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.

Automated summary

A new monoanionic nitrogen-phosphorus ligand was designed and used to synthesize several uranium complexes. The reactivity of these complexes was investigated, and it was found that the ligand is an effective platform for the construction of species with uranium-metal bonds.