Reversible Dihydrogen Activation and Hydride Transfer by a Uranium Nitride Complex

Abstract

Cleavage of dihydrogen is an important step in the industrial and enzymatic transformation of N into ammonia. The reversible cleavage of dihydrogen was achieved under mild conditions (room temperature and 1 atmosphere of H ) by the molecular uranium nitride complex, [Cs{U(OSi(O Bu) ) } (μ-N)] 1, leading to a rare hydride-imide bridged diuranium(IV) complex, [Cs{U(OSi(O Bu) ) } (μ-H)(μ-NH)], 2 that slowly releases H 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 U species [Cs{U(OSi(O Bu) ) } (μ-NH)(μ-CH CHN)], 3 and [Cs{U(OSi(O Bu) ) } (μ-HCOO)(μ-NHCOO)], 4.

Reversible Dihydrogen Activation and Hydride Transfer by a Uranium Nitride Complex

“…Thes olid-state structure of 3 ( Figure 2) shows the presence of two uranium ions bridged by an imido and aketimido (or azavinylidene) group.Acesium [25] Ellipsoids are set at 50 %probability;methyl groups are omitted for clarity. Thus,t he hydride addition to the acetonitrile results in the two-electron reduction of the nitrogen-carbon triple bond.…”

“…[25] Ellipsoids are set at 50 %p robability;m ethyl groups are omitted for clarity. In situ reactions of 2 with a) acetonitrile to give 3 and b) 2equiv of carbon dioxide to give 4.…”

“…Molecular structure of [Cs{U(OSi(O t Bu) 3 ) 3 } 2 (m-NH)(m-CH 3 CHN)], 3. [25] Ellipsoids are set at 50 %p robability;m ethyl groups are omitted for clarity.…”

Reaction of CO2 with a Vanadium(II) Aryl Oxide: Synergistic Activation of CO2/Oxo Groups towards H‐Atom Radical Abstraction

“…Although DFT predicts for this hypothetical complex the same bridging arrangement as observed by Maron, Okuda, Cummins, and co‐workers, the energy profile was less favorable with respect to the simple deoxygenation. The scenario provided by ts6 is therefore somewhat reminiscent of a frustrated Lewis pair, whose high reactivity is sufficient to perform dihydrogen activation among other remarkable transformations . In other words, by the positioning of CO 2 in a bent–bridging coordination mode on a preformed V–O–V unit (ts6 in Figure ), electron density is enhanced at the C atom at the expense of the oxo O atom, thus creating the perfect scenario for hydrogen abstraction not only by the C atom but also by the bridging oxide.…”

The Mechanism of Sugar C−H Bond Oxidation by a Flavoprotein Oxidase Occurs by a Hydride Transfer Before Proton Abstraction

“…These factorsh ave led to the increasedu se of enzymesa sb iocatalystsi nb oth preparative and industrial scale applications. [9,[15][16][17] The functionalization of CÀHb onds throughahydride transfer mechanism, as occurs in various enzymes, has received significant attention in theoretical and experimental investigations, [18][19][20][21][22][23] because understanding the reaction mechanisms underlying CÀHo xidation in these enzymes is instrumental for devising efficient industrial biocatalysts. CÀHb ond oxidation can be catalyzedb ym any flavoenzymes by the simple transfer of ah ydride equivalent to their flavin cofactors such as those in the reactions of alcohold ehydrogenase, [24] choline oxidase, [25] choline dehydrogenase, [26] amine oxidases, [27,28] vanillyl-alcohol oxidase, [29] aryl-alcohol oxidase, [30] cholesterol oxidase, [31] 5-hydroxymethylfurfural oxidase, [32] ands ugar oxidase.…”