Ferromagnetic interaction in a polynuclear gadolinium complex: structure and magnetic studies

Acetylsalicylic acid reacts with gadolinium(III) ions to yield a new gadolinium complex (1) displaying a chain structure which has been determined by single crystal X-ray crystallography: monoclinic P21/n(no. 14), a= 13.5709(13), b= 6.7141(9), c= 22.7232(17), = 99.705(14)°, Z= 4. The thermal dependence of the MT product (M= molar magnetic susceptibility) has been measured and analysed according to the analytical expression of an infinite chain of classical spins derived by Fisher. The GdGd interaction is weak but surprisingly is ferromagnetic with a magnitude of 0.037 cm–1. Modelling of the field dependence of the magnetization at 2 K corroborates this result. It should be emphasized that (1) is the first example of a polynuclear gadolinium complex displaying a ferromagnetic GdGd interaction and having a fully determined structure.