Molecular Alkalyne-Earth Complexes for Homogeneous Catalysis
Keywords: alkaline-earth metals, homogeneous catalysis, hydroelementation, dehydrocoupling.
The synthetic molecular chemistry of the large alkaline earths (Ae = Ca, Sr and Ba) is booming. It is now established that the reactivity of these earth-abundant metals is different from that of their lighter magnesium analogue. Many examples now exist in the recent literature of catalytic processes using low Ae catalyst loadings and mild conditions. Beyond the design of original architectures constructed around these metals, we have shown that stable, well-defined complexes of the large alkaline earths act as competent homogeneous catalysts for a broad range of atom-efficient catalysed reactions. For instance, they allow for the chemoselective creation of C–N (amines) and C–P (phosphines) bonds through the controlled hydroamination and hydrophosphination of alkenes. We have also implemented them to create bonds between heteroelements (Si, N, O, etc.) in the dehydrogenative couplings of mono/poly-amines with hydrosilanes, boranes, borinic acids etc. These green processes that release little or no by-products are optimized to generate highly valuable molecular products or polymer materials.