Molecular geometry capped trigonal prism

The trimeric structure of [Th(TPP)(0H)2]3-2H20 has been confirmed by Kadish et al. (1988). The six hydroxyl ligands in the molecular unit form a trigonal prism of which the triangular faces are capped by two water molecules and the rectangular faces are capped with three thorium atoms (fig. 2a). The three domed TPP units lie parallel to the threefold axis (fig. 2b) and each of the thorium atom assumes a distorted square antiprismatic geometry. The Th-Th separation is 3.960(3) A and does not suggest any metal-metal interaction. 

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