Two Three‐Dimensional Metal‐Organic Frameworks Constructed from Alkaline Earth Metal Cations (Sr and Ba) and 5‐Nitroisophthalicacid – Synthesis,Charaterization, and Thermochemistry

Two MOFs of Sr^II(5‐NO₂‐BDC)(H₂O)₆] ( 1 ) and Ba^II(5‐NO₂‐BDC)(H₂O)₆] ( 2 ) have been synthesized in water using alkaline earth metal salts and the rigid organic ligand 5‐NO₂‐H₂BDC. The compounds were characterized by elemental analysis, infrared spectrum, thermal analysis, and X‐ray crystallography. Crystal structure analyses have shown that the two complexes are isostructural as evidenced by IR spectra and TG‐DTA. Both compounds present three‐dimensional frameworks built up from infinite chains of edge‐sharing twelve‐membered rings through O–H···O hydrogen bonds. The specific heat capacities of the title complexes have been determined by an improved RD496‐III microcalorimeter with the values of (109.29 ± 0.693) J mol⁻¹ K⁻¹ and (81.162 ± 0.858) J mol⁻¹ K⁻¹ at 298.15 K, and the molar enthalpy changes of the formation reactions of complexes at 298.15 K were calculated as (4.897 ± 0.008) kJ mol⁻¹ and (2.617 ± 0.009) kJ mol⁻¹, respectively.