Microwave-assisted Synthesis of Pentamethylcyclopentadienyl Iridium Dihalide Dimers
Abstract
[Cp*IrCl2]2 is a common precursor used to synthesize a large family of organometallic catalysts. While [Cp*IrCl2]2 is commercially available, dimers featuring other halides are not, though they have been reported as intermediates in other transformations. Traditional synthetic methods for the preparation of these halide dimers are time consuming, requiring reflux for 48 hours. We have developed a new method utilizing microwave-assisted synthesis (MAS) that significantly decreases the time required to prepare [Cp*IrCl2]2 and other halide dimers. Reagents were heated at reflux in sealed reactors for 15 min at 120°C, and products were isolated using traditional methods with yields comparable or exceeding literature methods. [Cp*IrCl2]2, [Cp*IrI2]2, and [Cp*IrBr2]2 were synthesized using MAS and characterized by NMR spectroscopy, UV-Visible spectroscopy, and elemental analysis. These dimers were then used to synthesize a series of mononuclear iridium bipyridine complexes with varying halide ligands. This series of complexes was characterized electrochemically to identify potential electrocatalysts for future study.
Microwave-assisted Synthesis of Pentamethylcyclopentadienyl Iridium Dihalide Dimers
[Cp*IrCl2]2 is a common precursor used to synthesize a large family of organometallic catalysts. While [Cp*IrCl2]2 is commercially available, dimers featuring other halides are not, though they have been reported as intermediates in other transformations. Traditional synthetic methods for the preparation of these halide dimers are time consuming, requiring reflux for 48 hours. We have developed a new method utilizing microwave-assisted synthesis (MAS) that significantly decreases the time required to prepare [Cp*IrCl2]2 and other halide dimers. Reagents were heated at reflux in sealed reactors for 15 min at 120°C, and products were isolated using traditional methods with yields comparable or exceeding literature methods. [Cp*IrCl2]2, [Cp*IrI2]2, and [Cp*IrBr2]2 were synthesized using MAS and characterized by NMR spectroscopy, UV-Visible spectroscopy, and elemental analysis. These dimers were then used to synthesize a series of mononuclear iridium bipyridine complexes with varying halide ligands. This series of complexes was characterized electrochemically to identify potential electrocatalysts for future study.