Isolation of a Perfectly Linear Uranium(II) Metallocene.

Authors :: Guo FS
Tsoureas N
Huang GZ
Tong ML
Mansikkamäki A
Layfield RA
Source :: Angewandte Chemie (International ed. in English) [Angew Chem Int Ed Engl] 2020 Feb 03; Vol. 59 (6), pp. 2299-2303. Date of Electronic Publication: 2020 Jan 03.
Publication Year :: 2020
Abstract: Reduction of the uranium(III) metallocene [(η <superscript>5</superscript> -C <subscript>5</subscript> <superscript>i</superscript> Pr <subscript>5</subscript> ) <subscript>2</subscript> UI] (1) with potassium graphite produces the "second-generation" uranocene [(η <superscript>5</superscript> -C <subscript>5</subscript> <superscript>i</superscript> Pr <subscript>5</subscript> ) <subscript>2</subscript> U] (2), which contains uranium in the formal divalent oxidation state. The geometry of 2 is that of a perfectly linear bis(cyclopentadienyl) sandwich complex, with the ground-state valence electron configuration of uranium(II) revealed by electronic spectroscopy and density functional theory to be 5f <superscript>3</superscript> 6d <superscript>1</superscript> . Appreciable covalent contributions to the metal-ligand bonds were determined from a computational study of 2, including participation from the uranium 5f and 6d orbitals. Whereas three unpaired electrons in 2 occupy orbitals with essentially pure 5f character, the fourth electron resides in an orbital defined by strong 7s-6d z 2 mixing.<br /> (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)