SYNTHESIS AND SPECTRAL STUDIES OF SOME 7-COORDINATED RARE-EARTH-METALCOMPLEXES

4-diaminobenzophenonimino)-2-benzamido-ethanamide, dabbe, has been syn thesized and characterized. The ligand dabbe was found to coordinate w ith the trivalent lanthanide metal ions to give Ln(III) metal complexe s of the type [Ln (dabbe)(2)Cl-3].4H(2)O where Ln=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy and Y. The complexes were studied by elemental analyses, el ectrical conductance, magnetic susceptibility, electronic, infrared an d NMR (H-1 C-13 and La-139) spectral techniques. Various bonding param eters (beta, b(1/2), % delta and eta) were calculated from the electro nic spectra of the Pr(III), Nd(III), Sm(III) and Dy(III) complexes and suggest weak covalent bond formation in the complexes. The theoretica l oscillator strengths (P-calcd) and a set of three intensity paramete rs (T-lambda-2,T-4,T-6) computed from the Judd-Ofelt equation are foun d to be in reasonable agreement with the experimental values. An appro ximate mean M-L distance, R(Ln-O) Angstrom in case of the Pr(III) comp lex was found to be 2.56 Angstrom from the energy of the H-3(4)-->P-3( 0) transition. IR and NMR spectral data suggest a neutral bidentate na ture of dabbe in the complexes. Low site molecular symmetry in the pre sent complexes is proposed on the basis of La-139 NMR spectra.