Covalency and chemical bonding in transition metal complexes: An ab initio based ligand field perspective

Singh, Saurabh Kumar; Eng, Julien; Atanasov, Mihail; Neese, Frank

doi:10.1016/j.ccr.2017.03.018

Cited by 224 publications

(235 citation statements)

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“…Furthermore, we have also computed the ab initio ligand field parameters (AILFT) and effective spin‐orbit coupling constant ( ζ ) considering ten quartet roots in all the complexes . It is established that a decrease in Racah parameter (or the so‐called electron‐electron repulsion parameter) and SOC constant ( ζ ) on complexation gives an idea of covalency in the metal‐ligand complexes compared to the free ion.…”

Section: Magneto‐structural Mapsmentioning

confidence: 99%

“…Furthermore, we have also computed the ab initio ligand field parameters (AILFT) and effective spin-orbit coupling constant (z)c onsidering ten quartet roots in all the complexes. [27] It is established that ad ecrease in Racah parameter (or the socalled electron-electron repulsion parameter) andS OC constant (z)o nc omplexation gives an idea of covalency in the metal-ligand complexes compared to the free ion. Therefore, we have computed both the nephelauxetic reduction in Racah parameter( B)a nd effective SOC constant fora ll the complexes 1-12 and compared the values to the free Co II ion value (B 0 )a nd analysed in all the complexes (see Figure 7).…”

Section: Magneto-structural Mapsmentioning

confidence: 99%

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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: Magneto‐structural Mapsmentioning

confidence: 99%

Section: Magneto-structural Mapsmentioning

confidence: 99%

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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“…[9] Thec omputed triplet ground state of 8 is separated from the singlet by as ignificant adiabatic energy gap of 41 kJ mol À1 . [18] TheS OMOs of 8 exhibit predominant IrÀO p*character,resulting in equal spin density distribution over the iridium and oxygen atoms (Figure 3c). (19); N1-Ir1-O1 176.53 (7).…”

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confidence: 99%

“…(19); N1-Ir1-O1 176.53 (7). 7:I r1-O1 1.935(3), Ir1-N1 1.900(4);N 1-Ir1-O1 177.35 (18). 8:Ir1-O1 1.827(4), Ir1-N1 2.040(4);N1-Ir1-O1 173.6(6).…”

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confidence: 99%

A Terminal Iridium Oxo Complex with a Triplet Ground State

et al. 2019

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Aterminal iridium oxocomplex with an open-shell (S = 1) ground state was isolated upon hydrogen atom transfer (HAT) from the respective iridium(II) hydroxide.E lectronic structure examinations support large spin delocalization to the oxygen atom. Selected oxot ransfer reactions indicate the ambiphilic reactivity of the iridium oxom oiety.C alorimetric and computational examinations of the HATrevealed ab ond dissociation free energy for the IrO À Hb ond that is sufficient for hydrogen atom abstraction towardsC À Hbonds and small contributions from entropya nd spin-orbit coupling to the HATthermochemistry.

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“…[8b] In analogy to imido complex 1,t hree sharp,y et strongly paramagnetically shifted 1 HNMR signals between + 21 and À75 ppm in [D 8 ]THF at room temperature (d H (1): + 20 to À60 ppm) and no 31 PNMR signals were found. [18] TheS OMOs of 8 exhibit predominant IrÀO p*character,resulting in equal spin density distribution over the iridium and oxygen atoms (Figure 3c). Thet hird signal (d H % À75 ppm) shows approximately linear (Curie) dependence of d vs. T À1 below ca.…”

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confidence: 99%

A Terminal Iridium Oxo Complex with a Triplet Ground State

et al. 2019

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Covalency and chemical bonding in transition metal complexes: An ab initio based ligand field perspective

Cited by 224 publications

References 100 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

A Terminal Iridium Oxo Complex with a Triplet Ground State

A Terminal Iridium Oxo Complex with a Triplet Ground State

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Covalency and chemical bonding in transition metal complexes: An ab initio based ligand field perspective

Cited by 224 publications

References 100 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

A Terminal Iridium Oxo Complex with a Triplet Ground State

A Terminal Iridium Oxo Complex with a Triplet Ground State

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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