Two‐dimensional Cobalt‐Carboxylate Framework with Hourglass Trinuclear Co3(COO)6(DMA)3 Secondary Building Unit

The two‐dimensional (2D) cobalt‐carboxylate framework of the hxl type with the formula [Co 3 (bdc) 3 (DMA) 3 ] · DMA was synthesized in a mixture of the ionic liquid 1‐butyl‐3‐methylimidazolium tetrafluoroborate [BMIm][BF 4 ], HBF 4 and N , N ‐dimethylacetamide (DMA) via solvothermal reaction. The structure of [Co 3 (bdc) 3 (DMA) 3 ] · DMA (bdc 2– = benzene‐1,4‐dicarboxylate) consists of an hourglass trinuclear secondary building unit (SBU) with the first octahedral (oct)‐octahedral and square‐pyramidal (sq‐pyr) coordinated cobalt atoms in the sequence Co oct –Co oct –Co sq‐pyr with terminally coordinated DMA molecules. These SBUs are bridged by six bdc 2– ligands into a two‐dimensional layered structure.