Complex [Er2(Ala)4(H2O)8]·(ClO4)6, 1, Mr = 1431. 8, mono-clinic, space group C2/c with cell parameters a= 18. 21(1), 6 = 14. 67(2), c=17. 19(3)(?), β=101. 60(8)°, V = 4495(4)(?)3, Dc=2.11g/cm3, Do = 2. 09g/cm3, Z = 4, F (000) = 2808, μ= 42. 30cm-1; Complex [Eu2(Ala)4(H2O)8]·(ClO4)6, 2, Mr = 1401.4, monoclinic, space group C2/c, a = 18. 16(4) , b = 14.52(2), c=17. 35(1)(?), β=102. 3(1)°, Z = 4, V= 4468(11)(?)3. The structure of complex 1 is refined by full-matrix least - squares method with 3348 observed reflections (I≥3σ (I)) to R = 0. 048 and Rw= 0.060. The two erbium ions in the dimeric complex cation [Er2(Ala)4(H2O)8]]6+ are connected by four bridging carboxylato groups, each pair of the carboxylato groups is coplanar with the two Er(III) ions and the dihedral angle between the two planes is 91. 42*. Each Er3+ion is coordinated by four carboxylato oxygen atoms and four water oxygen atoms, assuming a square antiprism arrangment. The alanine exists in the form of CH3CH (+NH3) COO- , and the mo Complex [Er2 (Ala) 4 (H2O) 8] · (ClO4) 6, 1, Mr = 1431. mono- clinic, space group C2 / c with cell parameters a = 18. 21 (1), 6 = 14 . 67 (2), c = 17.19 (3) (?), Β = 101.60 (8) °, V = 4495 (4) (?) 3, Dc = 2.11 g / cm3, Do = 2. Complexes Eu2 (Ala) 4 (H2O) 8] (ClO4) 6, 2, Mr = 1401.4, monoclinic, space group C2 / c, a = 18. 16 (4), b = 14.52 (2), c = 17.35 (1) (?), β = 102.3 (1) °, Z = 4, V = 4468 (11) (?) 3. The structure of complex 1 is refined by full-matrix least-squares method with 3348 observed reflections (I ≥ 3σ (I)) to R = 0. 048 and Rw = 0.060. The two erbium ions in the dimeric complex [Er2 (Ala) 4 (H2O) 8]] 6+ are connected by four bridging carboxylato groups, each pair of the carboxylato groups is coplanar with the two Er (III) ions and the dihedral angle between the two planes are 91. 42 *. Each Er3 + ion is coordinated by four carboxylato oxygen atoms and four water oxygen atoms, assuming a square antiprism arrangment. The alanine exists in the form of CH3CH (+ NH3 ) COO-, and the mo