Abstract
Dicaesium hexa-nitratothorate(IV), Cs2[Th(NO3)6], was synthesized in the form of colourless crystals by reaction of thorium nitrate and caesium nitrate in aqueous solution. The Th atom is located on an inversion centre and is coordinated by six chelating nitrate anions. The resulting ThO12 coordination polyhedron is best described as a slightly distorted icosa-hedron. The Cs atom also has a coordination number of 12, but its coordination polyhedron is considerably more distorted. The crystal packing can be derived from an hexa-gonal dense packing (hcp) of idealized spherical CsO12 and ThO12 units. The CsO12 units form a distorted hcp arrangement and half of the octa-hedral sites are occupied by the ThO12 units.