Cleavage mechanisms platinum ions

The mechanism of action, and organization of the catalytic sites, in hydrogenases are different from a solid catalyst such as platinum. For a start, the reaction of H2 with hydrogenase involves heterolytic cleavage into a hydron and a hydride. This contrasts with the reaction of H2 at the surface of a metal such as platinum, which is usually considered to involve the homolytic cleavage into two hydrogen atoms. Moreover in the enzyme, the catalyst is a cluster of metal ions (with oxidation states +2 or -h3) rather than the metal (oxidation state 0). 

Ketones with branching in the a position may be anodically cleaved at a platinum electrode in CH3CN-LiC104 [38]. A mechanism was proposed that involved generation of carbenium ion on a cleavage of the ketone radical cation, analogous to reactions in photochemistry and mass spectroscopy ... 

The kinetics of solvolysis of complexes cis- and // a 5-[Pt(N02)2L2] (L=ammonia, pyridine, or triethylphosphine) in acetic acid-sulphuric acid mixtures have been compared with those in aqueous sulphuric acid. The mechanism is loss of a nitro-sonium ion from the protonated complex. Whether this protonation takes place at the nitrito-ligand or at the metal is not known, but definitive evidence favouring the latter could not be obtained. Platinum-carbon bond cleavage in cw-[Pt(C6H4Y)2-(PEt3)2], studied in methanol and methanol-water mixtures, takes place by electrophilic attack by a proton,... 

---