Study of Spin Crossover Property of a Series of X‐OMe‐SalEen (X=6, 5 and 4) Based Fe(III) Complexes

Abstract

Abstract Three complexes bearing the molecular formula [Fe(X‐OMe‐SalEen) 2 ]NCY⋅nH 2 O; X=6, Y=S, n=0 ( 1 ); X=5, Y=S, n=1.5 H 2 O ( 2 ) and X=4, Y=Se, n=0 ( 3 ), where 6‐OMe‐SalEen=2‐((E)‐(2‐(ethylamino)ethylimino)methyl)‐6‐methoxyphenol, 5‐OMe‐SalEen=2‐((E)‐(2‐(ethylamino)ethylimino)methyl)‐5‐methoxyphenol, and 4‐OMe‐SalEen=2‐((E)‐(2‐(ethylamino)ethylimino)methyl)‐4‐methoxyphenol, have been synthesized, characterized and their spin crossover behavior has been studied. The ligands differ in the position of the methoxy group (ortho, meta, and para) of the phenoxide ring directly bonded to the Fe center. Complex 1 and 3 comprise Fe III centers, whereas rare crystallographically independent high‐spin and low‐spin Fe III centers are present in complex 2 . Complex 1 shows a sharp and hysteric spin crossover behavior with a hysteresis loop having 4 K width. Complex 2 shows spin crossover for the Fe III LS in solvated form which after desolvation becomes stable at the high spin. Complex 3 shows abrupt and incomplete spin crossover above room temperature. Magneto‐structural correlation and UV‐Vis spectroscopy have been done to study spin‐crossover behavior and the spin transition temperature of the complexes.