This project is jointly supported by the Inorganic, Bioinorganic and Organometallic Chemistry Program and the Solid State Chemistry Program. The focus of the project is the chemistry of quasi-one-dimenional chain-like compounds, which are of interest in the materials area because of unusual magnetic properties and electrical conductivity. The properties of chain compounds which exhibit phase transitions or which have unusual structures will be investigated by structural, magnetic, and theoretical studies. Magnetic susceptibility and preliminary magnetization studies on aqua(N-(salicylaldiminato)glycinato)copper(II) hemihydrate, CuNSG, have revealed a discontinuity in the magnetic susceptibility versus temperature plot at 2.1 K. This discontinuity was initially identified as a spin-Peierls transition. Analysis of the available magnetization data by 10-spin cluster calculations now suggest that this discontinuity is the temperature at which the progressive, temperature-dependent dimerization of the chain is terminated. New magnetization and EPR studies will be performed to determine whether this explanation is correct. The available and new magnetization data will be analyzed with 14-spin cluster calculations, and EPR studies on single crystals will be carried out to determine the temperature dependence of the dimensionality of the system. The phase transitions which have been identified in related carboxylato- or carbonato-bridged chain compounds will be investigated by low-field magnetic susceptibility studies and EPR using single crystals. The next-nearest neighbor chain hydrazinium copper chloride is an example of a system with frustration, and a phase transition was predicted and observed. The mechanism by which the system relieves the frustration will be determined. Spin ladder chains which may exhibit frustration, and integer spin chains which may exhibit Haldane gaps will be investigated by structural, magnetic, and EPR studies.
