[en] Central to the production of new antibody-conjugated radioisotopes for diagnostic or therapeutic use is the development of fundamental main-group and inorganic chemistry. In this respect, ¹⁰⁹Pd is an attractive isotope for radioimmunotherapy. It has a suitable half-life (13.1 hr) and suitable physical properties (β=1.02 MeV, 100%). It decays to a 40 sec half-life ¹⁰⁹Ag which emits an 88 keV γ, making it suitable for imaging. The authors' approach to this endeavor involves the application of functionalized phosphorus hydrazides which form kinetically robust complexes with transition metals/metallic radioisotopes. The -COOH functionality in the bifunctional chelate after activation can be used to conjugate onto peptides/proteins to generate a new genre of metal-conjugated biomolecules for applications in nuclear medicine. The synthesis, spectroscopic and X-ray crystallographic analysis of bifunctional chelates are discussed