Divalent Actinides and Transactinides: Inorganic and Organometallic Complexes

Abstract

This article presents an overview of the chemistry of divalent actinide molecular compounds, as well as a brief discussion about prospects for divalent chemistry of transactinide elements. In the introduction, a survey of the stability of the +2 oxidation state for actinides and transactinides is presented, the scope of the article is elucidated, and previous review publications related to the subject are identified. The main body concisely covers experimental results that have provided evidence for formation of divalent actinide molecular species. The initial section reviews some studies performed in the relatively “exotic” realms of gas phase and noble gas matrices. The majority of the article is devoted to the more characteristic territory of coordination chemistry in solutions and solids. An emphasis is on recent experimental developments that led to the first syntheses of complexes of divalent thorium, uranium, neptunium, and plutonium. Speculation on potential future developments in divalent actinide and transactinide chemistry is presented in closing.

Electrochemical Studies of Selected Lanthanide and Californium Cryptates

“…These examples are largely restricted to halides, − triflates, − cyclopentadienylides, dithiocarbamates, , iodates, ,− hydroxypyridonates, , and borates, and even in these cases some of the compounds are quite historic and do not even vaguely meet modern standards of characterization. The situation is even more pronounced for complexes containing An 2+ cations beyond uranium . These are currently limited to a handful of Np 2+ and Pu 2+ organometallic complexes and the binary AnX 2 compounds (An = Am, Cf; X = Cl, Br, I). − In short, there are no Am II or Cf II molecular complexes for which single-crystal structures have been reported.…”

“…The situation is even more pronounced for complexes containing An 2+ cations beyond uranium. 47 These are currently limited to a handful of Np 2+ and Pu 2+ organometallic complexes and the binary AnX 2 compounds (An = Am, Cf; X = Cl, Br, I). 48−50 In short, there are no Am II or Cf II molecular complexes for which single-crystal structures have been reported.…”