Chemoselective Hydrogenation with Supported Organoplatinum(IV) Catalyst on Zn(II)-Modified Silica

Well-defined organoplatinum­(IV) sites were grafted on a Zn­(II)-modified SiO2 support via surface organometallic chemistry in toluene at room temperature. Solid-state spectroscopies including XAS, DRIFTS, DRUV–vis, and solid-state (SS) NMR enhanced by dynamic nuclear polarization (DNP), as well as TPR-H2 and TEM techniques revealed highly dispersed (methylcyclopentadienyl)­methylplatinum­(IV) sites on the surface ((MeCp)­PtMe/Zn/SiO2, 1). In addition, computational modeling suggests that the surface reaction of (MeCp)­PtMe3 with Zn­(II)-modified SiO2 support is thermodynamically favorable (ΔG = −12.4 kcal/mol), likely due to the increased acidity of the hydroxyl group, as indicated by NH3-TPD and DNP-enhanced 17O­{1H} SSNMR. In situ DRIFTS and XAS hydrogenation experiments reveal the probable formation of a surface Pt­(IV)-H upon hydrogenolysis of Pt-Me groups. The heterogenized organoplatinum­(IV)-hydride sites catalyze the selective partial hydrogenation of 1,3-butadiene to butenes (up to 95%) and the reduction of nitrobenzene derivatives to anilines (up to 99%) with excellent tolerance of reduction-sensitive functional groups (olefin, carbonyl, nitrile, halogens) under mild reaction conditions.