Ruthenium and osmium carbonyl nitrosyl complexes: Matrix infrared spectra and density functional calculations for M(CO)2(NO)2 and M(CO)(NO) (MÂ =Â Ru, Os)

► Laser-ablated ruthenium or osmium atom reactions with CO and NO mixtures in solid argon. ► Metal carbonyl nitrosyls including M(CO)(NO) and 18-electron configuration M(CO)2(NO)2 molecules (M = Ru, Os). ► The observed absorption bands of reaction products are identified by isotopic substitution and DFT calculations. ► The bonding and reaction mechanism are discussed in detail.