Topological Ligand Design. II. The Definition and Derivation of Extended and Complex Ligand Graphs
Susumu TAKAMOTO · Bulletin of the Chemical Society of Japan · 1980
Abstract An extended ligand graph is a set of several points corresponding to donor atoms, where each pair of points is connected by n lines when these atoms are able to form n chelate rings with a metal ion. These graphs can cover all the ligands, but they may not express the geometrical patterns of some complicated ligands clearely enough for them to be discriminated. A complex ligand graph is a set of some main points and sub-points connected by sub-lines, where the main points, sub-points, and sub-lines correspond to donor atoms, carbon atoms forming chelate bonds, and chemical bonds among them respectively. All the complex ligand graphs can then be systematically derived from donor-atomic graphs, which are composed of only main points and main lines and are equivalent to the simple ligand graphs previously designed. Another designing method of ligands is proposed for a certain coordination sturcture. A complex ligand graph to which no more sub-points or sub-lines can be added is called a parent ligand graph. Then all the complex ligand graphs for such a coordination are derived from the parent ligand graphs by neglecting some sub-points or by removing some sub-lines successively.