Chelates of dicumarol I: Preparation and structure identification of magnesium chelate

A magnesium chelate of dicumarol was prepared by reacting a suspension of dicumarol and magnesium oxide in 50% water-methanol. GLC, thermogravimetric, and elemental analyses showed that this compound has a 2:1 ligand-metal stoichiometry with 2 moles of water associated with the complex. Although the chelate does not melt, two endothermic peaks at 205 and 274 degrees were observed in the thermogram, in contrast to a single endothermic peak corresponding to a melting point of 288 degrees for dicumarol. IR spectroscopy indicated that the magnesium is bonded between the carbonyl at C-2 and the oxygen at C-4' (or vice versa).