Structures and magnetic properties of a trinuclear angular [Ni3] and a heptanuclear wheel-like [Ni7] complexes with a Schiff base ligand

Abstract

The presence of large magnetic anisotropy with nickel(II) ions facilitates the single-molecule magnet (SMM) behavior in multimetallic nickel(II) complexes. Herein syntheses under ambient conditions, characterizations, crystal structures, and experimental magnetic analyses of an angular [NiII3L4] and a wheel-like [NiII7L6] complexes of general formula [Ni3L2(μ-L)2(μ-OH2)2(CF3CO2)2] (1) and [Ni7(μ-L)6(μ-OMe)6]Cl2·6H2O (2) (HL = 2-{(3-ethoxypropylimino)methyl}-6-methoxyphenol) have been reported. The angular core of trimetallic neutral complex 1 is assembled using four L−, two bridging water molecules, and two bound trifluoroacetate anions. In contrast, the heptanuclear complex 2 features a planar wheel-like arrangement with a central NiII enclosed by a {NiII6} hexagon bound to six MeO− and six L−. The isolation of these two aggregates of varying nuclearity and metal ion: ligand anion ratio indicated the importance of reaction conditions and crystallization to follow the bottom-up assembly processes. Experimental magnetic studies showed antiferromagnetic interactions between the central and terminal NiII ions in complex 1 and competing ferro- and antiferromagnetic interactions in the wheel-like complex 2.