Synthesis, structure and luminescent properties of rhenium(I) carbonyl complexes containing pyrimidine-functionalized N-heterocyclic carbenes

Synthesis, structures and photophysical properties of a series of neutral fac-[Re(CO)3(C^N)Cl] complexes, where C^N is a pyrimidine-functionalized N-heterocyclic carbene [3-methyl-1-(2-pyrimidine)imidazol-2-ylidene, 1; 3-n-butyl-1-(2-pyrimidine)imidazol-2-ylidene, 2; 3-benzyl-1-(2-pyrimidine)imidazol-2-ylidene, 3; 3-mesityl-1-(2-pyrimidine)-imidazol-2-ylidene, 4] are reported. These complexes have been characterized by 1H NMR, 13C NMR, elemental analysis, and IR spectra. Their electrochemical and photophysical behaviors, along with the X-ray crystal structures of 2 and 4, are also reported. In both degassed CH2Cl2 solutions and solid state at room temperature, complexes 1–4 exhibit the emissions at 515–570nm.