Liddle Group publication in Angewandte Chemie International Edition

The elusive HAsAsH molecule has been isolated in a crystalline diuranium complex after more than two hundred years of inconclusive or discredited claims regarding its synthesis.

Molecular structure of HAsAsH trapped between two bulky uranium triamidoamine units. Carbon-bound hydrogen atoms are omitted for clarity.

The work was carried out by Dr Ben Gardner, a postdoctoral research fellow in the research group of Prof. Steve Liddle, and has been published as an Open Access article in the leading chemistry journal Angewandte Chemie International Edition (DOI:10.1002/anie.201508600).

First suggested as a reaction product by Humphry Davy in 1810, HAsAsH, a heavy analogue of the fundamental molecule ethylene, has had a chequered past with many claims to its synthesis being disproven over the years. The paucity of information about this molecule stemmed from a lack of methodologies to make it and its intrinsic instability in the absence of bulky stabilsing groups. As part of work investigating uranium-arsenic chemistry (Nat. Chem. 2015, 7, 582), also carried out by Dr Ben Gardner, the team discovered that HAsAsH can be assembled at uranium and protected by a large triamidoamine ligand bound to uranium. The work determined that the HAsAsH unit is strongly reduced by the two uranium fragments, confirming theoretical predictions that it would be an excellent electron acceptor ligand.

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