CRYSTAL-STRUCTURE AND LUMINESCENCE OF EU(DBM)(3)TPPO COMPLEX

The crystal structure of tris (dibenzoylmethanato) (triphenylphosphine oxide)europium (III), C63H51O7PEu, has been determined by single crys tal X-ray diffraction. The complex crystallizes in the triclinic space group P (1) over bar with two molecules in a unit cell. The cell dime nsions are a=12.336 (3), b=18.729 (5), c=11.502 (3) Angstrom, alpha=95 .86 (2), beta=103.14 (2), gamma=87.89 (2)degrees. The total number of 6969 independent reflections was used for the structure determination. The final calculated R value is 0.055. The central europium ion is he pta-coordinated by seven oxygen atoms. The polyhedron is a distorted c apped trigonal prism with the Eu-O separation of 2.305-2.367 Angstrom. The high resolution excitation and emission spectra measured at 77 K indicate two Eu (III) sites in the complex. The symmetries of the Eu ( III) sites are C-2 nu and Cs respectively. The lower symmetrical C-s s ite predominates. A comparison of the emission spectra for Gd(DBM)(3)T PPO doped by 1% Eu(III) with those for Eu(DBM)(3)TPPO complex shows no significant differences pointing to the same two sites.