STRUCTURAL AND SPECTROSCOPIC CHARACTERIZATION OF THE MACROCYCLIC COMPLEX - [TB(CRO4)(H2O)(C22H26N6)]CENTER-DOT-0.5(CR2O7) (H2O)

The title complex was obtained by anion metathesis from [Tb(CH3COO)2(C22H26N6)] (CH3COO). 4H(2)O and K2CrO4 in aqueous solution. The compound crystallizes in the triclinic space group P $($) over bar$$ 1 with a = 8.384(2), b = 10.425(2) c = 15.752(2)Angstrom, alpha = 98.82(2), beta = 93.52(2), gamma = 97.22(2)degrees, and Z = 2. The structure is ionic and consists of a (+1) complex cation balanced in a 2:1 ratio by a disordered dichromate ion. The 9-coordinate Tb(III) is linked to the six nitrogen atoms of the macrocyclic ligand L = C22H26N6, as well as to a water molecule and a bidentate chelating chromate situated on opposite sides of the macrocycle. The infrared spectrum shows, in addition to the pattern of the macrocyclic ligand, the absorptions arising from the stretching modes of the bidentate chelating CrO42- ligand and of the Cr2O72- counterion.