An eight-connected metal organic framework based on Cu₅ clusters: Synthesis, structure, magnetic and catalytic properties

Abstract

A reaction of copper acetate, 5-nitroisophthalic acid in a water-methanol mixture under solvothermal condition results in a new metal-organic framework compound, [Cu₅(µ₃-OH)₂(H₂O)₆{(NO₂)-C₆H₃-(COO)₂}₄].5H₂O, (<b style="">1</b>). The compound contains Cu₅ pentameric cluster units connected by 5-nitro isophthalate (NIPA) moieties forming a CdCl₂-like layer, which are further connected by another NIPA moiety forming the three-dimensional structure. The water molecules in (<b style="">1</b>) can be reversibly adsorbed. The removal of water accompanies a change in the colour as well as a structural re-organization. Magnetic studies suggest strong antiferromagnetic correlations between the Cu₅ cluster units. The compound (<b style="">1</b>) exhibits heterogeneous Lewis acid catalysis for the cyanosilylation of imines with more than 95 % selectivity. Compound (<b style="">1</b>) has been characterized by IR, UV-vis, TGA, powder XRD studies.