Transition metal phosphate complexes  are coordination complexes with one or more phosphate ligands.  Phosphate binds to metals through one, two, three, or all four oxygen atoms.  The bidentate coordination mode is common.  The second and third pK's of phosphoric acid, pK and pK, are 7.2 and 12.37, respectively. It follows that  are sufficiently basic to serve as ligands.  The examples below confirm this expectation. Molecular metal phosphate complexes have no or few applications.