Combinatorial topology of salts of inorganic oxoacids: zero-, one- and two-dimensional units with corner-sharing between coordination polyhedra.

A method of graphical representation of heteropolyhedral units is applied to a wide range of salts of inorganic oxoacids (phosphates, arsenates, sulfates, chromates, molybdates, selenates, selenites, tellurites, etc.). Only those heteropolyhedral units that fulfill the following criteria are considered: (i) units with corner-sharing between coordination polyhedra only; (ii) units with no linkage between chemically and geometrically identical polyhedra; (iii) only zero- (finite clusters), one- (chains) and two- (sheets) dimensional units. More than 80 different topologies are considered. For 2D units (sheets), the concepts of basic graph and topological isomerism are formulated. Three different types of geometrical isomerism are recognized for chains, sheets and finite clusters: orientational isomerism, cis-trans -isomerism, and isomerism induced by the presence of cations with stereoactive lone pairs of electrons. Different geometrical isomers can be described by means of orientation matrices and connectivity diagrams. Relationships between different topologies are investigated. [ABSTRACT FROM AUTHOR]