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1、金属有机化合物的基元反应一般有四类基元反应1配体的配位和解离反应2氧化加成反应和还原消除反应3插入反应和消除反应(反插入反应)4和金属络合的配体被进攻的反应插入反应与反插入反应插入反应为不饱和键插入到M-H,M-C之间的反应。它主要有两种类型:1AB分子插入后分别与金属和R基团相连。2AB分子插入后A同时与金属和R基团相连Definitions;MigratoryInsertion-MINumberingdescribeswhichatomsoftheinsertedligandarebondedtoMandXaftertheinsertionOppositeofins
2、ertioniselimination(or“deinsertion”inUSA)A=BisoftenCOA=BisoftenanalkeneDefinitions;Elimination-EThisisthesameasthelastslidewitharrowsgoingbackwardsNamedbywhichatomcontainsthemigratinggroupUnfortunatelytheterm“1,1-elimination”etc.israrelyused,eventhoughit’stheoppositeofa1,1-insertion!1,1-
3、MigratoryInsertionanda-EliminationStereochemistryatcarbonConfigurationatastereogeniccarbonisretainedSameappliestothereverse,i.e.a-eliminationCO的插入反应:由于CO和金属配位,金属的d电子向CO的反键轨道反馈,导致M-R键的削弱,同时CO中的碳-氧键也被削弱。插入反应这一过程有两种可能的途径1CO插入到M-R键中2与金属相连的R基团迁移到CO上1,1-MigratoryInsertionanda-EliminationMechan
4、isticquestionsTheabovereactionhasbeenstudiedindetail,andmuchisknownaboutthemechanism研究表明是按R基团迁移的的途径进行的R基团迁移不可能得到4,研究表明产物1:2:3的比率为1:2:1,而且没有4生成。1,1-MigratoryInsertionanda-EliminationWheredoestheCOcomefrom?COthatisinsertedintoMn-Mebondis“unlabelled”,soitmusthavecomefromwithinthecomplex(i.e
5、.mechanismisintramolecular)The13COintheproducthasremainedcistoacylandhasnotmovedatalltothetranssite.Inotherwords,thereactionisunderkineticcontrol(I.e.thefirst-formedproductisobserved).1,1-MigratoryInsertionanda-EliminationIsthisacisprocess?The13Clabelledacylproductwassynthesisedbyanalter
6、nativerouteshownabove,andwasthenheatedtopromoteeliminationOnlythecisisomerwasobserved,thereforeinthereversereaction(the1,1-MI)themethylgroupmustbereactingwithaCOthatiscistoit.ThislogicreliesonthePrincipleofMicroscopicReversibility…Inasinglestepreversiblereaction,themechanismoftheforwardr
7、eactionisthesameasthatofthereversereaction1,1-MigratoryInsertionanda-EliminationWhichMoves?TheCOortheMe?Thetwoproductsarethesame,sohowdowetellwhichmechanismishappening?Considerthetwopossibilities…COinsertionor“COmoves”Memigrationor“Memoves”1,1-MigratoryInsertionanda-Elimi