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

A monoanionic nitrogen-phosphorus ligand (CH3)(2)(NCH2CH2NHPPr2)-Pr-i (L3) was designed and the corresponding U(IV) chloride complex {[(CH3)(2)(NCH2CH2NPPr2)-Pr-i](2)UCl2} (1) and U(IV) iodide complex {[(CH3)(2)(NCH2CH2NPPr2)-Pr-i](2)UI2} (2) were readily synthesized. Complexes 1 and 2 were fully characterized and the reactivity of complex 1 was further investigated. Complex 3 {[(CH3)(2)(NCH2CH2NPPr2)-Pr-i](2)U(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)(2)(NCH2CH2NPPr2)-Pr-i](2)U[o-N(CH3)(CH2)C6H4CH2]} (4) was isolated by the reaction of complex 1 with two equivalents of o-N(CH3)(2)C6H4CH2K. Moreover, the reactivity of 1 with a series of transition metal precursors was also investigated, from which heterometallic clusters {[(CH3)(2)(NCH2CH2NPPr2)-Pr-i](2)UCl2(mu-Cl)RuCl}(2) (5), {[(CH3)(2)(NCH2CH2NPPr2)-Pr-i](2)UCl2Rh(mu-Cl)}(2) (6) and {[(CH3)(2)(NCH2CH2NPPr2)-Pr-i](2)UCl2Ir(mu-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.