Oxalate Bridged Copper Pyrazole Complex Templated Anderson-Evans Cluster Based Solids

TLDR: In this paper, the Anderson-Evans type solids were synthesized from an aqueous solution containing sodium molybdate, chromium chloride, cupric chloride and pyrazole at room temperature.

Abstract: The synthesis of four new Anderson-Evans type cluster based solids was carried out from an aqueous solution containing sodium molybdate, chromium chloride, cupric chloride and pyrazole at room temperature: [{Cr3O(CH3COO)6(H2O)3}2{H7CrMo6O24}]·24H2O, 1; [{Cu2(ox)(pz)4}{H7CrMo6O24}]·11H2O, 3; [{Cu(pz)2(H2O)2}{Cu2(ox)(pz)4}{H5CrMo6O24}]·8H2O, 4; and [{Cu(pz)3Cl}{Cu2(ox)(pz)4}{H6CrMo6O24}]·8H2O, 5. In 1, the discrete Anderson-Evans cluster aggregates with trimeric chromium acetate cationic complex through supramolecular interactions. In 3–5, the Anderson-Evans cluster is covalently linked into a 1D chain through oxalate bridged copper pyrazole units. In 3, the chains are further stabilized by water oligomers. In 4 and 5, the chains are covalently linked into 2D sheets by different copper pyrazole complexes. The oxalate molecules in 3–5 are probably generated in situ in the reaction medium, through a reductive coupling of dissolved carbon dioxide assisted by copper pyrazole units.