Synthesis, characterization and crystal structure determination of Mn (II) ion based 1D polymer constructed from 2, 2′ bipyridyl and azide group, its thermal stability, magnetic properties and Hirshfeld surface analysis

Abstract

The 1-D polymeric complex (I) is having formula [Mn(2,2′-BP).(N3)2]n, which has been crystallized in distilled water and characterized by elemental analyses, FT-IR spectrum, powder X-ray diffraction analyses and single-crystal diffraction analysis. This polymer possesses 1D helical chains or coils where Mn–azide–Mn forms the base of the coil which is alternatively garlanded by rigid bi-pyridine rings, where coordinates are in anti-fashion. The Mn (II) ions in the repeating units are linked by two end-on azide groups which extend through the two end-to-end azide ligands to the next unit forming a 1-D polymeric chain. The present study suggests that the use of this rigid and neutral building block leads to give better arrangement of the polymeric motif with [010] chains in 2-c uninodal net. During investigation of strong or weak intermolecular interactions, X-ray diffraction analysis and Hirshfeld surface analysis give rise to comparable results but in Hirshfeld surface analysis, two-third times more results of close contacts are obtained. The fingerprint plots demonstrate that these weak non-bonding interactions are important for stabilizing the crystal packing. Magnetic properties of the complex (I) were analyzed on the basis of an alternating ferro- and antiferromagnetic Heisenberg chain of Mn (II) ions. The J-exchange parameters found are J1=64.3K (45.3cm−1), and J2=−75.7K (−53.3cm−1). Magnetic properties are discussed in comparison with those of other similar molecular magnets of [Mn(L–L)(N3)2]n type.