Cooperativity in boron- and carbon-based pincer complexes

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In this project we plan to develop a new mode of metal-ligand cooperative bond activation with implications for applications in homogeneous catalysis, using transition metal complexes with boron- and carbon-based pincer-type ligands. We found that carbodiphosphorane-based (CDP) rhodium(I) complexes of this type react with organic germinal dichlorides via initial oxidative addition and subsequent cooperative cleavage of the second C–Cl-bond. The resulting rhodium(III) complexes formally contain a CDP-stabilized carben as ligand. The unusual bonding situation in these ligands will be investigated in detail for a number of related complexes.The cooperative bond activation of germinal dihalogenes will be investigated for other organic dihalogenes as well as for dichlorides of group 13 and 14 elements. On the basis of these experiments we intend to develop catalytic reactions using (sustainable) reductants that regenerate a rhodium(I)-species from the activation products and induce a carbene transfer. The synthesis of corresponding boron-based complexes, that formally contain a ligand-stabilized boride as ligand, represents a major challenge. We are going to address this challenge by developing a fitting stabilizing environment for the central boron atoms and combining it with suitable metal fragments and ligand spheres. The reactivity and catalytic activity of the resulting complexes will be investigated with respect to the corresponding CDP-based complexes.