MAGNETIC AND STRUCTURAL STUDIES OF COPPER-LANTHANOID COMPLEXES - THE SYNTHESIS AND STRUCTURES OF NEW CU(3)LN COMPLEXES OF 6-CHLORO-2-PYRIDONE (LN=GD, DY AND ER) AND MAGNETIC STUDIES ON CU2GD2, CU4GD2 AND CU3GDCOMPLEXES

The synthesis and structural characterisation of three copper-lanthano id complexes are reported. The compounds, of general formula [Cu(3)M(c hp)(8)-(NO3)(S)][M = Gd, S = H2O in 2; M = Dy, S = H2O in 3; M = Er, S = (H2O)(0.5)(MeOH)(0.5) in 4; chp = anion of 6-chloro-2-pyridone], ar e made by reaction of [Cu-2(chp)(4)] (1) with the hydrated lanthanoid nitrate salt in methanol. Structural studies reveal the three copper a toms lie in an approximate hemisphere about a central lanthanoid atom. Magnetic studies on 2 and two further Cu-Gd complexes show ferromagne tic coupling between the 3d and 4f metals. Consideration of these resu lts along with magnetic data previously reported for Cu-Gd compounds l eads to a correlation between the magnitude of this exchange coupling and the exponential of the Cu ... Gd distance. This is the first magne to-structural correlation reported for mixed d-block/f-block metal com plexes.