Our primary aim is to synthesize and determine the geometric and electronic structures of various oxygen-carrying metal complexes which can serve as models of the naturally-occurring blood pigments hemoglobin and myoglobin. Our objective is to obtain from these compounds, by the techniques of X-ray diffraction and infrared spectroscopy quantitative information regarding the geometry of the bound oxygen molecule and detailed data on the changes which occur in the 02 molecule and the metal chelate when they bind together. Such information is essential to a full understanding of the nature of the binding and a quantitative description of the metal-oxygen bond. These concepts, in turn, are necessary if we are to understand oxygen transport in living beings. Initially, we will prepare high-quality single crystals of oxygenated Cobalt Salen derivatives """"""""CoSalen""""""""(Salen = N, N'- ethylenebis(salicylideniminato)) and then expand our efforts to make other oxygenated metal Salen derivatives, such as FeSalen. Specifically, we seek to prepare two series of CoSalen oxygen adducts: those which have identical in-plane ligands but different axial bases, and those which have identical axial bases but different in-plane ligands. Meaningful structural results should then clarify the role of the axial base in the binding of 02 and the effects (if any) that the in-plane substituents have on this interaction. Because the number of combinations of CoSalen substrates, axial bases, solvents, and solution temperatures to be tested will be substantial, a systematic screening process will be set-up to test the products of each reaction for oxygen up-take and crystal-forming propensity. X-ray data will be obtained at liquid nitrogen temperatures and the structures solved by Patterson- Fourier heavy-atom techniques or direct methods. To complete our structural characterization scheme, a correlation of the 0-0 stretching frequencies and 0-0 bond distances will be attempted.
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