High pressure crystal chemistry of transition metal diantimonides

High-pressure crystal chemistry of transition metal diantimonides is discus sed. Two types of pressure-induced phase transitions, marcasite-type to CuA l2-type and marcasite-type to pararammels-bergite-type, occur in this famil y The former is found in CrSb2 and the transition is accompanied by a chang e in bonding character from the mixed ionic and covalent to metallic. The l atter is found in NiSb2 and can be explained by effective packing of NiSb6 octahedra. The local environment of nickel atom remains unchanged during th e transition. The phase transition sequences in transition metal diantimoni des, together with other dipnictides and dichalcogenides, are schematically summarized.