Half-sandwich Iridium Compounds Synthesis And Properties

Norbornene polymerization has been widely used in industrial productions due to the special optical and mechanical properties of the polymers.It has been established that different methods of polymerization produce polynorbornene with different microstructures. Ring opening metathesis polymerization(ROMP) produces polynorbornene with double bonds remaining in the polymer backbone.Up to now,there are two major types of catalysts used for ROMP of norbornene:one is tungsten,molybdenum,rhenium and ruthenium catalysts as metal halides or metal oxides in combination with alkylating agents,the other is metal carbene complexes based on tungsten,molybdenum or ruthenium,etc.Another type of polymerization is vinyl-type polymerization.It opens the p-component of the double bond in norbornene,keeping the bicyclic unit in the polymer chain.Catalysts containing titanium, zirconium,cobalt,chromium,nickel and palladium have been reported for vinyl-type polymerization of norbornene and copolymerization of norbornene with acyclic olefins. Recently,our group has also developed some high activity late transition metal catalysts for vinyl-type polymerization.Although the catalysts for ROMP and vinyl polymerization have been widely developed,there are only a few iridium complexes involved in this field In addition,there are several reports on catalysts which can initiate both ROMP and vinyl-type polymerization,such as titanium and cobalt,depending on the cocatalyst ratio or the type of cocatalyst.however,the polymers obtained by those catalysts are only mixtures of the two types,and cannot be separated effectively.This thesis is mainly based on the syntheses of half sandwich iridium complexes with[N,N] or[N,O]ligands,the discovery of special catalytic behavior toward norbornene polymerization,and the study of their catalysis properties.For the complexes which demonstrate no activity for the norbornene polymerization,structural and crystallization properties are studied in other manners:(1) The syntheses and catalytic behavior of half sandwich iridium complexes with[N,O] ligandsA series of half sandwich iridium complexes containing hydroxyindanimine and Salicylaldiminato ligands were synthesized and characterized by IR,NMR,Elemental Analysis and X-Ray determinations;special properties of those complexes toward norbornenc polymerization were discovered;the steric effect of ligands in ring-opening polymerization of norbornene was studied;the mechanisms of the special behavior were discussed. (2) The syntheses of 16/18 electron complexes and the discussion of their electronic properties.A series of half sandwich iridium complexes containing Anilido lmine ligands were synthesized and characterized by IR,NMR,UV,CV,Elemental Analysis and X-Ray determinations;theoretical calculations of all the 18/16-electron species were performed to study their bonding characters and electronic properties.(3) The syntheses of bidentate isocyanide ligands and their reaction with Cp*Ir[S₂C₂(B₁₀H)₁₀] and Cp* Ir[S₂C₂(B₁₀H₈(OCH₃)₂)]Three bidentate ligands were synthesized;the reaction of those ligand with 16 electron complexes bearing Anilido Imine ligands,Cp*Ir[S₂C₂(B₁₀H)₁₀]and Cp*Ir[S₂C₂(B₁₀H₈(OCH₃)₂)]were studied;the crystallization behaviors of those complexes assisted by some solvent molecules were discussed.