Fluoride Complexes of Cyclometalated Iridium(III)
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Abstract
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