Synthesis and properties of tetramethyl(η5-pentamethylcyclopentadienyl)iridium(V), dimethyl-di-µ-methylene-bis[(η5-pentamethylcyclopentadienyl)iridium(IV)], and related complexes from reactions of di-µ-chloro-dichlorobis[(η5-pentamethylcyclopentadienyl)iridium(III)] with hexamethyldialuminium

Abstract

The intermediate [{(C₅Me₅)IrMe₃}₂AlMe](2b) from reaction of [{(C₅Me₅)Ir}₂Cl₄] and Al₂Me₆ in pentane, reacted with ligands (L = PPh₃ or C₂H₄) to give [(C₅Me₅)IrMe₂L], and with a hydrogen-acceptor (acetone) to give the dimethyl-di-µ-methylene complex [{(C₅Me₅)IrMe}₂(µ-CH₂)₂]. The most unusual reaction of (2b) was the oxygenation to give a 40% yield of the iridium(V) complex [(C₅Me₅)IrMe₄]. Other complexes which were formed in these reactions in lower yields include the chloro(methyl)-di-µ-methylene complex [{(C₅Me₅)Ir}₂Me(Cl)(µ-CH₂)₂] and the trinuclear di-µ₃-methylidyne complex [{(C₅Me₅)Ir}₃(µ₃-CH)₂]. The complexes have been characterised spectroscopically and by comparison with their rhodium analogues. Mechanisms for the reactions are proposed.