The electronic structures of newly synthesized homoleptic ruthenium complexes [Ru(Ln)2]+2 (n=1-4)   bearingunsymmetric pyridine based bis N-heterocyclic carbene (NHC) pincer ligands are investigated with DFT and TDDFT calculations. The complexes feature the coexistence of a five membered and a six membered ruthenacycle within the same ligand frame work, allowing an ideally octahedral CNHC-Ru-NPy bite angle close to 90�. In solid state, an impressive 3MLCT lifetimes in microseconds are detected, among which [Ru(L4)2]+2  with four benzimidazol-2-ylidene donors exhibits the longest time. Geometries of all of the complexes in the singlet (S0) and triplet (T1) states were optimized by using the B3LYP functional with the LanL2DZ basis set. Low-lying singlet excited states are predicted and their optimized geometries and vibrational frequencies are obtained utilizing TDDFT calculations. The absorption and phosphorescence spectra are then simulated with Franck-Condon factor calculations. The theoretical results are compared with cyclic voltammetry and observed spectra.

Theoretical study on the absorption and phosphorescence spectra of ruthenium complexes bearing unsymmetric CNC' pincer ligands

248th National Meeting (2014)

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