Zn₂(etim)₂CO₃, the Ethylimidazole Analog of the Zinc Methylimidazolate Framework

Zeolitic imidazolate frameworks (ZIFs) attract broad scientific interest due to their structural relation to zeolites. As a consequence, identical underlying zeolite‐like net structures can be identified in ZIF‐compounds. By functionalization of the imidazolate linker by alkyl‐ or aryl residues, the crystallization of ZIFs into new framework topologies and direct control of network formation is facilitated. Using imidazolate linkers with different functionalization rarely leads to the formation of the same underlying net. By reacting zinc nitrate and 2‐ethylimidazol (Hetim) in DMF under ambient atmosphere, Zn 2 (etim) 2 CO 3 denoted as ZIF‐CO 3 ‐2 is obtained, as there are two carbon atoms in the alky residues of 2‐ethylimidazolate. The presence of 2‐ethylimidazolate and carbonate in the bulk phase is confirmed by IR‐spectroscopy and the structure is elucidated from laboratory X‐ray powder diffraction data. The underlying net is identified as moganite ‐type ( mog ), and surprisingly, the compound found to be isostructural to Zn 2 (mim) 2 CO 3 , ZIF‐CO 3 ‐1, with mim = methylimidazolate. The replacement of 2‐methylimidazolate by bulkier 2‐ethylimidazolate leads to an anisotropic deformation of the unit cell. This results in ellipsoidal channels, running in c ‐direction, which are more rounded in ZIF­‐CO 3 ‐2 compared to ZIF­‐CO 3 ‐1.