In this week’s issue of Nature magazine Arnold et al. have published an intriguing reactive complex of the notoriously stable uranyl dication [UO₂]⁺ that cleaves C-Si bonds and yields a functionalized U=O bond. This was accomplished by first encapsulating the UO₂ into a cyclic macrocycle, followed by the addition of the metal (either iron or zinc bound to the inner U=O bond) with a silylamide base. The major product is shown in the figure below.

Reprinted by permission from Macmillan Publishers Ltd: Nature, advance online publication, 17 January 2008 (doi:10.1038/nature06467) The crystal structure was also taken and is shown above. This reactivity was explained by postulating an U(VI) K₂ intermediate not observed. Postulated mechanism below.

Reprinted by permission from Macmillan Publishers Ltd: Nature, advance online publication, 17 January 2008 (doi:10.1038/nature06467)

A solution to the problem of determining the presence of the postulated intermediate might simply be to take mass specs along the course of the reaction; as one described prep takes 42 hours. In the end, this work literally builds the scaffold for future chemists to begin functionalizing uranyl. Although, no mention is given how to un-encapsulate the newly derivatized uranium.

Note 1: Link to article — Reduction and selective oxo group silylation of the uranyl dication

Mitch

The discovery of a new isotope of Bohrium, by Nelson et al., was published yesterday in PRL. In total, 8 events of ²⁶⁰Bh were reported. Unfortunately, the new isotope is not long-lived enough to be of practical chemical interest. A summary of the decay properties is summarized in the Nuclear Trading Card format shown below.

The yellow color signifies the observation that it decays by alpha emission 100% of the time. Fortunately the nuclide decays into ²⁵⁶Db, which is long-lived enough for chemistry, and the results taken with this paper and others updates the known decay properties of Dubnium-256. The updated trading card is below.

In this case the red signifies an ~30% electron capture branch. We hope you enjoy the announcement of a new member to the Bohrium family, and have fun with your new nuclear trading card.

Note 1: Link to article: Lightest Isotope of Bh Produced via the ²⁰⁹Bi(⁵²Cr, n)²⁶⁰Bh Reaction

Mitch