To conclude, our survey of oligomeric and larger clusters that could be present during ZIF formation, is consistent with the available experimental data and provides additional insight into the key processes that lead to the formation of crystal nucleation species. We have shown how the variety of DFT, and tight binding methods are comparable in accuracy, and allow the consideration of a wide range of species. This study provides important insight into the pre-nucleation of ZIFs, and paves the way to achieving synthesis control by a fundamental understanding of its underlying physicalchemistry.