Anion-Templated Assembly and Magnetocaloric Properties of a Nanoscale {Gd38} Cage versus a {Gd48} Barrel

The comprehensive study reported herein provides compelling evidence that anion templates are the main driving force in the formation of two novel nanoscale lanthanide hydroxide clusters, {Gd38(ClO4)6} (1) and {Gd48Cl2(NO3)} (2), characterized by single‐crystal X‐ray crystallography, infrared spectroscopy, and magnetic measurements. {Gd38(ClO4)6}, encapsulating six ClO4− ions, features a cage core composed of twelve vertex‐sharing {Gd4} tetrahedrons and one Gd⋅⋅⋅Gd pillar. When Cl− and NO3− were incorporated in the reaction instead of ClO4−, {Gd48Cl2(NO3)} is obtained with a barrel shape constituted by twelve vertex‐sharing {Gd4} tetrahedrons and six {Gd5} pyramids. What is more, the cage‐like {Gd38} can be dynamically converted into the barrel‐shaped {Gd48} upon Cl− and NO3− stimulus. To our knowledge, it is the first time that the linear M‐O‐M′ fashion and the unique μ8‐ClO4− mode have been crystallized in pure lanthanide complex, and complex 2 represents the largest gadolinium cluster. Both of the complexes display large magnetocaloric effect in units of J kg−1 K−1 and mJ cm−3 K−1 on account of the weak antiferromagnetic exchange, the high NGd/MW ratio (magnetic density), and the relatively compact crystal lattice (mass density). The birdcage: Two novel nanoscale lanthanide hydroxide clusters, {Gd38} and {Gd48}, are reported. Moreover, the {Gd38} cage can be dynamically converted into the {Gd48} barrel upon Cl− and NO3− stimulus (see figure). Both complexes display large magnetocaloric effects due to the dominant weak antiferromagnetic interactions, the high NGd/MW ratio, and the relatively compact crystal lattice.