Multi-NMR studies (Al-27, F-19, P-31) show that, in the presence of pyrophosphate at pH 7, fluoride and aluminum (Al3+) ions combine in aqueous solution, to generate a wide variety of ternary complexes. Among the latter, a new class of stable complexes, showing J(FF) and J(FP) coupling constants, has been identified in which two octahedral aluminum cations are bound by two pyrophosphate moieties, with a common fluorine atom bridging the two aluminum ions. Both the pyrophosphate groups and the fluoride ion contribute to the stability of these molecules. The existence of J(FF) couplings provides evidence for the octahedral coordination of aluminum in these complexes.