The present article describes ruthenium nitrosyl complexes with the {RuNO}6 and {RuNO}7 notations in the selective molecular frameworks of [RuII([9]aneS3)(bpy)(NO+)] 3+ (43+), [RuII([9]aneS3)(pap) (NO+)]3+ (83+) and [RuII([9] aneS3)(bpy)(NO)]2+ (42+), [Ru II([9]aneS3)(pap)(NO)]2+ (82+) ([9]aneS3 = 1,4,7-trithiacyclononane, bpy = 2,2′-bipyridine, pap = 2-phenylazopyridine), respectively. The nitrosyl complexes have been synthesized by following a stepwise synthetic procedure: {RuII-Cl} → {RuII-CH3CN} → {RuII-NO 2} → {RuII-NO+} → {Ru II-NO}. The single-crystal X-ray structure of 43+ and DFT optimised structures of 43+, 83+ and 42+, 82+ establish the localised linear and bent geometries for {Ru-NO+} and {Ru-NO} complexes, respectively. The crystal structures and 1H/13C NMR suggest the [333] conformation of the coordinated macrocyclic ligand ([9]aneS3) in the complexes. The difference in π-accepting strength of the co-ligands, bpy in 43+ and pap in 83+ (bpy < pap) has been reflected in the ν(NO) frequencies of 1945 cm-1 (DFT: 1943 cm-1) and 1964 cm -1 (DFT: 1966 cm-1) and E°({RuII-NO +}/{RuII-NO}) of 0.49 and 0.67 V versus SCE, respectively. The ν(NO) frequency of the reduced {Ru-NO} state in 42+ or 8 2+ however decreases to 1632 cm-1 (DFT: 1637 cm -1) or 1634 cm-1 (DFT: 1632 cm-1), respectively, with the change of the linear {RuII-NO+} geometry in 43+, 83+ to bent {RuII-NO} geometry in 42+, 82+. The preferential stabilisation of the eclipsed conformation of the bent NO in 42+ and 82+ has been supported by the DFT calculations. The reduced {RuII-NO} exhibits free-radical EPR with partial metal contribution revealing the resonance formulation of {RuII-NO}(major)↔{Ru I-NO+}(minor). The electronic transitions of the complexes have been assigned based on the TD-DFT calculations on their DFT optimised structures. The estimated second-order rate constant (k, M-1 s -1) of the reaction of the nucleophile, OH- with the electrophilic {RuII-NO+} for the bpy derivative (4 3+) of 1.39 × 10-1 is half of that determined for the pap derivative (83+), 2.84 × 10-1 in CH 3CN at 298 K. The Ru-NO bond in 43+ or 83+ undergoes facile photolytic cleavage to form the corresponding solvent species {RuII-CH3CN}, 22+ or 62+ with widely varying rate constant values, (kNO, s-1) of 1.12 × 10-1 (t1/2 = 6.2 s) and 7.67 × 10-3 (t1/2 = 90.3 s), respectively. The photo-released NO can bind to the reduced myoglobin to yield the Mb-NO adduct. © The Royal Society of Chemistry.