The dependence of electronic properties of [Cu3O12]-17, [Ba8Cu3O12]-1
and Y8Cu3O12]+7 model clusters on the axial oxygen positions, O(2), ar
e investigated using quasi-relativistic CNDO/1 molecular orbital metho
d. No evidence of the double-well potential of the Jahn-Teller type is
found. Barium layer lowers the sensibility of O(2) electron propertie
s to the Cu-O(2) stretching.