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 -[Ru II (bipy)(L)(Cl) 2 ]( C1 – C4 ) (L = XC 6 H 4 N NC(COMe) NC 6 H 4 (2-SMe), X = H (L1), C1 ; CH 3 (L2), C2 ; Br (L3), C3 ; NO 2 (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 1 H NMR) and cyclic voltammetry. The electrochemical parameters ( E L ( L )) of the azoimine ligands (L1–L4) are reported. The electronic excitations of a representative complex ( C3 ) are interpreted by DFT and TDDFT calculations.