Complexes of low-valent f-elements and of uranium in particular are excellent candidates for small molecule activation. Differing sterical and electronic environments at the U(III) and Ln(II) centers have a critical impact on the geometry, stability and reactivity of the reduction products. Careful tuning of the ligand is also essential to promote two-electron transfer which is rare in U(III) chemistry. Notably, bulky siloxide ligands can be used to isolate stable U(III) complexes which act as two-electron reducing agent in the reaction with a variety of small molecules such as CS2, CO2 and azides,[1] chalcogenides and reduce toluene to afford arene complexes. Moreover, the sterical demand and electron-rich coordination environment of homoleptic siloxide complexes of Eu(II) and Yb(II) leads to the reduction of azobenzene, carbon disulphide and carbon dioxide and the ready release of the reduction products, a prerequisite for the implementation of catalytic cycles.[2] Finally, siloxide ligands lead to the formation of heterobimetallic complexes enabling the multimetallic cooperativity in uranium mediated reduction of carbon dioxide.[3] The redox chemistry of f element complexes with siloxides and other bulky ligands will be presented together with the structure and properties of original compounds. [1] C. Camp, J. Pécaut and M. Mazzanti, J. Am. Chem. Soc. 2013, 135, 12101. [2] J. Andrez, J. Pécaut, P-A. Bayle, M. Mazzanti Angew. Chem. Int. 2014, 53, 10448–10452. [3] O. Cooper, C. Camp, J. Pécaut,, C. E. Kefalidis, L. Maron and M. Mazzanti, J. Am. Chem. Soc. 2014, 136, 6716–6723.

Small molecule activation by complexes of low-valent f elements

249th National Meeting (2015)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.