Application of Density Functional and Density Functional Based Ligand Field Theory to Spin States

Daul, Claude; Zlatar, Matija; Gruden, Maja; Swart, Marcel

doi:10.1002/9781118898277.ch2

Cited by 10 publications

(12 citation statements)

References 162 publications

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“…LFDFT includes both dynamical correlation (through the DFT exchange-correlation energy) and non-dynamical correlation (via LF Configuration Interaction). With LFDFT procedure, all customary molecular properties can be calculated, [88][89][90][91][92][93][94] including ZFS parameters, 19,20,95,96 however, its accuracy decreases with increasing metal-ligand covalency. 97 Comparison between experimentally determined and calculated ZFS parameters in PBPY-7…”

Section: Mössbauer Spectroscopymentioning

confidence: 99%

Combined Experimental and Theoretical Investigation of the Origin of Magnetic Anisotropy in Pentagonal Bipyramidal Isothiocyanato Co(II), Ni(II), and Fe(III) Complexes with Quaternary-Ammonium-Functionalized 2,6-Diacetylpyridine Bisacylhydrazone

et al. 2019

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The magnetic anisotropy in pentagonal bipyramidal complexes of Co(II) (1 and 2), Fe(III) (3 and 4) and Ni(II) (5) with 2,2′-[2,6-pyridinediylbis(ethylidyne-1-hydrazinyl-2ylidene)]bis[N,N,N-trimethyl-2-oxoethanaminium] equatorial ligand and isothiocyanato axial ligands has been investigated by magnetic susceptibility measurements, powder X-band EPR spectroscopy, Mössbauer spectroscopy, ab initio, and LFDFT calculations. The studied complexes display three distinct types of magnetic anisotropy. Co(II) complexes (1 and 2)show an easy plane anisotropy with large and positive D values and negligible rhombicity.Ni(II) complex ( 5) has uniaxial magnetic anisotropy with negative D value. Fe(III) complexes (3 and 4) have small ZFS parameters. Theoretical modeling was used to rationalize the magnetic anisotropy in these systems and to identify the most important excited states that are responsible for the zero-field splitting. These excitations are a consequence of the electronic structure of the central metal ion in ideal pentagonal bipyramidal coordination.

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Section: Mössbauer Spectroscopymentioning

confidence: 99%

Combined Experimental and Theoretical Investigation of the Origin of Magnetic Anisotropy in Pentagonal Bipyramidal Isothiocyanato Co(II), Ni(II), and Fe(III) Complexes with Quaternary-Ammonium-Functionalized 2,6-Diacetylpyridine Bisacylhydrazone

et al. 2019

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“…This led to the SSB-D functional in 2009 and, after refinement to make it numerically more stable and including Grimme’s D 3 dispersion energy, to the S12g functional . Specific examples of application of these DFAs to transition-metal complexes can be found in our recent book chapter …”

Section: A Surprising Connection Between Bimolecular Sn2 Reactions An...mentioning

confidence: 99%

“…47 Specific examples of application of these DFAs to transitionmetal complexes can be found in our recent book chapter. 48 A number of observations should be added: none of the SSB-D and S12g functionals, nor other ones that are popular for chemistry (B97-D 3 , 44,46 B3LYP-D 2 , OPBE, etc. ), satisfy the uniform-gas limit, that is, the exchange enhancement factor F(s) does not go to 1 at s = 0 but to a value between 1.038 and 1.087 (depending on the functional).…”

Section: A Surprising Connection Between Bimolecular S N 2 Reactions ...mentioning

confidence: 99%

Spinning around in Transition-Metal Chemistry

2016

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The great diversity and richness of transition metal chemistry, such as the features of an open d-shell, opened a way to numerous areas of scientific research and technological applications. Depending on the nature of the metal and its environment, there are often several energetically accessible spin states, and the progress in accurate theoretical treatment of this complicated phenomenon is presented in this Account. The spin state energetics of a transition metal complex can be predicted theoretically on the basis of density functional theory (DFT) or wave function based methodology, where DFT has advantages since it can be applied routinely to medium-to-large-sized molecules and spin-state consistent density functionals are now available. Additional factors such as the effect of the basis set, thermochemical contributions, solvation, relativity, and dispersion, have been investigated by many researchers, but challenges in unambiguous assignment of spin states still remain. The first DFT studies showed intrinsic spin-state preferences of hybrid functionals for high spin and early generalized gradient approximation functionals for low spin. Progress in the development of density functional approximations (DFAs) then led to a class of specially designed DFAs, such as OPBE, SSB-D, and S12g, and brought a very intriguing and fascinating observation that the spin states of transition metals and the S2 barriers of organic molecules are somehow intimately linked. Among the many noteworthy results that emerged from the search for the appropriate description of the complicated spin state preferences in transition metals, we mainly focused on the examination of the connection between the spin state and the structures or coordination modes of the transition metal complexes. Changes in spin states normally lead only to changes in the metal-ligand bond lengths, but to the best of our knowledge, the dapsox ligand showed the first example of a transition-metal complex where a change in spin state leads also to changes in the coordination, switching between pentagonal-bipyramidal and capped-octahedron. Moreover, we have summarized the results of the thorough study that corrected the experimental assignment of the nature of the recently synthesized Sc adduct of [Fe(O)(TMC)] (TMC = 1,4,8,11-tetramethylcyclam) and firmly established that the Sc-capped iron-oxygen complex corresponds to high-spin Fe. Last, but not least, we have provided deeper insight and rationalization of the observation that unlike in metalloenzymes, where the Fe-oxo is usually observed with high spin, biomimetic Fe-oxo complexes typically have a intermediate spin state. Energy decomposition analyses on the trigonal-bypiramidal (TBP) and octahedral model systems with ammonia ligands have revealed that the interaction energy of the prepared metal ion in the intermediate spin state is much smaller for the TBP structure. This sheds light on the origin of the intermediate spin state of the biomimetic TBP Fe-oxo complexes.

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“… a The spin density and charges on iron were determined by NBO analysis. b Only the β-LUMOs are shown, as they are significantly lower in energy compared to that of the α-LUMOs. Calculations were done on the OPBZ/cc-pVTZ level of theory. − …”

Section: Resultsmentioning

confidence: 99%

Combination of Scanning Probe Microscopy and Coordination Chemistry: Structural and Electronic Study of Bis(methylbenzimidazolyl)ketone and Its Iron Complex

et al. 2017

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Here, we report the bulk synthesis of [FeII(BMBIK)Cl2] bearing the redox noninnocent bis(methylbenzimidazolyl)ketone (BMBIK) ligand and the synthesis of the similar complex [FeI(BMBIK)]+ on a Au(111) surface using lateral manipulation at the atomic level. Cyclic voltammetry and scanning tunneling spectroscopy are shown to be useful techniques to compare the coordination compound in solution with the one on the surface. The total charge, as well as the oxidation and spin state of [FeI(BMBIK)]+, are investigated by comparison of the shape of the lowest unoccupied molecular orbital (LUMO), visualized by tunneling through the LUMO, with theoretical models. The similar reduction potentials found for the solution and surface compounds indicate that the major effect of lowering the LUMO upon coordination of BMBIK to the iron center is conserved on the surface. The synthesis and analysis of [FeI(BMBIK)]+ using scanning tunneling microscopy, scanning tunneling spectroscopy, and atomic force microscopy are the first steps toward mechanistic studies of homogeneous catalysts with redox noninnocent ligands at the single molecule level.

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Application of Density Functional and Density Functional Based Ligand Field Theory to Spin States

Cited by 10 publications

References 162 publications

Combined Experimental and Theoretical Investigation of the Origin of Magnetic Anisotropy in Pentagonal Bipyramidal Isothiocyanato Co(II), Ni(II), and Fe(III) Complexes with Quaternary-Ammonium-Functionalized 2,6-Diacetylpyridine Bisacylhydrazone

Combined Experimental and Theoretical Investigation of the Origin of Magnetic Anisotropy in Pentagonal Bipyramidal Isothiocyanato Co(II), Ni(II), and Fe(III) Complexes with Quaternary-Ammonium-Functionalized 2,6-Diacetylpyridine Bisacylhydrazone

Spinning around in Transition-Metal Chemistry

Combination of Scanning Probe Microscopy and Coordination Chemistry: Structural and Electronic Study of Bis(methylbenzimidazolyl)ketone and Its Iron Complex

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