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.