The purity of complexes 1 -3 was confirmed by elemental analysis studies and powder X-ray diffraction measurements (Figures ). The thermal stability of all complexes was estimated by thermogravimetry analyses (TGA) from 303 K to 573 K with a scan rate of 10 K min -1 under a nitrogen atmosphere (Figure ). The TGA analyses of 1 and 2 show that both complexes are well stable up to 500 K, indicating the absence of interstitial solvent molecules which is also consistent with the single crystal X-ray structure studies (vide infra). It is important to mention that the noteworthy thermal stability might be coming from the intense chelating nature of both the dbm and bik-Et/ bik-Me ligands. Importantly, the absence of interstitial solvent molecules offers us an opportunity to explore the effect of ligand only on the magneto-structural relationship of the complexes without any interference coming from the interstitial solvent molecules, which is rarely noticed in SMM studies. In contrast, the TGA curve of complex 3 shows continuous weight loss in the range of 304 -331 K (ca. 4 %) and 340 -375 K (ca. 4 %), suggesting the loss of interstitial solvent molecules.