The reaction of [RuNO(Py)₂Cl₂OH] with bipyridine in water–ethanol media results in trans-(NO, OH)-[RuNO(Py)(Bpy)ClOH]⁺ with an acceptable yield (60–70%) as hexafluorophosphate salt. Further treatment of the hydroxy-complex with concentrated HF quantitatively leads to trans-(NO, F)-[RuNO(Py)(Bpy)ClF]⁺. Despite the chirality of both coordination spheres, the hexafluorophosphate salts crystallized as racemates. A NO-linkage isomerism study of the obtained complexes was performed at 80 K with different excitation wavelengths (405, 450, 488 nm). The most favorable wavelengths for the MS1 isomer (Ru-ON) formation were 405 and 450 nm, where the linkage isomer populations were 17% and 1% for [RuNO(Py)(Bpy)ClOH]PF₆ and [RuNO(Py)(Bpy)ClF]PF₆. The shift of the excitation wavelength to the green (488 nm) sharply decreased the MS1 population. The IR-spectral signatures of MS1 were registered. Reverse-transformation Ru-ON (MS1)-Ru-NO (GS) was investigated for [RuNO(Py)(Bpy)ClOH]PF₆ using IR and DSC techniques that made it possible to determine the kinetic parameters (E_a and k₀) and decay temperature.

A set of new coordination compounds of the formula [RuNO(L)Cl₃], with L representing the bidentate ligands bipyrimidine (bpym), bipyridine (bpy), or phenanthroline (phen), was prepared and fully characterized. For the isomeric species fac-[RuNO(bpym)Cl₃] (1), fac-[RuNO(phen)Cl₃] (2), mer-[RuNO(phen)Cl₃] (3), fac-[RuNO(bpy)Cl₃] (4), and mer-[RuNO(bpy)Cl₃] (5), an evaluation of the photoresponse in DMSO was performed under excitation with 450 nm using a continuous-flow arrangement that enabled the simultaneous acquisition of IR and UV-Vis spectral data. Quantum yields for photoinduced release of NO were determined as follows: 5.4 ± 0.5% for fac-[RuNO(bpym)Cl₃] (1); 0.8 ± 0.1% for fac-[RuNO(phen)Cl₃] (2); 0.6 ± 0.1% for mer-[RuNO(phen)Cl₃] (3); 3.7 ± 0.1% for fac-[RuNO(bpy)Cl₃] (4); 2.1 ± 0.1% for mer-[RuNO(bpy)Cl₃] (5). The product of the photolysis of compound 5 in acetonitrile solution was isolated and structurally characterized as mer-[Ru(CH₃CN)(bpy)Cl₃] (6). Taking into account the presence of typical DNA intercalating ligands, the complexes can be potentially exploited as photoNORMs.

A series of novel complexes with the general formula [RuNO(L)Cl₃], where L is a bidentate ligand (bpym, bpy, phen), was synthesized and characterized. The photochemical activity of fac-[RuNO(bpym)Cl₃] (1), fac-[RuNO(phen)Cl₃] (2), mer-[RuNO(phen)Cl₃] (3), fac-[RuNO(bpy)Cl₃] (4), mer-[RuNO(bpy)Cl₃] (5) in DMSO was quantified under 450 nm irradiation using a flow-through system, allowing simultaneous IR and UV-Vis spectral monitoring. Quantum yields for photoinduced release of NO were determined as follows: 5.4 ± 0.5 % for fac-[RuNO(bpym)Cl₃] (1); 0.8±0.1 % for fac-[RuNO(phen)Cl₃] (2); 0.6±0.1 % for mer-[RuNO(phen)Cl₃] (3); 3.7±0.1 % for fac-[RuNO(bpy)Cl₃] (4); 2.1±0.1 % for mer-[RuNO(bpy)Cl₃] (5). The product of photolysis of compound 5 in acetonitrile solution was isolated and structurally characterized as mer-[Ru(CH₃CN)(bpy)Cl₃] (6). Taking into account the presence of typical DNA intercalating ligands the complexes can be potentially exploited as photoNORMs.