Synthesis and reactivity of a uranium(iv) complex supported by a monoanionic nitrogen–phosphorus ligand

Abstract

A monoanionic nitrogen–phosphorus ligand (CH₃)₂NCH₂CH₂NHPⁱPr₂ (L3) was designed and the corresponding U(IV) chloride complex {[(CH₃)₂NCH₂CH₂NPⁱPr₂]₂UCl₂} (1) and U(IV) iodide complex {[(CH₃)₂NCH₂CH₂NPⁱPr₂]₂UI₂} (2) were readily synthesized. Complexes 1 and 2 were fully characterized and the reactivity of complex 1 was further investigated. Complex 3 {[(CH₃)₂NCH₂CH₂NPⁱPr₂]₂U(C₁₂H₈)} with a uranium cyclopentadiene unit was constructed by the reaction of 1 with 2,2′-dilithiobiphenyl, which is a rare example of a homoleptic metallafluorene containing an actinide element. In addition, a U(IV) bi-alkyl complex {[(CH₃)₂NCH₂CH₂NPⁱPr₂]₂U[o-N(CH₃)(CH₂)C₆H₄CH₂]} (4) was isolated by the reaction of complex 1 with two equivalents of o-N(CH₃)₂C₆H₄CH₂K. Moreover, the reactivity of 1 with a series of transition metal precursors was also investigated, from which heterometallic clusters {[(CH₃)₂NCH₂CH₂NPⁱPr₂]₂UCl₂(μ-Cl)RuCl}₂ (5), {[(CH₃)₂NCH₂CH₂NPⁱPr₂]₂UCl₂Rh(μ-Cl)}₂ (6) and {[(CH₃)₂NCH₂CH₂NPⁱPr₂]₂UCl₂Ir(μ-Cl)}₂ (7) were isolated. The U–Rh and U–Ir single bonds were observed in complexes 6 and 7, respectively. This study further confirms that the nitrogen–phosphorus ligand is an effective platform for the construction of species with U–M bonds.