Sandwich-type polyoxoanions based on A--GeW9[image omitted]. Synthesis and characterization of [(A--GeW9O34)2(MOH2)3CO3]13-(M=Y3+, Sm3+, and Yb3+) polyoxoanions

The title complexes were synthesized at room temperature by the reaction of A--GeW9[image omitted] with MCl3 (M = Y3+, Sm3+, and Yb3+) in 0.1 mol L-1 sodium carbonate solution and characterized by elemental analysis, FT-IR, UV, 13C- and 183W-NMR spectroscopies, and thermogravimetric analysis (TGA). Two-line 183W-NMR spectrum with 2 : 1 intensity ratio confirms that [(A--GeW9O34)2(MOH2)3CO3]13- contains an anion of D3h symmetry. The difference of the two chemical shifts = 30.56 affirms the presence of A--GeW9[image omitted]. The chemical shift of the single-line 13C-NMR spectrum of [(A--GeW9O34)2(MOH2)3CO3]13- and frequencies of stretching vibrations of all three complexes affirm the presence of coordinated carbonate. TGA shows that the complexes are thermally stable up to 430 degrees C.