Binuclear Two-Coordinate Coinage Metal Complexes

The model for rational design of carbene metal amide (cMa) complexes with large oscillator strengths while also decreasing the energy of the singlet and triplet splitting (dEST) is presented. A series of binuclear cMa complexes bearing Janus carbenes have been synthesized and studied. The binuclear cMa complexes exhibit short lifetimes (tau = 200-300 ns) with high photoluminescence efficiencies (PL >95%). The radiative rates of binuclear cMa complexes are 3~4 times faster than that of the corresponding mononuclear cMa complexes. Analysis of temperature-dependent luminescence data indicates that the fluorescent lifetime for the singlet state (tS1) of binuclear cMa complexes are near 12 ns with a dEST of 40-50 meV. The presented compounds provide a general design for cMa complexes to achieve small values for dEST while retaining high radiative rates.