Strongly coupled binuclear uranium-oxo complexes from uranyl oxo rearrangement and reductive silylation

The most common motif in uranium chemistry is the d0f0 uranyl ion [UO2]21 in which the oxo groups are rigorously linear and inert. Alternative geometries, such as the cis-uranyl, have been identified theoretically and implicated in oxo-atom transfer reactions that are relevant to environmental speciation and nuclear waste remediation. Single electron reduction is now known to impart greater oxo-group reactivity, but with retention of the linear OUO motif, and reactions of the oxo groups to form new covalent bonds remain rare. Here, we describe the synthesis, structure, reactivity and magnetic properties of a binuclear uranium–oxo complex. Formed through a combination of reduction and oxo-silylation and migration from a trans to a cis position, the new butterfly-shaped Si–OUO2UO–Si molecule shows remarkably strong UV–UV coupling and chemical inertness, suggesting that this rearranged uranium oxo motif might exist for other actinide species in the environment, and have relevance to the aggregation of actinide oxide clusters.JRC.E.6-Actinides researc

The influence of the invasive shrub, Lonicera maackii, on leaf decomposition and microbial community dynamics

Amur honeysuckle (Lonicera maackii) is an exotic invasive shrub that is rapidly expanding into forests of eastern North America. This species forms a dense forest understory, alters tree regeneration, negatively affects herb-layer biodiversity, and alters ecosystem function. In a second-growth forest in central Kentucky, we examined the timing and production of leaf litter and compared litter chemistry, decay rates, and microbial community colonization of Amur honeysuckle to that of two native trees, white ash (Fraxinus americana) and hickory (Carya spp.). The distribution of Amur honeysuckle was clumped, allowing us to compare differences in decomposition under and away from Amur honeysuckle shrubs. Amur honeysuckle leaf litter had significantly higher nitrogen, lower C:N, and lower lignin than the other species, and decomposition rates were greater than 5× faster. Despite the much higher rate of Amur honeysuckle decomposition compared with the native species (p \u3c 0.0001), decomposition of all species was significantly slower (p = 0.0489) in sites located under Amur honeysuckle shrubs. Nitrogen concentration increased through time in decomposing Amur honeysuckle litter; however, total mass of N rapidly declined. We found the initial microbial community on leaf litter of Amur honeysuckle was distinct from two native species and although all microbial communities changed through time, the microbial community of Amur honeysuckle remained distinct from native communities. In summary, a distinct microbial community that may originate on Amur honeysuckle leaves prior to senescence could explain the rapid decay rates