INVERSION OF CONFIGURATION AROUND THE 7-COORDINATED COBALT CENTER INDUCED BY AN INTERACTION BETWEEN SUGARS AND TETRAHEDRAL OXOANIONS

Seven-coordinated,cobalt(II) complexes containing N-glycosides from ma nnose-type aldoses and tris(2-aminoethyl) amine (tren), [Co((aldose) ( 3)-tren)]X(2). nH(2)O (1a, aldose = D-mannose (D-Man), X = Cl-; 1b, al dose =6-deoxy-L-mannose (L-Rha), X = Cl-; 2a, aldose = D-Man, X = Br; 2b, aldose = L-Rha, X = Br) and [Co((aldose)3-tren)]SO4.nH(2)O (3a, al dose = D-Man; 3b, aldose = L-Rha), were prepared and characterized. Th e sign of the CD spectra for 1 and 2 containing halide anions is oppos ite to that of 3 with a SO42- anion, showing the inversion of absolute configuration around the metal center, Delta reversible arrow Lambda induced by an interaction between the sugars and the SO42- anion.