Non-Covalent Fluorine-Silica Anchoring of a Molecular Platinum(II) bis(NHC) Catalyst: Structure, Interface Control, and Hydrosilylation Activity.

Abstract

Heterogenized molecular catalysts commonly rely on covalent grafting to solid supports. Cleavage of these linkages under catalytic conditions, however, can compromise structural definition and control at the interface. Here, we introduce a ligand-encoded anchoring strategy in which a platinum(II) bis(NHC) complex is immobilized on mesoporous silica (SBA-15) exclusively through directional, non-covalent F-Si interactions. The molecular pre-catalyst trans-[Pt(L^F)₂Cl₂] was structurally characterized by single-crystal X-ray diffraction and multinuclear solution-state NMR spectroscopy. Advanced solid-state MAS NMR experiments, including ¹⁹F{²⁹Si} REDOR, combined with molecular dynamics simulations, establish well-defined F-Si contacts with internuclear distances on the Å-scale and reveal the organization of the pre-catalyst at the silica interface. A model hydrosilylation reaction demonstrates catalytic activity and retention of the molecular species on the support during turnover. This work establishes non-covalent interface engineering as a viable strategy for structurally defined heterogenized catalysis.