A Combined Experimental and Theoretical Study on the Magnetic Properties of a Family of Bis(μ‐phenoxido)dicopper(II) Complexes Bearing ω‐[Bis(2‐hydroxy‐3,5‐dimethylbenzyl)amino]alkan‐1‐ol Ligands

Abstract

Abstract Five new neutral bis(μ‐phenoxido)dicopper(II) complexes, [Cu 2 (μ‐HL1) 2 ] · 3EtOH · H 2 O ( 1 ), [Cu 2 (μ‐HL2) 2 ] · 1.65H 2 O ( 2 ), [Cu 2 (μ‐HL3) 2 (μ‐H 2 O)] ( 3 ), [Cu 2 (μ‐HL4) 2 ] ( 4 ) and [Cu 2 (μ‐HL5) 2 (μ‐H 2 O)] ( 5 ), were prepared from a family of ω‐[bis(2‐hydroxy‐3,5‐dimethylbenzyl)amino]alkan‐1‐ol ligands (H 3 L1–H 3 L5 derived from 2‐aminoethanol, 3‐aminopropanol, 4‐aminobutanol, 5‐aminopentanol and 6‐aminohexanol, respectively) bearing a [O,N,O,O′] donor set. In complexes 3 and 5 , there is also a bridging water molecule between the metallic centres. The copper(II) coordination planes of all these complexes form a roof‐like structure (the bridging O atoms are located at the top of the roof). The structural differences found for the different complexes and their relation with the magnetic properties is discussed below. Magnetic studies of these dinuclear complexes showed that J values vary from –470.8 to –91.2 as the Cu–O–Cu angles ( θ ) vary from 100.66(9) to 92.76(7)°. DFT theoretical calculations produced the corresponding magnetic exchange coupling constants, finding that these values are quite near to the experimental ones. A linear relationship between the calculated J values and θ was observed, clearly supporting that the major factor controlling the magnetic exchange coupling in this series of complexes is, by far, the Cu–O–Cu bridging angle. The crossover point below which the magnetic behaviour changes from antiferromagnetic to ferromagnetic coupling is predicted at ≈ 89°. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)