CRYSTALLOGRAPHIC STUDY OF THE BARIUM(II) COMPLEX OF A LARIAT ETHER WITH LONG PENDENT ARMS

The crystal structure of the Ba(II) complex of the ligand L (L = 7,16-bis(2-o-hydroxyethyl-2- oxyethyl)-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane) is reported. The complex [Ba(L)]I2·3H2O crystallizes in the monoclinic space group C2/c with a=11.378(1), b=15.682(2), c=18.222(2) Å, β=96.28(8)°; Z=4, V=3231.87 Å3, Dm=1.80 g cm-3, Dc=1.82 g cm-3. The final conventional R factor was 0.032. The barium is eleven coordinate in the complex, with a water molecule occupying an apical position. The BaO oxygen bond lengths average 2.874(3) Å, and the BaN bond lengths 3.079(3) Å. The structure is used to rationalize the higher stability of the BaII complex of L than is found for other metal ions in terms of the ability of barium to coordinate all the donor atoms of the ligand. © 1990.