Metal–Organic Frameworks Based on Unprecedented Trinuclear and Pentanuclear Metal–Tetrazole Clusters as Secondary Building Units

Solvothermal reactions of manganese­(II) chloride tetrahydrate with a bis-tetrazole ligand, 2,6-di­(1H-tetrazol-5-yl)­naphthalene (H2NDT), in N,N′-dimethylformamide (DMF)/MeOH mixed solvent at two slightly different temperatures, 75 and 100 °C, led to two different metal–organic frameworks (MOFs), [MnII3O­(HNDT)2(NDT)­(DMF)3] (1) and [MnII5O2(HNDT)2(NDT)2(DMF)8] (2), with different net topologies. Single-crystal X-ray diffraction studies reveal that 1 is constructed from an unprecedented trinuclear building block, [MnII3O­(CN4)6], as a 6-connected trigonal prismatic secondary building unit (SBU) of topological D3h site symmetry, and that the ligand in the HNDT–1/NDT2– deprotonation states is a linker, where two tetrazole (CN4) groups of the ligand are connected via a rigid naphthyl group. The tetrazole groups in 1 adopt a 1,2-μ-bridging mode with the manganese­(II) ions to form a μ3-oxo trinuclear SBU. The trigonal prismatic SBU in 1 is connected to six neighboring SBUs to form a three-dimensional MOF of acs net topology. 2 is constructed from an unprecedented pentanuclear building block, [MnII5O2(CN4)8], as an 8-connected tetragonal prismatic SBU of topological D4h site symmetry. The tetrazole groups in 2 adopt monodentate, 1,2-μ- and 2,3-μ-bridging bidentate and 1,2,3-μ-bridging tridentate binding modes with the manganese­(II) centers to form a bis-μ3-oxo pentanuclear SBU of local C2 site symmetry. The tetragonal prismatic SBU in 2 is connected to eight neighboring SBUs to form a 3-D MOF of bcu net topology.