A survey is given of recent original structural results on heterometallic species incorporating uranyl ions, particularly with carboxylate ligands.

The first crystal structure of uranyl citrate is reported, as well as that of uranyl sodium tricarballylate; both compounds are polymeric, with all acid groups coordinated, but they differ strongly in their coordination modes; the resulting assembly architecture is either three-dimensional with [(UO₂)₂(Hcit)₂]²⁻ metallacycle subunits with citrate or two-dimensional with tricarballylate.