Clusters with a Zr6O8 core

Clusters with the resilient Zr6O4(OH)4 core are important building blocks for metal–organic framework structures and cluster-reinforced polymers. The triangular faces of a Zr6 octahedron are capped by µ3-O and/or µ3-OH groups, and the Zr6 cluster core is surrounded by a shell of organic ligands, mostly carboxylate ligands. The basic chemistry of Zr6O4(OH)4(OOCR)12 clusters and their dimers is reviewed, including modifications of the ligand shell and expansion of the cluster core by means of additional zirconium atoms or other transition metals.