Metal-organic frameworks based on iron oxide octahedral chains connected by benzenedicarboxylate dianions

Three new iron benzenedicarboxylates have been synthesized by solvothermal techniques, and their structures determined from single crystal X-ray data: Fe(OH)(BDC)(py)0.85 (1), Fe(BDC)(DMF) (2), and Fe(BDC)(py)0.42(DMF)0.25 (3) (BDC = 1,4-benzenedicarboxylate, py = pyridine, DMF=N,N-dimethylformamide). Compounds 1 and 2 are the Fe(III)- and Fe(II)-structural analogs of the known Cr benzenedicarboxylate compound (MIL-53). Both contain trans corner-sharing FeO6 octahedral chains connected by benzenedicarboxylate dianions. Compound 3 contains chains of iron oxygen octahedra that share both corners and edges. Each chain is linked by BDC to six other chains to form a three-dimensional framework. Crystal data: 1, space group I2/a, a=6.889(2), b=11.073(3), c=18.280(6)Å, β=92.6(1)°; 2, space group Pn21a, a=19.422(2), b=7.3022(5), c=8.8468(7)Å; 3, space group P21/n, a=9.234(2), b=17.243(3), c=9.978(2)Å, β=93.9(1)°.