gaveless than ( pzTiNzt'i(p2 wrs prcparedb1' stirring a tolucneor dicthl"lether -20 0.01 equivof dibutyl ketoneand cyclohexanone,respectivell. solulionol' [('p.Till l , under nitrogcnat "C fbr scvcralhours. " 1,4-Tetramethylenebis(cyclopentadieny- | )zi rconi um (I \' | \\'as prc- ln gcnenrl. It-p.Til. und its hldridc precursorrnust be handledunde r pared and chromatographedbv ii procedureanalogous to that used rigorouslrO..-f'rce conditions l'or thc rcactionsto succeed.i\s prc- for I substitutingCplZrCll (0.58g; 2.0 mmol) for Cp:TiCl1. Chro- viouslrrcportcd.rr thc hldridc is plrophoric.Onc sarnplcignitcd rn matographingthc ycllow reactionmixture with CFCIzCFICl gavc rr llusk duc to ir snllll lir lclrk.No problcmsw'erc encountercd u'itlr a clear,colorless solution that wasca.0.02 M in product.\l'arming thc rcsiducsof'the rcactionsrcportcd hcrc. but cuution is rccon.r- the solutionto room temperaturercsulted in a white precipitateand rrrcrrdedu il h :rl l rcltctions i nr trlr i ng ()rg:ln()titir n()ccnc \pccic\. a hvdrocarbonmixture containing l59oe thllenc and 85oznbutenes. Reaction of l('p2f i12 with Eth-v-lene.Thc gra\-grcen hrdridc oC-- Thermolvsisol'the chromatographcdsolution at 250 gavc 30,2n (Cp.Till), rr (107nrg:0.60 mmol)was stirred in tolucncut -78 o( . ethyleneand 709i,butcnes. Bromination gavc I ..1-dibromobutane.but f:thr'lcnc(l-i nrl:1.2 mmol)wasadded by slringeandthesolution uus the Cp2ZrBr2could not bc isolated.Treatment with anhy'drousHCI wrrrrlcdto -.15 oC. The soliddissolvcd as thc reactionwas stirrcd lirr gavebutaneandCp2ZrClz (isolated by filtrationsmp219 240'C). -1h at this tcnrpcrature.The argon atmosphcrerr'as rcplaccd b_r'onc but the rcactionwas not cleancnough to obtain a ratio of butaneto ol'carbonnronoxidc. and thc reaction nrixturewas allowed to $'ann Cp2ZrCl2.Carbony'lation of solutionsof CplZr(CH:).r beforechro- t()r(x)ll tcnrpcrrrturcov'e r sevcralhours. Aftcr l2 h a l2%ryield (birsecl matographl-gave onlv a 2ozn)'icld of cvclopcntanone. on (('plTiH), )of'cvcl()pcntanoncwas dctectcd in solutionb1 Cil (' Thermal Decompositionof l. 3, 4, 5. and Cp2Zr{CH2)r.Chroma- ll'rrnI{(-l qucnchuus substitutcdlbr thecarbon monoxide. u sintilrrr tographedsolutions of thcsc compoundswere prcparedas described r icldol' butlrnc w as obtaincd. oC above.They weredecomposcd at 250 b)' injectingsaniples of thc Reactionof ('p2'I'iN2'tiCpzwith t-thvlene.A dark-bluc solutionol' cold solutionsdircctlf into thc gas chromatograph.Pentane and ('p.Ti\.TiC'p. \\,aspreparcdlr f'rorn I nrnrolol'(Cp:TiH), and l5 hexanewere used as internal standardsto detcrmine the product rnl ol'tolucncor cthvl cthcr.F.thrlcnc (-50 nrl. 2 mmol) wasintroduccd balance(80 95ol")and yieldsol-hvdrocarbons. Solutions of I wcrc rrt -7lJ oC al'tcrthc nitrogcnatmosphere had becn replacedb1' argon. oC decomposedat 0 and -20 b)'iitting the tubeswith new scrunr T'hcreuction uas allowcdttt u'arm to -30 oC u'hcreuponit changcd oC oC stoppersand storingthem at 0 for severalhours and at -20 for to u grccn-brou'ncolor. Alier I h. aliquotslvcrc allowcd to reactwith severaldays. Subsequent analvses gavc thc sameresults, indicating tl(-1. CO. and Br; l-or(il.C analysis.Butanc, cyclopentanonc. and oC complctedecomposition. The sampleswe rc coolcdto -40 before 1."1-dibronrobutanc\\'crc obtarned in l0 l-s?, y'ield bascd on GLC analysis.and the productbalanccs wcre within l0o/oof that for (('p:TiH ),. Thc brominequcnch was not usedin toluenebccausc thc the 250 "C decomposition.The data obtainedin thesedecompositions rctcntiontimcs of 1.4-dibronrobulaneand benzy'lbromidearc slmr- are sunrmarizedin Tablc L |ltr. Thermal f)ecompositionof (CsMes)Ti(CH2)a.Bis ( pentamcthylcl - Reductionof ('p2l'i( l2 with Lithium Naphthalenidein the Presence r.-rI clopentadienyl)titanium( IV) dichloridcr 197mg: 0.25 mmol) was of llthvlene.,,\ solutiono{' lithium naphthalcnidewas preparedbr oC. slurried in 3 ml of ethyl cther at -7ll A solutionof 1,4-dili- stirringa I M solutionoi naphthalcncin tctrahvdrol'uranwith a slight thiobutane(0.28 rnmol) in ethcr was addedrapidly by syringe.The exccss ol lithrurnw ire. During the first hour the exothermicrcaction oC mixture was gradually warmed to -rl5 with stirring and main- u,ascoolcd occasionalll' with an ice bath to maintain the tenrperaturc tainedat this tempcraturelbr I h, giving an orange-brownsolution. at 1.5o(- or bclow.Al'ter f-ivc additional hours, the titer,typicalll l.T Methanol (50 pl) was injectedto destroythe excesslithium rcagcnt. M. u'asdctcrmrncdrl br quenchingan aliquot with deoxygenated Removingthc solventat -40'C (0.1 Torr) and triturating the re- \\'atcrirnd titrating with standardl-lCl. sulting brown solidswith 3 ml ol CFCITCFICI gavea dark orangc Bis(clclopcntadicnl'l)titaniumdichloridc (0.2-5 g: 1.0mmol) u'as solution.Samples oi thc cold solutionwere injccteddirectly into the suspcndcdin l5 nrl ol-tolucncat --50 oC by rapid stirring under an oC. gaschromatograph to dccomposeat 250 The reactiontube was cthllencatmospherc. l-ithium naphthalenide (2. I mmol) w:rsaddcd oC then fittcd with a ncw serumstopper and storedat 0 for several in dropsover I 5 nrin. Most of thc CpzTiCl: dissolvedduring thrspc- hours and the decompositionwas judgcd complete when two successrve riod.Thc rernainderdissolvcd during an additional30 min of stirring analysesgave the snmercsult. The sampleswere cooled to -40 "C for at -'10 oC. The ethvlencatmospherc u'as rcplaced by carbonmon- GLC analysis,and no significantloss of gascsu,as observed. The oxidc und thc reactionnrirturc was allowcd to warm to roonrtcm- ethylene to butene rertiowas unal'fectedby chromatographing thc pcratureovcr 4 5 h. ,Al'ter6 h at 25 oC,0.17mmol of'cyclopcntanonc solutionthrough alumina. $as prcscnt.A more prolongedreaction at -s0oC did not increasethe (CsMeqL,t):Ti(CH:)+was prepared and decomposedby thc same f ield. procedurefrom (CsMcaEt )2TiCl2. Reductionof Cp2TiCl2in the Presenceof Norbornene.Bis(cyclo-

Journalof theAmerican Chemical Society / 9S:21/ October13, 1976 6535 pcntadien)'l)titaniunrdichloride (0.2,5 g; 1.0rnmol) and norbornene Reactionof ICp2Til2with 1,7-Octadiene.This reactionwas carried (0.20g; 2.I rnnrol)wcrc stirrcd in l0 nrlof tolueneat -50 "C. Lithium ou1using (Cp:Titl). ( t07 mg. 0.60nrmol) and 1.7-octadiene(0.1 I naphthalenide(1.2 ml of a 1.7M solution)was added dropwisc ovcr ml.0.72 mmol) in toluene.using a procedureanalogous to that dc- oCl. l5 nrinand the reactionwils warmed to -30 After 30 min of ad- scribcdfor thc rcactionof ICp.Ti]l rvithethvlene. Thc only identified ditionalstirring thc solutionwas carbony'lated by allowingit to warm ketonicproduct \rAs /ran.r-herahydroindan-2-one (12). ir 1742cm-r: slow'ly'tol5 oC under I atm of CO. Onll'one productwas dctected the cis-isonrerl4 and hcrahl'droindan-l-one could not be detected br G l-C u ith the samerctcntion time asthc ketonedimer 9 produced in thc Gl-C tracc. and. if prescnt,u'erc formed in lields lcssthan in thc rcaction of norbornencwith Fe(CO)s.rr A, 24o,/"y-ield was 0.59,i,. rncasuredusing octadecane as an internalstandard. Pcnlane (-10 ml) Reductionsof zirconocenedichloride in the presenceof ethyleneand u'asadded and thc reactionmixturc shaken in air wrth I M HCI until norbornenewere conducted in a fashion analogousto thoseof tita- thc rcd color had dischargedand no more solidsprecipitated. Aftcr noccnedichloride. Ethylene gave onlv lolocyclopentanone. The vield f iltratirrn.the solutionwas dricd ovcr NalSOa. Removingthe solvcnt oi the kctonedinrer was -5o/owith a stoichiometricamount of norbor- yields at rcduccdpressure left a -v-ellowoil, which subscqucntlysolidiiied. ncne and 8o/owhen a tenfold excesswas used.These are based Thc kctoncdimcr 9 was isolatedb1 preparativeTl-C on silicagelon on CpzZrCll. clutionu'ith hcxanc:cth)l acetale (9,l ). The purccompound u'as the Acknowledgment. This work was supported by the National c\().trans.cxokctonc dimer:tr NMR (CDCllr)r)2.-l-5 and l.l6 (m. -1 tJ. bridgchead).1.9-l and 1.70(d. 4 H. ./ = l.5llz. clclopcntanone). ScienceFoundation. Grant MPS 74-20946. l.-i l.l (nr.ttIl. CH.Cltr ). 1.0.1(m,'1 H.bridge). Nlassspectral Referencesand Notes lnulrsisgavc a parention at nl/e I16. [. sc ol a tcnfoldcxcess ol' norborncnc(2. I g. 2 I rnnrol,)in conditions (1) John A. LyonsFellow, 1972-1974. (2) P Davidson,M. F. Lappert,and R. Pearce, Acc. Chem. Res.,7,2Q9 :inrilur 1othose reportcd abovc pr.oduced a yicld of'ketoncdinrcr of' J. (1974); Rev (1976); M. C. Baird, J. Organomet.Chem.. ?5',i,. Chem. .76,219 bescdon C'p1TiCl..Whcn thc rcactionsolution was heatedto 64. 289 (1974\: P. S. Braterman and R. J. Cross. Chem. Soc., Rev., 2, 27 1 75 o(' lirr l-5h under carbon monoxidc.no incrcascin the lield of (1973);R. R. Schrock and G. W. Parshall,Chem. Rev., 76, 243 fi976]'. kctttncu lrstrbscrr cd (3) J. X. McDermott. J. F. White, and G. M. Whitesides, J. Am. Chem. Soc.. 95, 4451 (1973), ibid. preceding paper in this issue. Reductionof ('p2'IiCl2 with Lithium Naphthalenidein the Presence (4) Preliminary report: J. X. McDermott and G. M. Whitesides, J. Am. Chem. of Benzonorbornadiene.Benzonorbornadicncl+ (0.1a g. 1.0 mmol). Soc., 96,947 (1974\. ( (0 (90 (5) K. Clauss and H. Bestian,Justus Liebigs Ann. Chem.,654, 8 (1962). plTiCll l3 g:0.-50nrnrol), and CtJr(Ctl-')r6CHr mg.GLC ''Organometallic intcrnalstrrndard)wcrc dissolved in ca. l0 ml oidry tolueneunder (6) P. C Wailes,R. S. P. Coutts,and H. Weigold, Chemistry -40 o('and of Titanium.Zirconium, and Hafnium", Academic Press,New York, N.Y.. rrrg()n.Thc mixture was cooledto a THF solutionof 1974. lithium naphthalenide( I . I mmol) wasadded slowly by syringc.After (7) G. M. Whitesides, J F. Gaasch, and E R. Stedronsky, J. Am. Chem. Soc., stirring for I h at -40 oC. the argonatmosphere was replacedwith 94. 5258 (1972\. "Homogeneous New York, N.Y., carbonmonoxide. and the reactionmixture was allowedto warm to (B) B. R. James, Hydrogenation",Wiley, 1974. room tcmpcratureover several hours. The mixture wasanalyzed by (9) G. Fachinetti and C. Floriani, J. Organomet. Chem., 71, C5 (1974\. GLC. Removal of the solvent and preparativeTLC (silica gel, (10) A qualitativetheoretical discussion of this problem is presentedby Hoft lEtOAc:9hexane) afforded a fraction with R7 0.32 0.44. Recry's- mann. (11) J. E. Bercaw. R. H. Marvich,L. G. Bell, and H. H. Brintzinger,J. Am. Chem. tallization from ether gave a white powder identifiedas the exo. (1972). oC 9oc.,94,1219 trans,cxodimer (41 mg; 260/o)on the basisof mp 224-225 (lit.t+ (12) H. H. Brintzingerand J E. Bercaw,J. Am. Chem. Soc., 92, 6182 mp223 224"C\:ir 1725cm-t (lit.t+ll22cm-r), NMR (CCll) D (1970) (13) F N. Tebbe. Am Soc.. 95. 7870 1.60(m, 4 H).2.13(d. / = tl HZ= 2H\.215 (d, = 8H2.2 H). 3.35 L. J. Guggenbergerand J. Chem. "r (1973). (s,2 H),3.53(s.2 H).7.10(m.8 H). Theyieldof thisketone in the (14) A. Davisonand S. Wreford, J. Am. Chem. Soc., 96, 3017 (1974). rcaction mixture beforeworkup was determined to be 48o/oby GLC. (15) (a) K. Shikata, K. Nishino, K Azuma, and Y. Takegami, Kogyo Kagaku Repetition of the experimentusing a fivefold excessof benzonorbor- Zasshi. 68. 358 (1965);(b) M. E. Vol'pin and V. B. Shur. Nature(London\, ( nadieneraised the yield to ca. 909o. 209. 1236 1966). (16) J J. Salzman and P. Mosimann,Helv. Chim. Acta, 50' 1831 (1967). trans-I,2-Bis(chloromethyl)cy-clohexane.In a flame-dried flask (17) G. W. Watt, L. J. Baye, and F O. Drummond,Jr', J Am Chem. Soc., 88, under nitrogcn was placedtrans- 1,2-bis(hydroxymethyl)c_r-'clohex- 1138 (1966) aners16.2 g. 50 mmol) and 50 nrl of rcagcntcarbon tetrachloride. (18) R E. Dessy, R B King, and M. Waldrop, J. Am. Chem. Soc.. 88' 5.112 Tri-n-butylphosphine(32 g. ll0 mmol) was addedover a 4-5-min (1966). (19) E. E. Van Tamelen, W Cretney,N. Klaentschi,and J. S. Miller, J' Chem. periodwith solutionwas stirringat room temperature.The rcfluxed Soc.. Chem. Commun., 481 (1972\; T. J. Katz and N. Acton, Tetrahedron ,]r970\: for 1,5h. Examinationof the resultingreaction mixture by'NMR Lett.,28,2a97 E. E. Van Tamelen et al., J. Am. Chem. Soc.' 91. showedno residualOH absorption.A flashdistillation followed by' 1551(1969) (20) A. Bennett,Chem. Rev.,62,611 (1962);R.Jones, ibid.,68,785 (1968); a fractionaldistillation afforded 3.8 g (4lulo)of thc transdichloride: M. F. R. Hartley,ibid.. 69,799 (1969). -120'C:densitl, bp (l5 Torr) l.l.l g/ml: N\,{R (CDClr)6 3.62(m, (21) R. R. Schrock, J. Am. Chem Soc., 96, 6796 (1974);A. Sanders elal.' ibid.' 4 H). I .0 2.2(m, l0 H) GLC analysissuggcstcd that thismateriil 95, 5430 (1973); N. J. Cooper and M L. H. Green, J. Chem- Soc.. Chem. was )9tio./oone component. Commun.,761 (1974\; A S. Khachaturov,L. S. Bresler,and l. Y. Poddubnyi' Chem., 42, C18 (1972]t.L. J. Guggenberger and R. R cis- 1,2-Bis(chloromethyl)cyclohexanewas preparedusing a similar J. Organometat. Am. Chem.9oc.,97,6578 (1975). -ll2 oC;density Schrock,J. proccdurc.bp (l-sTorr) l.l4g/ml:NMR (CDClr) (221 M. A. Bennett,R. N. Johnson,and l. B. Tomkins, J. Am. Chem. Soc., 96' r)-1 -50 (d,4 H), 1.0 2.4(m. l0 FI). 61 (1974);N Acton etal . ibid.,94,5446 (1972);A. R. Fraser etal.' ibid.. 1,2-Bis(lithiomethyl)cyclohexanone.This cis and trans dilithium 95, 597 (1973);R Noyori.Y. Kumagai,and H. Takaya, ibid.' 96' 634 (1974); l. J. Harvieand F. J. McQuillin,J. Chem. Soc., Chem. Commun',806 (197a); rcagentswere prepared in diethylether using a procedureanalogous F. W. Grevels, D. Schulz, and E. Koerner von Gustor, Angew. Chem'. lnt. to that for the preparationof 1.4-dilithiobutane,except that high- Ed. Engl.. 13,534 (1974); G. Fachinettiand D. Floriani,J. Chem. Soc., sodium (loloNa) lithiurn dispersion(Foote Mineral Co.) u'asuscd Chem. Commun., 66 (1974\. (23) (1974);R. insteadof lithium wire. Typical yields for convcrsionof CHzCI to E. L. Muettertiesand J. C. Sauer,J. Am. Chem- Soc., 96, 3411 Cramer, Acc. Chem. Res.' 1,186 (1968);G. wilke etal.' Angew' Chem', groups were CHrl-i -50o/o. tnt.Ed Engt..5, 151 (1966);C. A. Tolman. J' Am' Chem' Soc , 92,6777 Preparation and Carbonylation of I l. Bis(cyclopentadienyl)tita- (1970);M. G. Barlow et al., J. Organomet.Chem., 21' 215 (1970). nium dichloridc(0.13 g: 0.50nrmol) was stirred in l0 ml of ctherat (24\ A. Zecchina, E. Garrone, G. Ghiotti, C. Morterra, and E. Borello' J' Phys. oC, (1975):J Boor, Macromol.Rev 115(1967);D. C -78 and trans-1,2-bis(lithiomethyl)cyclohexane (0.5-5 mmol) Chem.,79, 966 Jr.' ,2. H. Ballard,Adv. Cata\.,23,263 (1973);T. Keri, "Kinetics of Ziegler-Natta .1973 in cthcr u'asadded by syringe.The mixture rvasstirred for -5h with Polymerization",Halsted Press, New York, N.Y., oC slow rvarmingto -20 to givc a dark orangesolution. Thermoll,sis (25) R. H. Grubbsand T K. Brunck, J. Am. Chem. 9oc.,94, 2538 (1972\. of an aliquotby injectioninto the inletof the G[-C at 250'C gavea (26) C. P. Casey and T. J. Burkhardt,J. Am. Chem. Soc ,96, 7808 (1974);T. McGinnis,ibid.,97, 1592 (1975);R. H. Grubbs,P. L. Burk' substantialamount of 1.7-octadiene.The solutionwas coolcd to -50 J. Katz and J. o(.. and D. D. Carr, ibid.97,3265 (1975);E.L. Muetteflies,lnorg- Chem.' 14' placedunder an atmosphercof CO. and allowcdto warm to room 951 (1975):J. L. Herissonand Y. Chauvin, Makromol Chem., 141' 161 temperaturcover scveralhours. GLC analysisusing tetradecane as (1970). an internalstandard gavc a 20olovield (basedon Ti) of isomerically' (27) J. C. Mol and J. A. Moulyn.Adv. Catal., 24, 131 (1975):W. B. Hughes' Or- ganomet. Chem. Synth.. 1,341 (1972): M. L. Khidekel', A. D. Shebaldova, purc /rdn.f-hexahydroindan-2-one (9).16 Compound l3 wasprepared and l V. Kalechits, Russ.Chem. Rev, 40,669 (1971);N. Calderon,Acc. and carbonylated by'the same proccdurc to give a 209,i,I'ield of cr.l- Chem. Res . 5, 127 (1972\ 1t' hcrahl droindan-l-,-rnc ( | -1). (28) H. C. Brown, G. W Kramer. A. B. Levy. and M. M. Midland'"Organic Syn-

Mt'Dernrott, Wilsctn,Whitesides I Bi,s(t't'clopentadienyl)titanium(lV'ih[etalloci t /*'.t 6536

thesesvia , Wiley, New York, N.Y., 1975. (32) S Bankand B. Bockalh. J. Am Chem.Soc.,93, 430 (1971I S. Bankand (29) D. F. Shriver, TheNtanipulation ol ai-SensitiveCompounds , Mccraw-Hilt. I Bochrath.lDtd., 94, 6076 (1972) New York, N-Y.. 1969,Chapter T. (33) J. Manlzarisand E Weissberger,J. Am. Ch€m.Soc.. 96, 1873(1974). {30) G. M. Whitesides,C. P. Casey,and J. K. Kfiege\ J. An. Chem. Soc.,93, (34) G Wittigand E Knauss,Chem- Be., 91, 895 ( 1958) 1379(1971). (35) G A Haggisand L. N.Owen, J. Chem.Soc., 389 (1953). (31) D. Feitlerand G. M. Whitesides,/rol9. Chem., 15, 466 ( 1976). (36) H. Shechterand D K B'ain'.J. Am Chem.Soc., 85, 1806( 1963).