Characteristic Structures and Photophysical Properties of Nine-Coordinate Europium(III) Complexes with Tandem-Connected Tridentate Phosphane Oxide Ligands

Structures and photophysical properties of f-block metal complexes with tandem-connected tridentate phosphane oxide ligands, {bis[o-(diphenylphosphoryl)phenyl]phenylphosphane oxide}tris (hexafluoroacetylacetonato) europium (III) [Eu(hfa)(3)(DPPPO)], {bis[o-(diphenylphosphoryl)pyridyl]-phenylphosphane oxide}tris (hexafluoroacetylacetonato)europium(III) [Eu(hfa)(3)(DPPYPO)] and {bis[o-(diphenylphosphoryl]benzothienyliphenylphosphane oxide[tris(hexafluoroacetylacetonato)europium (III) [Eu(hfa)(3)(DPBTPO)], are reported. The coordination geometries of Eu(hfa)(3)(DPPPO) and Eu(hfa)(3)(DPBTPO) provide characteristic distorted, capped square antiprism structures with nine-coordinate oxygen atoms. The emission properties related to the electric transition are characterized by the emission spectra, the emission quantum yields, the emission lifetimes, and the radiative and non-radiative rate constants. Eu-III complexes with tridentate phosphane oxide ligands offer relatively high emission quantum yields (> 60 % in [D-6]acetone) due to their low-symmetric and low-frequency vibrational structures. The electric dipole transition intensities in the emission spectra depend on the chemical structures of tridentate phosphane oxides. The characteristic photophysical properties of polyhedral f-block metal complexes, nine-coordinate Eu-III complexes with tridentate phosphane oxide, are demonstrated for the first time. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)