Microwave-Accelerated C,N-Cyclometalation as a Route to Chloro-Bridged Iridium(III) Binuclear Precursors of Phosphorescent Materials: Optimization, Synthesis, and Studies of the Iridium(III) Dimer Behavior in Coordinating Solvents

Bartosz Orwat; Myong Joon Oh; Maciej Zaranek; Maciej Kubicki; Rafał Januszewski; Ireneusz Kownacki

doi:10.1021/acs.inorgchem.0c01071

Microwave-Accelerated C,N-Cyclometalation as a Route to Chloro-Bridged Iridium(III) Binuclear Precursors of Phosphorescent Materials: Optimization, Synthesis, and Studies of the Iridium(III) Dimer Behavior in Coordinating Solvents

Inorg Chem. 2020 Jul 6;59(13):9163-9176. doi: 10.1021/acs.inorgchem.0c01071. Epub 2020 Jun 21.

Authors

Bartosz Orwat^{1

2}, Myong Joon Oh^{1

2}, Maciej Zaranek^{1

2}, Maciej Kubicki¹, Rafał Januszewski^{1

2}, Ireneusz Kownacki^{1

2}

Affiliations

¹ Faculty of Chemistry, Adam Mickiewicz University in Poznań, St. Uniwersytetu Poznańskiego 8, 61-614 Poznań, Poland.
² Center for Advanced Technology, Adam Mickiewicz University in Poznań, St. Uniwersytetu Poznańskiego 10, 61-614 Poznań, Poland.

PMID: 32564601
DOI: 10.1021/acs.inorgchem.0c01071

Abstract

We present the results of our research on the use of microwaves as an unconventional heat source for the acceleration of iridium(III) chloro-bridged dimer preparation. The results enabled us to revise and improve known guidelines for the very quick and highly efficient synthesis of iridium(III) dimeric complexes in a very simple isolation manner. According to the developed methodology, the already known dimers containing ligands based on the 2-phenylpyridinato motif, as well as new ones stabilized with functionalized benzo[h]quinolinato and 2-phenoxypyridinato-based ligands, were efficiently synthesized. The scope of the incorporated ligands included compounds equipped with electron-donating (-Me, -OMe, -OPh, -NMe₂), electron-withdrawing (-F, -Br, -CF₃, -C₆F₅), and hole-transporting (-NPh₂, -C₆H₄NPh₂) groups. The obtained complexes were characterized by NMR, X-ray diffraction, and electrospray ionization mass spectrometry methods, and their behavior was examined in the presence of coordinating solvents such as dimethyl sulfoxide and acetonitrile. Investigation of the interactions between the above-mentioned solvents and dimers enabled us to confirm the ability of the former to cleave μ-chloride bridges, which enriches the knowledge in the field of organometallic chemistry. This knowledge can be particularly useful for the scientists working in the field of iridium-based materials, helping to avoid misinterpretation of the spectroscopic data.