A Mn<sub>17</sub>Octahedron with a Giant Ground-State Spin: Occurrence in Discrete Form and as Multidimensional Coordination Polymers

The one-electron reduction of (tbsL)Fe3(thf)1 furnishes [M][(tbsL)Fe3] ([M]+ = [(18-C-6)K(thf)2]+ (1, 76%) or [(crypt-222)K]+ (2, 54%)). Upon reduction, the ligand tbsL6− rearranges around the triiron core to adopt an almost ideal C3-symmetry. Accompanying the (tbsL) ligand rearrangement, the THF bound to the neutral starting material is expelled, and the Fe–Fe distances within the trinuclear cluster contract by ~0.13 Å in 1. Variable-temperature magnetic susceptibility data indicates a well-isolated S=+1112 spin ground state that persists to room temperature. Slow magnetic relaxation is observed at low temperature as evidenced by the out-of-phase χM″ component of the alternating current (ac) magnetic susceptibility data and by the appearance of hyperfine splitting in the zero-field 57Fe Mössbauer spectra at 4.2 K. Analysis of the ac magnetic susceptibility yields an effective spin reversal barrier (Ueff) of 22.6(2) cm−1, nearly matching the theoretical barrier of 38.7 cm−1 calculated from the axial zero-field splitting parameter (D = −1.29 cm−1) extracted from the reduced magnetization data. A polycrystalline sample of 1 displays three sextets in the Mössbauer spectrum at 4.2 K (Hext = 0) which converge to a single six-line pattern in a frozen 2-MeTHF glass sample, indicating a unique iron environment and thus strong electron delocalization. The spin ground state and ligand rearrangement are discussed within the framework of a fully delocalized cluster exhibiting strong double and direct exchange interactions.

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“…40 The

χ_{M}^{'} T

vs T plot shown in Figure S10 displays a smooth monotonic increase above 2.4 K to the ideal value of 17.875 cm 3 K/mol for an

S = +1 \frac{11}{2}

( g = 2). The abrupt decrease below 2.4 K correlates with slow magnetic relaxation effects.…”

Section: Discussionmentioning

confidence: 90%

Maximizing Electron Exchange in a [Fe₃] Cluster

et al. 2016

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“…1(a)]. For a torsional spring constant K ¼ 10 À18 N Á m [15], S ¼ 37 (for a Mn 17 SMM [16]), and a moment of inertia I x ¼ 10 À36 kg Á m 2 , we obtain ! r ¼ ffiffiffiffiffiffiffiffiffiffi ffi K=I x p $ 1 GHz and $ 0:02.…”

Section: Prl 106 147203 (2011) P H Y S I C a L R E V I E W L E T T Ementioning

confidence: 99%

Macrospin Tunneling and Magnetopolaritons with Nanomechanical Interference

et al. 2011

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We theoretically address the quantum dynamics of a nanomechanical resonator coupled to the macrospin of a magnetic nanoparticle by both instanton and perturbative approaches. We demonstrate suppression of the tunneling between opposite magnetizations and destruction of magnetopolaritons (coherent magnetomechanical oscillations) by nanomechanical interference. The predictions can be verified experimentally by a molecular magnet attached to a nanomechanical bridge. DOI: 10.1103/PhysRevLett.106.147203 PACS numbers: 75.80.+q, 75.45.+j, 75.50.Xx, 85.65.+h The first direct observation of quantum behavior of a macroscopic mechanical resonator constituting a nanoelectromechanical system (NEMS) has been reported recently [1]. This opens a wide range of new possibilities for testing quantum-mechanical principles on macroscopic objects and has the potential to impact sensor technology. NEMSs have also been suggested to operate as qubits and memory elements for quantum-information processing [2]. Proposals and realizations of two-level systems (e.g., superconducting qubits) coupled to mechanical modes [2,3] allow quantum measurements on the mechanical resonator. Here, we study quantum effects in a NEMS coupled to a ferromagnetic nanoparticle such as a singlemolecule magnet (SMM).The dynamics of a magnetic order parameter and a mechanical resonator are coupled by conservation of angular momentum [4]. The magnetization dynamics of a ferromagnetic particle [4] as well as macrospin-tunneling oscillations in a SMM [5] should in principle induce magnetomechanical motion. However, the semiclassical treatment fails when the coupling becomes stronger and quantum mechanical effects such as freezing of spin tunneling [8] manifest themselves, as discussed below.In this Letter, we consider a torsional nanomechanical resonator [see Fig. 1(a)] consisting of a load (e.g., a magnetic nanoparticle or a SMM attached to a paddle) and a mechanical link to the base (e.g., a nanotube or a chemical bond). The projection of the wave function of the macrospin on the two lowest energy levels is equivalent to a harmonic oscillator coupled to a two-level system [6]. The interference effects discussed here can be understood by considering a mechanical resonator in the nth excited state [see Fig.

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“…Magnetic polymetallic complexes constructed from different paramagnetic metal ions and functional organic ligands have always attracted intense interest due to their fascinating structures, [1] intriguing magnetism, [2] as well as important magnetostructural relationships. [34] Acting as one of typically heterodonor ligands in neutral and/or anionic form, [5] oximato-based organics have always demonstrated to be versatile ligands for generations of commonly observed low nuclearity to remarkable high nuclearity systems by chelating and/or bridging different metal centers.…”

Section: Introductionmentioning

confidence: 99%

Oximato-derived metal complexes with triangular and linear magnetic subunits: Synthesis, structure, and magnetism

Zhang

Liu

et al. 2016

Inorganic and Nano-Metal Chemistry

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Three oximato-based oligomeric metal complexes, {[Cu 3 (H 2 O)(µ 3 -OH)(mpko) 3 (NO 3 )]·3H 2 O·NO 3 } (1), {[Cu 6 (μ 3 -OH) 2 (mpko) 6 (Br) 4 ]·8H 2 O} (2), and {[Fe 3 (mpko) 6 ]·ClO 4 ·2.5CH 3 CN} (3) (mpkoH = 1-(pyrazin-2-yl)ethanone oxime), were synthesized by varying different spin carriers, and structurally and magnetically characterized. Structural determinations reveal that 1 is a discrete triangular {Cu 3 ( 3 -OH)} 5+ molecule with two adjacent metal ions further bridged by chelating-bridging mpko  ligands. Complex 2 features a centrosymmetric hexanuclear entity with two triangular {Cu 3 ( 3 -OH)} 5+ subunits extended by a Downloaded by [University of Nebraska, Lincoln] at 05:18 04 June 2016 ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 2 pair of bridging -Br  anions. By contrast, 3 exhibits an approximately linear trinuclear entity with central Fe III ion connected with two external Fe II ions by six crystallographically unique mpko  ligands. Strong antiferromagnetic interactions with the coupling constant up to 223 (1) cm 1 are observed in the triangular subunits of 1 and 2. In 3, the central Fe III ion with S = 5/2 is almost magnetically isolated with the terminal Fe II ions with S = 0.

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A Mn₁₇Octahedron with a Giant Ground-State Spin: Occurrence in Discrete Form and as Multidimensional Coordination Polymers

Cited by 128 publications

References 7 publications

Maximizing Electron Exchange in a [Fe₃] Cluster

Maximizing Electron Exchange in a [Fe₃] Cluster

Macrospin Tunneling and Magnetopolaritons with Nanomechanical Interference

Oximato-derived metal complexes with triangular and linear magnetic subunits: Synthesis, structure, and magnetism

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A Mn17Octahedron with a Giant Ground-State Spin: Occurrence in Discrete Form and as Multidimensional Coordination Polymers

Cited by 128 publications

References 7 publications

Maximizing Electron Exchange in a [Fe3] Cluster

Maximizing Electron Exchange in a [Fe3] Cluster

Macrospin Tunneling and Magnetopolaritons with Nanomechanical Interference

Oximato-derived metal complexes with triangular and linear magnetic subunits: Synthesis, structure, and magnetism

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A Mn₁₇Octahedron with a Giant Ground-State Spin: Occurrence in Discrete Form and as Multidimensional Coordination Polymers

Maximizing Electron Exchange in a [Fe₃] Cluster

Maximizing Electron Exchange in a [Fe₃] Cluster