Investigation of the Electronic Structure of Aryl-Bridged Dinuclear U(III) and U(IV) Compounds

A family of dinuclear bis(Tp*) (Tp* = hydrotris(3,5-dimethylpyrazolyl)borate) uranium compounds with conjugated organic linkers was synthesized to explore possible electronic communication between uranium ions. Trivalent diuranium phenyl alkynyl compounds, Tp*2UCC(1,3-C6H4)CCUTp*2 (2-meta) or Tp*2UCC(1,4-C6H4)CCUTp*2 (2-para), and tetravalent diuranium phenylimido compounds, Tp*2U(N-1,3-C6H4–N)UTp*2 (3-meta) and Tp*2U(N-1,4-C6H4–N)UTp*2 (3-para), were generated from trivalent Tp*2UCH2Ph. All compounds were fully characterized both spectroscopically and structurally. The electronic structures of all derivatives were interrogated using magnetic measurements, electrochemistry, and were the subject of computational analyses. All of these data combined established that little electronic communication exists between the uranium centers in these trivalent and tetravalent diuranium molecules.