A Ferromagnetically Coupled Mn₁₉ Aggregate with a Record S=83/2 Ground Spin State

Abstract

Dedicated to Professor Hansgeorg Schnöckel on the occasion of his 65th birthday.The first evidence of single molecule magnet (SMM) behavior was discovered in the mixed-valence compounds [Mn [1] In the quest to synthesize SMMs that show hysteresis at higher temperatures, it has been recognized that large ground-state spins and a uniaxial anisotropy (large negative D and small E considering the following Hamiltonian anisotropy term:It is thus of interest to discover how to obtain the largest-spin ground state possible for a given size of aggregate. As well as having four unpaired electrons in its high-spin state, the Mn III ion is particularly useful for introducing large anisotropies through the presence of Jahn-Teller distortions in this configuration and has been the most thoroughly studied candidate for synthesizing new SMMs. Amongst the large number of aggregates containing manganese(III) in the literature, a Mn 25 cluster has been reported as having a ground spin state of 51/2.[4] Herein we report on the realization of the maximum-spin ground state of 83/2 for the aggregate [Mn

High spin cycles: topping the spin record for a single molecule verging on quantum criticality

“…Amongst other reasons this explains why highspin molecules remain notoriously rare. Mn 12 -acetate and Fe 8 , both with S = 10 ground states, dominated early endeavours in the field of single molecule magnetism. [3][4][5] Setting aside anisotropy for a moment, a simpler goal might be to achieve the highest possible spin state residing on a single molecule.…”

“Spin Tweaking” of a High‐Spin Molecule: An Mn25 Single‐Molecule Magnet with an S=61/2 Ground State

“…[5] Nevertheless, it is difficult to achieve a rational synthesis of a high-spin species from simple reagents, [6] and even then there is the danger that the anisotropy will be too low to either give an SMM or to give one with a reasonable barrier. Recent examples of such situations include Mn 10 , Mn 25 , and Mn 19 complexes with S = 44/2, [7] 51/2, [8] and 83/2 [9] ground states, respectively, but with minimal anisotropies (i.e. D values).…”

Directed Synthesis of {Mn18Cu6} Heterometallic Complexes

“…[1] One of the driving forces for this is their fascinating magnetic properties for example, single-molecule magnets [2] or magnetic refrigerants [3] and molecules with large spin ground states [4] or large anisotropy barriers. [5] The use of two, or more, different metal ions to assemble these clusters is an attractive synthetic target and controlling the bottom-up assembly of large heterometallic molecules is a considerable challenge.…”

“…Firstly, we use a preformed Cu II complex, which contains multiple, latent hydroxy binding sites, to target the trapping and encapsulation of an inner metal-oxo core. Secondly, the choice of Cu II as the central ion increases the flexibility further, due to its range of typical coordination environments from [4] to [4+2]. We report two compounds that contain a striking "core-shell" {Mn 18 6 Cl 6 ]Cl 2 ·10 H 2 O·6 CH 3 OH (3·10 H 2 O· 6 CH 3 OH) using NEt 3 /MeOH.…”