Isolation of U(ii) compounds using strong donor ligands, C5Me4H and N(SiMe3)2, including a three-coordinate U(ii) complex

New examples of uranium in the formal + 2 oxidation state have been isolated by reduction of Cptet 3U (Cptet = C5Me4H) and U(NR2) 3 (R = SiMe3) in the presence of 2.2.2-cryptand (crypt) to produce [ K(crypt)][ Cptet 3U] and[ K(crypt)][ U(NR2) 3], respectively. Both complexes have properties consistent with 5f36d1 electron configurations and demonstrate that the U(II) ion can be isolated with electron donating ligands.