Novel Supramolecular Assemblies of Co(III) & Cu(II) with Diethylenetriamine and Azide: Synthesis, Structure, Spectroscopic and Magnetic Studies

Abstract

AbstractIn exploring the role of increased ligand basicity as well as denticity on moving from ethylenediamine (en) or 1,3‐diaminopropane (1,3‐dap), on supramolecular solid formation, complexation involving diethylenetriamine (det) and azide with CoII and CuII afforded three new complexes [Co(det)2](N3)3 (1), [Co(det)(N3)3] (2) and [Cu2(det)2(N3)5(H2O)2Na] (3) under self assembling conditions and are characterized structurally and magnetically. Formation of 1 and 2 is sensitive to temperature of crystallization, while such a temperature influence could not be observed for CuII system due to lack of crystals at low temperatures. As expected with a tridentate ligand, strong chelation stabilizes 1 at LT and is a thermodynamically stable product, while isolation of 2 at RT conditions is under kinetic control. Decomposition of 2 at high temperatures (above 70 °C) as revealed through temperature dependent UV‐vis spectral studies also confirms its instability. Presence of three donor sites of det, leads to interesting structural pattern in Jahn‐Teller active CuII, resulting in cationic chains of [Cu(det)(N3)]n+ bridged by μ‐1,3 azido bridges to the neighboring [Na(H2O)2(N3)2]− units, thus leading to a 2‐D assembly of alternating layers of cationic and anionic chains in the unit cell of 3. Magnetic studies of 3 reveals anti‐ferromagnetic interaction between the copper ions (J=– 0.479 cm–1), in conformity with the bridge angle dependent magnetic behavior in azido bridged copper complexes.