STUDIES OF RARE EARTH METAL COMPLEXES OF AMINO ACIDS AND PEPTIDES. SYNTHESES AND CRYSTAL STRUCTURES OF TRIAQUO TRIS (N-ACETYLGLYCINE) LANTHANIDE Ln(CH_3CONHCH_2COO)_3(H_2O)_3(Ln = Nd^(3+),Eu^(3+) and Er^(3+))

The title complexes were synthesized and their crystal structures were determined. These complexes crystallize in trigonal space group R3 with 3 molecules in a unit cell and are isostructural to each other. Crystallographic data: complex 1, Nd(CH3CONHCH2COO)3(H2O)3, Mr = 546. 6, a= 16. 582(4), c = 5. 982(2)(?), V= 1424. 5(8)(?)3, Dc=1. 91gcm-3, F (000) = 819, μ = 28.06cm-1, R(Rw) = 0. 048(0. 061); complex 2, Eu (CH3CONHCH2COO)3 (H2O)3, Mr = 554.3, a = 16.564(10), c=5.974(3)(?), V = 1418(2)(?)3,Dc= 1. 95gcm-3, R (Rw) = 0. 018 (0. 025), F (000) = 828, μ= 33. 83cm-1; complex 3, Er-(CH3CONHCH2COO)3(H2O)3, Mr = 569. 6, a = 16. 476(7), c=5. 946(6)(?), V = 1398(2) (?)3, D, = 2. 03gcm-3, R (Rw ) = 0. 020 (0. 027) , F (000) = 843, μ= 46. 25cm-1. These complexes adopt mononuclear structure, in which Ln(Ⅲ) ion is coordinated to six oxygen atoms from three ligands and three oxygen atoms from water molecules with the polyhedron of 4,4,4-tricapped triangular prism. The carboxy-lato group of the ligand bonds to Ln(III) ions in bidentate chelate mode, and the pep-tide group does not take part in coordination.