Construction of a High Nuclear Gadolinium Cluster with Enhanced Magnetocaloric Effect through Structural Transition.

Starting from a dinuclear complex {Gd 2 (L) 2 (NO 3 ) 4 (H 2 O) 2 }·2(CH 3 CN) ( 1 ) based on 2,6-dimethoxyphenol (HL), a nonanuclear cluster {Gd 9 (L) 4 (μ 4 -OH) 2 (μ 3 -OH) 8 (μ 2 -OCH 3 ) 4 (NO 3 ) 8 (H 2 O) 8 }(OH)·2H 2 O ( 2 ) was obtained via modulating the amount of the ligand and base. Both of them have been structurally and magnetically characterized. Complex 1 decorates the Gd 2 core bridged by double μ 2 -phenoxyl oxygen atoms and coordinated neutral CH 3 CN molecules, while 2 features the Gd 9 core with a sandglass-like topology. Magnetic investigations reveal that the weaker antiferromagnetic interactions between adjacent metal ions exist in complex 2 than in 1 , which is in agreement with the theoretical results. Meanwhile, the magnetocaloric effect with a maximum -Δ S m value changes from 27.32 to 40.60 J kg -1 K -1 at 2 K and 7 T.