Synthesis, characterization, and reactivity of a uranium(VI) carbene imido Oxo complex

We report the uranium(VI) carbene imido oxo complex [U(BIPM TMS)(NMes)(O)(DMAP)2] (5, BIPMTMS=C(PPh 2NSiMe3)2; Mes=2,4,6-Me3C 6H2; DMAP=4-(dimethylamino)pyridine) which exhibits the unprecedented arrangement of three formal multiply bonded ligands to one metal center where the coordinated heteroatoms derive from different element groups. This complex was prepared by incorporation of carbene, imido, and then oxo groups at the uranium center by salt elimination, protonolysis, and two-electron oxidation, respectively. The oxo and imido groups adopt axial positions in a T-shaped motif with respect to the carbene, which is consistent with an inverse trans-influence. Complex 5 reacts with tert-butylisocyanate at the imido rather than carbene group to afford the uranyl(VI) carbene complex [U(BIPM TMS)(O)2(DMAP)2] (6). Three not of a kind: An unprecedented arrangement of three formal multiply bonded ligands to one metal center, where the coordinated heteroatoms derive from different element groups, is found in the uranium(VI) carbene imido oxo complex [U(BIPM TMS)(NMes)(O)(DMAP)2] (Mes=2,4,6-Me3C 6H2). © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.