Is a radical bridge a route to strong exchange interactions in lanthanide complexes? A computational examination

Rajeshkumar, Thayalan; Rajaraman, Gopalan

doi:10.1039/c2cc33483f

Cited by 90 publications

(62 citation statements)

References 39 publications

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“…pentadentate organic ligand L with Dy(NO3)3 and DyCl3, respectively (L = 2,6-bis(1-salicyloylhydrazonoethyl) pyridine; Figure S1). As the overall electronic structure of a Dy III ion is very sensitive to its coordination environment, minor changes in the ligand systems can significantly affect the magnetic properties of the complexes [15][16][17]. Most of the reports on Ln-based SMMs concentrated mainly on either changing the Ln ion keeping the ligand system constant [18][19][20] or changing the ligand but keeping the coordination environment around the Ln ion unchanged [8].…”

Section: Resultsmentioning

confidence: 99%

Modulating the Slow Relaxation Dynamics of Binuclear Dysprosium(III) Complexes through Coordination Geometry

2016

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A class of two dinuclear dysprosium based complexes 1 and 2 were synthesized by employing salicyloylhydrazone derived pentadentate ligand (L). Structural analysis reveals that in complex 1, two Dy III centers are in muffin (C s ) coordination geometry while in 2, one Dy III center is in bicapped square antiprism (D 4d ) and other one is in triangular dodecahedron (D 2d ) coordination geometry. AC magnetic susceptibility measurements disclose that complexes 1 and 2 exhibit single-molecule magnet (SMM) behavior, with effective energy barrier of 36.4 and 9.7 K, respectively. The overall studies reveal that small differences in the coordination environment around the Dy III centers played a significant role in the difference in relaxation dynamics of the complexes. In order to elucidate the role of intermolecular interactions between nearby Dy III centers in the magnetic relaxation behavior, a diamagnetic isostructural Y III analog (3) was synthesized and magnetic behavior was examined.

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Section: Resultsmentioning

confidence: 99%

Modulating the Slow Relaxation Dynamics of Binuclear Dysprosium(III) Complexes through Coordination Geometry

2016

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“…With a delocalized electron on the N-O-C-N-O plane, effective magnetic couplings can be always observed in such complexes owing to the direct overlap of the orbitals containing unpaired electrons [3]. Especially in the one-dimension -Rad-Ln-Rad-Ln-Rad-complexes, notable intrachain interactions are also identified between next-nearest-neighbor (NNN) spins for both radicals and Ln(III) ions [4].…”

Section: Introductionmentioning

confidence: 99%

Two new mononuclear tri-spin lanthanide–nitronyl nitroxide radical complexes: Syntheses, structure and magnetic properties

Liu

Zhang

et al. 2015

Inorganic Chemistry Communications

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“…We used a triple zeta valence (34) basis set on Cr and split valence polarization for the rest of the elements (35). Calculations were performed on models of 3 and 4 where the pivalates were replaced by acetates, as in previous work (36,37). The magnetic exchange interactions were extracted using the pairwise interaction model (38) based on the energies of five spin configurations, given in SI Text, which were calculated for both 3 and 4.…”

Section: Methodsmentioning

confidence: 99%

A classification of spin frustration in molecular magnets from a physical study of large odd-numbered-metal, odd electron rings

Baker

Timco

Piligkos

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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124

103

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The term "frustration" in the context of magnetism was originally used by P. W. Anderson and quickly adopted for application to the description of spin glasses and later to very special lattice types, such as the kagomé. The original use of the term was to describe systems with competing antiferromagnetic interactions and is important in current condensed matter physics in areas such as the description of emergent magnetic monopoles in spin ice. Within molecular magnetism, at least two very different definitions of frustration are used. Here we report the synthesis and characterization of unusual ninemetal rings, using magnetic measurements and inelastic neutron scattering, supported by density functional theory calculations. These compounds show different electronic/magnetic structures caused by frustration, and the findings lead us to propose a classification for frustration within molecular magnets that encompasses and clarifies all previous definitions. ,4,7-triazacyclononane). One area where molecular magnetism might contribute is in spin frustration (3), which is important in condensed matter physics in areas such as spin ice (4) and spin liquids (5). Potential model systems would be odd-numbered metal rings where the metal array forms equilateral triangles, or regular pentagons, heptagons, and larger 2D rings. Alternatively 3D solids made from regular odd-numbered rings should also be frustrated, e.g., regular tetrahedra and octahedra contain triangular faces and regular icosahedra contain pentagonal faces.Studies of spin frustration in molecular systems are largely restricted to that of triangular trimetallic species (6, 7). There are a few reports of five-metal rings but no detailed magnetic studies of such compounds (8), with the exception of a {Cu 5 } cage (9). The only significant examples of larger frustrated molecules are studies of the {M 30 } Keplerates (10) and a recent report of a heptametallic {VO} 7 ring (11), where the studies are limited to low temperature magnetization. There is also a report of an {Fe 9 } complex that can, very approximately, be described as a nine-metal ring (12).A further difficulty is that precisely what is meant by frustration varies in this area. The strictest definition used in molecular magnetism, from Kahn (13), states that frustration must result in a spin degenerate ground state, typically a degenerate pair of S = 1/2 states. Surprisingly, this definition excludes all possible models built from integer spins, as in such cases (for example a regular pentagon of s = 1 spins), the ground total spin state is unique and has S = 0. This definition thus seems prohibitively strict. At the other extreme, the term frustration has been used to describe cases where there are competing antiferromagnetic interactions, even where those interactions result in a unique spin ground state that can be described using a classical picture, with spins represented as arrows pointing alternately up and down. This definition seems, if anything, too permissive.We have reported studies of...

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Is a radical bridge a route to strong exchange interactions in lanthanide complexes? A computational examination

Cited by 90 publications

References 39 publications

Modulating the Slow Relaxation Dynamics of Binuclear Dysprosium(III) Complexes through Coordination Geometry

Modulating the Slow Relaxation Dynamics of Binuclear Dysprosium(III) Complexes through Coordination Geometry

Two new mononuclear tri-spin lanthanide–nitronyl nitroxide radical complexes: Syntheses, structure and magnetic properties

A classification of spin frustration in molecular magnets from a physical study of large odd-numbered-metal, odd electron rings

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