A series of monomeric platinum (II) hydroxo supported by bulky diimine ligands have been synthesized and fully characterized. A thorough investigation of their corresponding reactivity have been carried out to determine if they participate in a water splitting cycle.
Heating bis hydroxo at elevated temperatures (>80oC) in the presence of arene C-H bonds resulted in the double 1,2-C-H bond addition to form the corresponding bis phenyl complex with loss of H2O. This process was found to be catalyzed by in-situ produced platinum particles. 1,2-addition of H2 across the Pt-OH bonds was also observed but the corresponding platinum hydride species were too unstable to characterize or isolate.
Several of the platinum (II) hydroxo species form stable adducts with silver bis-N-triflimide, where the silver cation was found to be engaging in a Lewis acid/base interaction with the hydroxide moiety. These silver supported adducts were found to activate aromatic C-H bonds at room temperature and a mechanistic study was carried out.
The platinum (II) hydroxo compounds were also found to rapidly and reversible insert CO2. In one instance, insertion was followed by elimination of water to form an isolable carbonate species. The CO2 inserted products were found to be favoured at low temperature, and removal of CO2 from the system resulted in complete reversion back to the hydroxo species.