Giant Ising-Type Magnetic Anisotropy in Trigonal Bipyramidal Ni(II) Complexes: Experiment and Theory

Ruamps, Renaud; Maurice, Rémi; Batchelor, Luke J.; Boggio‐Pasqua, Martial; Guillot, Régis; Barra, Anne Laure; Liu, Junjie; Bendeif, El‐Eulmi; Pillet, Sébastien; Hill, Stephen; Mallah, Talal; Guihéry, Nathalie

doi:10.1021/ja308146e

Cited by 141 publications

(172 citation statements)

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“…Even with a low temperature (2 K) and high field (5.5 T), the magnetization for 57 is 1.25  B , which is much lower than the saturation value for an S = 1 center (2.2  B with g iso = 2.2). In addition, non-superimposable M vs. H/T isotherms at different temperatures confirmed the presence of significantly higher magnetic anisotropy [92]. In addition to the magnetic data, HF-EPR studies of a single crystal of 57 were performed and simulations of the spectra yielded magnetic anisotropy parameters of D = -179 cm -1 and E = 1.6 cm -1 , with an isotropic g factor of 2.4 (estimated from the room temperature  M T value).…”

Section: Page 30 Of 85mentioning

confidence: 78%

“…A c c e p t e d M a n u s c r i p t Edited June 25 experimentally difficult to restrict the coordination environments of these complexes unless conformationally rigid chelating ligands are used; thus, TBP complexes with exact D 3 symmetry are scarce [88,[92][93][94]. A small distortion from axial symmetry can significantly modify the magnetic anisotropy.…”

Section: Page 30 Of 85mentioning

confidence: 99%

“…Detailed experimental and theoretical investigations have been performed using two mononuclear penta-coordinated complexes, i.e., [Ni(Me 6 tren)Cl]OTf (57) and [Ni(Me 6 tren)Br]Br (58), which incorporate Ni II in almost ideal TBP geometries (Fig. 20) [92]. The theoretical investigations predicted that the axial ZFS parameter D was within a range of -100 to -200 cm -1 .…”

Section: Page 30 Of 85mentioning

confidence: 99%

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Magnetic anisotropy in two- to eight-coordinated transition–metal complexes: Recent developments in molecular magnetism

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Sutter

2016

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Section: Page 30 Of 85mentioning

confidence: 78%

Section: Page 30 Of 85mentioning

confidence: 99%

Section: Page 30 Of 85mentioning

confidence: 99%

See 1 more Smart Citation

Magnetic anisotropy in two- to eight-coordinated transition–metal complexes: Recent developments in molecular magnetism

Bar

Pichon

Sutter

2016

Coordination Chemistry Reviews

385

249

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“…Others and we have already demonstrated the large effect of the distortion in the coordination sphere on the magnitude and the nature (Ising or XY) of the anisotropy in molecular complexes. [41][42][43][44][45] Recently, X-ray Absorption Spectroscopy (XAS) at the L 2,3 edge of Ni performed on CsNi II Cr III (CN) 6 nanoparticles demonstrated the presence of axially distorted Ni II ions (NiN 6-x O x species) that belong mainly to the particles' surface. [ 29 ] X-ray magnetic circular dichroism (XMCD) studies allowed assessing the orbital contribution (<L Z >), responsible for the magnetic anisotropy, which was found larger for the Ni II surface ions (<L Z > = 0.32) than for those located in the volume (<L Z > = 0.23).…”

Section: Introductionmentioning

confidence: 99%

Magnetization Reversal in CsNi^IICr^III(CN)₆ Coordination Nanoparticles: Unravelling Surface Anisotropy and Dipolar Interaction Effects

Prado

Mazérat

Rivière

et al. 2014

Adv Funct Materials

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5402www.MaterialsViews.com wileyonlinelibrary.com their post-modifi cation. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] We have reported an alternative surfactant-free synthesis that led, by adjusting the physico-chemical para meters, to the formation of stable colloidal aqueous solutions of nanocrystals with a narrow size distribution. [ 25,26 ] This stability originates from the negatively charged surface and has been exploited to set a versatile simple synthetic route for core-multishell heterostructured nanoparticles. [ 17 ] The method is based on a seed-mediated growth in solution of a shell on the as-obtained colloids either using the same PBA coordination network or another one. [ 17,[25][26][27][28][29] It was quite remarkable to observe that the size distribution of the resulting objects was of the order of 10%. Then, knowing that the cell parameter of the PBA networks is about 1 nm, which corresponds to two atomic layers ( Figure 1 ), such a size distribution corresponds to a control during the growth in solution over one monolayer. [ 17 ] The control of the monodispersity and the absence of stabilizing agents in these anionic objects allowed their organization in thin fi lms, [ 30,31 ] their use for surface nanopatterning, [ 32 ] and is essential for the analysis of their magnetic behaviour (see below).In a fi rst communication, [ 27 ] we have reported a series of cubic-like coordination nanoparticles of the ferromagnetic network CsNi II Cr III (CN) 6 ( T C (bulk) = 90 K) with sizes ranging from 6 to 30 nm and a narrow distribution (10-20%), using the seedmediated growth process. The study of the magnetic properties of these particles dispersed in a polymer (polyvinylpyrrolidone, PVP, for instance) allowed us determining experimentally the single domain limit size that was found to be around 15-16 nm. Below this size, as expected, a uniform reversal of the magnetization was observed. These results were in line with a Néel-Brown thermal activated magnetization reversal process with a relaxation governed by an anisotropy energy proportional to the volume of the particles, with no detectable surface anisotropy effect. [33][34][35] However, upon decreasing their size surface effects may become dominant and contribute greatly to the magnetic anisotropy of nanoparticles. [ 36,37 ] As evidenced in thin fi lms and nanoparticles, surface anisotropy constant is found higher by many orders of magnitude than that of the bulk. [ 1,38,39 ] Specifi cally in PBA nanoparticles, the role of surface anisotropy cannot be neglected because the coordination sphere of the divalent metal ions (Ni II ions here) present on the surface can be different from those belonging to the

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“…A lowering of the symmetry is therefore necessary to observe the property. Molecules with the same symmetry but with different electronic configurations of the magnetic ion (different metal ions or different oxidation states) lead to completely different magnetic anisotropies (easy axis or easy plane and with or without rhombic contribution) so that the ways to improve SMMs are far from being intuitive [16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Tools for Predicting the Nature and Magnitude of Magnetic Anisotropy in Transition Metal Complexes: Application to Co(II) Complexes

et al. 2016

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This work addresses the question of the identification of the excited states that are mainly responsible for the magnitude and nature of the magnetic anisotropy in high-spin mononuclear transition metal complexes. Only few states are actually responsible for the single ion magnetic anisotropy, and these states can be anticipated from rather simple rules. We show that in high-spin complexes atomic selection rules still prevail and that molecular selection rules from the symmetry point group are more selective than those of the double group. The predictive power of these rules is exemplified on a penta-coordinate Co(II) complex investigated with correlated ab initio calculations, including relativistic contributions. The electronic structure of excited states coupled to the ground state through spin-orbit coupling informs us about the nature (either axial or planar) of their contribution to the anisotropy. From this information, it is possible to anticipate the nature and strength of the ligand field and predict the magnetic anisotropy, which may guide the synthesis of improved anisotropic complexes. Such results can also be used to improve the quality of ab initio calculations of the spin Hamiltonian parameters and to reduce the computational cost.

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Giant Ising-Type Magnetic Anisotropy in Trigonal Bipyramidal Ni(II) Complexes: Experiment and Theory

Cited by 141 publications

References 89 publications

Magnetic anisotropy in two- to eight-coordinated transition–metal complexes: Recent developments in molecular magnetism

Magnetic anisotropy in two- to eight-coordinated transition–metal complexes: Recent developments in molecular magnetism

Magnetization Reversal in CsNi^IICr^III(CN)₆ Coordination Nanoparticles: Unravelling Surface Anisotropy and Dipolar Interaction Effects

Tools for Predicting the Nature and Magnitude of Magnetic Anisotropy in Transition Metal Complexes: Application to Co(II) Complexes

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Giant Ising-Type Magnetic Anisotropy in Trigonal Bipyramidal Ni(II) Complexes: Experiment and Theory

Cited by 141 publications

References 89 publications

Magnetic anisotropy in two- to eight-coordinated transition–metal complexes: Recent developments in molecular magnetism

Magnetic anisotropy in two- to eight-coordinated transition–metal complexes: Recent developments in molecular magnetism

Magnetization Reversal in CsNiIICrIII(CN)6 Coordination Nanoparticles: Unravelling Surface Anisotropy and Dipolar Interaction Effects

Tools for Predicting the Nature and Magnitude of Magnetic Anisotropy in Transition Metal Complexes: Application to Co(II) Complexes

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Magnetization Reversal in CsNi^IICr^III(CN)₆ Coordination Nanoparticles: Unravelling Surface Anisotropy and Dipolar Interaction Effects