2D H-bonding molecular magnets based on [Ni(mnt)2]− monoanion: Syntheses, crystal structures and magnetic properties

Two new H-bonding molecular magnets based on [Ni(mnt)2]− monoanion have been synthesized and characterized structurally. In crystal of 1, [Ni(mnt)2]− monoanions form the π-stacked sheets and the neighboring anionic sheets are held together via H-bonding interactions between –NH groups of diprotonated benzene-1,4-diamine and CN groups of mnt2− ligands. In crystal of 2, the neighboring anionic dimers form an anionic column via Ni…S contacting interactions, and these anionic stacks arrange into a sheet which is parallel to crystallographic ab-plane. The H-bonding interactions between diprotonated 1,4-diazabicyclo[2.2.2]octane cations and [Ni(mnt)2]− monoanions as well as between cations and solvent MeCN molecules stabilize the lattice. Magnetic susceptibility measurement for 1 indicates an activated magnetic behavior in the high-temperature range together with a Curie tail at the lower temperature range, but the magnetic feature deviates from the magnetic exchange model for a spin dimer with S = 1/2. The magnetic nature of 2 reveals the presence of strongly antiferromagnetic interactions between the nearest-neighboring spins, the larger energy gap between spin ground and excited states results in a weakly paramagnetic property.

Graphical abstractTwo new H-bonding molecular magnets were designed. In their crystals, magnetic [Ni(mnt)2]− monoanions form the π-stacked sheets and the neighboring anionic sheets are held together via H-bonding interactions between -NH groups of cations and CN groups of mnt2− ligands.Figure optionsDownload full-size imageDownload as PowerPoint slide