Uranium metallocene complexes of the 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidinato ligand, (hpp)(-).

The utility of the 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidinato ligand, (hpp)(-), in uranium chemistry has been probed by synthesizing metallocene complexes and studying their reactivity. (C(5)Me(5))(2)UMe(2) reacts with 1 equiv of Hhpp to form (C(5)Me(5))(2)(hpp)UMe, 1, which does not react further with Hhpp. (C(5)Me(5))(2)UCl(2) reacts with Khpp to form (C(5)Me(5))(2)(hpp)UCl, 2, which similarly does not react with additional Khpp. Complex 2 reacts with NaN(3) to form the azide complex, (C(5)Me(5))(2)(hpp)UN(3), 3. The trivalent uranium (hpp)(-) metallocene complex, (C(5)Me(5))(2)(hpp)U, 4, can be synthesized by the reaction of [(C(5)Me(5))(2)U][BPh(4)] with Khpp and from 2 with KC(8). Complex 4 can be oxidized with Ph(3)P horizontal lineSe to produce the tetravalent product, [(C(5)Me(5))(2)(hpp)U](2)(mu-Se), 5. The reaction of 4 with Me(3)SiN(3) provides the pentavalent uranium complex, (C(5)Me(5))(2)(hpp)U(=NSiMe(3)), 6.