Redox properties of anionic platinum carbonyls embedded in NaX zeolite Original Research Article

It was found that platinum anionic carbonyls in NaX zeolites can be repeatedly recarbonylated after oxidation by NO as well as after reduction by hydrogen similarly as was previously found after the oxidation by O2. The substitution of bridge bonded CO ligands by oxygen was assumed to conserve the Pt features. NO and hydrogen most probably play a similar role, interacting preferentially with these CO ligands. The absence of either oxidative or reductive atmosphere during vacuum heat treatment of Pt anionic carbonyls leads, contrary to the above conditions, to the simultaneous removal of bridge and on-top bonded CO ligands; the decomposed anionic carbonyls can be recarbonylated yielding again both types of CO ligands, however, wavenumbers of their IR bands are shifted to higher values. Formation of either Pt anionic carbonyls of higher nuclearity or of neutral Pt carbonyls is suggested to explain the upward shift of the IR bands.