ic7b02216_si_001.pdf (127.86 kB)

Understanding the Scarcity of Thorium Peroxide Clusters

Download (127.86 kB)
journal contribution
posted on 25.10.2017, 12:09 by Shane S. Galley, Cayla E. Van Alstine, Laurent Maron, Thomas E. Albrecht-Schmitt
The reaction of Th­(NO3)4·5H2O with 3 equiv of 2,2′,6′,2″-terpyridine (terpy) in a mixture of acetonitrile and methanol results in formation of the trinuclear thorium peroxide cluster [Th­(O2)­(terpy)­(NO3)2]3. This cluster is assembled via bridging by μ–η22 peroxide anions between thorium centers. It decomposes upon removal from the mother liquor to yield Th­(terpy)­(NO3)4 and Th­(terpy)­(NO3)4(EtOH). The peroxide formation appears to be radiolytic in origin and is, most likely, generated from radiolysis of water by short-lived daughters generated from 232Th decay. This cluster does not form when freshly recrystallized Th­(NO3)4·5H2O is used as the starting material and requires an aged source of thorium. Analysis of the bonding in these clusters shows that, unlike uranium­(VI) peroxide interactions, thorium­(IV) complexation by peroxide is quite weak and largely ionic. This explains its much lower stability, which is more comparable to that observed in similar zirconium­(IV) peroxide clusters.