COBALT(II), NICKEL(II) AND IRON(III) HALIDE ADDUCTS WITH THEOBROMINE

Adducts of theobromine (L) with Co(II) and Ni(II) chlorides, bromides and iodides and Fe(III) chlorides and bromides were synthesized by refluxing 2:1 molar mixtures of L and the hydrated metal salt in triethyl orthoformate-ethyl acetate. Solid complexes of the CoL2X2 (X = Cl, Br), CoL2I2· H2O, NiL2X2·2H2O (X = Cl, Br, I) and FeL2X3·H2O (X = Cl, Br) types were isolated. Characterization studies suggest that the new adducts are neutral monomeric with terminal unidentate L, halo and, wherever applicable, aqua ligands. The Co(II) complexes are distorted tetrahedral for X = Cl, Br and pentacoordinated for X = I, while the Ni(II) and Fe(III) adducts are hexacoordinated. The pyrimidine N1 and imidazole N9 ring nitrogens were considered as equally likely to act as the binding site of terminal theobromine. © 1990.