Crystal structure of {[Er III (BHT)3(azopy)}nnC5H12 (2) {[Er III (BHT)3(azopy)}nnC5H12 crystalizes in the monoclinic crystal system in the P 21/c space group in forms of slightly elongated purple prisms as determined by scXRD structural analysis. Table summarizes the crystallographic parameters for compound 2. {[Er III (BHT)3(azopy)}nnC5H12 forms slightly wavy coordination chains along the b crystallographic direction with the azopy acting as a bridging ligand connecting 'Er III (BHT)3' units (Figure ). The spaces between the chains are filled with pentane as the crystallization solvent.