(Isonitrile)platinum(II) Complexes of an Amido Bis(N-heterocyclic carbene) Pincer Ligand

Five
Pt­(II) complexes bearing a 3,6-di-tert-butyl-1,8-bis­(1H-imidazol-1-yl)-9H-carbazole (BIMCA) backbone
and different isonitrile ancillary ligands were synthesized and photophysically
characterized. The solid-state structures were determined by X-ray
crystallography, all of which showed a distorted-square-planar geometry
where isonitrile moieties protrude from the Pt–carbazole plane.
In the solid state, these complexes show biexponential phosphorescence
with lifetimes up to 25 ms and quantum yields ranging from 5% to 22%.
In solution, these complexes are weakly emissive with a nanosecond-scale
lifetime. Density functional theory calculations indicate that the
highest occupied Kohn–Sham orbital (HOMO) and the lowest unoccupied
Kohn–Sham orbital (LUMO) reside primarily on the MeBIMCA ligand.