MU(3)-HYDROXO)HEXA(MU(2)-CARBOXYLATO-O,O')-BRIDGED TETRANUCLEAR TERBIUM(III) CUBANE COMPLEX

A novel tetranuclear terbium(III) complex )(pybet)(6)(H2O)(8)][Tb-4(OH )(4)(pybet)(6)(H2O)(7) (NO3)](ClO4)(14). 6H(2)O has been synthesized a nd shown by X-ray crystallography to have a cubane-like Tb-4(mu(3)-OH) (4)(mu(2)-carboxylato-O,O')(6) core. The ligand pybet is pyridinoaceta te, C5H5H+-CH2CO2-. Magnetic susceptibility data were measured for thi s Tb-4 complex in the range of 2.0-320 K and in fields of 1.0 G to 50. 0 kG. It is concluded that either there is very weak antiferromagnetic exchange interaction (J = -0.015 cm(-1))or there is a small crystal-f ield splitting of the F-7(6) Tb-III ground state. (C) 1997 Elsevier Sc ience Ltd