Two-dimensional metal coordination networks hydrothermal synthesis, crystal structure, and thermal properties of [M(ox)(bpy)] (M = Fe, Co, Ni, Zn; ox = C2O42- ; bpy = 4, 4'-bipyridine) and [MCl2(bpy)] (M = Fe, Co, Ni, Co/Ni)

Abstract

Two-dimensional metal coordination polymers with a general formula [M(ox)(bpy)] (M = Fe, Co, Ni, Zn; ox = C2O4^2- ; bpy = 4, 4'-bipyridine) and [MCl₂(bpy)] (M = Fe, Co, Ni, or Co/Ni; 1:1 molar) bpy = 4, 4'-bipyridine) have been designed and synthesized via the hydrothermal method. The compounds [Fe(ox)(bpy)](I), [Co(ox)(bpy)](II), [Ni(ox)(bpy)](III), and[Zn(ox)(bpy)](IV) represent the first coordination network structure constructed by bridging oxalate and 4,4'-bpy mixed ligands. The compounds [FeCl2(bpy)](V), [CoCl2(bpy)](VI), [NiCl2(bpy)](VII), and[ZnCl2(bpy)](VIII) represent a similar structure type constructed by bridging chlorine atoms and 4,4'-bpy ligands. Compounds I-IV are isostructural and belong to the orthorhombic crystal system, space group Immm (No. 71). Compounds V-VIII are also isostructural and belong to the orthorombic crystal system, space group Cmmm (No. 65). I-IV have a non-interpenetrated structure that contains layers of octahedral metal centers coordinated by two oxalate and two bpy ligands. In like fashion, V-VIII have a non-interpenetrated structure containing metal centers octahedrally coordinated to four bridging chlorine atoms and two bpy ligands at trans position. Thermogravimetric analyses (TGA) indicate that compounds IIV are thermally stable up to 300^oC, while compounds V-VIII are thermally stable up to 400^oC.