Gas-Phase Ion Chemistry of Metalloporphyrin Anions with Molecular Oxygen: Probing the Influence of the Oxidation and Spin State of the Central Transition Metal by Experiment and Theory.

We performed a comprehensive gas-phase experimental and quantum-chemical study of the binding properties of molecular oxygen to iron and manganese porphyrin anions. Temperature-dependent ion-molecule reaction kinetics as probed in a Fourier-transform ion-cyclotron resonance mass spectrometer reveal that molecular oxygen is bound by, respectively, 40.8 ± 1.