LAUSR

Abstract The equilibrium geometries, stabilities, chemical bonding, and aromaticity of the ground state of iridium low-nitride Ir 3 N 3 2+/0/2− clusters and their metal complexes Ir 3 N 3 M −/0 (M = Li, Na, K and Be, Mg, Ca) or Ir 3 N 3 M 2 (M = Li, Na, and K) are investigated using density functional theory (DFT) calculations. The bare Ir 3 N 3 2+/0/2− clusters favor perfectly planar D 3h structure. The neutral Ir 3 N 3 favors the 3 A 2 ″ triplet state, the Ir 3 N 3 2+ cation prefer to the 1 A 1 ′ singlet state, and the Ir 3 N 3 2− dianion is found also to be a 1 A 1 ′ singlet state. A detailed molecular orbitals (MOs) analysis reveals that the Ir 3 N 3 (D 3h , 3 A 2 ″) cluster possesses multiple (σ-, π-, and partial δ-) aromaticity and the Ir 3 N 3 2− (D 3h , 1 A 1 ′) dianion possesses double (σ- and π-) aromaticity. The Ir 3 N 3 2− (D 3h , 1 A 1 ′) motif structure was perfectly preserved in the pyramidal Ir 3 N 3 M −/0 and bipyramidal Ir 3 N 3 M 2 complexes, which also possess corresponding aromatic characters.