Allylic C–H Deprotonation of Olefins with PtII(OH) to Form η3-Allyl PtII Complexes in Water and Aprotic Organic Solvents

Hydroxo olefin platinum(II) complex (dpms)PtII(OH)(olefin) (olefin = cis-cyclooctene) reacts in water, in methanol, and, much faster, in aprotic solvents, DMF, acetone, or CH2Cl2 at 20 °C to produce the corresponding η3-allylic complex. Allylic C–H bond deprotonation in (dpms)PtII(OH)(cis-cyclooctene) is reversible, leading to the selective H/D exchange of the olefin in D2O solutions. Attempted olefin-for-olefin ligand exchange in (dpms)PtII(OH)(C2H4) with olefin = cycloheptene or cyclopentene aimed at the preparation of other (dpms)PtII(OH)(olefin) complexes in water–organic solvent mixtures leads to corresponding η3-allylic derivatives via the intermediacy of (dpms)PtII(OH)(olefin) species. Consistent with mechanistic tests and results of DFT calculations, the PtII(OH) group is responsible for deprotonation of the allylic C–H bond of the coordinated olefin.