Two Polynuclear Fe Complexes with Boat-like Core: Syntheses, Structures and Magnetic Properties

Abstract

Two novel polynuclear complexes {NaFe4(µ4-O)(L)4(µ2-Cl)[Fe(CN)5NO](H2O)(DMF)2} (1) and {NaFe4(µ4-O)(L)4(µ2-OEt)[Fe(CN)5NO](H2O)(DMF)2} (2) have been prepared using the tetradentate N-(2-hydroxyethyl)-3-methoxysalicylaldimine Schiff-base ligand (H2L) with the help of [Fe(CN)5NO]2- linkers, where the ligand was in situ synthesized through the condensation of o-vanillin and ethanolamine in the formation process of complexes. The resulting complexes possess “boat-like” structure constructed through three Fe ions and one Na ion with the fourth Fe ion acting as the “paddle”. The “hull bottom” contains an eight-membered metallamacrocycle with metallacrown-like motif and [-M-O-] repeat unit. Both complexes display three-dimensional frameworks through C-H···N hydrogen bonds, C–H···Cl hydrogen bonds, and π-π stacking interactions with the introduction of solvent molecules and coordination anions. Variable-temperature magnetic susceptibility measurements reveal strong antiferromagnetic couplings between the metal centers in complexes 1 and 2.