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theses

Metal acetylacetonates are significant since they were amongst the earliest metal compounds which were recognized as what later became known as coordination compounds. Additionally, they were significantly investigated during WWII as potentially useful in the separation of isotopes, especially of uranium because of their unexpected volatility. Consequently, much research was carried out over the years— a good deal of which was of suspect validity, which unfortunately cannot be checked because very little information was published on the syntheses and crystallization methods used in the preparation of the crystalline samples. Here, we report our efforts to clean the slate by reporting on those of Al(III), Mn(III), Co(III), Cr(III), Fe(III), V(III) and Ti(III). These studies were carried out with crystalline samples obtained from a wide variety of solvents and over the range 296-100K in attempts to reproduce, verify, and correct, at times, the claims made in print. Our results, covering over 100 samples, are detailed in this thesis. We have also made crystallographic measurements at temperatures other than 100K and 296K for crystals of Al(acac)3 and Mn(acac)3 guided by their thermochemical information using DSC and Cp measurements. The very small energy changes found by DSC and Cp measurements (of the order of 5-50 cal/mol) cannot be associated with 1st-order transitions, nor even of rotational barriers. We believe that this is a case of librations brought about by the higher temperatures.
In addition, we have explored the interaction of [(acac)2V=O](acac = 2,4-pentanedione) with a series of nitrogenous ligands which were chosen because of their ability to attach themselves onto the sixth (axial) position of such bis-acetylacetonates and because they have the capability of linking pairs of [(acac)2V=O] molecules, thus creating magnetically-coupled substances whose coupling would be interesting to document by electron spin resonance as well as by magnetic susceptibility vs. T. The results are rather surprising in that unexpected chemical reactions occurred which had not been envisioned, nor have been previously observed in preceding studies.

ETD_10176

Ph.D.

Includes bibliographical references

doi:10.7282/t3-b117-eb17

ETD doctoral

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