Redox effects of low-spin Ru(ii/iii) on slow magnetic relaxation of Ru-Mn(iii) 1D cyanide-bridged complexes

Spin dynamics phenomena of a cerium(III) double-decker complex induced by intramolecular electron transfer

Switchable spin dynamic properties in single-molecule magnets (SMMs) via an applied stimulus have applications in single-molecule devices. Many SMMs containing heavy lanthanoid ions with strong uniaxial magnetic anisotropy have been reported to exhibit SMM characteristics in the absence of an external magnetic field. On the other hand, SMMs containing light lanthanoid cerium(III) (Ce3+) ions exhibit field-induced slow magnetic relaxation. We investigated the chemical conversion of a diamagnetic Ce4+ ion (4f0) to a paramagnetic Ce3+ ion (4f1) in Ce-phthalocyaninato double-decker complexes (TBA+[Ce(obPc)2]- (1) and TBA+[Ce(Pc)2]- (2)) which exhibit field-induced SMM behaviour due to a 4f1 system. The phthalocyaninato ligands with electron-donating substituents (obPc2- = 2,3,9,10,16,17,23,24-octabutoxyphthalocyaninato) in 1 have a significant effect on the valence state of the Ce ion, which is reflected in its magnetic properties due to the mixed valence state of the Ce ion. Given that Ce double-decker complexes with π-conjugated ligands undergo intramolecular electron transfer (IET) to the Ce ion mixed valence state, characterised by a mixture of 4f0 and 4f1 configurations, we examined the dynamic disorder inherent in IET influencing magnetic relaxation.

Various Structural Types of Cyanide-Bridged FeIII-MnIII Bimetallic Coordination Polymers (CPs) and Polynuclear Clusters Based-on A New mer-Tricyanoiron(III)Building Block: Synthesis, Crystal Structures, and Magnetic Properties

Four cyanide-bridged Fe^III–Mn^III complexes {[Fe(qxcq)(CN)₃][Mn(L¹)(H₂O)]}[Mn(L¹)(H₂O)(CH₃OH)](ClO₄)·1.5MeOH·0.5H₂O (L¹ = N,N′-bis(3-methoxy-5-bromosalicylideneiminate) (2), {[Fe(qxcq)(CN)₃][Mn(L²)]}₂·0.5H₂O (L² = N,N′-ethylene-bis(3-ethoxysalicylideneiminate)) (3), [Fe(qxcq)(CN)₃][Mn(L³)] (L³ = bis(acetylacetonato)ethylenediimine) (4), [Fe(qxcq)(CN)₃][Mn(L⁴)]·1.5MeOH·0.5CH₃CN·0.25H₂O (L⁴ = N,N′-(1,1,2,2-tetramethylethylene)bis(salicylideneiminate)) (5), were prepared by assembling a new structurally characterized mer-tricyanoiron(III) molecular precursor (Ph₄P)[Fe(qxcq)(CN)₃]·0.5H₂O (qxcq⁻ = 8-(2-quinoxaline-2-carboxamido)quinoline anion) (1) and the corresponding manganese(III) Schiff base compound. Complexes 2and 3containa cyanide-bridged heterobimetallic dinuclear entity, which can be further dimerized by self-complementary H-bond interactions through the coordinated water molecule from one complex and the free O₄unit from the adjacent complex. Complexes 4 and 5 area one-dimensional coordination polymer (CP) comprised of the repeated [Mn(Schiffbase)-Fe(qxcq)(CN)₃] units. Complex 4 shows a linear-chain conformation with two trans-located cyano groups bridgingthe neighboring Mn units, while complex 5 is a zigzag-like 1D CP, where the two cyano groups in cis configurationfunction as bridges. In bothcomplexes 4 and 5, the inter-chain π–πstack interactions within the aromaticrings of cyanide precursor extend the 1D chain into the supermolecular 2D networks. The magnetic property has been experimentally studied and theoretically fitted over the four Fe(III)-Mn(III) complexes, revealing the antiferromagnetic interaction in complexes 2 and 4 and the unusual ferromagnetic coupling in complexes 3 and 5 between the Fe(III) ion and the Mn(III) ion bridged by the cyano group. Furthermore, the different magnetic coupling nature has been analyzed on the basis of the magneto-structure correlation of the mer-tricyanometallate-based Fe(III)-Mn(III) magnetic system.

The syntheses, crystal structures, electrochemical and magnetic properties of tri-nuclear cyanide-bridged complexes [cis-MII(bpy)2(CN)2]2MnIII(salcy) (PF6) (M = Fe, Ru, Os)

Three cyanide-bridged heteronuclear complexes, [cis-M(bpy)₂(CN)₂]₂Mn(salcy) (PF₆) (M = Fe, 1; M = Ru, 2; M = Os, 3; bis(salicylideneiminato) dianion) were synthesized and fully characterized. Complexes 1 and 2 show low temperature antiferromagnetic order.

Transition metal redox switches for reversible "on/off" and "slow/fast" single-molecule magnet behaviour in dysprosium and erbium bis-diamidoferrocene complexes

We present an in-depth experimental study of a new class of heterometallic, redox-switchable single-molecule magnets (SMMs).

Single-molecule magnets (SMMs) are considered viable candidates for next-generation data storage and quantum computing. Systems featuring switchability of their magnetization dynamics are particularly interesting with respect to accessing more complex logic gates and device architectures. Here we show that transition metal based redox events can be exploited to enable reversible switchability of slow magnetic relaxation of magnetically anisotropic lanthanide ions. Specifically, we report anionic homoleptic bis-diamidoferrocene complexes of Dy³⁺ (oblate) and Er³⁺ (prolate) which can be reversibly oxidized by one electron to yield their respective charge neutral redox partners (Dy: [1]^–, 1; Er: [2]^–, 2). Importantly, compounds 1 and 2 are thermally stable which allowed for detailed studies of their magnetization dynamics. We show that the Dy³⁺[1]^–/1 system can function as an “on”/“off” or a “slow”/“fast” redox switchable SMM system in the absence or presence of applied dc fields, respectively. The Er³⁺ based [2]^–/2 system features “on”/“off” switchability of SMM properties in the presence of applied fields. Results from electrochemical investigations, UV-vis-NIR spectroscopy, and ⁵⁷Fe Mössbauer spectroscopy indicate the presence of significant electronic communication between the mixed-valent Fe ions in 1 and 2 in both solution and solid state. This comparative evaluation of redox-switchable magnetization dynamics in low coordinate lanthanide complexes may be used as a potential blueprint toward the development of future switchable magnetic materials.