Radioactive metals complexed with phosphonate derivatives of dicyclopentadienebis (methylamine)

Complexes of radionuclides with a compound of the formula (X-N(-Y)-CH2-),(A-N(-B)-CH2-)Perhydro-4,7-Methanoindene wherein substituents A, B, X and Y are each independently selected from radicals including hydrogen, hydroxyalkyl (wherein the alkyl group contains 2-6 carbon atoms) phosphonic, sulfonic, methylenephosphonic, methylene-, ethylene- and propylene-sulfonic, carboxylic acid radicals (having 2-4 carbon atoms) and the alkali or alkaline earth metal, ammonia and amine salts, thereof and wherein at least one A, B, X and Y is methylenephosphonic acid or a salt thereof. Tc-99m complexes have been found useful for imaging the skeletal structure of animals