An unprecedented trigonal coordination geometry for the uranyl ion in its complex with p-tert-butylhexahomotrioxacalix[3]arene

Whereas the environment of the uranyl ion in its coordination complexes has always been observed to comprise four, five or six donor atoms close to its equatorial plane, it appears to be pseudo-trigonal, with three oxygen donor atoms only, in the complexes with p-tert-butylhexahomotrioxacalix[3]arene. This is the lowest coordination number ever observed in a uranyl complex.