Pentanuclear Spirocyclic Ni<sub>4</sub>Ln Derivatives: Field Induced Slow Magnetic Relaxation in the Dysprosium and Erbium Analogues
Pooja Shukla, Soumalya Roy, Dependu Dolui, Walter Cañón‐Mancisidor, Sourav Das
Abstract
Five pentanuclear heterometallic isostructural complexes, [Ni 4 Ln(L) 2 (LH) 2 (CH 3 CN) 3 Cl] · x H 2 O · y CH 3 OH {Ln = Y III ( 1 ), Gd III ( 2 ), Tb III ( 3 ), Dy III ( 4 ) and Er III ( 5 )} [for 1 and 2 , x = 2, y = 1; for 3 , x = 6, y = 2; for 4 , x = 5, y = 1; for 5 , x = 2, y = 2] were prepared by the reaction of ( E )‐2‐(hydroxymethyl)‐6‐{[(2‐hydroxyphenyl)imino]methyl}‐4‐methylphenol (LH 3 ) with LnCl 3 · 6H 2 O and Ni(OAc) 2 · 4H 2 O in the presence of tetrabutylammonium hydroxide (TBA‐OH) base. The structural characterization reveals that compounds 1 – 5 contain a spirocyclic pentanuclear core [Ni 4 Ln(µ 3 ‐O) 4 (µ 2 ‐O) 4 ] 3+ where two triangular motifs [Ni 2 Ln(µ 3 ‐O) 2 (µ 2 ‐O) 2 ] 3+ are fused together through a common vertex of the Ln III ion. The central Ln III ion forms an eight‐coordinated distorted triangular dodecahedron geometry, while the nickel(II) ions form a distorted octahedron geometry. Comprehensive dc magnetic studies reveal that antiferromagnetic exchange interaction exists between the Ni II centres. The ac susceptibility measurement revels that dysprosium and erbium analogue shows field induced slow magnetic relaxation with an anisotropic barrier ( U eff ) of 25.12 cm –1 and 22.13 cm –1 respectively.