Twofold cryo N2 cleavage by Ta4+ clusters occurs via a multistep across edge-above surface (AEAS) mechanism across submerged barriers.

We present the cryo IR-PD spectra of the coadsorbed [Ru(H)(N)] and [Ru(N)(H)] species differing in the adsorption sequence of H and N, which we record via application of tandem cryo ion trapping. We observe strong evidence for dissociative H adsorption, and the spectra reveal differences in the Ru-H stretching region, which we assign to distal and proximal hydrogen atom locations on the Ru cluster, their migration likely hindered by preloaded nitrogen molecules and unaffected by subsequent N adsorption.

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 ± 1.4 and 67.4 ± 2.2 kJ mol to the Fe or Mn centers of isolated tetra(4-sulfonatophenyl)metalloporphyrin tetraanions. In contrast, Fe and Mn trianion homologues were found to be much less reactive-indicating an upper bound to their dioxygen binding energies of 34 kJ mol. We modeled the corresponding O adsorbates at the density functional theory and CASPT2 levels. These quantum-chemical calculations verified the stronger O binding on the Fe or Mn centers and suggested that O binds as a superoxide anion.

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