New heterodinuclear pivalates (HPiv) 6 EuTb(Piv) 6 (5) and (Phen) 2 EuTb(Piv) 6 (6), where Piv=(CH 3 ) 3 CCO 2 − , the 2,2-dimethylpropanoate anion, and Phen=1,10-phenanthroline, were synthesized. The structures and compositions of the heterodinuclear molecules were determined by X-ray diffraction and based on magnetic measurements, inductively coupled plasma atomic emission spectrometry (ICP-AES) and the results of the research on the thermal decomposition and vaporization of the complexes. Under UV excitation, complex 6 exhibits luminescence and complete intramolecular excitation energy transfer to the Eu 3+ ions involving singlet levels of the Phen ligand and f–f levels of the Tb 3+ ions.