Crystal Structure of Regularly Th -Symmetric [U(NO3 )6 ]2- Salts with Hydrogen Bond Polymers of Diamide Building Blocks.

Hexanitratouranate(IV), [U(NO3 )6 ]2- , has been crystallized with anhydrous H+ -involving hydrogen bond polymers connected by selected diamide building blocks. Thanks to the significant moderation of electrostatic interactions between the anions and cations, the molecular structure of [U(NO3 )6 ]2- in these compounds is regularly Th -symmetric. The f-f transitions stemming from 5f2 configuration of U4+ are strictly forbidden by the Laporte selection rule in such a centrosymmetric system, so that the obtained compounds are nearly colourless in contrast to other UIV species usually coloured in green.