A Diferrous Single‐Molecule Magnet

Abstract

The diferrous complex [Fe 2 (acpypentO)(NCO) 3 ] (1), (acpypentO -= the anion of 1,5-bis[2-pyridyl(1-ethylimino)]-pentane-3-ol) was studied by spectroscopic (dual-mode Xband EPR and 57 Fe-Mössbauer) and magnetic (AC magnetic susceptibility) techniques. Complex 1 (A. K. Boudalis et al., Inorg. Chem. 2004, 43, 1574 was previously shown to exhibit an intramolecular ferromagnetic coupling with important single-ion anisotropies with marked differences in the singleion electronic parameters of the two iron sites. In this contribution, additional studies are carried out to probe its dynamic magnetic properties. Mössbauer spectra recorded at liquid helium temperatures indicate slow paramagnetic relaxation and a ground state of the system characterized by a nonKramers doublet with an Ising-type anisotropy, a condition which favours single-molecule magnet (SMM) behaviour. A

A Family of Enneanuclear Iron(II) Single‐Molecule Magnets

“…[31,32] With regard to dynamic magnetic properties, it is generally assumed that the samples are www.chemeurj.org characterized by inhomogeneities, with one part undergoing slow relaxation and another part undergoing fast relaxation. [18] In the present cases, we have established that the electronic structures of the ground states are rather complicated. From the M versus H experiments at low temperatures, it became apparent that the ground states of these systems could not be characterized by a well-defined spin with an effective zero-field splitting D to which an energy barrier could be directly assigned.…”

“…This family of SMMs represents the second example of an iron(II) SMM family, besides the cubane complexes [Fe 4 (L) 4 A C H T U N G T R E N N U N G (MeOH) 4 ] (L= sae 2À , the dianion of 2-salicylideneamino-1-ethanol, [16] and L = 5-Br-sae or 3,5-Cl 2 -sae, [17] the respective bromo and chloro derivatives thereof), while we have recently reported [Fe 2 A C H T U N G T R E N N U N G (NCO) 3 (acpypentO)] as another Fe II SMM. [18] Results and Discussion…”

Manipulation of spin cluster qubits by electric field induced modulation of exchange coupling,g-factor, and axial anisotropy

“…Analogous experiments involving the electric component of the field can be performed to demonstrate the spin-electric coupling, mediated by the modulation of any parameter of the spin Hamiltonian [11]. Electron spin resonance in the presence of an applied electric field also represents a useful tool for investigating the spin-electric coupling in different classes of systems [13][14][15]. In this respect, one should however consider that this approach gives access to transitions and linear superpositions that differ from the ones we focus on here, and that a given spin-electric coupling can produce an effect in one case and not in the other.…”

“…Purely spin systems, such as paramagnetic defects and molecular nanomagnets [9,10], are characterized by approximately frozen orbital degrees of freedom. In spite of this, coherent control of the spin state by electrical means is viable also in these systems and has been demonstrated in the last years [11][12][13][14][15]. From a theoretical point of view, the effect of an applied electric field in a molecular nanomagnet can be described by the modulation of the parameters that enter the spin Hamiltonian.…”

Rare “Janus”-faced single-molecule magnet exhibiting intramolecular ferromagnetic interactions

“…Unlike Mn compounds, Fe-based SMMs are scarce in the literature. Only a few trivalent Fe III SMMs16 have been reported to date and divalent Fe II examples are limited to three examples, viz ., an ,17 a family of cubanes,18 and a nonanuclear compound 19. Although organic bridging ligands assist in the thermodynamic stability, solubility, and crystallinity of 0-D compounds, their presence as neutral linkers often limits the magnetic properties and dynamics of SMMs, leading to competing magnetic interactions, moderate-to-weak magnetic couplings, and low-lying excited states, among others 11–14,16–19.…”