Zn1 clusters: In clusters with only one Zn 2+ cation, there is a clear stabilization as imidazolate coordination increases reaching a maximum for the four-fold coordinated [ZnIm 4 ] -2 complex. The solvent is in excess with respect to the nitrate, so initially every Zn 2+ cation will be solvated with ethanol molecules. But, if enough nitrate ions are available, these will gradually displace the coordinating ethanol molecules (see also energetics in Table ). The following clustering route can be envisaged, considering stabilization due to nitrate (formation energies in parentheses): .85 eV). Note that, in agreement with our conclusions outlined in Sec. 3.1, the [ZnIm 3 N] -2 (-4.02 eV) complex is energetically unstable with respect to the [ZnIm 3 ] -complex. Furthermore, a subsequent increase in Zn-imidazolate coordination to achieve the (square pyramidal) five-and (octahedral) six-fold coordinated clusters [ZnIm 5 ] -3 and [ZnIm 6 ] -4 (-4.11 eV and -3.39 eV respectively) induces a destabilization of the cluster, supporting the argument for pre-nucleation being dominated by tetrahedral Zn species.