Supramolecular Spintronic Devices: Spin Transitions and Magnetostructural Correlations in [Fe₄^IIL₄]⁸⁺ [2×2]‐Grid‐Type Complexes

Abstract

The magnetism of a series of tetranuclear complexes of the [Fe4IIL4]8+ [2x2]-grid-type was investigated, revealing the occurrence of spin transition behavior within this class of compounds. The phenomenon depends directly on the nature of the substituent R(1) in the 2-position on the central pyrimidine group of the ligand L. All Fe(II) ions in compounds with R(1) substituents favoring strong ligand fields (R(1)=H; OH) remain completely in the diamagnetic low-spin state. Only complexes bearing R(1) substituents attenuating the ligand field by steric (and to a lesser extent electronic) effects (R(1)=Me; Ph) exhibit spin transition behavior triggered by temperature. In general, gradual and incomplete transitions without hysteresis were observed for magnetically active complexes. The systems described provide approaches to the development of (supra)molecular spintronics.

A Nanoscale Molecular Switch Triggered by Thermal, Light, and Guest Perturbation

“…Below 10 K, the c M T values decrease more rapidly because of zero field splitting of the HS states. We note that the largest discrete systems that exhibit SCO thus far are the Fe 4 II grids reported by Lehn and co-workers, [15] which are significantly smaller than the nanoball presented here.…”

Solid‐ and Solution‐State Studies of the Novel μ‐Dicyanamide‐Bridged Dinuclear Spin‐Crossover System {[(Fe(bztpen)]2[μ‐N(CN)2]}(PF6)3⋅n H2O

“…In this regard, the synthesis and characterization of the first tetranuclear iron(ii) SCO compound has recently been reported. [10] In our pursuit of new polynuclear SCO compounds, we have explored an alternative synthetic approach based on the use of [Fe II (L)(X)] n + moieties, where L is a pentadentate ligand and X is a labile solvent molecule or an anionic ligand susceptible to being substituted by a suitable bridge-which is dicyanamide in the complexes discussed in this paper. Toftlund, McKenzie, and co-workers adopted this strategy in similar pentadentate compounds from a bioinorganic perspective (see ref.…”

Templating Open‐ and Closed‐Chain Structures around Metal Complexes of Macrocycles

“…A lot of beautiful science has emerged with this challenge, as shown by the grid structures created by Lehn [1] and Thompson, [2] or the panel structures created by Fujita.[3] A particularly attractive idea is to template the structure about an otherwise innocent ion to modify the structure without changing electronic properties. The work of Saalfrank et al in which different sized metallocryptands were templated is particularly relevant here, [4] as is the work of Raymond and coworkers in which the geometry of the molecule is varied from a dimetallic helix to a tetrahedron depending on the presence of a tetrahedral counterion.…”

“…[6] With the Cr-F-pivalate system, octa-, [6] nona-, [7] and decanuclear metal rings could be synthesized by variation of the template. If 1,4,7, Figure 2) [8] results. The fifteen metal sites define an "S", in which a Ni 2+ ion is located at the center of the "S" and two Ni …”