Understanding the formation of metal-oxide based inorganic solids: Assessing the influence of tetrazole molecule

The hydrothermal reaction of Cu(II) salt, ammonium heptamolybdate and 4-ptz (5-(4-pyridyl) tetrazole) at different synthetic conditions yields two compounds [Cu(4-Hptz)(Mo2O7)] (1) and [Cu(4-Hptz)2(H2O)3]2[Mo8O26] (2). Both the compounds 1 and 2 are characterized by routine elemental analyses, IR-, thermogravimetric studies and unambiguously characterized by single crystal X-ray crystallography. Compound 1 exhibits a 3D bimetallic oxide framework, constructed from the tetrazoles and {CuMo2O7} oxide phase. The coordination ability of nitrogen atoms in the tetrazole ring makes the ring acting as a template in the formation of {Cu4Mo6O10} rings, made up of [Mo2O7]2− anions and Cu(II) octahedra; the stacking of these {Cu4Mo6O10} rings along crystallographic c axis results in the formation of 3D bimetallic oxide framework. Compound 2 consists of infinite octamolybdate chains and Cu–tetrazolate complex cation. The formation of oxide phase under hydrothermal conditions is discussed, giving importance of the role of geometry of the tetrazole ring.