A series of ruthenium(II) carbonyl complexes of the types [RuCl2(CO)2L]2·nH2O {n = 1, L = L1, L3}; [RuCl2(CO)2(L)(H2O)]·nH2O {n = 1, L = L2, L4, L6 and n = 2, L = L7}; [RuCl(CO)2(L-H)(H2O)]2 {L = L5}; [RuCl2(CO)2]3(L)2 {L = L8} were synthesized where L is 6R-5,6- dihydrobenzoimidazo[1,2-c]quinazoline (R-Diq; R = phenyl: L1/furyl: L2/thiophenyl: L3/o or p-hydroxyphenyl: L4, L5/o or p- hlorophenyl: L6, L7/dimethylaminophenyl: L8). The Ru(II) complexes were characterized by elemental analyses, conductivity measurements, TGA, infrared, electronic, NMR and mass spectral techniques. An octahedral geometry around the metal ion was proposed for all the complexes and monomeric, dimeric and trimeric stereochemistry was suggested. The catalytic activity for few ruthenium(II) complexes towards oxidation of benzyl alcohol, hydroquinone and cyclohexanol was also investigated.