Magnetic and Structural Studies of Copper–Lanthanoid Complexes; the Synthesis and Structures of New Cu₃Ln Complexes of 6‐chloro‐2‐Pyridone (Ln = Gd, Dy and Er) and Magnetic Studies on Cu₂Gd₂, Cu₄Gd₂ and Cu₃Gd Complexes

The synthesis and structural characterisation of three copper–lanthanoid complexes are reported. The compounds, of general formula [Cu 3 M(chp) 8 (NO 3 )(S)] [M = Gd, S = H 2 O in 2 ; M = Dy, S = H 2 O in 3 ; M = Er, S = (H 2 O) 0.5 (MeOH) 0.5 in 4 ; chp = anion of 6‐chloro‐2‐pyridone], are made by reaction of [Cu 2 (chp) 4 ] ( 1 ) with the hydrated lanthanoid nitrate salt in methanol. Structural studies reveal the three copper atoms lie in an approximate hemisphere about a central lanthanoid atom. Magnetic studies on 2 and two further Cu–Gd complexes show ferromagnetic coupling between the 3d and 4f metals. Consideration of these results along with magnetic data previously reported for Cu–Gd compounds leads to a correlation between the magnitude of this exchange coupling and the exponential of the Cu…Gd distance. This is the first magneto‐structural correlation reported for mixed d‐block/f‐block metal complexes.