Nitric oxide and nitroxyl formation in the reduction of trans-tetraamminenitrosyltriethylphosphiteruthenium(II) ion

► The ruthenium phosphite nitrosyl complex can be reduced by one or two electrons. ► NO or HNO can be achieved as products depending on the nature of the reductant. ► Coordinated NO- and HNO singlet forms are more stable regarding to triplet ones. ► pKa value for coordinate HNO (singlet) is 9.9.