Ditopic bis-terdentate cyclometallating ligands and their highly luminescent dinuclear iridium(III) complexes

A new family of bridged cyclometallating ligands is reported, which incorporate two terdentate N<^>C<^>N-coordinating binding sites linked via pyrazine, pyrimidine or pyridazine units. Dinuclear Ir(III) complexes of one ligand have been prepared and crystallographically characterised; they display intense red phosphorescence.