CHEM.RES.CHI NESE UNI VERSI TI ES 2009,25( 2) ,228— 233 M ass Spect rom etri c St udi es on M et a1 . hexaf lu0r0benzene Ani oni c Compl e xe s ( M=Ag, Au,Pd,Pt ,Pb and Bi ) SUN Zha ng ,SU N Shu. t a o ,LI U Hong. t ao ,ZHU Qi . he ,GAO Zhe n a nd TANG Zi . c hao , . Be ji i n g Nat i o nal La bo r at or yfo r Mo l e c ul ar Sc i e n ce s ( BNLMS ) ,St at e Ke y Labo r a t o y r o fMo l e c u l ar Re ac t i on Dyna mi c s Ce nt e r o fMo l e c ul ar Sci e nc e , I n s t i t u t e o fCh emi s t r y,Chi ne s e Ac ad emy o fSc i e nc e s , Be o ' i n g 1 00 08 0, R.Chi na 2. St at e Ke y La bor at o r y o fMol e cu l ar Re ac t i o n Dy nami c s ,Da l i a n I ns t i t ut e o fCh e mi c al Ph ys i c s , Ch i n e s e Ac a de my o fSc i e nc e s ,Dal i an 1 1 60 23 , R.Chi na Abs t r ac t The a ni o ni c p r o duc t s f r om t h e r e a c t i ons be t we e n me t a l ( M=Ag,Au, Pd, Pt , Pb a nd Bi )va pou r p r o duc e d by l ase r abl at i on and he xaf luor obe nzene s eeded i n car ri er gas( Ar 1 wer e s t udi ed by means of a homemade r ef lect r on t i me - o f - li f g ht ma s s s p ec t r ome t r y( RTOF- M S) . Exp e r i me nt al r e s ul t s s ho w t ha t t he do mi na nt pr od uc t s we r e【 M C6 F6 ] 一 compl exes f or t he r eac t i ons of Ag,Au,Pd a nd Pt wi t h C6 F6 ,whi l e t he domi na nt pr oduc t s wer e【 M C6 F5 ] 一compl exes f 0r t he r eact i ons of Pb n d a Bi wi t h C6 F6 .The or f mat i on mechani s ms of t he produc t s,i ncl udi ng t he adsor pt i on of me- t al cl ust er ani ons on he xaf luor obenzene and t he C— F cl eavage i nduced by met al cl ust e r ani ons .wer e di scussed. Keywords Ti me- of - fi ght mass s pect r omet er;M et al cl us t er ;Ani oni c compl ex;React i on mecha ni s m Art i cl e ID 1005- 9040( 2009) - 02- 228・ 06 ha r dt 川 ca r r i e d out PES s t udi e s of M2 Bz- ( M=Pt ,Pd, 1 I nt roducti on n d a Pb)cl us t e r a ni ons.Bowe n gr oup[ 2 2 -2 4 】conduc t ed The i nteract i ons of met al s wi t h organi c mol e. cul es are of f undam ental i nteres t t o chem i cal a n d ma. teri al s ci ences.Compounds cons i st i ng of met aI cl us— ters and mul t i pl e organi c mol ecul es are preval ent i n cl assi cal orga n omet al l i c and coor di nat i on chemi st ry, PES s udi t es of M ( Bz) n - ( M=Ti ,Co,Fe,Ni )cl us t e r ani ons.I t i s known t hat benzene mol ecul es a r e prone to bei ng di ssoci at ed by m et al ani oni c cl ust ers.On t he s ur face of ma n y act i ve met al cl ust ers,for exampl e V【 5 1 Pt『 2 6] Nb a n d Rh[ 2 7] benzene can be dehydro. , whi ch coul d provi de useful i nfornlat i on for f ur t her unders ta n di ng som e i mport ant heterogeneous cat al yt i c pr ocesses【 一钔 , genmed or di ssoci at ed,wherei n t he hydrogen at om s are al ways observed t o evol ve as H2 si nce t he reac— . I n recent years. many exper i ment al[ 一1 6】 and t heor et i cal [ 1 7 —20 J i nvest i gati ons on t he i nt eract i ons 0f ti ons a r e t her m odynam i cal l y prefer red.Besi des ,t he s tudy on t he i nt eract i on of t r n si a t i on m et al a n d phenyl was r epor ted.Xi ng et a1 . 1 Z8 1 repor ted t he genera ti on of met al cl ust ers wi t h benzene i n gas phas e have been r ep0r t ed.Ar ment r out P [ 1 2 , 1 3 ]s t udi ed M Bz, + f M = Ti — Cu,Ag:Bz=be nze ne)vi a c ol l i s i on- i nduc ed di s . 【 M pheny1 ] 一( M=Mn,Cu)compl exes .The phe nyl — c oi na ge met al compl exes[ Ag C6 H5 ] 一a nd[ AumC6 H5 ] 一 soci at i on exper i ment s.Duncan group[ 9 ' 1 4】conduct ed ( l一 3) ,a nd t he phenyl — l ead me t a l compl exes phot odi s s oci at i on s t udi es on MBz ( M=Fe ,Mg,Ag [ Pb C6 H5 ] 一 ( =1 — 5)we r e s t udi ed by vi r t ue of PES a nd de ns i t y f unct i onal t he or y( DFT) [ , 们. a nd Bi )a nd VBz by me ans of i nf r red a a bs or pt i on spect roscopy. Bowers et a1 . [ 们 i nvest i gat ed vana. di um/ benzene cat i oni c cl ust ers by i on mobi li t y s pec. t r om et y .Li r n et a1 . 1 J s t udi ed t he di ssoci ati on of For hexaf luorobenzene.t he subs ti t t l t i on of luo. f r i ne f or hydrogen on t he benzene ri ng can bri ng t he change of t he bond st rengt h of i oni c丌compl exes.The subs t i t ut i on of f 1 uori ne for hydrogen on t he benzene M nBz a n d CrBz by Four ier t ransf or m. i on cycl ot ron r es ona nc e( FT- I CR) .Naka j i ma and Ka ya 一 , pe r — f ormed mass spect rometr y and phot oi oni zat i on st udi es on M- Bz c l us t er s a nd t he i r cat i ons ( M=Sc - Cu)as r i ng shoul d set st r onger a ni oni c bi ndi ng wi t h ben— zene— ri ng f luori nati on,but t hi s f act has apparentl y not been veri ied experi f ment al l y.The st udy of t he reac. ti ons of met al s wi t h C6 [ 3 一。 has not been extended . wel l as t he s t udi es of va n adi um. . r ena a a ni oni c com. . pl e xes by phot oe l ec t r on s pec t r os copy( PES) .Eber - Kaya gr oup u s t udi ed 【 ( C6 F6 ) l _a nd [ Au( C6 F6 ) ] 一 Co r r e s po ndi ng a u t ho r .E— mai l :g a oz @i c c a s . a c. c n Recei ved M ar ch 26,2008;acce pt ed M ay 6,2008. S up pose d by t he Na t i ona l Na t u r a l Sc i e nc e Fo und a t i on o f Ch i na ( No. 20 433 08 0) No. 2 SUN Zhang et al 229 compl exes by PES.Dunbar et a1 . L s t udi ed t he reac. di cul ar to t h e mol ecul r bea a m a n d wer e ref lect ed t o— t i ons of Au十 a nd Au。wi t h C6 F6 .However ,l i t t l e i s known about t he possi bi l i t i es f or a ni ons atached t o wa rd t he de t e ct oL mi cr oc ha nnel pl tes a ( MPC) .The r es ol ut i on( M/ AM)of RTOF- MS i s be te r ha t n 2000,s o face of benzene.The cl ust eri ng of f l uori de[ 34 】a n d i t i s easy t o assi gn t he product s by t he m ass spect r um. chl ori de[ , 。 ] i 0ns wi t h s om e ar omati cs i ncl udi ng . some par t i al l y f luor i nat ed benzenes ,has been report ed, and i t i s consi dered that t hese ar e hydr ogen. bound 3 Resul t s and Di scussi on The ani oni c pr oducts from the react i ons of al l t he compl exes not t o be ver y rel eva nt t o t h e 7 z - . bound st udi ed met al sampl es wi t h C6 F6 were genera t ed under compl exes of m et al ni a ons. the si mi l r experi a ment a1 condi t i ons as s hown above. W e carri ed out a mass spect romet ri c i nvest i gat i on The wa ve l engt h of t he l as e r ( 1 064 nm or 532 m )us u ed of t he r eact i ons bet ween hexaf luor obenzene seeded i n o r t f he abl at i on had l i t tl e efect on t h e product di s仃i — c ar r i e r gas a nd met al ( M Ag,Au,Pd,Pt ,Pb a nd Bi ) but i on.The seedi ng of hexaf lurobenzene i n t he cari er vapour produced by l aser abl ti a on.El ect roni cal l y,Ag gas ( Ar )ca n pr o mot e t he gr owt h of me t al c l us t e r s n d a Au have a fi l l ed d shel 1 combi ned wi t h a 5s a n d whose underl yi ng mecha ni sm has been report ed i n t he 6s val ence shel 1 .respect i vel y.Pd a n d Pt have a 4d ” publ i shed paper[ 2 8 ] The r eact i ons bet w een m et al s and and 5d 6s val ence shel 1 .respect i vel y.And Pb a n d Bi orga ni c mol ecul es ca n efect i vel y rel ax t he i nt em a1 have a 6s n d 6s a . val ence s hel l ,res pect i vel y. ener gy of t he pl asma generat ed by l aser abl at i on on Because of t hei r di ferent val ence el ect rons.仇 e do. met aI sam pl e.whi ch i s adva nt ageous t o the f o rma ti on mi nant pr oduct s of t he react i ons of t hese metal s wi t h of l r ger a si ze cl ust er speci es i n t he st ar t i ng par t of t he C6F6 are di f ferent f rom each ot her.The react i on me. reacti on channe1 .Thi s phenomenon has al ready been Observed i n 0ur Dr evi ous experi m ents[ 28 , 3 8, 3 9 1 chani sms,i ncl udi ng t he adsorpt i on of metal cl ust er . ani ons on hexafl uOr Obenzene and t he sel ecti ve C——F The experi ment s show t ha t t he l ower part i al cl eavage of t he hexanuOrObenzene i nduced by met al pr es s ur e of hexaf luor obe nze ne ( <0. 1% of he t mi xed cl ust er n i a ons were pr oposed. gas )f avor s t he f or m at i on of ni a oni c c l us t er s .Ot he r . wi s e,som e byproduct s,such as mul t i pl e hexaf luor o— 2 Exper i m ent al Met hods benze ne compl e xes 【 ( C6 F6 ) 】 一 ,woul d a ppe r.The a The apparat us used i n t he experi m ent s mai nl y pr esent at i on of t he domi nant a ni oni c products i dent i — consi s ted of a homem ade ref lect r on t i me—of- li f ght ned by t he m ass spect u m i r s not sensi t i ve t o t he l aser ma ss s pect r ome t er ( RTOF— M S1 wi h a l t a se r s ys t e m. i ntensi t y a n d t he pressure of car ri er gas used i n t h e The det ai l of the aDpa r at us has been publ i shed el se. experi ment s.whi ch wi l l be di scussed i n t he f ol l owi ng whereL / 1 and onl y an out l i ne i s gi ven bel ow. part s. , The me t a l ( M)di s k t a r ge t s ( pur i t y>99. 9%)i n t he sour ce chamber of I OF. M S were abl ted by a a 3. 1 Product Anal ysi s by M ass Spectrom et ry pul s e d l a s er bea m(1 064 nm or 532 nm Nd: YAG l as e L Fi gs . 1 —3 s how t he ypi t c al ma s s s pec t r a of a ni o— 5 Hz ~1 0 mJ/ puls e1 a n d t he t argets wer e r ot at ed du. ni c product s f rom t he r eact i ons bet ween di ferent va. ri ng t he exper i ment s.The l aser -i nduced pl asma was por i ze d me t al s peci es ( M=Ag,Au,Pd,Pt ,Pb and Bi ) car ri ed by t he m ol ecul ar bea m gener at ed from a n d hexaf a l uorobenzene mol ecul es,r espect i vel y.The pul sed val ve t a a backi ng pressure of about 400 kPa of hi gh resol ut i on Of I oF. M S al l ows t h e exact i dent i . rgon( a pur i t y 99. 99%) ,i n whi c h he xa f 1 uor obenze ne icati f on of t he i sot opi c di st r i buti on i n the mass regi on was seeded.The vol um e r at i o of hexaf luqrobenzene i n of these s pect ra.Al l t he mass spect ra were ca r eful l y t he mi xed gas was not more t ha n 0.1% . The cal i bra ted accordi ng to t he m ass number of pure m et a1 M m- hexaf1 uorobenzene a ni ons generat ed f rom t h e cl us ters. r eact i ons of metals wi t h hexaf luorobenzene were en. h e a n Fi gs . 1( A)a nd ( B) show t i oni c product s t r ai ned by t h e carr i er gas t ha t under went a l ow pre t h hexafl uOrObenzene a n d f rom t he r eact i ons of Ag wi s s ur e ( 10 Pa、i n t he s our c e c ha m ber .Af t e r pa s si ng a Au wi t } l hexaf luorobenzene。Fr om Fi g. 1.we ca n i den— s ki mm er,al l t he pr oduct s entered i nt o t he accel erat i on t i f y four di ferent seri es of a ni oni c com pl exes: a r ea i n t he s pec ros t c opi c cha m be r ( 10- 4 Pa) .The ani o. [ [ V [ mC6 F4 】 一 ,I M C6 F5 ] 一 ,[ MmC6 F6 ] 一a nd [ M C6 F7 ] 一 ( M=Ag a nd Au) ,a n d[ M C6 F6 】一compl e xes ar e do— ni c cl ust ers were accel era t ed i n t h e di rect i on per p en. 230 CHEM .RES.CHI NESE UNI VERSI TI ES Vb1 . 25 mi nant ani oni c product s.The i nt ensi ti es of t hese com- r eact i on of Ag and benzene, ma n y f ragment s pl exes i n m ass s pect r um decreas e wi t h the i ncrease of [ AgC Hk ] 一( 1 —1 2, 1 — 5)a re pr es e nt ed bas ed on number m.These res ul ts are i n agreement wi t h t he t he mass spect u m r whose i nt ensi t i es a r e t he sam e as publ i shed resul t s【 jl 1 . The di ier f ence bet ween t he t he ones of he t domi na nt pr oduc t s[ Ag C6 H5 ] 一 ( 1 , compl exes contai ni ng Ag or Au i s t hat t he number m 2 .Thi s fact s hows h at t t he benzene r i ng i s broken up ofAg cal l reach 2 and t he number m OfAu Cal l reach 4. by Ag cl ust er ani on.W l e ca n see t ha t i n Fi g. 1,t he i n- Howeve ̄ f or t he react i ons of Ag and Au wi t h benzene, t ens i t i es of t he pea ks at t r i but e d t o[ Ag2 C F 一 ( 4—7, t he domi na nt pr oduc t s ar e【 M C6 H5 ] 一 ( M=Ag n d a Au, k= -4. 51 ar e very weak whi ch shows t ha t t he s ubst i t u— l一 31 dehydrogenat ed compl exesL J .and t her e a re t i on of luori f ne f o r hydrogen on t h e benzene ri ng f a- = no【 M C6 H4 ] 一 ,【 M C6 H6 ] 一a n d I S C6 H7 ] 一c ompl e xes vors t he s t abi l i zat i on of t he aroma ti c ri ng. accordi ng t o t he mass spect u m .Especi r al l y f o r t he 70 t ( Fl i ght ) /  ̄ s 90 l10 l30 150 l70 190 t ( Fl i ght ) / gs Fi g . 1 Ty pi c a l mas s s pe c t r a o f a ni o ni c pr o duc t s o bt ai ne d f r om r e ac t i on s be t we e n v apo r i ze d Ag ( A) , Au( B) and hexaf luorobenzene,re spect i vel y The i ns e t i n( A)s hows t he e nl a r g e d pa r t of he t s pe c t r um.( A)▲ Ag mC6 F4 一 ( =1 , 2 ) ;_Agn , C6 Fs - ( m=1 , 2 ) ;・AgmC6 F6 一 ( =1 , 2) ; A C6 F7 ( =1 , 2) .( B)▲ AumC6 F4 一 ( =1 - 4) ;-AumC6 F5 一 ( =1 -4 ) ;・AumC6 F6 - ( m=1 -4 ) ;V Au mC6 F7( m=1 - 4) ・ rA . q l Fi gs . 2( A)a nd ( B)s how t he a ni oni c pr oduc t s Howeve r ,Li u et a1 . r epor t e d t hat t he pr oduc t s rom t f he reacti ons of Pd wi t h hexaf luor obenzene and r om the r f eact i on bet ween Pt and benzene a r e Pt wi h hexaf t l uor obe nz ene,r es pe ct i vel y I n Fi g. 2, t hr e e s e r i es of 【 M C6 F5 ] 一 =l 一 3) , v I C6 F6 ] 一 ( =1 — 4) a nd [ M C6 F7 】 一 ( =1 — 4) ( M: = Pd a nd Pt ) compl exes a r e i de nt i ied,a f n d t he 【 M C6 F6 ] 一com- 【 Pt C6 H4 ] 一 , [ Pt C1 2 Hk ] 一 a nd [ Pt mC6 H4 …( C6 H6 ) 】 一 ( m 1—4)compl e xes a nd t he r e a r e no [ Pt mC6 Hs ] 一 , [ Pt mC6 H6 ] -a n d[ Pt mC6 H7 ] 一compl e xes pr es e nt .Eber — ha r dt et a1 . r epor t e d t he chemi s or pt i on of be nz ene pl exes are dom i na nt ani oni c product s.The i nt ensi t i es on Pd and Pt ani ons,but the resol uti on of t hei r mass of pea ks assi gned to t hese compl exes i n t he mass spect ra was too poor t o r esol ve t he number of hydr o- s pect r a decrease wi t h t he i ncrease of number m . gen at om s i n t he products. t ( Fl i g ht ) /  ̄ t ( Fl i ght ) /  ̄s Fi g. 2 Typi cal mas s spec t ra of ani oni c product s obtai ned rom f re act i ons bet ween vapor i zed Pd( A) ,Pt ( B) and he xaf luorobenzene,res pect i vel y The i ns e t s i n t he s pe ct r a s how he t e nl ar ge d p ar t oft he s pe c t r a ,r e s pe c t i ve l y.( A)_PdmC6 F5 一 ( m l 一3) ;・Pd mC6 F6( m 1 —3) ; V Pd, ” C6 F7( 1—4) . ( B)一 Pt m C6 Fs - ( m=l -3) ;・P C6 一 ( 1 —4) ;T C6 F7 一 ( m=1 — 3) . Fi gs . 3( A)and( B)s how t ypi c al mas s s pec t r a of t he ani oni c products f rom t he react i ons of Pb wi h t ( m=l 一 5) ,[ Pb C6 F5 ] 一a nd[ Pb C6 F6 ] 一 ( m 1—6)a re hexaf luorobenzene and Bi wi t h hexanuorObenzene. i dent i ied,and [ f ebmC6 F5 ] 一def l uor i na t e d c ompl exes ar e domi nant ni a oni c pr oduct s.I n Fi g. 3( B) ,t he f ive I n Fi g_ 3( A) ,t he f our s er i e s of[ Pb 】 一 ,[ Pbm" C6 F4 ] 一 s er i e s of [ Bi 】 一 1 — 5) ,[ Bi C6 F3 ] 一( m 2— 5) , No. 2 SUN Zhang etal [ Bi C6 F4 ] 一 ( 1 — 5) , Di C6 F5 ] 一 ( m l一5) a nd = 231 l 一1 6, l 一 5) f r agme nt s a n d met al cl us t er s 【 Bi C6 F6 ] 一 1 — 4)a r e i de nt i ied,and 【 f Bi C6 F5 ] 一 [ Pb 】 一 ( =1— 1 1)pr es e nt on t he bas i s of t he mass defl uori nat ed compl exes are dom i nant ani oni c pro— spect rum a n d they al l have i ntense peaks.But f or t he ducts.These experi ment al res ul t s are si mi l ar to t hose react i ons of Pb or Bi wi t h C6F6,t he i nt ensi t i es of of t he r eact i on bet ween Pb and benzene,i n whi ch t he domi na nt pr oduc t s a r e[ Pb C6 H5 ] 一 l 一 5)de hy- drogenat ed compl exest 1 5] Nevert hel ess t he di ff e— [ M C 一 =1 — 4,, 2 =4— 6, 1—3)f ra gment s i n t he mass spect rum a r e very wea k ,whi ch s hows t h at t he subst i t uti on of luori f ne f or hydrogen on t h e ben- . rence i s so promi nent t hat for t he r eacti on between Pb and C6 H6 ,t he r e a r e ma ny 【 Pb C Hk ] 一 ( 1—2, zene ri ng favors t he st abi l i zat i on of t h e a r om at i c ri ng. t ( Fl i ght ) /  ̄ t ( Fl i ght ) /  ̄ Fi g. 3 Typi cal m ass spect ra of ani oni c products o bt a i ne d f r om r ea c t i ons be t we e n vapor i z e d Pb( A) , Bi ( B) and hexaf luorobenzene,respecti vel y The i ns et i n( A)s ho ws t he e nl ar ge d pa r t of t he s pe c t r u m.( A)・Pbm- ( , , F ] : 1 ——6) ;▲ Pb mC6 F4 _ ( =1 —6) ;・PbⅢC6 Fs - ( m=1 — 6) ;V Pb C6 F6 一 ( =l 一6)( B)・Bi ? H - ( =1 — 5) ;◆Bi C6 F3 一 ( , , 2 =2—5) ;▲ Bi 卅C6 F4( =1 — 5) ;_Bi mC6 F5( =1 ~5 ) ;V Bi 卅C6 F6 _ ( =1 — 5) . From t he experi ment al resul ts shown above,we met al s or coi nage m etal s wi t h benzene have been can get t he concl usi on t hat t he di st ri but i ons of m e di scussed i n previ ous publ i cat i on【 1 5 , 28, 4 6】 A ccor— products generated from t he react i ons between me— di ngl y t he for m ati on mechani s ms of t he ani oni c t a l s ( M=Ag,Au,Pd,Pt ,Pb a nd Bi )a nd he xa f l uor o- pr oduc t s【 M C6 Fn 】 一 ( =l一 6, 5— 7)ar e pr opos ed benzene are di fferent f rom each ot her.a n d t he do. as Schem e 1. mi nant product s from t he reacti ons bet ween m e— . Ar [ Mm] 一 十( C6 F6 ) ——} 【 M …( C6 F6 ) ]— —} 【 M C6 F6 ] 一 ( 1 ) A r t a l s ( M=Ag,Au,Pd a nd Pt )and he xaf luor obenz ene [ M r+( c6 F6 ) ——} 【 M …( C6 F6 ) ] 一— —} [ Mm] +[ C6 F6 ] 一 ( 2) are di ff erent f rom t hose generated f rom t he react i ons 【 M ] _ +( c6 F6 ) —— 【 M …( c6 F6 ) r_ _ 【 M C6 F5 】 一 +【 c6 F7 】 ( 3) be t ween me t al s ( M=Pb and Bi )a nd he xaf luor oben— 【 M ] _ +( c6 F6 ) —_ ÷ [ M …( c6 F6 ) r 兰 ! 【 M C6 F5 1 +[ c6 F7 】 一 ( 3 ) zene.Compar ed w i t h t he react i ons of m etal s wi t h 【 M 】 ( c6 F6 ) —— [ M …( c6 F6 ) r ! 【 M C6 F7 】 _ +【 c6 F5 】 ( 4) be nz ene ,t he i nt e ns i t i es of peaks of t he【 M C F — 【 Mm] _ +( c6 F6 ) — } 【 M …( c6 F6 ) r 【 M卅C6 F7 】 一 +[ c6 F5 r ( 4 ) [ M r ( c6 F6 ) ——} 【 M …( c6 F6 ) r 【 M C6 F5 ] - +MF ( 5) r agm ent f pr oduct s pr esent ed i n t he mass spect rum are very weak.Thi s i m pl i es t hat t he s ubst i t ut i on of fl uori ne f o r hydrogen on t he benzene ri ng favors t he st abi li zat i on of t he aromat i c ri ng.I t i s known t hat t he bond ener gy of phenyl — F i s 54 kJ/ mol hi ghe r han t t hat of phenyl - H[ 41 ] Some publ i cat i ons[ 一 】show . t hat t he C— H bond act i vat i on reacti on by t ransi ti on m et al s i s t hermodynam i cal l y f avor abl e and has l ess energY barri er than t he C— F bond act i vat i on reacti on. So i f the m etal cl uster a ni ons have not ener gy enough t hey can not dest roy the aromat i c ri ng of hexaf luo— robenzene. 3. 2 Form at ion M echani sm Scheme 1 Possi bl e f ormat i on mechani sms of【 M mC6 F^r ( J , l =l一 6,, l =5— 7)compl exes From Fi gs.1— 3.we can al so s ee ma n y ani oni c ragme f nt pr oduct s[ C6 F5 ] 一 ,[ C6 F6 ] 一a nd [ C6 F7 ] 一 . However,t he experi ment s di d not show t hat t he ca— t i ons[ C6 F5 ] ,[ C6 F6 ] and [ C6 F7 ] ar e t ot al l y ob— served i n t he same experi ment.Thi s f act i mpl i es t hat t he generat i on of these a ni oni c f r agment s r esul t s f rom t he generati on of m etal ani oni c cl ust er s.Thi s si t uat i on i s si mi l ar t o t hat of t he r eact i ons bet ween m et al s and benzene.Xi ng f口, . [ 28 】r eport ed t hat t he C— H cl eavage of benzene was caused by t he metal cl ust er ani ons. The f or m ati on mechani sm s of t he product s For【 MmC6 F6 ] 一pr oduc t s,t he mos t pos s i bl e me— cha ni s m i s t he pa hwa t y(1 )i n Sc he me 1.I n t he cl us — [ M C6 H5 ] 一gener a t ed rom f t he r e ac t i ons of t r ns a i t i on t er i on source,t he met al speci es di r ect l y m erge i nt o 232 CHEM .RES.CHI NESE UNI VERSI TI ES Vl 01 . 25 the hexaf luorobenzene/ argon reagent. The excess As f o r t he bondi ng pat ter n of t hese domi na nt energy,whi ch i s l ef wi t hi n m etal cl ust er s due t o l a— product s,we pr opose t he fol l owi ng bondi ng pat t er n. ser abl ati on or t he col l i si on process wi t h hexaf luo— For t he [ MmC6 F6 ] 一compl e xes ,t he mos t pos si bl e robenzene,can exci t e t he react i on sys tem t o f orm bondi ng pat t er n i s t he i nt eracti on of m etal cl ust ers [ Mm…( C6 H6 ) ] 一i nt e r medi a t e. And t hi s i nt er medi a t e i s wi t h : r -or bi t al of C6F61 1 7, 4 7, 48 ] col l i ded by Ar at om s subsequentl y, whi ch t akes compl exes,the mos t possi bl e one i s t hat t he C6F a wa y t he e xces s ener gy t o f or m[ MmC6 F6 ] 一pr oduc t s, group bonds on t he met al cl us t er vi a t he met al - or breaks down the weak “bond” of t he car bOn盯bondI [ 2 9, 30 , 4 6] [ M …( C6 H6 ) ] 一i nt er medi at e t o f or m[ C6 F6 ] 一,s hown i n t he pa t hwa y( 2)i n Sc he me 1. . For t he [ MmC6 F5 1 一 . 4 ConcI usi ons For【 MmC6 F5 ] 一a nd [ M C6 F7 ] 一pr oduc t s ,t he I n summ ary,the react i ons bet ween t he metal mos t pos si bl e me cha ni s ms ar e t he pat hwa ys( 3)and s peci es ( M Ag,Au,Pd,Pt ,Pb and Bi )va por i ze d by ( 4)i n Scheme 1.Whe n t he C—F bond i s br oken l aser abl at i on and hexanuorobenzene seeded i n ca r. down due t o t he col l i s i ons bet wee n[ Mm…( C6 H6 ) ] 一 a nd[ C6 F6 ] ,t he F at om c an bond wi t h[ C6 F6 】t o f or m ri er gas have been s tudi ed by a ref l ect r on t i me— 【 C6 F7 ]a nd[ MmC6 F5 ] 一c ompl e xe s ,or F at om bonds gai ned f rom t he r eacti ons bet ween m et al s d C6 F6 wi t h[ M C6 F6 】t o f or m 【 MmC6 F7 ] 一and 【 C6 F5 ] .The are metal - hexanuOrObenzene compl exes.whi ch are el ec t r on can al s o equal l y bond wi t h [ C6 F5 ] and di fferent f rom t he ones of t he r eacti ons bet ween [ C6 F7 ] ,s o t he pat hway( 3 )and pa t hwa y( 4 )a r e bot h metal s and benzene[ 28, 29, 40] The dOmi nant ani Oni c possi bl e. The probabil i t y of t he col l i si on bet ween products observed i n Ag,Au,Pd and Pt syst ems are 【 M …( C6 H6 ) ] 一 and [ C6 F6 】i s compa r at i vel y s mal l [ M C6 F6 ] 一compl exes ,a nd t he ones obs er ved i n Pb of- li f ght mass s pect romet r y. The ani oni c products . due t o t he s mal l vol ume r a t i o of[ C6 F6 ]i n t he ca r r i er a nd Bi s ys t e ms ar e[ M C6 F5 ] 一def luor i na t e d com— gas,s o t he i nt ens i t i es of t he pe aks of【 M C6 F5 ] 一and pl exes.The r eact i on mechani sms of t hese products 【 MmC6 F7 ]i n mas s s pec t r um a r e weak.I n or der t o are proposed,i ncl udi ng t he adsorpti on of m et al cl us- pass t hr ough the above react i on pat hways, i t i s ter ani ons on hexaf luOrObenzene and t he C——F cl ea. needed t o over come t he hi gher ener gy barr i er of vage of hexaf luorobenzene i nduced by m et al cl ust ers t r a ns i t i on s t at es ( TS) t of t he Dr oduc t s .The exces . i n t he gas phase.To conf ir m the geom et ri c s tr uct ures si ve energy wi t hi n hot metal cl ust er s provi ded by of t hese compl exes,t he st udy by combi nati on of t he l aser vapor i zat i on is com pet ent t o overcome t he phot oel ect ron s pect roscopy and ab i ni t i o cal cul at i ons ener gy bar ri er. f or t he[ M C6 F6 ] 一and[ MmC6 F5 ] 一compl exes i s now For heavy met al s Pb and Bi ,t he domi nant pr oduct s a r e 【 M C6 F5 ] 一 compl e xes , a nd t he [ MmC6 F7 ] 一pr oduct s di s appear acc or di ng t o t he ma s s spect rum . So t he f or m a ti on m echani sm of 【 MmC6 F5 ] 一 ( M=Pb and Bi)i s di f f e r ent f r om t ha t of [ MmC6 F5 ] 一 ( M=Ag,Au,Pd a nd Pt ) .The mos t poss i bl e f or ma t i on mechani sm of[ MmC6 Fs ] 一i s pa t hway( 5) i n Schem e 1.The heavy met al s Pb and Bi abl at ed by l as er a r e pr one t o f or m cl us t er s[ Mm] 一 ,whi ch a r e i denti ied i f n mass s pect rum .W hen t he i ntermedi t e a [ Mm…( C6 H6 ) ] 一 col l i des wi t h me t al M or[ M 】 ,a n i nset react i on wi t h t he cl eavage of C— F bond t akes pl a ce,a nd t he pr oduct[ MmC6 F5 ] ~yi el ds wi t h r el ea — si ng F at om .The F a t om can bond wi t h M t o form M F.Thi s cl eavage of C— F bond i s not easy t o t k e a pl ace due t o t he hi gher bar ri er of t ransi ti on s t a t e( TS) ,a nd t he e xces s i ve ener gy wi t hi n hot m et al cl ust er s provi ded by l aser vapori zat i on pro— mot es t he f or mat i on of[ MmC6 F5 ] 一compl e xes . under way. 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