Protonation, transition metal nitrosyl complexes

We suggest that the initial step is heterolytic splitting of H2 or Dj, leading to the protonated or deuterated transition metal nitrosyl hydrides or deuterides, respectively. H/D exchange via the second nitrosyl ligand might lead to the mixed hydride-deuteride complex, which in a reverse reaction forms HD, and regenerates the cationic catalyst. 

Reactions of transition-metal complex-coordinated ligands with protonic acids can yield N—H bond-containing products. Coordinated nitrosyl groups react with HCl ... 

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