Synthesis and SMM behaviour of trinuclear versus dinuclear 3d-5f uranyl(v)-cobalt(ii) cation-cation complexes.

Trinuclear versus dinuclear heterodimetallic UV O2 + Co2+ complexes were selectively assembled via a cation-cation interaction by tuning the ligand. The trimeric complex 2, with a linear [Co-O[double bond, length as m-dash]U[double bond, length as m-dash]O-Co] core, exhibits magnetic exchange and slow relaxation with a reversal barrier of 30.5 ± 0.9 K providing the first example of a U-Co exchange-coupled SMM.