Influence of anion induced geometry change in Zn() on the magnetization relaxation dynamics of Dy() in Zn-Dy-Zn complexes

A family of hetero-trinuclear metal complexes with the general molecular formula [Zn 2 Dy(L 1 ) 2 (OAc) 4 ] (X) where X = (NO 3 ) 0.92 (Br) 0.08 ( 1 ), ClO 4 ( 2 ), Cl ( 3 ) and PF 6 ( 4 ) were structurally characterized using a Schiff base ligand (HL 1 ). The Dy( iii ) ion in 1-4 exhibits distorted square anti-prism geometry; however, the extent of distortion observed around Dy( iii ) in these complexes differ from each other. Consequently, 1-4 show distinct magnetization relaxation dynamics, with the anisotropic energy barrier of 25.4 cm −1 , 12.9 cm −1 , 14.08 cm −1 and 55.5 cm −1 , respectively. The detailed electronic structure of 1-4 and the experimentally observed magnetization relaxation dynamics trends were rationalized using ab initio calculations. The detailed investigation discloses the non-zero influence of the anion themselves and the anion induced geometry change in Zn( ii ) affects the electronic structure of Dy( iii ), which in turn affects the magnetization relaxation dynamics. Overall, the study unveils an unprecedented methodology i.e. change in geometry of Zn( ii ) by altering the anion in the crystal lattice to modulate the relaxation dynamics of Dy( iii ). A series of [Zn 2 Dy(L 1 ) 2 (OAc) 4 ](X) where X = (NO 3 ) 0.92 (Br) 0.08 ( 1 ), ClO 4 ( 2 ), Cl ( 3 ) and PF 6 ( 4 ) complexes were synthesized and their dc and ac magnetic data investigated. Experimental results are validated through MOLCAS calculations.