A synthetic strategy for switching the single ion anisotropy in tetrahedral Co(<scp>ii</scp>) complexes

Vaidya, S.; Upadhyay, Apoorva; Singh, Saurabh Kumar; Gupta, Tarkeshwar; Tewary, Subrata; Langley, Stuart K.; Walsh, James P. S.; Murray, Keith S.; Rajaraman, Gopalan; Shanmugam, Maheswaran

doi:10.1039/c4cc08305a

Cited by 121 publications

(83 citation statements)

References 44 publications

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“…This type of complexes is ideal for showing enormous negative D value in d 7 electronic configuration . This correlation is valid only when the donor atoms are kept constant, which is O and S donor in the complexes 1 – 5 as the change in donor atom results in a drastic change in these parameters . The estimated D value increases from complexes 1 to 5 .…”

Section: Resultsmentioning

confidence: 96%

Magnetic Anisotropy in Co^IIX₄ (X=O, S, Se) Single‐Ion Magnets: Role of Structural Distortions versus Heavy Atom Effect

Sarkar

Tewary

Sinkar

et al. 2019

Chemistry An Asian Journal

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Mononuclearf our coordinate Co II complexes have drawn ag reat deal of attention as they often exhibit excellent single-ion magnet (SIM) properties. Among the reported complexes, the axial zero-field splitting parameter (D)w as found to vary drastically both in terms of the sign as well as strength. There are variousp roposals in this respects uch as structural distortions,h eaviera tom substitution, metalligand covalency,t uning secondary coordination sphere, etc. that are expected to control the D values. To assess the importance of structurald istortions vs. heaviera tom substitution effect, herew eh ave undertaken detailed theoretical studies based on the ab initio CASSCF/NEVPT2 methodt o estimate zero-field splitting parameters for twelve complexes reported in the literature. Our test set includes the {Co II X 4 } (where X = O, S, Se) core structure where the D value was found to vary from + 19 to À118cm À1 .B ased on the structural variation, we have classified the complexes into three types (I-III)w here type I complexes were found to exhibit the largestn egative D value as desired for SIMs. The other two types (II and III)o fc omplexes have been found to be inferior with respect to type I. The secondary coordination spherew as also found to influence D,a ss ubstitution on the secondary coordination sphere atom was found to significantly alter the magnitude of D values. Particularly,t wo structuralp arameters, namely,t he dihedrala ngle between the two ligand planes and the ffX-Co-X polar angle were found to heavily influence the sign and strength of D values. Our analysis clearly reveals that these structural factors are much more important than the heavier atom substitution,o r metal-ligand covalency.Alarge variation in the D and E/D values among these complexesd espite possessing av ery close structuralsimilarity offers an exquisite playground for a chemistt odesign and develop new-generation Co II -based SIMs.

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Section: Resultsmentioning

confidence: 96%

Magnetic Anisotropy in Co^IIX₄ (X=O, S, Se) Single‐Ion Magnets: Role of Structural Distortions versus Heavy Atom Effect

Sarkar

Tewary

Sinkar

et al. 2019

Chemistry An Asian Journal

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“…The double well model holds up in the case of monometallic cobalt(II) SMMs with negative D values [9,[11][12][13][14][15][16][17][18][19], but the observation of similar behaviour in monometallic cobalt(II) complexes with positive D values [20][21][22] suggests that the picture is more complex. Indeed, slow relaxation in positive-D compounds is a phenomenon that is not yet fully understood-although attempts have been made to explain it [23,24].…”

Section: Introductionmentioning

confidence: 90%

Evidence of Slow Magnetic Relaxation in Co(AcO)2(py)2(H2O)2

et al. 2016

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Abstract:The monometallic pseudo-octahedral complex, [Co(H 2 O) 2 (CH 3 COO) 2 (C 5 H 5 N) 2 ], is shown to exhibit slow magnetic relaxation under an applied field of 1500 Oe. The compound is examined by a combination of experimental and computational techniques in order to elucidate the nature of its electronic structure and slow magnetic relaxation. We demonstrate that any sensible model of the electronic structure must include a proper treatment of the first-order orbital angular momentum, and we find that the slow magnetic relaxation can be well described by a two-phonon Raman process dominating at high temperature, with a temperature independent quantum tunnelling pathway being most efficient at low temperature.

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“…Finally, it was recently observed that a simple ligand field modification within a series of Co II tetrahedral complexes resulted in sign and magnitude changes in the axial ZFS parameter. The slow relaxation of magnetization was detected in all cases [70]. Tetrahedral complexes with a d 6 electronic configuration are also expected to exhibit magnetic anisotropy and some Fe II complexes with S = 2 have been investigated.…”

Section: Tetrahedral Geometrymentioning

confidence: 96%

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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A synthetic strategy for switching the single ion anisotropy in tetrahedral Co(ii) complexes

Cited by 121 publications

References 44 publications

Magnetic Anisotropy in Co^IIX₄ (X=O, S, Se) Single‐Ion Magnets: Role of Structural Distortions versus Heavy Atom Effect

Magnetic Anisotropy in Co^IIX₄ (X=O, S, Se) Single‐Ion Magnets: Role of Structural Distortions versus Heavy Atom Effect

Evidence of Slow Magnetic Relaxation in Co(AcO)2(py)2(H2O)2

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

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A synthetic strategy for switching the single ion anisotropy in tetrahedral Co(ii) complexes

Cited by 121 publications

References 44 publications

Magnetic Anisotropy in CoIIX4 (X=O, S, Se) Single‐Ion Magnets: Role of Structural Distortions versus Heavy Atom Effect

Magnetic Anisotropy in CoIIX4 (X=O, S, Se) Single‐Ion Magnets: Role of Structural Distortions versus Heavy Atom Effect

Evidence of Slow Magnetic Relaxation in Co(AcO)2(py)2(H2O)2

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

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Magnetic Anisotropy in Co^IIX₄ (X=O, S, Se) Single‐Ion Magnets: Role of Structural Distortions versus Heavy Atom Effect

Magnetic Anisotropy in Co^IIX₄ (X=O, S, Se) Single‐Ion Magnets: Role of Structural Distortions versus Heavy Atom Effect