Reticular chemistry applied on coordination polymers of Copper(I) cyanide with tridentate ligands: effect of the ligand flexibility and donor properties on topology, dimensionality and reaction behavior in solvothermal conditions

A study of the effect of flexibility of tri-chelating ligands on the overall topology of CuCN derivatives is reported. In particular, we selected two ligands with different degree of aromatic condensation: 2,2’:6’,2’’-terpyridine (tpy) and 2-(2’-pyridyl)-1,8-naphthyridine (pyNP). We obtained a new coordination polymer of pyNP [(CuCN)3(pyNP)]n (1), three coordination polymers of tpy ([(CuCN)3(tpy)]n (2), [(CuCN)(tpy)]n (3) and {[Cu(tpy)][Cu(CN)3]}n (4)), and one molecular compound, [Cu2Cl(CN)(pyNP)] (5). All products have been characterized by SC-XRD and Raman/IR spectroscopies. Results indicate that an hexagonal net can be obtained, but the two ligands show different effects on the topological fragments of cyanocuprate. An accurate vibrational analysis demonstrated to be diagnostic of the structural patterns in these systems, especially for cyanide stretching modes. We observed different behavior between tpy and pyNP in solvothermal condition. In the first case it was not possible to obtain a pure product, and Cu(II) derivatives have been identified; while using pyNP a pure phase was obtained, that suggests a preference toward Cu(I) coordination. It was also observed that the addition of CN ions promotes CuCN solubilization, increasing products yields, with effects on the nature and crystallinity of the obtained products.