Spectroscopic, structural and photophysical characterization of chloro-bridged iridium(III) and rhodium(III) dinuclear complexes with 1-phenyl-1H-pyrazole and their analogues with 1-(2,4-difluorophenyl)-1H-pyrazole.

This paper deals with the synthesis and spectroscopic characterization of four important precursors, dinuclear [(C^N)2Ir-μ-Cl]2 and [(C^N)2Rh-μ-Cl]2 complexes, containing deprotonated 1-phenyl-1H-pyrazole or 1-(2,4-difluorophenyl)-1H-pyrazole as cyclometallating (C^N) ligands. The molecular structures of these μ-chloro-bridged complexes were confirmed by X-ray crystallography. These complexes showed luminescence in 1 : 1 MeOH/EtOH glasses at 77 K but were non-emissive in dichloromethane solutions at room temperature. A time-dependent DFT (TDDFT) study was conducted to gain insights into the electronic structures of these systems.