Single‐Crystal to Single‐Crystal Transformations and Magnetic Properties of a Series of "Butterfly" NiII2LnIII2 Compounds: SMM Behavior of the Dysprosium(III) Analogue. Issue 24 (19th June 2018) - Mandal, Shuvankar
Abstract : This investigation reports syntheses, crystal structures, and magnetic properties of a series of "butterfly" Ni II 2 Ln III 2 compounds of compositions [Ni II 2 Ln III 2 L4 (NO3 )2 (MeOH)2 ] (1, Ln = Gd;2, Ln = Tb;3, Ln = Dy;4, Ln = Ho;5, Ln = Er) and [Ni II 2 Ln III 2 L4 (NO3 )2 (H2 O)2 ]· 2H2 O (1A, Ln = Gd;2A, Ln = Tb;3A, Ln = Dy;4A, Ln = Ho;5A, Ln = Er), where H2 L is the Schiff base ligand, obtained on [1+1] condensation of 3‐ethoxysalicylaldehyde and 2‐aminophenol. The five compounds1A –5A are formed as a result of single‐crystal to single‐crystal transformations (SC–SC) of the five compounds1 –5 . The dc and ac magnetic measurements carried out for the five stable compounds1A –5A reveal the following: (i) overall ferromagnetic interaction exists in all of the Ni II 2 Ln III 2 compounds1A –5A ; (ii) both Ni II ··· Ni II and Ni II ··· Gd III interactions in the Gd III analogue1A are ferromagnetic, with J values of 1.83(0.08) cm –1 and 0.285(0.002) cm –1, respectively; and (iii) only the Dy III analogue3A exhibits single‐molecule magnet (SMM) properties, with an energy barrier ( U eff ) of 25 cm –1 and a relaxation time ( τ 0 ) of 8 × 10 –8 s. Comparison of the structures and properties of the compounds in the present investigation with those of analogous systems derived from a related ligand reveals remarkable differences. Abstract : Five "butterfly" Ni II 2 Ln III 2 compounds and their SC–SC transformed "butterfly" Ni II 2 Ln III 2 compounds, derived from a Schiff base ligand, obtained on [1+1] condensation of 3‐ethoxysalicylaldehyde and 2‐aminophenol, are reported. The dc and ac magnetic properties of the five stable compounds are described.