Infrared, ultraviolet, and nuclear magnetic resonance spectroscopies have been used to obtain quantitative data to establish the nature of bonding in alkali and alkaline earth acetylacetonates. Most of these acetylacetonates are salt-like; however the properties of lighter metal complexes reflect a covalent (“benzenoid”) character. Within a family the change from benzenoid to ionic character is quite abrupt, occurring between lithium and sodium compounds for the alkali metals, and between beryllium and calcium for the alkaline earths, with the magnesium compound being intermediate. The ionic compounds hydrolyze readily unless totally water-free environments are used. The claim of a more covalent structure for the hydrated form, as opposed to the non-hydrated form of a given acetylacetonate is not supported by the results of this study.