Synthesis and structure of [U{C(PPh(2)NMes)(2)}(2)] (Mes=2,4,6-Me3C6H2): A homoleptic uranium bis(carbene)complex with two formal U=C double bonds

Treatment of H2C(PPh(2)NMes)(2) (1, Mes = 2,4,6-Me3C6H2) with two equivalents of (BuLi)-Li-t afforded the methandiide complex [Li-2{C(PPh(2)NMes)(2)}(2)](2) (2); reaction of 2 with [UI3(THF)(4)] gave [U{C(PPh(2)NMes)(2)}(2)] (3), which is the first homoleptic uranium bis(carbene) complex with two formal U=C double bonds.