Investigations into the stereochemistry of nucleophilic attack on olefins coordinated to palladium(II) and platinum(II)

Abstract

A study of the oxidative hydrolysis of olefins in the presence of [Pd(dien)H 2O] 2+ and [Pd(en)(H 2O) 2] 2+ (dien = diethylenetriamine, en = ethylenediamine) has indicated that where possible nucleophilic attack on the olefin by hydroxide ion involves prior coordination of the hydroxide to palladium(II). However where no coordination site cis to the olefin is available, as in [Pd(dien)(olefin)] 2+ in neutral solution, direct attack on the olefin by hydroxide ion occurs without prior coordination. Such attack is very slow compared to that involving prior cis-coordination. Some unsuccessful experiments to establish the stereochemistry of methoxide ion attack on preformed platinum(II)—olefin complexes are reported and reasons for their failure discussed.