Ruthenium(II) bipyridine complexes incorporating (NN′S) azoimine ancillary ligands. Synthesis, spectroscopy, solid state structure and DFT calculations

Abstract

Four ruthenium complexes of N’NS donor thiomethyl-azoimine ligands (L) of the general type trans-[RuII(bipy)(L)(Cl)2](C1–C4) (L=XC6H4NNC(COMe)NC6H4(2-SMe), X=H (L1), C1; CH3 (L2), C2; Br (L3), C3; NO2 (L4), C4) have been synthesized by the reaction of ruthenium trichloride trihydrate with the corresponding L ligands and bipyridine (bipy) in refluxing ethanol. The molecular structure of trans-[Ru(bpy)(L3)(Cl)2](C3) in the solid state is reported. The thiomethyl-azoimine ligands (L) bind as NN′ bidentate ligands with no direct Ru–S interaction. Furthermore, the complexes have been characterized by spectroscopic data (IR, UV/Vis and 1H NMR) and cyclic voltammetry. The electrochemical parameters (EL(L)) of the azoimine ligands (L1–L4) are reported. The electronic excitations of a representative complex (C3) are interpreted by DFT and TDDFT calculations.