Synthesis of 4,7-bis(diphenylphosphoryl)-1,10-phenanthroline and a dinuclear Eu<sup>III</sup> complex thereof

4,7-Bis(diphenylphosphoryl)-1,10-phenanthroline (L), a new promising ligand, has been synthesized in six preparative steps, the key step having been the reaction of 4,7-dichloro-1,10-phenanthroline with Ph<sub>2</sub>PLi. Treatment of the synthesized ligand with europium(III) (2-thenoyl)trifuoroacetonate, Eu(tta)<sub>3</sub>, unexpectedly yields a dinuclear complex [Eu<sub>2</sub>(tta)<sub>4</sub>(CF<sub>3</sub>COO)<sub>2</sub>(L)<sub>2</sub>], in which each Eu<sup>III</sup> atom is N,N<em>'</em>-chelated by one L ligand and O-coordinated by the second L ligand.