Fluoride Complexes of Cyclometalated Iridium(III)

Many
electroluminescent devices rely on cyclometalated iridium­(III).
Their advancement depends on access to reactive starting materials
because of the inertness of Ir­(III). Notably, fluoride complexes of
bis­(cyclometalated) Ir­(III) are scarce. Syntheses of bridged and terminal
fluorides are reported here. New compounds are luminescent and thermally
reactive; they are characterized by ground-state and optical methods.
Crystal structures were determined for one bridging and one terminal
fluoride complex. The terminal fluoride shows intramolecular hydrogen
bonding to an adjacent 3,5-dimethylpyrazole ligand; a lesser interaction
may occur between F and a nearby aromatic C–H bond. Terminal
fluoride complexes react with carbon-, silicon-, and sulfur-based
electrophiles. The new complexes phosphoresce with microsecond lifetimes
at 77 and 298 K. Density-functional theory calculations indicate triplet
states with little contribution from fluoride. The compounds herein
are versatile phosphors having the ground-state reactivity of late
transition metal fluorides.