High-pressure methods as a tool in organometallic syntheses: facilitation of oxidative addition to platinum(II)

High-pressure (2 GPa) batch reactors now commercially available may offer substantial accelerations of organometallic syntheses, without resort to heating, when the activation process is multicentered or involves the generation and solvation of ions. As an example of the latter class of reactions, the kinetics of the oxidative additions of methyl and ethyl iodides (RI) to dimethyl(2,2′-bipyridine)platinum(II) in acetone have been studied over the pressure range 0-200 MPa. The volumes of activation ΔV 1 ≠ , if assumed to be constant over this range, are −11.7 ± 0.3 and −9.7 ± 0.7 cm 3 mol −1 , respectively, implying an acceleration of ca. 3000-fold for a batch synthesis of this sort at 2 GPa. However, a possible slight pressure dependence of ΔV 1 ≠ may reduce this acceleration to ca. 1 000-fold. The ΔV 1 ≠ data and the 500-fold retardation on going from R = Me to R = Et are consistent with an S N 2 attack of Pt 11 on the α-carbon in the alkyl iodides, forming I − and [RMe 2 Pt(bpy)] + . Key words: volumes of activation, high pressure, oxidative addition, platinum(II), organometallic syntheses.