Study On The Synthesis And Catalytic Friedel-Crafts-Type Alkylation Reactions Of Substituted Tetramethylcyclopentadienyl Rhenium Carbonyl Complexes

Organometallic complexes containing the cyclopentadienyl have become of great importance because of that cyclopentadienyl has been recognized as a powerful,easy-to-access,and versatile ligand for the construction of robust and catalytically competent transition-metal complexes.And these types of compounds have found significant applications in catalysis?olefin polymerization,hydrogenation of ketones,alcohol oxidation?and in the construction of molecular materials,which has attracted wide attention of chemists.Here we designed and synthesised the synthesis of eleven alkyl-or aromatic-substituted tetramethylcyclopentadienyl rhenium carbonyl complexes,and the effects of the substituents on the final structures of the complexes were discussed.We also researched their catalytic reactivities in Friedel-Crafts alkylation of aromatic compounds.The details are as follows:Firstiy,six alkyl-substituted tetramethylcyclopentadienyl rhenium carbonyl complexes [??5-C₅Me₄R?Re?CO?₃]?R= allyl?7?,ⁱPr?8?,nBu?9?,tBu?10?,Bz?11?,CH?CH₂?₄?12??and five aromatic-substituted tetramethylcyclopentadienyl rhenium carbonyl complexes [??5-C₅Me₄R?Re?CO?₃]?R= Ph?18?,4-CH——3Ph?19?,4-OCH₃Ph?20?,4-ClPh?21?,4-BrPh?22??have been synthesized by treating the alkyl-or aromatic-substituted tetramethylcyclopentadiene ligands inrefluxing xylene.The eleven new complexes were characterized by elemental analysis,IR,¹H NMR and ¹³ C NMR spectroscopy.The crystal structures of all complexes were determined by X-ray crystal diffraction analysis,showing that they exhibit typical three-legged piano-stool structures,being mononuclear carbonyl complexes.In each of these complexes,the Re atom is ?5-coordinated to the cyclopentadienyl ring,plus three terminal CO ligands.Then,the catalytic reactivities of all them in Friedel-Crafts alkylation of benzene derivative were studied,showing that they have catalytic activities which are effected by different substituting groups of tetramethylcyclopentadienyl;Compared with traditional catalysts,they need lower amounts of catalyst.