Transmuting elements is not possible with chemical transformations. However, using the concept of “electronic transmutation”, aluminum can be made to act similar to silicon. Silicon hydrides are known to have homodinuclear double bonds, such as that in Si₂H₄. The Al=Al double bond has been otherwise notoriously difficult to synthesize.

Kit H. Bowen, Johns Hopkins University, Baltimore, MD, USA, and colleagues have generated LiAl₂H₄^– by coating an aluminum rod with a thin layer of LiAlH₄ powder, and then ablating it with a pulsed laser beam. The resulting anions were characterized using mass spectrometry and photoelectron spectroscopy. Due to the donation of electrons from lithium to aluminum, the Al₂H₄^2– kernel in the LiAl₂H₄^– cluster is both isoelectronic and isostructural to Si₂H₄, and an Al=Al double bond is observed.

The team used quantum chemical calculations to examine more than 10,000 possible isomers of this cluster and discovered that the global minimum (pictured, Al in yellow, H in blue, Li in red) has an Al=Al double bond and is in excellent agreement with the measured spectrum. Using similar electronic transmutation strategies, other exotic chemical bonding situations and compounds could be realized.

• On the Existence of Designer Al=Al Double Bond in the LiAl₂H₄^– Cluster via Electronic Transmutation,
  Katie A. Lundell, Xinxing Zhang, Alexander I. Boldyrev, Kit H. Bowen,
  Angew. Chem. Int. Ed. 2017.
  DOI: 10.1002/anie.201710338