Organometallic crystal architectures have been examined in terms of extramolecular interactions between molecules and ions. Attention has been focused on the modelling of van der Waals crystals by means of empirical atom—atom pairwise potential energy calculations and on the possibility of generating theoretical crystal structures to be compared with those experimentally determined. Examples of crystal generation techniques for simple binary carbonyls have been reviewed. It has also been shown that organometallic crystal enginnering takes advantage of both the great structural flexibility of organometallic molecules as well as of the possibility of linking ligands via hydrogen bonds. The importance of charge assisted. C—H—-O hydrogen bonds in the construction of supramolecular aggregates is stressed.