SEARCH Articles Figures Tables Bonding between metal atoms and organic pi systems Conjugate pi system Conjugated Pi Systems and Pericyclic Reactions Conjugated pi-electron systems Cyclic conjugated pi system Cyclic pi systems Delocalized pi systems Extended pi system Ligands Having Extended Pi Systems Linear pi systems Molecular Orbital Theory for Cyclic Conjugated PI Systems Molecular Orbital Theory for Linear Pi Systems Molecular Orbitals and Pericyclic Reactions of Conjugated Pi Systems PI System Another Second Messanger Pi Systems Investigation by Ultraviolet and Visible Spectroscopy Pi-conjugated systems Pi-electron system Pi-space and Requirements Concerning the Model Material System