Reversible Dihydrogen Activation and Hydride Transfer by a Uranium Nitride Complex.

Cleavage of dihydrogen is an important step in the industrial and enzymatic transformation of N2 into ammonia. The reversible cleavage of dihydrogen was achieved under mild conditions (room temperature and 1 atmosphere of H2 ) by the molecular uranium nitride complex, [Cs{U(OSi(Ot Bu)3 )3 }2 (μ-N)] 1, leading to a rare hydride-imide bridged diuranium(IV) complex, [Cs{U(OSi(Ot Bu)3 )3 }2 (μ-H)(μ-NH)], 2 that slowly releases H2 under vacuum. This complex is highly reactive and quickly transfers hydride to acetonitrile and carbon dioxide at room temperature, affording the ketimide- and formate-bridged UIV species [Cs{U(OSi(Ot Bu)3 )3 }2 (μ-NH)(μ-CH3 CHN)], 3 and [Cs{U(OSi(Ot Bu)3 )3 }2 (μ-HCOO)(μ-NHCOO)], 4.