Topology of 2-Periodic Coordination Networks: Toward Expert Systems in Crystal Design

We have performed comprehensive topological analysis of 2-periodic coordination networks in 10 371 metal-organic compounds. Both local and overall topologies of complex groups were determined, classified, and stored in the electronic databases. Two plane nets, square lattice (sql) and honeycomb (hcb), were found to compose two-thirds of all the coordination networks. Strong correlations were found between local topological characteristics (coordination numbers of atoms or complex groups, coordination figures, formalized coordination modes of ligands and coordination formula) and the overall topology that in many cases allowed us to predict possible topological motifs from the data on chemical composition with high probability. The possibility to develop an expert system that could envisage local and overall topology of periodic coordination networks is discussed, and an example is given of how such a system can work.