Flash Communication: Synthesis of Osmabenzimidazoisoquinolines from Osmabenzenes Via Classical Nucleophilic Aromatic Substitution Reactions

As one of the most important N-containing polycyclic aromatic hydrocarbons, benzimidazo[2,1-a]isoquinoline derivatives are of great interest due to their unusual biological activities and photophysical properties. Herein, we present the SNAr reaction of osmabenzene with 1-aminoisoquinoline to access unique metal-containing benzimidazo[2,1-a]isoquinoline derivatives. Comprehensive DFT calculations, including NICS, AICD, EDDB, and NOBD analysis, reveal the aromaticity switching of the osmabenzene ring of the resulting osmabenzimidazoisoquinolines. Additionally, these conjugated condensed metallacycles exhibit effective narrowing of the HOMO–LUMO gap, resulting in red-shifted absorption bands.