This award is made in the Inorganic, Bioinorganic and Organometallic Program in support of the research of Dr. Roger Willett. The research will address the structural, electronic spectroscopic, magnetochemical and EPR properties of monomeric, dimeric and higher-order Cu(II), Mn(II) and Ni(II)-halide complexes. An emphasis will be a study of the variation of the geometric and electronic structure of the complexes with temperature, either by phase transitions or by dynamic Jahn-Teller interactions. The principle experimental techniques utilized will be X-ray diffraction methods, EPR and NMR. %%% This research involves the study of certain fundamental properties and processes in mixed organic/inorganic crystalline materials. Studies will focus on the changes that occur in these systems as the temperature is varied. Included are materials that exhibit continuum properties in the crystalline phase and that mimic the physical properties of lipids and other phenomena.