Metal-organic structures with formate and sulfate anions: Synthesis, crystallographic studies and hydrogen storage by PM7 and ONIOM

Six coordination complexes: {[H2NMe2][Co(CHO2)(3)]}(n) (1), [Co(bpy)(CHO2)(2)](n) (2), [Cu(dmf)(CHO2)(2)](2)(3), {[H2NMe2][Cu(CHO2)(3)]}(n) (4){[H2NMe2](4)[Fe4O2(dmf)(4)(SO4)(6)] (5) and [Co-3(bPY)(SO4)(3)](n) (6) have been efficaciously synthesized using solvothermal techniques and slow evaporation. Two compounds (5 and 6) containing the sulfate anion (SO42-) with iron (III) and cobalt (II) had never been described in the Cambridge Structural Database. In all complexes, the transition metal is hexacoordinated with a distorted octahedral geometry and displays a three-dimensional supramolecular architecture through hydrogen bonding interactions [N-H center dot center dot center dot O]. Formate (CHO2-) and sulfate (SO42-) anions were very important to the assembly of the three-dimensional MOFs and can be regarded as the template for all structures. All metal-organic complexes were identified by single-crystal X-ray diffraction, elemental composition and Fourier-transform infrared spectroscopy. In this paper, we propose the PM7 and ONIOM calculations as two effective methods in the determination of hydrogen storage. The weight percentage (wt %) of the hydrogen stored in the small cavities of the PCPs studied were: (1) 1.03 wt %, (4) 1.01 wt %, (6) 0.28 wt %. (C) 2019 Elsevier B.V. All rights reserved.