Ruthenium(II) complexes of the type [Ru(CO)(L)(2)( B)] (L = novel bidentate Schiff base ligand; B = PPh3, pyridine (py), piperidine (pip), morpholine (morph) or AsPh3) have been prepared by reacting [RuHCl(CO)(PPh3)(2)(B)] (B = PPh3, py, pip or morph) or [RuHCl(CO)(AsPh3)(3)] with two novel bidentate Schiff base ligands derived from 4-(1-methyl-1- mesitylcyclobutane-3- yl)-2-aminothiazole in 1 : 2 molar ratio in benzene. Complexes have been characterized by analytical, spectroscopic (IR, UV, H-1, C-13- and P-31 NMR) and magnetic data. An octahedral structure has been tentatively proposed for all the new complexes. The thermal properties of the ligands and their complexes have been studied by TGA. The new complexes have been used as catalyst in aryl-aryl coupling and also subjected to antibacterial and antifungal activity studies.