Luminescent diiridium(III) complex with a bridging biuretato ligand in unprecedented N,N′:O,O′ coordination

The synthesis, crystal structure, and photophysical properties of the novel bis-cyclometalated complex Λ,Δ-[Ir2(μ-biuretato-N,N′:O,O′)(ptpy)4] (2), with ptpy = 2-(p-tolyl)pyridinato, prepared in the reaction of [{Ir(μ-Cl)(ptpy)2}2] (1) with biuret under basic conditions, were investigated. This new compound displays intense green phosphorescence, e.g. with λem = 518 nm, ɸPL = 55%, and τ = 1.5 μs in poly(methyl methacrylate) at 300 K, assigned to a 3MLCT/LC excited state.