The forefront of research into the complexes of uranium reveals chemical transformations that challenge and expand our view of this unique element. Certain ligands form multiple bonds to uranium, and small, inert molecules such as nitrogen and carbon dioxide become reactive when in complex with the metal. Such complexes provide clues to the catalytic future of uranium, in which the applications of the element extend far beyond the nuclear industry. Most excitingly, the ability of uranium to use its outermost f electrons for binding ligands might enable the element to catalyse reactions that are impossible with conventional, transition-metal catalysts.

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Towards uranium catalysts.

Synthesis, Structure, and Reactions of Hydride, Borohydride, and Aluminohydride Compounds of the f-Elements.

Titanium (IV) catalysis in the reduction of phosphine oxides

Publisher Summary Much new information about compounds of the lower oxidation states of uranium and thorium has accumulated during the past decade, and the rapid development of the organometallic chemistry of these elements has enhanced interest in this topic. Simple compounds of trivalent uranium have a long history.; Thischapter focuses on the developments since the Gmelin Uranium supplementary volumes. The chapter discusses thermodynamic and related data on trivalent ions, U 3+ and T H3+ by pulse radiolysis, complexes of uranium (III), and so on. Pulse radiolysis of U 4+ solutions produces U 3+ , which can be detected by its absorption spectrum. Uranium (IV) can also be reduced to U (III) photochemically. Pulse radiolysis also leads to the production of Th 3+ in perchlorate solution. The chapter discusses the main features of the absorption spectra. Oxidation of U 3+ by dissolved air is always quite rapid, and preparations must be conducted in completely air-free systems. The chapter also discusses several organometallic compounds, including substituted cyclopentadienyls, anionic U(III) organometallics, and others.

Compounds of Thorium and Uranium in Low (<IV) Oxidation States

The reactivity of [U(cp)3(AlH4)](1)(cp =η5-C5H5) has been studied. With (CH3)3CNC it gives [U(cp)3{CHNC(CH3)3}], with pyridine [U(cp)3(NC5H6)], with CH3CN [U(cp)3(NCHCH3)] and [U(cp)3(NHCH2CH3)], with (CH3)3CNCO, which probably inserts into the U–H bond, [U(cp)3{NC(CH3)3CHO}]. All these new complexes have been characterized by standard spectroscopic methods. In addition compound (1) reacts with ROH, acetaldehyde, and acetone to give the respective [U(cp)3(OR)], with BH3·S(CH3)2 giving [U(cp)3(BH4)], and with CH3l giving [U(cp)3l].

G.R. Franklin

Papers

Reactions of uranium hydride with some organic and organometallic compounds