![A new series of [M(B11H11)2] 3-anions with metals in their highest known oxidation states](https://i0.wp.com/lightsources.org/wp-content/uploads/2025/12/Rozszerzenie_SlabonSOLARISweb.jpg?resize=700%2C516&ssl=1)
In collaboration with Prof. Finze’s research group (University of Würzburg) and Dr. Alexey Maximenko (SOLARIS National Synchrotron Radiation Centre at Jagiellonian University) Prof. Adam Slabon’s research group has successfully synthesized and comprehensively characterized a new series of anions of the type [M(B11H11)2]3- (M = Cu, Ag, Au). The nido-[B11H11]4- ligand coordinates to copper, silver, and gold stabilizing them in the exceptionally high formal oxidation state +V. This is the highest oxidation state known to date for these metals. XANES analysis, carried out by Dr. Alexey Maximenko, additionally confirmed the unusually high oxidation state of copper in K3[Cu(B11H11)2]·5H2O.
DFT calculations showed the relative stability of different structural isomers, while experimental investigations revealed an unusual property of the silver complex. X-ray structural analyses of single crystals revealed that [Ag(B11H11)2]3⁻exists in equilibrium between two coordination forms: a kinetically stable η5 species with Ag(V) and a labile η2species with Ag(I). When cooled below 130 K, a reversible phase transition occurs in which the ligand coordination changes from η5 na η2 and reverts back when heated. This is the first observation of such low-temperature isomerization in this class of compounds.
Read more on the SOLARIS website
Image: Reversible transition between (n-Bu4N)3[Ag+V(η5 – B11H11)2] and (n-Bu4N)3[Ag+I (η2-B11H11)2]