Sequential coordination and oxidative addition of terminal alkynes to the Tp′PtMe fragment

A series of η2-bound terminal alkynes coordinated to the Tp′ platinum(II) methyl fragment (Tp′ = hydridotris(3,5-dimethylpyrazolyl)borate) has been synthesized. These complexes are thermally unstable and undergo slow oxidative addition upon gentle heating, resulting in the formation of alkynyl–hydride platinum(IV) complexes. The rate of conversion from Pt(II) reactants to Pt(IV) products was monitored and activation parameters have been calculated. The entropies of activation of these reactions suggest that the third arm of the Tp′ ligand is dissociating to facilitate oxidative addition of the alkyne C–H bond.