One of the major challenges of science in the last few years of the second millennium is learning how to design materials which can fulfill specific tasks. Ambitious as it may be, the possibilities of success are not ne li ble provided that all the different expertises merge to overcome the limits of eXIsting disciplines and forming new paradigms science. The NATO Advanced Research Workshop on "Magnetic Molecular Materials" was organized with the above considerations in mind in order to determine which are the most appropriate synthetic strategies, experimental techniques of investigation, and theoretical models which are needed in order to develop new classes of magnetic materials which are based on molecules rather than on metallic or ionic lattices. Why molecules? The answer may be obvious: molecular chemistry in principle fine can tune the structures and the properties of complex aggregates, and nature already provides a large number of molecular aggregates which can perform the most disparate functions. The contributions collected in this book provide a rather complete view of the current research accomplishments of magnetic molecular materials. There are several different synthetic approaches which are followed ranging from purely organic to inorganic materials. Some encouraging successes have already been achieved, even if the critical temperatures below which magnetic order is observed still are in the range requiring liquid helium.

Linear chain substances span a large cross section of contemporary chemis try ranging from covalent polymers, organic charge transfer complexes to nonstoichiometric transition metal coordination complexes. Their common ality, which coalesced intense interest in the theoretical and experimental solid-state-physics/chemistry communities, was based on the observation that these inorganic and organic polymeric substrates exhibit striking metal-like electrical and optical properties. Exploitation and extension of these systems has led to the systematic study of both the chemistry and physics of highly and poorly conducting linear chain substances. To gain a salient understanding of these complex materials rich in anomalous anisotropic electrical, optical, magnetic, and mechanical properties, the convergence of diverse skills and talents was required. The constructive blending of traditionally segregated disciplines such as synthetic and physical organic, inorganic, and polymer chemistry, crystallography, and theoretical and experimental solid state physics has led to the timely devel opment of a truly interdisciplinary science. This is evidenced in the contri butions of this monograph series. Within the theme of Extended Linear Chain Compounds, experts in important, but varied, facets of the discipline have reflected upon the progress that has been made and have cogently summarized their field of specialty. Consequently, up-to-date reviews of numerous and varied aspects of "extended linear chain compounds" has developed. Within these volumes, numerous incisive contributions covering all aspects of the diverse linear chain substances have been summarized. I am confident that assimilation of the state-of-the-art and clairvoy ance will be rewarded with extraordinary developments in the near future.

Linear chain substances span a large cross section of contemporary chemistry ranging from covalent polymers, to organic charge transfer com plexes to nonstoichiometric transition metal coordination complexes. Their commonality, which coalesced intense interest in the theoretical and exper imental solid state physics/chemistry communities, was based on the obser vation that these inorganic and organic polymeric substrates exhibit striking metal-like elec,trical and optical properties. Exploitation and extension of these systems has led to the systematic study of both the chemistry and physics of highly and poorly conducting linear chain substances. To gain a salient understanding of these complex materials rich in anomalous aniso tropic electrical, optical, magnetic, and mechanical properties, the conver gence of diverse skills and talents was required. The constructive blending of traditionally segregated disciplines such as synthetic and physical organic, inorganic, and polymer chemistry, crystallography, and theoretical and ex perimental solid state physics has led to the timely development of a truly interdisciplinary science. This is evidenced in the contributions of this monograph series. Within the theme of Extended Linear Chain Compounds, experts in important, but varied, facets of the discipline have reflected upon the progress that has been made and have cogently summarized their field of speciality. Consequently, up-to-date reviews of numerous and varied aspects of "extended linear chain compounds" have developed. Within these vol umes, numerous incisive contributions covering all aspects of the diverse linear chain substances have been summarized.

Linear chain substances span a large cross section of contemporary chemistry ranging from covalent polymers, to organic charge transfer com plexes to nonstoichiometric transition metal coordination complexes. Their commonality, which coalesced intense interest in the theoretical and exper imental solid state physics/chemistry communities, was based on the obser vation that these inorganic and organic polymeric substrates exhibit striking metal-like electrical and optical properties. Exploitation and extension of these systems has led to the systematic study of both the chemistry and physics of highly and poorly conducting linear chain substances. To gain a salient understanding of these complex materials rich in anomalous aniso tropic electrical, optical, magnetic, and mechanical properties, the conver gence of diverse skills and talents was required. The constructive blending of traditionally segregated disciplines such as synthetic and physical organic, inorganic, and polymer chemistry, crystallography, and theoretical and ex perimental solid state physics has led to the timely development of a truly interdisciplinary science. This is evidenced in the contributions of this monograph series. Within the theme of Extended Linear Chain Compounds, experts in important, but varied, facets of the discipline have reflected upon the progress that has been made and have cogently summarized their field of specialty. Consequently, up-to-date reviews of numerous and varied aspects of "extended linear chain compounds" have developed. Within these vol umes, numerous incisive contributions covering all aspects of the diverse linear chain substances have been summarized."

Molecular Magnetism: From Molecular Assemblies to the Devices reviews the state of the art in the area. It is organized in two parts, the first of which introduces the basic concepts, theories and physical techniques required for the investigation of the magnetic molecular materials, comparing them with those used in the study of classical magnetic materials. Here the reader will find: (i) a detailed discussion of the electronic processes involved in the magnetic interaction mechanisms of molecular systems, including electron delocalization and spin polarization effects; (ii) a presentation of the available theoretical models based on spin and Hubbard Hamiltonians; and (iii) a description of the specific physical investigative techniques used to characterize the materials. The second part presents the different classes of existing magnetic molecular materials, focusing on the possible synthetic strategies developed to date to assemble the molecular building blocks ranging from purely organic to inorganic materials, as well as on their physical properties and potential applications. These materials comprise inorganic and organic ferro- and ferrimagnets, high nuclearity organic molecules and magnetic and metallic clusters, spin crossover systems, charge transfer salts (including fulleride salts and organic conductors and superconductors), and organized soft media (magnetic liquid crystals and Langmuir-Blodgett films).

Molecular Magnetism: From Molecular Assemblies to the Devices reviews the state of the art in the area. It is organized in two parts, the first of which introduces the basic concepts, theories and physical techniques required for the investigation of the magnetic molecular materials, comparing them with those used in the study of classical magnetic materials. Here the reader will find: (i) a detailed discussion of the electronic processes involved in the magnetic interaction mechanisms of molecular systems, including electron delocalization and spin polarization effects; (ii) a presentation of the available theoretical models based on spin and Hubbard Hamiltonians; and (iii) a description of the specific physical investigative techniques used to characterize the materials. The second part presents the different classes of existing magnetic molecular materials, focusing on the possible synthetic strategies developed to date to assemble the molecular building blocks ranging from purely organic to inorganic materials, as well as on their physical properties and potential applications. These materials comprise inorganic and organic ferro- and ferrimagnets, high nuclearity organic molecules and magnetic and metallic clusters, spin crossover systems, charge transfer salts (including fulleride salts and organic conductors and superconductors), and organized soft media (magnetic liquid crystals and Langmuir-Blodgett films).

One of the major challenges of science in the last few years of the second millennium is learning how to design materials which can fulfill specific tasks. Ambitious as it may be, the possibilities of success are not ne li ble provided that all the different expertises merge to overcome the limits of eXIsting disciplines and forming new paradigms science. The NATO Advanced Research Workshop on "Magnetic Molecular Materials" was organized with the above considerations in mind in order to determine which are the most appropriate synthetic strategies, experimental techniques of investigation, and theoretical models which are needed in order to develop new classes of magnetic materials which are based on molecules rather than on metallic or ionic lattices. Why molecules? The answer may be obvious: molecular chemistry in principle fine can tune the structures and the properties of complex aggregates, and nature already provides a large number of molecular aggregates which can perform the most disparate functions. The contributions collected in this book provide a rather complete view of the current research accomplishments of magnetic molecular materials. There are several different synthetic approaches which are followed ranging from purely organic to inorganic materials. Some encouraging successes have already been achieved, even if the critical temperatures below which magnetic order is observed still are in the range requiring liquid helium.