Divalent metal ions are required virtually in every stage of genetic information transfer, and have profound effects on the structures and functions of nucleic acids. This article reviews the current developments of X-ray diffraction studies of metal ion interactions with nucleic acid constituents. The following important findings and topics are briefly presented ; metal binding sites, metal binding effects on the structural dimensions and conformations of nucleic acid constituents, molecular structures of metalnucleotide complexes, metal binding mode in ternary metal ion-nucleotide complexes containing aromatic heterocyclic ligands, which have been studied as a simple model for nucleic acid-metalion-enzyme system, and binding modes of anti-tumor agents, cisammine platinum (II) complexes with nucleic acids.
In the last decade a number of ternary molybdenum chalcogenides named Chevrel phase compounds, MxMo6X8 (M=metal ion ; X=S, Se and Te), have been investigated. Many of these compounds show properties as superconductors with high upper critical fields. Further, in some cases of M=rare earth elements, the coexistences of magnetism and superconductivity are observed. For these substances, the growth of large single crystals with good quality and the knowledge of the exact chemical composition are essential to the understanding of physical properties. Recently a series of compounds with more complicated structures, i. e. MxMo15X19, MxMo9X11 and M2Mo6 X6 (X=S, Se and Te) have also been prepared. Then the problems of these compounds in chemical side became more important. The present article reviews these substances from the viewpoint of crystal structure, crystal growth, nonstoichiometry and bonding character.