Synthesis and crystal structure of a new MOF-type indium pyromellitate (MIL-117) with infinite chains of unusual cis connection of octahedra InO4(OH)2

A new MOF-type indium pyromellitate (MIL-117) was hydrothermally synthesized at 483 K for 24 h. The structure of MIL-117 with structural formula In6(OH)6(btec)3(H4btec)·8–14H2O (btec = 1,2,4,5-benzenetetracarboxylate), orthorhombic (Pnmm) symmetry and unit cell parameters a = 8.2390(8), b = 22.251(2), c = 37.791(4) Å, V = 6928.2(11) Å3 was solved from single-crystal diffraction data. The three-dimensional open framework structure consists of infinite chains of unusual cis sharing In-centered octahedra linked to each other through the pyromellitate ligands. The three distinct In(III) cations are coordinated to four oxygen atoms from carboxyl groups and two μ2-hydroxyl groups in cis positions. The MIL-117 network delimits one-dimensional channels of 7.7 × 8.0 Å running along the a axis, where occluded water molecules are located. Although water species can be easily removed from the pore, no significant N2 or CO2 sorption was observed.

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