The Chemistry of Carbanions. XIII. the Nucl Ear Magnetic Resonance

IRopriorca from the Jouroal of Orgaorc Cbemisrry, 3l' 2481 t1967).1

The Chemistryof Carbanions. XIII. The Nucl ear Magnetic ResonanceSpectra of Various MethylmagnesiumDerivatives and RelacedSubstances

t-'- <- '

Herbert O. House,Roger A. Latham, and GeorgeiVl. Whitesides (1067)'l j [Reprinted from the Journal of Organic Chemistry, 3t' 2{81 I .Copyright 1967 by the..\meriean Chemical Society snd reprinted by permission of the copyright owner.

I The Chernistry of Carbanions. XIII. The Nuclear Magnetic Resonance Spectra of Various Methylmagnesium Derivatives and Related Substancesr"'b

Hnnsnnr O. Housn. Rocpn A. L.rrnrll.rc rND Cinoncn f [. WTuIESIDES

Department o.f Chemistry, JIassachusettsInstitute oi Technology, Combritlge, )lassachtrsells 02139

Receiled Augttsl 22, 1966

The nmr spectr& ef solu[ious of dinrethylmagnesium and methl'lmagnesittm bromide have been sttrdied in the preserrce,rf ,idded magnesirrm ulkoxides, nreth-v-llithium,magnesium bromide, and nuttglneselll) srits. Of partir:rrlar irrterest were the nrnr spectrl of the unsymmetrical magtresittnr reagents, methl'lc-r'clopentadien-vl- nr,,g,,eri,rni (4), pherr-r-lc1'clopen[adienl'lmugnesiurn(7), met.hy'lphenl'lmagnesitrm(2), lttcl :i,ii-tlimethylbrrtl'l- ,,r',.i.,1ro,,tldie1j'lmrrgti"sii,n,ito). Frr.rnrstudies of these spectr& rrI severll tempernLttt'es,iI rvas possible to tleternrirre the rltes,,i excfirrrge,rf .r,lk1'lgx)ups from one ntugttesitttrl&tot'rt to lttother and to strtdy the effecl of vlri'rrs lrlditives ou the rlte of this exchunge. These exchrrngesere retlrded by the good srllveIing agents 1,2-di- especillll., N,)i,N',)i'-teiramethyleth-v-lenediamine and are cl[al1'zetl b1' magnesittm bro- nrethrxyethirle"'fhe 1.1t1, ntitle. exchrrrrger-rf nrerhl.l groups beiween dimethl'lmirgnesirrrn atttl methvlcy'eklllentldienylmagnesittm t2)rrpllelrs t6 be,r birn,rlec,rlurrelr:tion rvhich is first order itt euclt relgent.. '\ sttrdy oi the exchatrgeof alkyl (10) gr,,,,p, ber,rveepthe rnixerl re&gent il,ii-dimethl'lbrrtylr:1'clrpentedienl'lmrrgnesitrm lttd bistil,l]-dimeth-vl- ii'.,tfi;nr.grresirrnr (9) iprlir:ltes ihrt the rlLe of exchange is subsrtrntillll'flster thln lhe rrlt,oof ctlrtfigttrationll ()ceurs i,,rrer.i,r,,'-"t,the CIIr-)[g bond. Ctrnsequently',the exchlnge re:rcliorr prinurrill'' wilh reten[ion of cort- fiqrrrltiou.

In iln effort to lellrtr more ilbout the structures of the rnerhyllithium (containing lithium bromide), methyl- ortrilrronrL'ttr,llicrellctDlrts invrllved in the addititln re- l.p&glesiqnl brortride, dinrethylnragnesiunl,&nd di- ructiorrsof orglttom:.Igllesiunrcompoullds,s'3 rve have nte[hylnrercuryrre presentcdin Table I. In agreentent stutlieclthe nmr spect,rtoI solutiotlscolltlrining various rvith earlier observatiortsfor alkylrnagnesiull brornides methl'lmugnesitlmtleril'atives tttld relateclcompounds.'r trrd the corresponclingclilllltl'lrnlr,gne5isJpc.2b'{a-c'n the Mixtures of Magnesium and Lithium Reagents.- spectrr.o[ methl'lmlgnesittmbromide and of dimethl'l- ()ur initial nleasurolt)entsof etltereai solutions of magnesiumlrre verl' -si111ikirboth in position of chemi- eal shift and in t3C-H coLrplingconstants. The posi- (l) (s) This resesrch lros been srlpporter-l by researeh grants from the tion of the methl'l signal for dimethylmagnesium rvas of Nationel Institutes of Hestth (Grant No. Gll-087{il) anether soltr- R. lL salincer itr "survev of Progress in ("lrernistr]'," Vol. l, A. F. Scott' tion bf isothermaldistillation and find it to be approxi- pp:)01-:|2'{; (c) Il. J. l'1d.. Acedernic Press Inc.. Nerv York, N' \'., lgti:1, (apparent mol wt 1.2G-1.2EX \\'rkehelr-1. Orgrtnometril. Chern. Reu., 1, l:Jl (11)liti). matell' monomeric (J) Prer.iorrs srrrtlies of the nntr spectrB 9f organotnagnesitttn compounds ntou)mer)at this concelltr&tionlevel. This observation (1962): inclrrrie (a) D. F. Evans errd J. P. IIaher, J. Chem..Joc.' 'i125 (b) for (c) is in egreementwith the resultsprevigusly obt&ined II. Rolithium bromide or the addition of sm&ll concentrstronsof manganese(II) lithium chltride. One possibleirrterpretation of this iodide gave solutions u'ith broad nmr methyl signals just n'rr' (Table IV) as increesedreactivity' is to supposethat & very low con- rvhich behaved in the senre eentnrtion of meth.r'llithium is formed b:" the equi- libriumillustrlted in eq 1.ro T.{sLnI\- The equilibration of methl'l groups in mixtures of Tnn EFrncr oF Lo$' CoucENTR.\TIo)-sor \[.rsc.\:iESE o]..rll: and methl'llithium is believed to dimethy'lmrgtresittm Nun Stcxals Fnort Etnen Sollrtoss complexesas proceed uio the formation of a series of or' II etuvl,ltt.{cNESIUrt H.ruroes illustrated in eq i3.?b This type of complex formatiotr Chemrcal sbift Ban t CH:Li w"r::' - (3) (C[Ir)z\Is + 2CH,'Li . (CHr)r]IgLi, t' (Cl{r)r\tglir ";:it Additive internal ha if - t rvith orgunolithitrm compottttds has been suggested Reacent (concn, (concn, Temp, T]1S' hetgn oC cps cps (rllthough in simpler form) for I tlttmber of metal de- moles, I.) moleszl.) (0.30) -30 90 :}'{+rl5 rivltivesle' r t 1rrd epl)ears to be trpplicable to the sub- CI{r}tgBr ( l.0l ) CHrBr -54 98 )c sequently disctrsseclrelction tlf methvlmagnesium bro- i CHs\[gBr" ( I .04) CFITBT(0.33) -30 92 6--{I mide rvith mlttg&nese comprtunds. CI{r\tgBr" (1.04) CI{rBr (0':i:}) + -30 90 2 on the Methyl Signal of Methyl- Effect of Manganese excess\[g" Reagents.-Irr our irritilrl preparations of magnesium CH,\lgI' (0.{)2) CFI3I (0.1S) t.30 92 l5l frottt ethercll nrethyl bro- nretlt-vlrrntgnesittttiltrortridc cI{,}IgI" (0.92 ) cHrI (0. l8 ) + -ilo 91 I -5 rrriclelnd ordirury Grigrurd-grrtde ltli-tgllesiutnturttittgs, excess \l g" '' the ttttrr spectl'u of tlie soltttiorts \\'ore fotrnd sotlretitrtes CII3\tgBro (1.42) CHrBr (0.5) -:i0 97 1'5 to exhibit :.rshrrt'p rrrethyl peak rttrd :-rtother times to CII,)lgBro ( 1.42) CI{rBr (0.5) + -ilO 97 I 'r' exhillil u llrorul rnethyl pelh w'hit'h bet::,rtttcstill broader \[ g" (tl.S l0-s; -li0 90 4-?'l' Irs the slltttit-rtrsw'ere allrt*'ctl to stttlld. The centers CllrltgBr" r,0.99) ltnlr X ltlt:lrted at . This re&gent w&s prep&red from ordinary Grignard-grlrle oi thc trroutl urtcl thtt shrtrp peltlts \\'ore b tuhich conlains small unlounts of msnganese. The ruppn;xirrnttciv the :jilllte prlsitirlrr; the broad peak ntugnesirrnr pe,ik g*dlally broadened over r period of 2;i-600 hr. " When tirr: tvltc'ttit rvlrs observetl lrt -,'l{o lnd broud- beclnre shtrrp coltl solrrtion tvas warmed ;e -li()o, the methyl signal was loctrtetl j],-r eneti trltett this solutirttt tvtls tllllrved to tt'ltrm tO room Dr l)l cps wirh o hllf-brnd rvidth of cps._f Thepeok gradtrullv 'f 'This tenrl)erlrtttre. he vlriltltle re'sult-suere traced to the brgutleired over & period of l-llJ7 hr. solrttion wrs 9[- it in the table by adding exgos'j soltrtiotts u'hitlir gi.IVct>rions tlf ctrmpler evidently forms small amount! o1 solrrb'e jJt;l)(lgti{); rb) I) O. .J. }Isrr, antl J. l). Roberrs, ssme way tlrst methylcopper(I) l.rtter,. \,r. ..1l. I l'orvu,tt. :e rvi th methylmagnesium bronride' .1. (trq. ('hcur..29, ;iti8ll ll96'l). complexe; Houso, f.,erg,rlr. rxo WHTTESTDES Vor.. ;ll

i . ; tr 2d, and referenr:es q. therein), wc, haci noted XloM C{,,MeOCt5rC1, o.16 c Hr v9 oc (aHrct) oi6M((FrcfJlc-oi M9 thar rlr* 'l I ra tfts(t Af .al' AJoM cHrMga{r addition of I nroleequiv of a ketoneor a tertiur' N i;tsta .^r 'f,t l N fTFtl ^f 35' I rri- \ / .ohol to I nrole equiv of . diarkylnragnesiunr . ,'i ,.,r,,,- JUt !\r- \--.-- U/ * ,*;-Li *./' L- p(CIIrt,][rr * JlrrBr., (-{) sirrnri;rorrritle ; thc resrrltirrgsolrrtions rta,.o comp:tr.lhl. -\lrr[:+:]CIIrflgI]r.--+ (CI.li)r\ln * :]]lglBr. (.-rr u'itlr srltrtirns ,f' the ulll'lnurgrrcsirrrrrbromide. Irr * rC[[r):\[rr+ CIllflgRr.-. rCIlrt,,JIrr-+ ]{s.Br, ({ir vieu' ,f rheser'('sults, \\'(-. \\L,r'e Jlr.orn;ltccl to stttclv tlr. llll)I'sl)L'ctrltof tlre rrtetltr'Irttugttelsitrnr (CII3),jfln+ f IB,--* r|ll,r.:]lg* Jlrr,, (T) lrlltoxidercll{orrt: obtlritretlllY tt'tlrttl])etIt()t'ethereul solrrtiorr of climetlnl- nrugrresirrnr tiorr to fornr lr conll)lc)xnlr,ngir.rre-{c lniorr (e(l (i) rvould w'itlr etlrrirrr(,l:rr.r-rnl()Llrrts 0f 3-methr.l-;;_ iJ-lrerrtruronr.()1. then serve to c(lrrilibrlte thc nrcth.vlgr,rups bet*.een I)ontlnol. rnlrgnesiurndi_jl_methvl_:i_ to olrtlin m*gnesiunl(II) rrrd nrungrurese(II) speeies. As l l)ont().\i(lo tho rer*{r)ntrrsed in elrrlit,r. ,strrrlics2t,'rl'rr l). resrrit.e:.rch mcthvl gr()ul)is brrrtletlf,,r. lr'p,r.ti,rr of the 1911s, lrrrtll0). time t' 'l prrri.rnrrgrrcticnurrrglrnese(II) sl)eeies rvith the lle:]JK.*, (ll'l'(,'111,1('((:llr,Oll--+ re-*ult thu,t the uvL,r.rgc nreth.r.lsigrul is broaclenecl. J(('ll,Clll1.r.,C(Ctll,iO-\lgCIIrJ.* CIIo (s r Appurentlr', rrt l,rv tenrperlrttrres thc e.xehurrgeof lle:.\ls + Oll,,(jll:('(X'll.('ll,--> methl'l gr()rrps(et1 (i) is sLrfficierrtlvslon' that the shtrlr ['(,'ll,(,'11,,):C(C)ll,,X)]lgCil,l" 11r r mcthl'l .signll lttribtrtable t, rrrctlr,,-lnu.r,gnesium bro- ltes\[g (_'l ----> niide rc'mrrins.16\\'herr + [((ll{]C:ll: t,:(-'( I,.,(J1,,.\[g these srltrti,rrs n.ith broacl (lll.,CII li :i:O(C'll31O]tgetJ,,1^r I r), meth]'lsignlll.s uro trerutr-'clw'ith exr,,es,s magnesium metlil. A.s 'l'uble the mrr.qirrrese(II)species is presunrablr.reducc,d tr.r su.rnrurizetiirr V *rrtl l'igtrr.el, the specrr.ir of nrettllie mu,nglneserT(e<1 7) rvith the re,sultthat the thesesolrrtiorrs \\'ere ess()r)titllv the srrmeirrespecti.,.c ,ri 'fhe rrormulshurp signal for nrethvlnragnesiumbromide re- the nrrrle,f formrttiorr. speetnr,exhibited t*.,, niain.s. It might be noterl that thi.s line-broaciening generul ure.'.r of ubsorption u,ttributable to methr.l groups phenomenonis the onlv pilrce in this strrcly.rvhere rve bourrtl to magnesiunr. The lorver field br,,,i,i (ca. rroterlrLnl- differences in the nmr sl)ectraivhich were rubsorptiorr 70 cps ulrfielclr'rom TltS) e.xhibitsmor.(, rlependent'rrrvhether the ()rgrrnomagnesiumcompounri firrestrueture rvherrcoolerl (-,j{i") rncl sharpensrvherr (,\7'). *'r.sobtainecl from ordirrarl' Grigrrrrcl-grademagnesium heated As the sunrpleis heeted.the trvo regi,rrr. ,f ubs,rptirn :lr tripll' sublinied mrg.esium. r'irthermore. this sh*r'penund begin to move together.. sirrce line broadening u'ts fotrnclonll- in instaneesrvhere r the t.'', pellts ,rbser'erllt ,\7o rlitl rrot Jxhilrir Irmrtrnrtrmrunt of magnesirrmu-as trellted rvith e.\cess lurrr-eviderrce tli'excrhunge broat.lerring. it is not appurerrr methl'l w'hetheror not hllirle. Thus. in the normal lrreparativepro- thesetu'o pellksrvorrld c,,llesce ot srrt- eedures rvhere lrrr exce-ss,f magrresitrnrmetal is em- ficic'ntlr- high ten)I)erutures.\\-e \\'ere unsuccessl'rrl plol'ed. rve hlve no rels()rrto believe thut the use ot irr oirtuirrirrr{slr,tisflctorv spectnr of theseether srlrr- ,rdinarl' Grignurcl-gruclenrugnesium rvoulcl be objec- t irns rLt higher terrrlreruttrres.The relutive &r(_,r.s tionabie. rrnder the tu'o regiorr.si,i lrbs,rption \\'ere altere,i Effect of Alkoxides on the Methyl signal of Methyl- siightll' u'lrr:rrthe srluti,rr.. \r'er.ediluted rvith etht,r. magnesium rrrrrldilrrriorr w'ith Reagents.-Irr eur.lierstudies tsee ref ib, the better.solvating solvent, t€tr.rL- ht'dr,rtur:rrr.crrrtre(l tlre.e r\r.o r.eqi,rrrs {lti) 9i lbsgrptr,,rr .\lthou(ir rre ditl .,1orrser'e an-r.signal f.r clre r'etrrl.lmonganesetll) to coiiagts(-'to rr,sirrqle peuk. 'fire sJreciesat lorv tern[)eratrlre, rlris rv'rrlrr utlcjitionof even Io be e.xpected lrecause of the lorv con_ r. (:entration of mansanese s;recies present, nrrrlL' ,I' becsuse their signals rvorrlcl be ver), nrlrgnesiurrrblr-rnrit.le cuusecl the absor.Llti,rn broad, and becgrr.gethe apparent chernicnl shifts of srrclr speeies rvorrltl proh- lr.rrgell-t, c,lllllse t, rl ringle peult ably be iarge. a:rd essentiaill.,, -*ingle pellr tl7) .{lthoush r'e have no rlata for \\-rrs,bscrve.(lw'herr the solutions etrrer solrrtions, in crluegus metJia tlre \\-er(l oxidat,ion peitentials for magnesium and mlng&ne.s6 [to manganese(II) I are .1.37anrl Ll8 r', respecri'ely: \l'. ]I. Larimeranrl .L II. Hildebrand, ,.Refer_ ence lJoclk,f In'rgrnic clremrstrv." (}r., Trre Jllcrnillun Nerv l,'rk, N. \.., I952, p i28. Auoust 1967 Tnp CnnMrsrRr-or Crns,rNroNs. XIII

'f.r-ecr: \' 'frtu Nvtr ] [ uruv t, Stcu.r t,s rou JI srnyL]r.\(iN llsrr;rr A r,ro.rr lrus Ix litHnu Sot,urrr-ry ChemicsIshift IJerd width rrpfield from internal ct helf- h erch t, oC Reactantc (concn., molesz l.) TemJr, TllS, cps eps tCII'):trts(0.36) + Etrc(OH)]te(0.36) iJr r b.0 l.\ 67.6 l.l ') rCI{,)r\tB(0.:i6) + Etrc(OH)}te(0.36) {1) 80.7 || 67.E I.0 '): (CI{r)rIIg(0.36)+ EtrC(OH)]le(0.36) :i._, 82.:j a .., 7{) 10 -.i6 (cl{,):\lg (0.36) f Fit.,C(OH)lle(0.;16) 96 r) lo r2 (cI{r)z\tg (o.36)+ Et'C(OH)]te (0.36)* \IgBr (0.O;td) .19 3:t..j,, 2; (CII')rlIg (0.:16)+ EtrC(Ot{)}Ie(0.36) * }IgBrz (0.036) 3.1 86" t.7 (cHr):]lg {0.:;6)+ Ilt:C(OH)}te (0.:16)* \[sBr.r(0.036) -66 .j 97.ti' 4 (CHl):\lg (0.;i4)+ Iit,'C(OH)lle{0.3-1) * }[gBr1(0.l7) :i,1 SE.E 1.4 lCHr)r\lg((|.:l(;)* [Et:C(\le)Ol!]ld (0.:i6) ,-il.:) rt.t 2.6 7{ 5 (o.:iti) tCH')r\lB + [Ijtrc(fIe)Ol:\Ig (0.36) * ]lgBrr (0.i16)' -ll.-r 9(| I (ClHr):\ [g (0.tr) + Et.rCO(0.Iu) .)') ,\.) 2..-r 7+ l1 (C)Hx)].\lgr0.lli) + Iit:CO (0.lli) -il {f; 6

7) I rCllrt.rllgr(l {}7r* lit:CO (0.07) * tetrahl'drofrrrand .)r) ll I .') .) 'CII,):\lg tl) 07) * EtrCO (().07)* tetrahydrofurrnd - .)I 1)s

r(lllr'r\lg rl). :iti ) * O

I r('ilr):Jlgrll;i{ir} n

a tlleric ethl'ltttlrgtte-*ittnrllrorrrrrle.r'i :ilrrl vltri()usnteiriul ('- F nrelrtsof the lr[)J)lrrontrnolcr:rrlur \\'eiqhts of ether.solrrtions ,f rlkvlmilgnesirrrn h:riirlcs'i'17h:rvc irrdiraterl trJ |cr,85 thcrrr z to he molromeric irr tliltrte so[rrtiorr.rB.\s rvill be rrott,rl in the srrbsetlrrentrlisr.rrssion. (llll' @ F rl:ltl, :rre entirclv consistent rvith this vieu'. Ilr rulle:rses *'here mixtrrr.r'.

o t-l- of Clrignar(l re:,rgerrtsrvere crumirre(l onvhere soluti.rrs r rr' obtaineclb1' trlding') nr.le etlrriv,t mrgnesium bronritlr. X ()r 75 to etlrrimolrrr mixtures of tw'o rlifferent dialkvlmagrrc- z |o sium re&gents \\'ere exlminecl, the spectra were c()ri- sistent rvith presence ,t C) the allir-lmugnesium bromitlc. tr rrnd rve forttrcino eviclence ior the Dresenceof t nrixcti a E. dialltl'lmagnesium relgent I. ) P6s The first of ll serie-",f mixerl rnethvlarl'lmugrresirrrrr O re&gents I rvhich rve studietl \\'r"s nrethvlphenvlnurg- = 7q nesiunr 2 obtlinerl ls one oi the compollents of an t'c1rri- trJ 25 50 librium mixture (er11(i) n'herrrlimethl'lm&gnesium I MOLE % OF CHaMo Cna urrrl _\[e:\[g* Plr:\[s T.* i\Ie]Iqph rlri) Figure 2.-Graph of nmr chemic:rl shift for CHrlIgX protons 2 ls. mole 9f dimethylmagnesium in dimethy'imagnesium-diphenyl- mlgnesiunr mixtures in ether solubion (dimethl'lmagnesium con- diphenvlnlrgrre'siunr \\'el'r,nri.retl t'fulrlc' \'I). In etlrtl centro,tion 0.21 lI in all cases). solution, ,rrrlv rr sirrgle nnll' nlettrvl sigturl u'its o[-s1-'1'1'1',1 u'hose ltosition \\'lts tielterrrlerrtrrllorr the filtio rii- trrrr)sier ancl rrbout the propertiesof nri.xeclmethl'lrlky'l- phenl'lmltgnesirrnr-rlintc'tlrvlnt:rgrrcsirrnrirr the s,,lu- rirl'l-) ('i.e., 'l'ltese irrr rnrgr)esiumspecies l) from studf ing the tirln (|igrrre ?). I'c'sultssrr{gest that the sirr!-{1. etluilibriunriilustrlted in e(l l;] b1' nmr techni(lues. nrethvi signlrl ol)scl'\'r'rlis the r.\'enrqL,signlrl obtrrirrt'rI Ile:llg * R,.r\lgi 2Rltslle ( l:i ) f,rr mcthl'l groul)s rvhich iLr'or.:rllirilv exchangirru lrt,- I t\r'eL'rrr-iirnet hvInutqrresirr nr lrrtI nrethliph€n)'lmuqrrt,:- ittnr (2) rvith thr: r"n(,tltvlsigrr:rl ol' thr: latter eomt)ourrrl \\'e rnticipated that thesestuclie,s w'oul(l not be profit- occurrir)g ir.t lor\'(]r'fit'lrl lrt't'rrusoof' rlccre:rseclshieltlirrs- lble u'ith mi.xturesof meth)'lmagnesiunrbromide and 'flre bv the plrcrr'l rirru. Irrcr thrrt rrrrullJrroxinurt.lv other ulkl'lmlgnesium bromides!rbc'eluse the vast bullt linelr relrrti.rrslripis ,lrtrrirrrtri([,'iqrrrr' 2) srrggest.stlrrrt ,rf crrrrent evidence inclicetes that these Grignlrd this excl)lnr{c (er1 l(i) is :rl)l)l'oxirrurtellstlrti-sticrLl. rerrqL'ntsexist in dilute ether or tetrlhl'drofurlrl solLl- \\then l[n o(ilrivllerrt iln]ount ,t' nllrqnesitrmbromidc u'rr. tiun r.rsthe monr)mericalkl'lmagnesium bromides (i.e., ludded to these solrrtions (or w'hen methvlnurglresnrr)l both ertuilibria1-l and 15 lie relativel-v-far to the right;. bromicie arrci pherrvlnurr4nesirrrrrbronricle \\'ere mixc,lt. As :.rresult, the lmount of mixed relgent I (eq 13) to the onlv high-fielcarbon- soltttion .l1t hrrt betorne rlirnerrc in rnore c()n(.entrate(l s

- T.rst.c\-[ '['rrr: Nrrtr ][r:trrvr.Srcs.rus 0r -\[trtunES()F \[B'r'svuu.\cNL)sIUM .rND l)rrnNt'1,]r.\(;NESIt'u l)ntttvrTIvEs r.r Iyrsnn, SolurrtoN Chemicel ahift, u!field oC Reegents (eonen, rnoles/ l.) {drlitive (eoncn, moles l.) Ternp, from internat TllS,o cps CII,IIgBT(0.20) * PhlIgBr (0.05) -:j (J 9t.5 CIlrflgBr (0.20)f Ph:\tgBr(0.20) -ij0 92 CII,)lgBr (0.20)+ PhltkBr {0.ttO) *:i() 9l CH'\tgBr (0.20) Phll t0.S{),1 -:l() 89.5 (CH'):\Ig1{).21)* I'hz}Ig(0.0;) -;j0 79.5 (CII,)rlts((1.21) * Phr\tg(0.11) *:10 I t .;) iCHr)rltg(0 2l) * I'hr\[g (0.21) -:j () /:t. o tCH,)rllg(0.21) * Phrllg 10.42) -: i() r I.;) tCIIr):\lg(0.21) * Ph:]ts (0.8;) -:i0 70.5 (CI{a):\Igt0.21) PhH n.68) -:i( ) rb.D (Cl{r)r}lg(0.21) f l'hlllg ((f.42) llgBr,l (0.6;l) -ij0 9l tCIIr)rlIg(0.21) Ph:\tg (0.42) \[gBr1 (0 06:]) -il0 t t ,D * .): rCIIr)rlIg(0.4llt * I'hr\lg (0.:'j()) .).., l:t.;) iCl{,r):}tg(0.41)l * Phr\tg (0.:j0) -62 EY (Cl{,')r\tg(0.41)) * Phr}tg t().iiO) - 71) 9;i" tCILr)1ltgt0.l6lii * Ph.r\lg(0.0R4) T I{ F-et her-aminer {l 99.5 (1,) (,-16:2S:ltj b.r'mole -tl 97.5"+ 106.5i

" Urrlessotherwise toted, the methl l signal band width rt half-height is .rpproximatell' I cps or less- | The bnnd *'idth st hslf- heighrwu l.tt cps. 'The band widih at half-heightwss li.; cps. d \, )i,:i', N'-tetramethylerhylerretlinnr irre. 'The bs,ndwidth or hllt-heighl wns l.i tps. / The band rvidth lt hrlf-heighi $'ns l.! cps. The rel:riive intensiiies of these trvo pelks rvere:il snd 69%.

Jherc.ti)r'ctuulecl ()rlr :rttontiorr to other mixeclreuge.rrts mixed reirgent 4. Solutiorts of' this rerrgent (0.0SN rleriveri t'ronr vuri()us conrbirrltiorrsof dimethl'lmriu- rur(l 0.117 l/) irr tetruhvclroirrnrrr\\'erL) foturd to be IIL'-siunl. cliethvl nrllgnt:siturl, clirreo[)er rt vlnurqr)L.sium. (li- rnor)omeric(lpplrettt mol rvt 1.0;l-1.07X nrottonter); phettvltttu,gtresittnr. :rn(l tiicvcloperrtlulietrvlmilqnesirr nl. t he muterial cotrlclbe -*rrb Ii metl rr r rr lt'r' rer I ttcecl pressure. r0 'fhe resultsfronr mixtures of tliethvlrnlrgrresiunr()r cli- Thc upfieldshift of the rrnrrnr()thvl peuh (Table VII) ncol)erttvlrtutgtresiunl\\'ith c.thcr soItttiotrs ot' the rnethvl for this nrixeci re:rgent tlkerr u'ith its mon()meri(l or I)hen.\'lreugerrts (slrnlmlrrizod irr thc lixllerimerrtul rri,rtrlreirr solrrtit)nand the rrbilitv ot' the mlteri:rl to Section)offcrctl rIo prrrticttlulirrfortnttiotr llevon(l thut strblime suggest that the nlrrtoriirl bc rrssigrredthe ltlrelrlv glitretl fronr methvlJlhenvlmrr!{ncsium.Horv- structureillustrated in formulrr4 irrn'hieh the methl'l- ever, mixturcs of riicvclopentadierr.r'lmaglresiLlmrvith m:.rgrresiumbond is &pl)roxinrrtelv perpendiculcr to eithcr dimethl'lnlrrgnesiumol' diphenvlnllqnesiumex- the plarre of the cvciopenturliern'lritrg.st The ab- h ibiterlseveri.ri st li l v o ordinatelv borrrtrl -solvent nroleerrles.In rrgreement u'ith the icleluthat the mixeri ft'rtgetrt4 t'epresentsa 3 4 fuvonrble arratrgement of Iiglncls botttied to milgne- lt higher field tharr the signal for dimethl'lmagrresium sium, the chemicrl shift observedlTlble \-II and Figure becruu-seof the maglretiornisotropv of the c)'clopent&- :3)for the ecluilibr:.r,tingmethf i gr()rrpsirr I mixture ob- clienl'l ring. Although this expectationproved to be tained from dime'th.r'lmlrgttesittntrtlld dicl'clopenta- correct (seeTrble \''II), o[ more interest w&s the f&ct dienl'lmagnesium wa.s not significlntll- raised rvhell that Drr ether solutiorr ()btained by' mixing the trvo &mounts of dicveLroentltclienvln)ltgltesitlmin excess mrrgrresiumderiviitives (ec117) deposited r white cr1's- tallirre material n'hich proved to be the soLrcnt-J'ree (:10) \\'lren tlre sarnple rvas lreaterl, i! ltn(ler\t etrt l)srtieI rlecotnposition as s'ell as srrbliruation. Samples n'lrich rvere srtblirnerl into the sourco of a mass t2'0) (a) Fl. \\'eisrcanrl li. (). liisclrer, Z. Anorg. Allqen. Chem.,178, 219 spectromeler g8\-e B peak at mre LO1 corresponrling to the molecular ion of (1U55);(b) G. \\'ilkinson, li. -\. Cotron, and J. ]I. uirmingham. J.Inorg. the mixed reaqeni { as rvell 8s a more intense y.leakac m/c 154 coresponding .\'ucl.Chem..l,05(l95ti);(e) 1"..\. CerttonsntlL. T. Reynolds,J. Am.Chcm. to the rnolecular ion of dicyclopentadienl'lma{nesium (3). Theae observa- .Soc.,80, 2ti9 (1958); (d) G. liraenkel. Il. E. Carter, .\. .\IcLachlan, and J. H. tions suggesc that the mixetl reagettt { tnar',lisproporliona[e (reverse of Rictrarrls,tbi,l.,E2,;8{tt (l9ti0): (e) L. Friedman,,\. P. Irsa, antl G. \l'ilkin- reaction in eq l7) rvhen heated. :o:r, ibrd.. 77, ?'689(lg5.i); (0 \\'. Strohmeier and I{. Landsfeld tZ. ){otur- (3 l),\ sample of this tnoterial bas been suppiied to Professor G. D. Strrckr'. lorsch., 16b, :r:J2(l9tiO) I lravo ret)()rterlthe preparation of the mi.red zinc Depertrnent of Clrenrrstry, University of Illin6is. for t[e purp()te of 6btninin( rea({}llts.ethl'lt'lcLrpentutlien;'lzinc, anrl phenylcl'clolrentadienl-lzinc. an X-ray c11'stal struc[ttre. Housn, L,rturv, Al'D WHITESTDES Vor,.::il

'f.rsl.c VII

THs NnR SpEcrtt.r clr .\ltxrr,'nus ()r. i\[p'rHyLrvr.\oNt]stu]r.\Nr) Cyct,opnNr.\ DrE N y r,Ir.\c NF:sr ullr l)n n rv.rnvns

Chemical shift upfield from inrernal TIIS (band wirlth ar half-height).o cps- Reagent (concn. molec,/!.) oC Solvent Temp, Cyclopentarlienyl si gnar Ilethyl signal (Cil{i)2tr[s(0.24) EtoO -30 - 360.56 -l) - Jtd. i) (CrH;)rFe EhO *30 -215 .'o (CiH,):NIg(0.30) + EtrO -:J() - 246, - SirE (C:,HiLFe(0.30) (CH')'Itg (0.36) Et2O-THF -30 lOri (l:1 by volume) CsH;\tgCHr(2.68) THF -30 _:t52 r27

a Po - CrHsltgCHr(2. ll) + THF -il0 - ,);).i . i) I2it.5 Et.O (2.11) C'H']IgCHr (1.72) + THF -:J0 -.J.l.J . D 125 Et:o (3.44) C'H'\tgCH, (1.27) + THF *;10 - ,)i).t . .) 124 EtrO (5.08) CsHJlgCHi (0.35) Et?O-THF 31.5 - 358.5 123 (85:15by mole lp) _28 _;t.ig 127 -82 _:i68 131.5(l.3) (0.32) C'H'][gCII3 EtrO-THF -30 - .),).) 1265 (8:92 by mole /6) CIII'\lgCI{r (0.32) + EtrO-THF *30 -;]59 l16.; )[gB12(0.16) (6:1).1by mole 16) - 12" -357 (2.5) 1225 (:t.1) C;H']IgCII, (1.34) + ErrO-TIIF 33 -;]62. ; {)9.5 \lgBr2(1.12) ( l: I by volunre) C'H'ftgCHr (0.54) TTIF -:|0 -;j.1(; 126 C,Ii,\[gCH3(0.54) + TTIF *:J0 -;J-t-t I l3 Licl (0.54) CrI{s-\[gCHr(0.;4) + TI]F *il0 l0s Licl (l.0s) C;ll']lgCIIr (0.2r) + Et,O-TIIF *:]0 - ;];g (0.7) lt5 (0.9) CII,ItsCIlr (0.14.'r) (2lJ:72 by mole /o) CsFIs\[gCH,(0.2't) f ErrO-TIIF -:J0 - 356 (0.6) l12 (0.6) (0.2.1) (:i6:64 -84 -35a CH.UgClI, by mole !f ) (l. o) 108fi..j) + 123(1.1)r CrHs-\IgCHr(0. 30) Et,O-D}IEd 3l - 357(0. 8) 128; (0.8) (12:88by molelp) -81 -3ir8.5 (1.()) l3l (l.6) CsIIs-\IgCHr(0.25) + EtrO-DIIE 3r - ;J;jg(0. 7) ll5 (0.8) CHTIISCHT(0.12.'r) (2S:72 -81 -:]59 jj) by molefr,) (l. l13 (3.;) + lj]1ri]. jir CsH;\IgCHr(0.18) EtrO-TI{F-amine" 3t'{. ir - 3,-rll(0. 8) 121(0.6) (37:;13:30 -O/ b"vmole f|) .;) -:i.rr7(0. 8) l2{.5 (l .2) CsHslIgCHs(0.18) + Et,,O-THF-amineo 38 -35e (0.8) ln.5 (2.3) CH,\IgCH, (0.09) (45:30:26by mole%) -27 -35e (l .0) 104.5(l.;)+122.;it i C'H'][g(CH, (0 23) + Etro-THF 30.5 -3.,4 (0.8) l2:t (0.7) CrH')[gCrHi(0.115) (69:31by mole$) - 8ir -355 (r. l) + -317 (1.2) 128 C;HJIgCHT(0. 17) * EhO-THF_Et,N *;10 - 3.1; (0. 6 ) l16 (l.0) (0.084) (26: - -3ir6 CH'Itg(CHr 50: 24 b-vmole /6) Z+ (1.1) 108(2.1) + r2g(2 )) ' In caseswhere no band width st half-h€ight is specified,the value is approrimately I cps or less. r An ether solution of c1.clrpenr,,- - dienehss multipletscentered st t74 end.-387 cps attributsble to the c!'clopentadieneprotons. . lirme solid precipitared-r.herrr1,,. sohrtionEss cooledto this t4mperrlrlre. d l,!-Dimethoxyethane. . N,N.N',N'-retrameihylethylenedinmine. of I mole equiv lvere added. This behavior, rvhich It is opp&rent from these data that e.\charrse()r i-sin contrast to the behavior observed in mixtures of both the methl'l groups (rvith dimethvlmagnesiunr, dimethl'lm!,gnesium and dipheny'lm&gnesium(Figure and the c1'clopentadienl'lgroups (rvith diel-cloperrrrL- 21, indicates that the equilibrium forming the mixed dieny'lmagnesium)of the mixed re:.rgentctll be slow-t,rl rersent 4 (eq 17) lies far to the right &nd a mixture ob- sufficientll' to observe the trvo sepa,ratesignals irr- tained from equimolar a,mountsof dimethl'lmagnesium tributable to the mixed re&gent4 and to the methr.i r.nci dicl'clopentadienylmagnesiumcontains primarill. or dicy'clopenta,dienl'lgrorrps of the exce-c.ss1-mnrerricrri the mixed recgent. The fact that this mixed reagenr reagent. The seplr&tiorr of the methl'l groups \\.ir: 4 i.smore stable than its s-l'mmetricaldisproportiona- sufficient to permit calculationof the pre-e.xchangelit'r'- tion products (eq l7) suggestedthat the exchangeof times for the methylmagnesium groups under sevL'nri methl'l or cy'clopentadieny'lgroups with this mixed eonditions. Ty'pical observed and calculated cur\:e: rr,tgenr might be slotrer than the aforementioned e.x- for these measurements at various temperatures r!l'(, ehangere:.rctions and led us to m&ke the lorv-tempera- presented in Figure -l and the rates of exchange ul'(, turL' meosuremerrtssummarized in Table VII and summarized in Ttble VIII. Of partieular interest ir -l-7. Figures the observation that the rates of e.\ehangeirre r.(,- Aucusr 1967 THn CHp)fIsrRI- on C.rnsrliloNs. XIII

'f,r'rur: VIII ClIr]lgCHf ll..rTr:s or Exr;x.rxct:or' Ilr:T ttr-L(lttot.lt's tl Ottc.rNt)Mu'f.\LLIUJIrxtuttr:s CoNr'UNtxc Typicalvalttes_..\rrlreniusparameters-Ra!ecerrgtants. -t 'l'enrgr, at - 'l5o' Jf Solvent colnpn, for l/ r, E^, -r -l oC sec kcal/mole -{ sec Rergents (concn, rnoles/1.) mole 7o -31.5 t3.B 10+16 r24 CsH;]tgC[Ir (0.29) + THF-ether 32{ -46 CHJIgCHT(0.14t) (72:23) 78.7 ': -60.5 6.2 -:J2.5 7.1 lo+e.e 25 CTHJIgCHI(0.25) + DIIEb-ether lc6 CI{,}tgCHr (0.125t (72:28) _JD.D 45 -73.3 8.3 12.1 l0+r: 0.63 CiH;][gCHr (0.18)+ Ether-TI'IF- 38 318 CHr\IgCH' (0.09) a,mined 10 45.4 (44: 30:26 ) - 6.5 12 -:18.5 L2.2 l0 +r.r.6 200 CrII;\lgCHr (0.24)f THF--ether 176d -;8.5 CHJIgCHT (0.24) (6a:36) 44.6 - 69.5 10.; -:13 11 4 l0+rr'' 50o C,I{:lIgCIl (0.17) f THF-ther- 5 ;00 -50 CU,ltgCU, to.oA+) triethvlsmine r02 (50::26:!+) -53 37.it -; I ti l0+'0 r {0 PhltsCH, (0.10) + THF-€thir- ; :il0d -2i CgifgCg, (t. tzl amireq 7:l (56:23:16) -32 0; Section. '1,2-Dimethoxyethane' The methods used to orleulate the dats tebul.Ited rre preseoted in the Experimeniol " ;in1 for the metbyl group of tbe mixed reagent, . \,N,\,,)i,-terrumethylethylenediomu[.- p.*"*J.tee lifirime.r reiers to the vglue n-li-Cft". ' CllcLrlotel from the Arrhenius p*rameteru sssrming bimoleculrr kinelics'

F rl t25 /\ trJ /i oCI -343.-rlF c0z

F a9 -,s. i \-- o 00730 sEc n' lJ- /\A 3o, il5 t\ zx -46 J \* oot27 5€C ol

l'- rO t!I -4e. -<: -.-/\-* a rvvrnq E- ,-\. )o -53' -'rJ \.- 00260 SEC

= 25 50 75 loo % UJ |--nr. '\.- T -56' -,r.J 00532 SEC C) MOLE% 0F c FlMocHa An t\- probons v' Figtrr.e ;i.-ciraph 0f nmr chemical shift for cHrlIgX -rrr. J oooo6sEc ,r. nill. c6 ciinrethylmagnesittm in dimethylmlgnesiumdicyclo- pentadienj'lmagnesium mi.xtures in ether-tebrahydrofttratt mix- An \* tures (6,:r-8i mole % ether). -*.r. -j \-/ o,.. s€c 23 CPS 25 C.PS. slightlv bi' itrcre&-sittgthe conceltratiop ()f tetra- tl,rded Figure .1.-observed (c') and calculated(pre-exchange life- h1'tlrofttritrrunc[ mrtrliecll]' bv trclding the bicierttate time r) nmr spectraof cHa]lg- protonsin a mlxture of ciH'- iigrntls 1.2-climeth0xl'ethane(5) orr especi*l11',tetr:.r,- ]IgCH, (0.29if ) and CI{r}IgCH] (0.145.,'11) in tetrahydrofttran- methylethllettedirtmitre(6).t' This ditr,mirre6 is dis- ether (72:28 bY mole %)'

(il2) Reacti0n of this dianrine rvitlr several dialkylmagnesirlm eompounds ( H' H:CH:N( C Hr ): formulsted as CHIOCHTCI'T:OCH3 C )'l'iC lras been fortnrl to f ielrl isolable monomeric complexes rvhich are 5 6 Me ']\,r | tinctl-"*more elfective in retarding the rate of exchange triethy'lamile rvhich c&nllot function as a bi- ,l\"1,-'*" \ -QHt than ls R\ ,r' clentateligand. The strikilg ability of this diamine 6 exchalge was further demtltt- -II€ 'r. | to retard the rate of R- -CHz strated b}' edding it t0 mixtures of dimethylmagnesiunr N- -M" and diphL.ylmag.esium. In the presenceof this di- M{ amine. the exchange of methyl groups between di- (a) L. I. Zsklrarkin, zh. ohshch.Khim.,3t, 3125 (196'l); chem. .lbstt.,6l' methl.lmagnesiumand the methyl phenyl mixed reagent L'SSII, S{, 3166 (196{). (b) G. !l.costes antl l.ltj97 (lgri-l);.1. Gen.chsrn. 2 becamesufficiently slorvat lorvtemperatures to pernlit J. .\. Ilesiotr,J. Chem.Jcrr.' Jer'!' .t' ?7 (lgtttt)' HousE. LltHllt. rxo WHTTE.sIDES Vor.. i:il

25 I it i I -3ss' l J i i'*-*- ooo2r sEc /i 2D /'./\ I -::,' .-.'/ \-- oooTr sEc if P 1\ \ /\ rq /\ o o -r"t'J,^, \-* oo,5 sEc J ;\

,"r,--/ .\ oozz4 sEc

15 4.0 4.5 5.0 o.0370 SEC I/T X IOJ Figrrreti.-Pl,r,f (l/r) /f \ l.g as e fu^cr,irrrof L/T for A, c,U,- \'/\-.- .\lgCIIr(o.lt).11) anrl (0.1{; 835'-'/ oo54o sEc---) CIIrltgCII't l/) i,rterrahvdroirrnrrr_ /, :!huj t7?::lsib'u' rnole il); B, C,tl;)IgCIIr (0.2; .lIi anti CII,_ l\ (0.12') ;\ -\lgcl[,r .l/) in tlirnethoxver,huue-et,her(72:]s bv rrr,,l. r\./, ''i.): (1, (o.lli -645. ':- c,lI;]lgclI,, .lI) lin

I '73' ''-/ t.-- ' r\l 25 -/ o zzo sEc \----l' L- 2( a oq 2{ a 0<

Frg'11'g.-r.--{)bserv.d (co ) :rrrtl .uL,rrIrtt'rr { 1r.t,-.xr:hu^gelife_ P tinre r)rtrrlr spectrtl fol CI[r]Ig- ltr.ot.onsirr rr rrri.xtlrreo[ CrI['; ItgCIIr (0.2{ J1) lnd CIfrllgCJIr (0.:,1{.lI) irr rerrrhr.drofrrrun_ echer (ti"[::itiby mole f i). The pre-exr,hlngt'lifetimu r referst, c', 1.5 the nrethvl grorrpsof the mi.rerl o re&gent. _)

thc rrbsc'r'v'lti,rr ,rf thc nrnr n)eIhvl sigrulls rr.ss,ciatetl \vitil rhe tw'r)s[)c0ies nn(i to pcrnrit e:rlcrrlltiorrof pr.e- o\cilungeliietirnt's rrn(i exchurrgenrtes (Tlble \-IIIt. 1'lie'p,sitirn ,f the erlrrilibrium(ur1 l6) \vls ols()irr- o.5 flLrencedb'the I)resencc,fthc diunrine6 -srrchthat the 4.O concentrutiorrof the mixed re'lrsentwirs dimini.shed. 4.5 5.O This observttirrr presumirbll' reflectsthe flct thlt at lel.{t ()neof thc' s)'mmetricl,lreagents is nlore strongl\- t/T x tO3 solvlted thun tl'remixerl reilgelrt Fig.re 7'-PLrt rf log (l/r) as a functi'rr of L/T f'r ,\, (o.17 In rlr) r.rr*rlrg.rrsn',,r,,,',or, mixt.ures,rf ciipirenl.l- C;II,flgCIIr ll ) and CIIrllgCFIr (0.094 .11) in er,her_ tetrahvdrofrrran-triethvlamine (2d:,i0:2{ nurqnesiunrllncl rlievclopentaclierrvl nlrgrresitrm (3) were by mole %); ll, C'H'\[gCilr (0.2{ J/) rnd CHr}IgCHr (0.2{ -}I) in tetrahr.rllr,- found to t'ornru nrixeclrertecrrh (er1 lS) u'hich cr1.-stu,l- (6.1:;lfi frtratr-ether b1- m,rle ?.). The pre-exchange liferi.rt, ,- lizecl fronr :ur ether-tetnrhvrlrrfrrr.rrn nrixtrlre rrs the lefers t, the r'ethvl group ri the mixe

llt()tronterir: (111y1;11r'crrtrnol u't 1.07-1.11 X nrorronrt)r). Theseob-servttiorrs lelrcl rrs to .suggesfthe structure irr- Ph /O rlicateclirr 7 for this srrbstlrrce.st,\s rvasthe c:.rserr-it lr -L -lti-o:) Phzllq - 1uls (1s) the' nrethvlevclrperrttrlien.r'lrelrgent 4, the e.xchlrrst, l- Etzo,THF I of cvcloperrtlclierrl'lgroups betu'eenthe pherrl'l nrixetl <.A=t retgent 7 urrcl tliel'cloperrtadienl'lmugrresiunt(3) \\.ir). \\zi 6 sufficientl-r'slorv rrt low- temper:.lttrresto permit tlr- 3 termirrl-rti,rrof' pre-e.\ch&rrgelifetimes (liigtrre ,\ rrrrrI Tlble IX) arrtirates of exchrirrge. Ix) for the c'ckrpentadie.vl protrrs of this reu,gerlr As had bec'nthe else w'ith the methl.l pherrl'lrerrgerrr \\'r..sshifted dorvrfielcl rvith respectto the corresponding 2, adclitirrrof iur equivalerrtumoturt of magnesiun br,- signll for the dicl'clrpentadierry'lreugent 3 as would be mide to the mixed c\-cloperltaclienl'lrelgents 4 tn T e.\pectedfrom the decreuserlshieiding br- the phenl.l led to ,solutions'u'ho-*e nmr spectra \r'ere consist(,rrr ring in the mixerl rerrgent. A 0.2(iJ1 srlution of the w'ith the presencc,of cvcloperrtudien-r'lnugnesiumbr..- mixetl relgent 7 in tetruhl'droful'r"ur\\'us frund to be nriclelrncl t:ithe'r nrethl'l- ,rr phe'n.r'lnrrrgrresirtnrbrorrrr, i.. .-\ucusr 1$67 THo CHSIIISTRT*or C.rns.r)iloNs. XIII

' T.rsLe I\ |i.r.lrsrrr'|.].rt.tt.ts(ll.:()t,'(.)r.r,t.r|l'EN'r\DIllr*\.I,(llt()UP;I).ion<;.t.rrl\|F;T.\l,LlL'l[tsruttBsCttx'r.rt.rtx Typical valttes -,\rrhenitrs parlmetercr- Solr-ent, conll)n, Te mgr, Ior l,/ r, c/,t oC -l Itetrqents (concn, molesz l.) mole ser: kcal/mole J .!rt - a ') +tr.tt0.{ C6[-Ii]lgC;[I'(0.!J) + C;II.\[gC'[[;(0.Il) Ether-TIIF .).) .)'t..) I.j.0r 0.6 l0 (6.r::t.1) {; 13; -- - rt'- ')/..) 't.)l .-r.) .) -. CoH;][gC;l'[;(0. ll ) + C;l'lr][gC;H; (().0;.,) TFIF-ether .r- -., (60:.{{.)) Coll;ItgC;fli (0.11) + C;Hrf IgC',[{'(0.0;-r-t) * THF-ether ;i2 ) l0{ " llgBrr (<0.025)" (.:;1):'11) 'The nlethodsused to ctrlcttlate[he dl[l tabrrlrrted&re presentedin the Experimental Section. b This solulion w&s prepa,red by' addinglIgBr.:(EtaO).: to the preceeciittgsolttti

T.\sr.uX R.rrss or Excu.rN(]E oF llntsvr ( Irrrlrpsr:i OR(i.\.\()vur-\LLICJItxtuttBs \T \'.\Rlous CtlxcosrR.\Tto\-s .\T -;;o o Sol vent 'r cornpn, I r for the C'llr srorrp I f or tlre Cl{r grorlps -.{,rrhenlus Parameters- -r -t L- -ftgsggng e,)nen, rntiles,l.- erher-TlIl', of CHrJlsCrtls, sec of Ct{,}tcCl[r. sec LAt (76 (.t.\IsCr[lr ('l{rII((.]llr nr o le Olrsrl Calcri' Obstl C.r lctib kcal mole --t ().:l'l 0. t(i {i7:;iii l;{) l:lli l ')0 I?S l-1.:,1+ l.l l017.lr l.r 0.I1 o.0.i; (i7:ii:i {u ++ +1) {{ 13.,r = l).S 1016.{t 0.E 'll -r- * 0.7 ().0.-);i t). 02(i 6fi:ii? 2t 2l JI 12.s 0.7 l0l5,E '' r') l. {).0.1I {) 0;:i 7{:2(i O') a- ')'t- 20 !.) I 0. 0-t0 r) ltili 7l: lS I,r()' Lr)-t ls' Iri tJ! l).j;i 0.1)i2 6s::iJ {;' {: l{)(r .Themethrrt|sllsc(ltl)l'ul('uhtethedatItab|tlxt,edlfePleselltedill!heEIperimentclsectit,|l.b t:S(x),l1_lsell.!."Thesevrrlrrt'srvererlbt:rilredlr1'cllr'rrl.rtirrgthelrithnreti(:nrerrlIl)fvthles:rLtenr[)ertllres

A snurller (:on(tontt'rttiottot' t)ritg-nc-sitlltrbronride \\'t[s uddecl to iL mi.\tltre oi clicl'clol)erltxdienvltnrrgllosittm 25 ( (3) .rrrtl lllrt:trvlcvciollc'tttutlierrvlnurgnesittnl 7) to lelrtt the effect of mitqn(]sitttttllronritle otI tlie ntte of exchllnge ,rf cvclolletrtutlicnl'I grottps. The tLLtl. presellted in Tu,ble IX. indicu,te thut sntull rtntotttttsof nlrtgllesiLlnl lJ bromide itrcrelr,sethe rute oi exchuttgestlhstllntillli'. \ To lerrrrrthe ltinctio or(lcf of ono oi the lforemett- 2A tioned e.\chllngo pr()eesses,the nlte-s of lncth\'I grottp (fl exchlnge betrveett rtimetlivlmltgrtesittnt rrll(l nteth)'l- o cvckrpentarlicrrl'lmugllesittnr (4) \\'efe tleterminecl &t -severcl concelltr:rtions. The reletiott rvus fotttrcl to be -cecorrd()rder over-lll, first rlrder in dimethl'lnragnesium, lnd first order i rr methl'lcvc lopentadienl'l milgllesiLtm. t.5 I;or a bimoleettltrr reactioll. the 111fgt)f exchange of methl'l groups is given b1' 3.0 33 rrte : A'[CI{r}IgCFI,ll[CIJ']tgC-FI,l (11)) C'orrseqttetttlv l/T x l03 Figure B.-Plot of log (l/r) as r funcbion of l/T for C'II,- I 7rcurrt"c'rrr, : A'ICHr\ tgC I{tl (2(h) \[gC'H' (0.22 .lf) and C;II;]IgC;H' (0.11 ,11) in ether-tetrt- : ( I /rr.rr.rrolrr" I A'/'2) [CIIrf Ig(--;l[.] l()b) hvdrofrtmtr (6'-r:35b""" mole %). 'flllle X lists the experinrerrtal vulues nreilsLtreclfor l/r tor the trvo kirrds of meth.r'lgrortps ut eech cott- componerrtssince irr this circttmstattceI/, for the centnrtion: for conrJlitrisorr.t.he eorresponclingvulues seeonclcomponent rvould be independentof the eon- for theseqLrDrrtities obtained from 20ll rirrclb b1'settinq centri,rtionof the first. Simihrll-, a mechanismthlt 'fhe A : S00 l/-r sec-r ilre also given.33 lgreement was bimolecular in either contponellt would predict betrr'e.errthc tn'o sets of nllmbers is s:.Ltisfactor)'. thrt L/r for that componentwould depend upon it.{ These rlte (lrtta clel,rlv do ttot sul)port rI mechi.lnism o\\'rr e()ncentrrltion; t his preclictionis rglrin not irr ior the exehurrgervhich is zeroorder in either'one()f the ilgreemerrtrvith the datr in Table X. Consideration of both these restllts alrd the afore- (;t;J) Tlris ralrre rrcs r-rbtainerl sometvhei arbitrarily frorrr the .\rrhenius mentioned retardation of exchangecaused by the addi- parameters obtained b-r' examinslion of the temperatrlre dependence of a (i.e., soiution 0.053 11 in nreth)'lcI'elopentadienl'lnragnesirtm sntl 0.02ti -l/ in di- tion of substances 5 rnd 6) rvhichserve as effective niethl'lmagnesiurn (thirrl entr-r', l'allle I). Uncertrinties in the concentra- bidentate donor ligrnds suggestthat the mechanism rlons of these solutions, togetlrer rvrth significunc virtiations in solveot com- illustrated in ec12l and 22 is rpplicableto this metal- r,losirions.rnake it rliflierrlt to clroose n single valrte for l s'lriclr rvoulrl fit all ot the solrttionsitt llris t:r!rlr'. metll exchrlltgeprocess. ,\ ntpicl preequilibrium in- HOUSN. I,,IIrIITT. AND WHITESIDES Vor,. jll

o 30 M[( cH])!;CHrC!rl. v, rrr : :u\{ f : :. . :f,L vq rr'lrctlrerthc Irvo nrtes lre etlrrivalcrrb(i.e., l,:, 1,,, Ol5M.lC!x1 !vq ('xch$nge n'ith irrversiorr). By' examining the r.rtft, ,rr cxchtnge oi clintethl'lbrrtl'l !{rolll)r.i(eq 2:l} bet.ivccrrtlrt' svnlrnctt'iclrl rleriv:rtive 9 lll(l the mixed relrqel)l l0 (,o t- l(CHr)rCCHzCHzlzNIg + -29' 9 i" 16' ;-\/+v- \aq'a -aa' /. 'r"'r".',t- Jr'r'. \--- o | . ' .a.i A J.t 3 ..,a.;.,/ L 50' **/l*.v'}l:.* - ,1..r,,r,.,.,^, *^y\^,,'1. -; i'V*" 2rCHr) g-€ .r. /' .' jt.-,-- -56' rCCHzCHzl\I i i'r*'r.' .*\ '\tu\\-" ':- / ,,i v -a7''/' \- *.F? \*. 2a cps l0 (cH3)3ccH2cH2 Fiqrrrel).-Obserwed (C') nnrr spectl'1,for the CI{:}tg protons of bi.irij,li-rlinrethl'lbrrty'l)nragnesirrnr(().:]0 ^11) in ether-rerr:I- i hvrirofrrrlrr(sl):ll b_"*mole c,i) a.rrdfor l nrixiureof bis(:J,ii- [(CH3)3CCHzCHr]zlVIg+ rlinrethvlbrr[r'l)nragnesirrnr(0.i]0 ltt .]/) end dicl'clopentrrclienl'lmag- 9 I rresirrnri().1.i .l/) iu tther-tetrahl'drofrrran(Sl:lg by moletl). (6) \v volvitrs^rii-ssoei:rtiorr of orre ol'Ilrol'e i()lverrt n)ole- l0 cules front one ()t the ()l'glnorlllrgrresitttnc()nrJ)()ttlr(ls (CH')TCCHzCH: (CHr)sCCHzCHz {ltrestrnrrrltl.r-t}re rlimetht'lmuqrrt'sirrrn) exltlrrins the' I I t'lIte tlcpt'ession,rltservccl olr :rrklinrl the che.llr,ting ltg Mg t23r liqlncls l,J-rlinrethoxvethrLrreurrd \,\,\',\'-tetnr- I nrcthvlethr-lcncrlirrnrirre.r{Sirrt:e rlettils,rf the nlothvl (CHs)rCCHzCHz

CHt..-- CH3\ - .ORI- fasr (srrnrnrurizerlin i"igureU), it is irpplrerrtthat €xcirurrgr, cHr'-]19--o*, oi rlimeth.r'lbutl'l gr()up:j is substantialll' fnster rlrrrrr CH.,* the rltte of configrrrlitiorurlinversion. Conseqrrenu\.. the exchullgereirctiott ,rcctlt's rvith 1s1911ttorr cH3\ I ra Ie Jrrintlrril-l' -ltg---oR. + t\lg of configurlIiorr. limiring cH{ I The l,rrv-temperlturesl)ectrum observed for the nrr.r- ture of 9 und l0 consistsof trvo similar A'\'X\'- o t)'pe mrrltipletssep:]rcted br,' ?5.E cps. As the rcrrr- pertlture is rai.reri,these first broaden and colllJtsc t,r cHr -IIg€ uHr CH.* orreA^.\'XX' spectrum as the ehemicll-shift I;V I differon('(, cH3iltg---cH3'v =aH)lr*-.-o*,+ ^)lg (22) betrveen9 rnd l0 is averaged bi' intermolecullr tr- chlnge. then colllrpseto an ArX, spectrumos inygl'si.rr RzO I of configuratiotl at the CH:fIg group becomesrulrirl. 8 Although the conrplexitl'ofthe Iineshnpes in the intt'r- meclilte exch&ngeregi()n milke detailed rate etlcrrlrr- e.\ch&ngestelt lre rrot knrlrvnin this crr.\e.tve hirverepre- tions difficrrlt.it is clear thlt correspondinglines irr the sentedthe'exchunge of methy'lgroups a-sthe cust()m:_rr\- multiplets of 9 rnd l0 e()rlleseelt &pproximatell'-l()'. four-centerprocess 8 proceedingrvith retention eon- of Hence rt this temperatLlre,the ra,teof exch&l)r{{r,rt figuration. rrlki'l group-sis tpproximttell- 57 sec-r. I,'ronr tlre To ol-rttirrnrore inf'rnrltiorr llllorrt the stereochenr- knorvrr Arrhenitrs plrranretersfol the inversiorr re:r(,- istrl- of thi-r ste[). \\'e huve e.xunrineclmixtrrres oh- tiorr.{st}rc itrversiorrrtte ut this tenrlterttrlrec:ur lrc trineci fr'rn bist:].:J-climethi'lbutvi)mtenesium(9) rrncl estinrltcrl to hc llpl)roximirteIr'10-3-10-'r i(,(,-i. dic;'eiopentrrcliertvlmugrresirrnr(3). Irr ether solrrtiorr, Corrserltterrtl.r',t'n thi.setantple, the ru,tcof irrversiorr,l the clinrethvlhut'lmugnesiumderiva,tive urrclergoes 9 l configttrlltionis slorverthlln the rlrte of e.xchar)gr'Irv rr relativell-sIrirv irrversiorr of eorrfigtrrrtiorrat the carbon fluctor of 10{-10'i. Whether the retction leudinq r, &tom lr(ljircerrtt, plilgttasirrnr,r'e(lrriring u tempenrture exchiurgeis related to thlt leu,ciirrgto irrversionis n,,r of upllrrxinurtelv100" t, give urr nmr -sigrrai *'hieh irr lpixrretrt fr,,rn the rrvuilirblerhrtrr. Bv urralogvu'irlr tl're trvo lrt C-1 hrrve beconree({uivtrlerrl.rd-* I)roton-{ the exehungerelrctiorr betn'een climethvlnragrresirrnr rtrr,i A questirrrof irrtere-stis rvhetherthe rote A'eof exchlnge nrethl'lc1'ekrltctttrrclienl'lnraqne'siunr,the nrte ot' ('\- of dimethl'lbrrtvlrrorrps tronr one mlgrresitrnrutom trr chatrgein et12il is prol-rablvconcerrtrution deperr,icrrr. rrnother is nruch laster thln the rute A; of configunr- B'n'eo r rt r:rst. Roberts lrrrdWi t llrrow'-sk\'{,{ have obserr.'r,ri tirtnll ittversiotr(i.e., l,:" ) A'i.exchonge rvith retention) thal the rllte of inversiotr of eottfigttratiorroi lri.- (3{) In etlrer-tetraht-,lrofrrran mi-rtures, \r'e l)resrrrne tLat the bulk of the (3,3-dimethl'lbut1'l)mtgrresiunrirr ether is iudeperrrlt'rrt magnesium species are coorrlinated l'ith tetrairydrofrrran rather than etlrer both of its eotrcentrltiottattcl of its methoclof prellrrrt- in vierv of the fact that the te[rahydrofrrran solva[es are favorerl ar equilib- tit.rrr. (Irr this dillk.r'lmugnesiumc()rrr- rium; see O. .\. IIollinssrr'rrrtlr. Ii. \\'. Srnalle]', anr.i S. K. Podrler, Inor0. tr)rirticulitr, Chen.. 3, J:l'J ( lgtj{). potrntlgrrve the sume.Jl)ectnt irt'espcctive of 'whetlielu 'f '\ucus'r 1{)67 Hn Cnnlllsrltr oF CTRBANIoNS. XIII 2+9:j

the ot'getrometallir' w:.ISprel)irred frsnr the ctlrresprlndittg C-irignarclreagellt lr). treltirrg etherell srtltttiotts rotttairtitrg l.e&ge1ts ald a1v specified additives rvit.lt excess 1,2-dibrom()- bv precipitatiorr of mrrglesium chloridc rvith dioxolle or ethrrne l11rl thett stirritrg the soltttiotts [ot'tlte relctiolt limes antl 'lhe from the cliullt.r'Imercrlr]' compouncl bv tr:rnsmetallt- et the relcti<-rrt temperrttllres spet'ifietl . resrrlting soltttit;ls tion.) It rt[)peurs possible, therefore' thlt excha,ltge were qltelrcherl irt lI ktl()wtt ex(:ess oi sturttillttl ltqtteouS hydr,l- Lr,ntlinversiott ntl.r' tltltc pltce bv reltctiotrs h:lving clii- r,hkrrir. lr.id. .\f ter I hese mixtttt'es lntrl lreett satttrated with .otlirrrrr t.hkrt'itletto intplove the errti poirrl), thel' were titrote(l ferettt ltinetic ortlers. w'ith strrrrtiut'ti utqrtettlls s()(littIIt ltvt'oxirlt: to l llhenophthaleirr of the sltectru of i.'igtrre I rvith tltose C,rm11rrisol errtl poirrt. Itr t:lnes n'ltet'e ltttitlt-.i.e'l ol' lltt' stlrtittg Orglno- published previottslr'{* indiclte tluit the temperature nrerullit'r'eagent. itrtlir,'llteti tlte preseltt'L'ot :oltle:rlkle'. This rrgreemellt provides ldetluate jrrsti- tional ltase rvhich was Itresellt. A soirrtir.rrrof Httorette itt ethet'\r'iL- treltte(l lvith excess etherell ficatiorr for ()ur use of lLobert's iitrd Witanorvski's meth)'llithirrnr t9 give rttt ol'cllge.olrlliott rvhit'h rvas 0.39 JI irr rtrte rlf Ctlttfigttrl- irctivlitiott plrrlmeters to estiniate the t)-flrr()renvllithium and t).1)7J/ irr nrethVllithirrnr. The nml'spe('- tionul ittversiott of bis(:1,:i-tlinreth1'lbtrt1'l)magrtesittnl trtrm 1;f this sr.rlrrtion lut'ketl iI[)sorpt ir.rrrrtttriltrttable to ttnitlnizet,l tt - l0o. Httrtrene ancl exhibitetl, irr lrdditiori tr) perlks trftribtrtable to ether' rrnd merhvllithirrnr, peaks rtttt'ibrtrrtblt' to flrrorenyllithittm.3i 3:' The spe.rlrrnr h1s t,,l'o Ltrv-fieltl rl,,rtlllt'ts t./ : I cps for each ExPerimental Section rvirh firrther syllittilg irpplrel)t [)rtl ll{)t te:olveti) at d 7.42 (2 H, ('-l to the I rrrrti s trttd to the 4 and 'l Preparationof Reagents.-Ethelell s,ltttir-rttstli methy'inrag- rrnd 7.1)l) [{t lttrillrrtable r,f the'l)-Httorettvllithitrnr. Itr rr,ltlitiotr, the 9-fltroren1'l- Iresitrnr ltrotttitle. rlinretlrvltrrlgttesittnr (f t'ottl tlinlethl'lmer(:ttr\'), I)r()torrs iirlri,,t,, :|)egrl'rrilr hus rr perrk rtt A .1.51 lt Il n'irh pertiall)' re- cliethl'lntrrglresittnt ( frottt rliethl-lmer'(fttr!'), prhertl'lmagttesittttt :olvetl:plittirrg (./ < I ,.1tst,C'r-ll ,rlr,l rrrrrltillletscentered 11t bronririe, rlipherr-r'lrrrugrtesitttrr (f rottt dipltetrvlnter('ltr\'), irttrl ('l l,r llte pt'otons positit,,tts plellttl'eti , (i.1)Srl IIr rrrrrlti.ti Ilt rtttt'ibrttllrlc lt ttrlgtresittttt ltlr,nritle (frottt etlt-r'lerre tlilrlolrlidel \\'el'e '['tre tttttltilrlt't.. ertrlt ol rvhilh hus the grgs- ,,I orglt'ttotttltgtte.irttttl'elgerlt: :. ;i, t;, rsrtl 7. lrttter Its 1l1evit,rrtsl1'rle.t'r'ilretl .2 litrtrlt tlte Irl)[)ety'tyt(.r'oiit I rilllet oi clo.ell':l)rt( e(i rlortlrlt't-,llpl)e&l'to resrtll 1.ls hlter.erltIr'orrglr lt (]elire fiItel sttsllerttletlott rt.iltlet'etl-glrts. 'l'lte lr'(,IIl('()ltlllirrg ('olttrtllllt vltlttes ot \.1), li.'l, :rtrtl1(l . I (:pS. f tttttrel itrtrl lt :it()l'llge lrrtt'et. otgltttotrretitilir: lellgelll.\ \r'ere Preparation of the Methylmagnesiunr Alkoxides.-The methvl- eirr.hstarrrlrrrrlize, l lrv lrrr ircitl-l.ut-efitt'rtl iotr. Irr rrritlitiott, rlttr trrrrt{pr.,:ipptrrlkoxitle sirtttllles lt'lto:t' 111111'l)r'r'tlir ilfe stttlrnrat'izetl lrret[,r'l r'(.rrgent:\r'r]r'e -tlrrrrllrrrlizerl llv tertt'(iott rvit]t tl iltrerhvl- lrv lrl,iirrg tlrt'itttlilltletl ltnltttlltts,l' lrt'glr" r'ltrotttrttoglltplrir':tltltlt'-i..]'t irr'l'llrle V rvert'olrtrrirrerI lrherrvl-il_r'lclrl,,r'irIe follorverl 'fl,",tt,r,{,,".irttrr ll'e:hl]-riistillt:rl :itnll)le>,ri li-tttr.t11l'l-:i-1rt'rrt:tltol,lj-perttlnotre. lrt,rtttitlt \l'lIFI)ttlifi('rl lrv telrelIle(l I'(f('l'1'stllliz:t- r)1.l-trrerlt-r'Ir.-r'r.lsltexlttr,rl ls etlrer' .,rlttll,,tt- 1,, soltttitltts rlf tli- tiorr florrr et lrer'-l)enzetr()rnirtttt'es. .\tt t:tlrttt'lrl .,rltttiott ol'tlti- t-'ilhtlt' el lttr' ()r' t'lltt't-tetrthl'drrlfrtt'lrrl st tlizetl llv lt volttlllel l l(' nrerlryltrtrrgtte.ittttt irr llrrr.ifiettnurgrresitrrrr lrrorrritle 11'11.rtrrrtlrrt 'l',r rrrixtrrle:. ulrtlritt lltt' rli(.i-rrrctllll-.i-1rt'rrt()\\')n)trgllesittltr ittr,rl-t'.i.tlr lrtr,trtirie it,tt. Ii-rt'c1rtitt t'etrltirr :lrecifictl [)le[)rIl lt- :l!1rl)l()errrl-rlovr:rl, lr solrttiott ol'ii.(i trrtrt,,lt'-.trlirrrtltltvlnugnesirttrr Ii,,rllrk ( lrigrutlti-grltrletrtltgttt'-ittttt tttl'tritrq- tilrr. rvlrt-.r.el,jlr-rrrltrr (l).ti rrr IO rrrl of ctlrt-,r'\vtts ll('i.Itctlsllt ct'::lvtlr- *'ttlt trvtl t).i37-g rvele etttlrlovtrl, tlttt trtlrqtresitrtttttletltl rt.erl itr tlris.ttltlV wiut tt"eti rrrnrr,[er ii-trtel[11'[-ii-1tt'rrtlrltli..\ltlrorrgh rrll the mlt- as trrr.rrirrq.slrorrr rr sltelilrl sirrrrlrltrr,i triltlv srtlrlinretlntlgltesitttttr! I)()r'li,,rr-,,i rrr irrl r.cntrrirrerlirr .oItttiotr lrl'tel tlrr. rtrl,Iiti,rrr,,I the fit'st nlolt' ;l-JIetht.l-ii-lrerrtrrrr0l \\'lrs llr.eptr|eti i!: pt'eviortslY tiest'rilretl.?'t r.rlrrivlrlerrt,rf tlre lel'tiltl'\'rtlt',,it,,1.:rrirlit1,111 oI tlte seCond nrolt: I:t[e;elrl .olrrtiorr-,rf Inetltlllitllitlrrt rvt't'ttllt'elrlrt'erl l't'ottt rltetlt.r'I ,:,irriv:tlerrri'c.rrttetl itt tltrl sellltt'ltti,tt r,l :r rvitite srllid w'hich rvru* llr.ourirlelurtl exr.r,.-[ithirrnr itr tlte tt.ttltl rvlrt'. .'\iter the solrttiott- irr.olrrllleitr etlrct'lttrtl itr tel t'lltvrllr)lrllitlr. \\'lrerr l0 ml of rltl hrrtl beerr filteretl, Ilrer' \r'ere :t uttrllrtrrrrples of methvl- prior ro rrse. -,\rr ethererrl solrrtir.,tt of bis( ii,il-tlirrlethvlbrttf i)- (, r I ller rvicl'tliopeII tadienv l- ,rt mr;re thatt r,-r-cioperr t rrtliet rv lnutgttesit rtrt + rtttr 1l rrl&gllestrrnr wrL\ [)lel)Dl'etl lr-r' the lttltlit,iorr .lig]ttiv nragrre-irrrrr (7) rvere rli:.rolvetl irr tettltltr-rlt'ofrtl'lltl tllld illiqttrtts I ni,rle erlrriv ot'tiio.ratte t() rtlt ether soltttiott of :i.i-dirnethl'l- ,rt the-*esolrrtiorrs wele h\'(lroIr'zeti rrrrritittlrttttl [ot'total base trr btttylmltqtresitrttt t'irLrt'itle ioll,,w'etl llv cetttriirtglttiott to sep&rilte tleternrirre the rorrt'etttt'lttitttt ol llle rll'gltllorllet&llic srlltttir-rtrs. the inst-rlrtblenrlrqtresittttt sltlt.. rvet't: itr otte &l'm ()f 11I!i.',- Reagents with 1,2-Dibromo- The 9r'glrttorlletillli('soltrtiotts lrlltt'erl Reaction of the organometallic ( thernrll tlistiIlttiorr lIp[)tt.l'lltlts( Stierltrfir' illt.-. Apparattts Ctr., ethane.-'flte rttsrtlts stttttrtlitl'izerl irr Tllllle III lvere obtlirted Irrr.., IlLronrfieltl. N. ,l .; urrti tet nrii\-(ll'otttt'ltttsoltltiorts cont&irr- rt.ere tltlne (:l5r .\ll preparuriorrs errrt trttlsfers r)f orgun(rnretirllic reagerlt!, irrg krr,)\\-lr (.()ll('etttrltiotts oi llhetrrrtrtltlettt: \\'el'e pla('ed irl the t:tlrrectetlantl ull bt''iling rrnrler a nitr()gen l!tIIlrrslrllerP. .\ll rneltinq I,()intslrre :8(:olr(1 rlfnr ot the ttpl)itl'lttlts. Itt tllt,'lI t'li-e, tlle &ppar11ttt: 1,1tlterttisest11leil' lltugllesltltrl sttlfAte las -50'. u1-1intsare lrlc()rrectetl. L'rtles" corr5.1irrirrg the :9irtti9rr.s \\'tl.i rleqlt-:etl lri' ,'9,rlittg to 'l'lre rlcterminerl $'itlr prnOluVprlls t,lrVtnq t{ent. infrarerI spectr& \lere I evltcttiltilrg, lttt(l l'e\\'ltl'n]itlg f() l'or)n] letll[)ellltttre. After thtl perkin-I,.lnrer iiJi infrurerl recorriinq spectroplro[orneter fitted $'itlr u Jlo,lel tu'o ltr-ltlitiorlol times, th(' ^\Iorlel tlegu>sirrq'1r.,,,,".. hud lteerr repelrteti gratinu. Tlre rrrrrr spectrc \\'ere rleternlinet.l at fi() \lc s'itlt a I'Arian prr)l)e -r'stenr wl.s r:o()lerlt() -\'( )o, evlt'ttuteti, .-eltlett. ltltd thett allrrverl .\-tiu nnlr sl)Pctrrrltleter, erlrtipl-re't rvitlr rr' \'-ti0-lo vSrirllle-tetllperBtrtre tlte volrttrreol':oltrtiott irr each &rnl ('l rnrl contr,rllt:r' Srreelr tvirltlrs rrere t;ulilrratetl rtslng u I(roirn-[lite \Ir'rrit'l to erltriliirrute lIl {0o rtrrtil 'l'lre rvls pert- (.ottstllrtl. .liiO orciilator. fre,lrrenr.r'()utpilt 0f tlris osctllstor clteckerI the ttpJ-rarlfrts t't'tttirittetl .\t lert.it.t$'o tletertnitrltittrr- rrsirrqI llerr lett-[)trr:kar,l .\[urlel 52-l(' eler:trtrtticrruttttter. Culil-rru- utlicallr. ( {:t7) .1. .\. l)ix,rtr, ['. .\. ( lrvitttter,utrrl I) tign,rf tlle telll)(.ruttlre ('()tltr()ller lras uct:otttplislrettb1'tnetsttritlg lreAk 'l'lre pt)stttuns l:l;1) ( l9ti.-)). selr&r:rt1)1s ill :t ttlellr:Jnol rtr e(llvlette Xlt c,rl sAtrrl.rle. tttttr lreUk ('urlturvsx srr'- ittterns'l (:lU) -\ gus t'ltrtttttulo&rulrltv coltrttttt pltt ke'l rritlr J0 )l' urr: e.r1presse,lirr r,-rt:les lrer set:9tt,l :rb(,\'c telrBrrtetlll'lsillne :rs Utt ri'i' us Urr urt ('lrrotrtos,r.1, l) rtas etttlrlovetl f'rr rttrlr:i' stilnriar(l or irr ,i Vlrirtes{pArts per rrrilltorlrelsttl e ll) letrtrtlletllr'lsilUrte l,entle(l (:r1)) generll errrlrlrr\.e,iis,lescrilreri lrr'.\. stelerttrark. {tun(lurrl). [,'ttless otlterrrise Itoterl. all nrutrs spectro rvere rleter- Tlre l)f()ce(lure inrernai " ( "Qrtantrtative ()rrlattit' Jlicroarrlrivsis lllekist'rrt \ery York' N \' rnine,i rrrth l ('l'i(' JIt,rtlelI l- t;t{) lllirss s[)ecIrotlre!er' "1 (l9tj()]' 1951, prr !',1'2-2u7. i:fti \\'. .\. llurlrer ltr,l \\'. 1,. .l'rll.v Irtctrq' Syn ,6, I I Housp, Lrrrt.r.rr. AND WHTTESTDES Vol. ;l-

T.r.sr,B\I \ rrn SpocrR.\ tlF ] [ t xrunes Cov'r.u s t I c Pue.v r lc yc Lop E NT.\ D r E f,i l- r.\r \(;\- E$t ull Clremical shift do*.nfield f rorn rnternal Tf IS (banrl *.rrltlr ar Itea(ents {c()ncn, rnoles; l.) , rc Solvent, nole , half-lreiqht,dcps Lrll,.\l((-;ll; tJ. ltir THF 36(i :]65.;' 366 ('qll']lqC:ll; r{) 2{) f \lgBr1 (ca.0.?6)" TIlF-erher(92:S) :164.; ;i65 (,'.11,-\lgC;H; (0.05,;) 1().il) * CrHrlIgCsFIs TFlF-ether(60:40r :;(itj.; (;1.8),3.:r2.5 (4. rir :t{i6( (1.0 (_',1{,}lgc;lI; I .0),3-18 r i0.n) + ciHs}Igc;FI;(0.0;4) + THF-ether (.:rg:-ll r ;ili;.; (0.7) -\lgBrlr<().02i)" (J''lI;)IgC;H;(0 22) + C;H5\[gC;H;r0.ll) Ether-TFIF (65:;l.i r ;i67(;1.2 ), 3;2 (3.I ) ' I:t cl--esn'here no band width at half-height r,'fhe is specified,the vnhre is rpprrxilrrrrtelr'1 r,ps ehemicaishiftfor a t).lt) .1/ :,,itltirinof dicl'clrtpetttadienvlmtrgnesirrm in elher-terrahvdrofrrr:rn(70:;i{i irl- m,rle f.; is ;];t i17..-t"." \ot tll of the magne,.irrrrr br, rmiiie wes -.ohrble.

''r'eredone ior each ()r'gun()metallic reagent strrdied. For. 0.1li r'_r'r'loperrturlienl'lclritinol.rnl) l2'.1-1J6" (lit.rz 123"), rur(l ,lrrr.ti ().()SE?l1 srlltttions of meth,r'lcvcltpentadienl'lmlgrresiurl pherr.r'lfrrlvelre.ntl) ,S?-S2.,-r"tlit.{3 ,q:lo),$.el.e olltained f ronr \[,,- {, irr tetrrrhvclroirrrlrr,the mole,.rilarl rveight r*l're.. forrnd rvere )ieil [,tlrr)r.irt()l.ies.^\ _solrrtiorrof .-rl.l)nrg (0.:]s{ mole) oi brrrz,,_ i II lnti 107, respe<:tivell'. These velrrescorre...[)onrl tq I.()7 alrl ;lhettotte,{r.il Itrg of llhettltrrtltt'ene( irn irrternll startdar.rrr, iur{t l.rt:Jtinres the rnolertrllr rveighr oi the nl()rronrer..Selrrti.,ns 6i I.liJ ntlttoles,ri tnethvlr'-r'r'Lrpt'rrtltlient'lrrrlgnesirrnrin .'r{} prl,,r lriren_r'lcvr,Lrpenturlierrr'lmogne-sirrnr(7) (().ltj .l1r irr tetr.rrhvrlro_ tett'ltlivrlrrrlltl'rtttlrttrl l0 rnl ol ttther u'ltsstirrerl &t l'(x)nttenl[)(,llr- irtrlrttgltve lttolet'ttllrrveighr vulrres of iill? lnrl ii{i, t,orr.esptlrtrlirrg ttrre for'\ hr'. Aiter rhe l'e:rctiorrrrrirrrrle hlrd been hr-rir.olr-zr,,i f ) l.()7 :rrrtl l.l l tinres f he lnolet:rrlrrrn'eight of the solvrteti u'itlt rttrJ(lrl(,()rt: .r,lutiulr r l)l[ \' ,)l luntn{}lliirltttl ,,utnt,,,,i,,,,, rll()ll()nlel'.I'lther solrttiortsof tlitttethvlnr:rgrresirrnr rrrrdmet[-r'l- lhlorirle, t he ot'gltrriclltver \\'ls s(fl)lu irto(1, (.()ntlliled rr.itlr r ir,. :rrugnesirun..;-p11rth)'l-ii-lterrtrlxirle\\'er.e prel-)rrrerl, srlprlartlizgtl, ethL'l'e\l tlrct of tlte ltrlrteorr:l)lllr:(', rrrrd lonr:entl'&t.e(l . -\ :,,lrt- :tntie

hydrazirre irr urlrret-rrr.ssoditurr hydroxide lfforded. rrfter rlistillu- Typicll valttes for totai t)iule r:ottrett[ratiotr and COnCenIr&tl()tI tion, dineolrerrtvlnrercru'\'tBus a glilssl'solid, mp ilS-ilS.'-'o(lit.'t6(l of neopentylmagnesirtm species llre summrrized in Table XII mp lll)'.-{(1"). lLrng with the nmr data for thesereagettts. .{ mi.rttrre of {6.6 g ({).1{ nrt-rie)of dirret.,perrtylrrrercrrrv,7.i10 Becarrse of the &pp&rer)t presence of elkoxide impttrities, the g ({).;30g-at()rtr) of mtgrresirrm trrrniltgs, rJg dr

x lr - tl'ar,t - cu ) - 'l''t'l__ (l - Xrrrr (I - x)rn : -,",I l.) | [(o) Ile I |-'ll I 't tt r I -Ltun - @t - - 7R I" *l L'll

,rf ba^sein neopenivlmagrresirrnr chloritie anri in dinarpentl'l- chemical shifts (ratlians [)er se(]()n(i)chlrar:terizing the two site. mognesiunr was rietermitred llv hvdroll'sis lnd srrbserlrrenbacid- involved in the exch&nge, I.:.{ rrttd 7'.,8are the relaxation lims.r,ri base titratiorr. In addition, the r:oncentrlt,ion of neopentyl- the protons a[ these sites in the tirsence of exchang€,X is the magnesittm species w&s me$srrred b-v adding u slight, excess of fraction of the methl-l gronpsoccttl;-r'ittq site B, and ra is the meen bromirre tu u coid. stirred aliqrrot,of the orql,llometallicsolrrtion pre-exchurge lifetime for the Ineth]'i gr()tlpsat site B. 1(c^,'i. r:ontainingl knorvrr&morrnt of tolrrene(as rrn internal standard). the relative intensitl' of the s|;..ro1ptirtrtspectrttm ab the freqttencv The aliqrtot wls clttenchetlin urlrreotrsanrrrronitrnr chloride soltr- <.rrrrrd 1le indicates thet rttt[r'the t'ell pert oi the expressiott itr tion and e.\cessbromirre wus renloved by reactiorr rvith soditrnr brrckets is considereti. Spectral caltrttiirtions\yere carried ortr snlfite. \:aprlr phue chronrltographir: anllysisrE wus entplol'ed on an IBlt 70$.1 comprtter tnd sDectr& \Yere plotted ttsing rt to deternrirre the anrrlrrrrI of rreopentvlbromide rvhich (.()rre- Cllcomp plotter'. Severul r:r'clesttf contptt'isrtnof observed and sponded to the concentr:,rtion of neopenlvlnrtrgnesirrmspecies. calr:rrlatedspeetr& rvet'ettsttalll' rerlrriretlto aehieve a satisfactorr' An arrthentie sample of rreolrentvlbronride[bp lOi-l{)tio, n:so fit. 1.4;i7,1;lit.{{tb bp t0-1.3' (7112mm), n$D l.-l:t701 wrs prepru.ed llronrinltiorr of neopentvlnrerr:rrlic - bv r:hloritle.16bControl ex- l/r;oy1)ri('rfj : ICH,]tgCI{ll-t e.xp( Ea/RT) (f.], perimetrts indicated that the soltttion.sdid nrrt cot)trrin alkoxides rlf neopentl'l alt'ohol. The solrrtitlns obtaineri from nalpentvl- The kinetic order of the exr:hlttge proces-{rvas established orrlr' mtgnesitrrn chloride u,lso contairretl 2,?,i.5-tetrilnrethvlhexlne. for the exchutrge of nreth-r'lgr()lt[)s betn'een dimethyimagnesirtnt ancl c1'clopentldienl'lmethl'lnrugnesittmin ether-THF solttti,rn ({tj) (a) ll. (iilrnrn rrnrlC. l.'.\\'rislrt, .I.;lnt.. Chem.5o,..,66,;J;}OJ(l9il:J): (Table X) . Arrhenirts p[rratlleterstor thi.srelction were obtaitteii (b) l'. ('. \\.lritrrrure,D. L. \l'ittle. arrtl Il. R. Harrinr{rn, tDi./.,51, 1.18.1(19:J1}); ir lelusl-sqrraresfil ,rf the tentpet'ittltre dependence of the (c) l-. ('. \\'lritttrore rrnrl D. Rolrrnrann. ihi,l.,61, l:r9 I t'19;]9): (rl) R. Crieqee, frorn P. Dirnrorlr, {rrrrlR. Sclrenrpf, Chen. Ber.,90, 1337 (1957). ({7) '\ sus t'ltrr)trtato(nrtrh fitted \r'ith o tlamc ionization tletector anrl u 'fi,. ,'olumn prrckerl rvitlr i('/o .Sl:13()silicone {urn insl)pttrlerlon Clrrom,rgrrb P rr'as ({1r) (u) .\..\l)ru:{urrr, "'l'he Prirrciple',rf Nttclear }[ugnctirnr," etnplol'erl frrr tlris attal.r'sis. ('f urenrlrrn l,rcss. ()xforri. 1961, Charrter l0: rl.r) R. Krrbo, .Vuooo Cinent,, (1958). (-18) .\ gas r:lrrorrttrtol1r*pir]'colrrtrrn pccketl rvit.lr IJorv (-'orning No. 710 Suppl..6, lO(i:t (1g57): (c) R. .\. Sur:k, -llol. Phrt.s.'l, lt'3 :ilicone oil rrtsJrenrlerl .rn ba.*e-rvaslrerl Chrotnosorh I) rt'g,serrrJrlolerl for this (50) .\..\llerlrrrrtl. II. S. Cirrrr.rt*kr' I. l'trus itrr(l R..\. Jleinzer, 'I"!'n rttrll ris. Chem. .Juc..6E :ilSir ( 1966). 2496 exchsnge retes to eq 25. For each of the other exehange re- rhenius plot with a positive curyalure. The reason for rhis actions (Trbles VIII and \), it wBs a^ssumedthat the exc[ange behavior was not investigated. was first order in eech component and on cnalogorrs kinetic treatmeni n'as epplied. This assumption concerning the kinetic Registry No.-CH3)[gBr, 75-16-1; CHr]IgI. 917- otder clesrl-r' he-s n,r infltrence on the values of. E" reported in 64-6; (CHr)2lIg,2999-7{-8; CH3Li, 917-5+-+; (CH3):- these tables; it does however influenee the valrres of ,t. Con- Hg, 593-7+-8 LiBr, 7550-35-8;)[gBr2, 7789-18--] seqrrentlr', ; : the valrres of .-t for e.xchangereactions in solutions CHrltgOC(CHr)(CHrCH.r):, containing Dlltr r)r terr&methyiethylenediamine 13132-19-9;[(CH,CH:).:- might be in C(CH')O 13132-20-2(CHrlIgO) ermr b-r'.vrme fector related to the concentrations and exponents lrtrIs, ; (CHr)-1,1-C6II,,, ln eq 2.i: this factor shorrld not e.xceedl0r. Attempts to obtain 13132-21-3;PhlIgBr, 100-58-3;Ph2\[g, 555-i{--}; 3c'.r!'3rlon psrsmeters for exchange of methylcyclopentadienyl- (CrH;)rFe,102-5-l-5; 9, -1-1{i9-61-8;(CH,),CCHzftsc'1. msgne;ium and dicy.clopentadienylmagnesium yielded an Ar- 13132-23-5;(CHr):Ug, 557-18-6.