Recurrent complex modules instead of molecules in non-molecular compounds - Describing and modelling modular inorganic structures

To compensate for a lack of molecules, several inorganic crystal structures are describable in terms of complicatedcomplex (this is the word normally used; se also the title of this paper) modules that occur in various crystalline compounds. The structures that share common modules can be correlated via series, and their investiga-tion belongs to a new branch of crystallography named modular crystallography. The crystal structures of members of a series so called polysomatic are typically based on at least two common mod-ules; these modules are stacked differently in various members of the series. If the modules shared by the members differ to some ex-tent, the series merotype and plesiotype series (see polysomatic se-ries) are defined. To illustrate the basic concepts of modular crystal-lography, examples of series based on modules of the perovskite structure that occur in layered organic-inorganic hybrids and super-conductors are presented. An unknown crystal structure can be mod-elled if relations with known members of a series are established. Examples of structure modelling for the silicates nafertisite, borne-manite, seidite-(Ce), kalifersite and tungusite are presented with the related series.