Reaction-temperature-dependent supramolecular isomerism of copper(I) coordination polymers with incorporated thiocyanate and in situ generated 5-methyltetrazolate ligands

The hydrothermal reaction of NaN3, acetonitrile and KSCN in the presence of [Cu(CH3CN)4]ClO4 yields two new d10 coordination polymers, [Cu2(μ3-SCN)(μ4-mtta)]n (1) and its supramolecular isomer [Cu2(μ4-SCN)(μ4-mtta)]n (2) (mtta = 5-methyl tetrazolate), involving in situ formation of the 5-methyltetrazolate ligand by cycloaddition of nitrile and azide. Compounds 1 and 2 were both found to crystallize in the orthorhombic Pbam system, with different unit cells, exhibiting interesting examples of supramolecular polymorphism. Both compounds are built by [Cu2mtta]+n ribbons connected by thiocyanate anions which act as μ3- and μ4-ligands in 1 and 2, leading to 2D and 3D coordination polymers, respectively. Short Cu(I)⋯Cu(I) distances were found in 1 and 2, which may be attributed to metallophilic Cu⋯Cu interactions. Thermogravimetric analyses indicate that compounds 1 and 2 are stable up to 265 and 340 °C, respectively.

Graphical abstractThe one step synthesis of copper(I) coordination polymers with incorporated thiocyanate and in situ generated 5-methyltetrazolate ligands.Figure optionsDownload full-size imageDownload as PowerPoint slide