Does Jahn-Teller effect happen on d9 tetrahedral complex?
Can anyone simplify Jahn-Teller effect for me? Any resources that could help me understand it better?
I was wondering about why the degenerate molecular orbits in cyclobutadiene are not actually degenerate. When you take into account the molecule is rectangular with different bond lengths that resulted in the energy levels changing (under the planar assumption the two middle ones were equal). Curious I did some googling and read a bit about the Jahn-Teller effect. What do they mean by a "non-linear polyatomic system" and why does removing degeneracy from the MOs (they are no longer equal) always result in a more stable molecule? Any insight or a book recommendation would be greatly appreciated. Thanks! For context this question arose from my organic chemistry class lecture I am currently taking.
Thanks again!
I can’t seem to wrap my head around the link between the Jahn-Teller effect and the ligand that a metal complex is made of. In copper(II) complexes, for example, is the distortion that the complex experiences dependent on the nature of the ligand? I have a pretty poor background in inorganic chemistry so any help is appreciated.
Undergrad inorganic student here. The J-T theorem as it is presented in class is simple, but looking deeper it seems to have a lot of connections to concepts I've learned elsewhere. I just can't connect the concepts. Help would be appreciated.
-
It seems like the high-symmetry, undistorted geometry of a molecule lies on an intersection of two potential energy surfaces... but I'm not sure what those two surfaces correspond to.
-
A lot of the sources I've found mention that the Born-Oppenheimer approximation breaks down in the vicinity of these intersections. The only way I could rationalize this is these are points were a small change in nuclear coordinates gives a large change in distribution of electrons, so the "slowness" of nuclear motion isn't slow enough that you can neglect it. Am I on the right track, or if not, what is the explanation?
-
The only other place I've encountered vibronic coupling is in the explanation for Laporte-forbidden electronic transitions. Some asymmetric vibration breaks centrosymmetry, and the transition is allowed. I always thought of d-d transitions as being allowed by symmetry-breaking displacements from the equilibrium geometry, and J-T molecules as higher-symmetry species with an equilibrium geometry that is "stuck" in the middle of a vibration. Am I thinking correctly, and how do these both originate from the same sort of coupling?
-
What exactly is going on when doubly-degenerate vibrational and electronic states couple? Is this how you get a J-T distorted molecule with elongations / compressions of two axes?
Thanks.
A Jahn–Teller-compressed OsO6 octahedron resulting in an unprecedented large splitting of the t2g levels and a diamagnetic ground state has been observed.
Abstract
The Jahn–Teller (JT) theorem constitutes one of the most fundamental concepts in chemistry. In transition-element chemistry, the 3d4 and 3d9 configurations in octahedral complexes are particularly illustrative, where a distortion in local geometry is associated with a reduction of the electronic energy. However, there has been a lasting debate about the fact that the octahedra are found to exclusively elongate. In contrast, for Na9Bi5Os3O24, the octahedron around Os6+(5d2) is heavily compressed, lifting the degeneracy of the t2g set of 5d orbitals such that in the sense of a JT compression a diamagnetic ground state results. This effect is not forced by structural constraints, the structure offers sufficient space for osmium to shift the apical oxygen atoms to a standard distance. The relevance of these findings is far reaching, since they provide new insights in the hierarchy of perturbations defining ground states of open shell electronic systems.
Introduction
https://ift.tt/3tSDbRA
The dark‐stable resting state of the biological oxygen‐evolving complex is shown to accommodate a rare type of functionally important MnIII orientational Jahn–Teller isomerism that is identified as the electronic origin of subsequent valence isomerism in the catalytic cycle of water oxidation.
Abstract
The tetramanganese–calcium cluster of the oxygen‐evolving complex of photosystem II adopts electronically and magnetically distinct but interconvertible valence isomeric forms in its first light‐driven oxidized catalytic state, S2. This bistability is implicated in gating the final catalytic states preceding O−O bond formation, but it is unknown how the biological system enables its emergence and controls its effect. Here we show that the Mn4CaO5 cluster in the resting (dark‐stable) S1 state adopts orientational Jahn–Teller isomeric forms arising from a directional change in electronic configuration of the “dangler” MnIII ion. The isomers are consistent with available structural data and explain previously unresolved electron paramagnetic resonance spectroscopic observations on the S1 state. This unique isomerism in the resting state is shown to be the electronic origin of valence isomerism in the S2 state, establishing a functional role of orientational Jahn–Teller isomerism unprecedented in biological or artificial catalysis.
https://ift.tt/3dK8nM2
Journal of the American Chemical SocietyDOI: 10.1021/jacs.0c10925
Stella Impano, Hao Yang, Richard J. Jodts, Adrien Pagnier, Ryan Swimley, Elizabeth C. McDaniel, Eric M. Shepard, William E. Broderick, Joan B. Broderick, and Brian M. Hoffman
https://ift.tt/3rxH0uR
Journal of the American Chemical SocietyDOI: 10.1021/jacs.0c10044
Hooman Yaghoobnejad Asl and Arumugam Manthiram
https://ift.tt/3qEU154
Exfoliation of 3D perovskite at the unit cell scale of ϵ‐MnO2 is proposed. The strategy involves a proton‐induced Jahn–Teller disproportionation, assisted by the removal of A‐site ions, dissolution of Mn2+ and reconstruction of MnO6 octahedra.
Abstract
Exfoliation of non‐layered (structurally) bulk materials at the nanoscale is challenging because of the strong chemical bonds in the lattice, as opposed to the weak van der Waals (vdW) interactions in layered materials. We propose a top‐down method to exfoliate ϵ‐MnO2 nanosheets in a family of charge‐ordered La1−x AE x MnO3 (AE=Ca, Sr, Ba) perovskites, taking advantage of the Jahn–Teller disproportionation effect of Mn3+ and bond‐strength differences. ϵ‐MnO2 crystallized into a nickel arsenide (NiAs) structure, with a thickness of 0.91 nm, displays thermal metastability and superior water oxidation activity compared to other manganese oxides. The exfoliation mechanism involves a synergistic proton‐induced Mn3+ disproportionation and structural reconstruction. The synthetic method could also be potentially extended to the exfoliation of other two‐dimensional nanosheet materials with non‐layered structures.
https://ift.tt/2FU0XZf
When there may be splitting in the UV Vis spectrum of certain bands of this, which kinds of excited states give rise to this splitting? I’m so confused
Hi Reddit,
I am Vitaly Beckman, an illusionist who fooled Penn & Teller twice on the CW's show Fool Us, with a recent episode being shot during the pandemic. I also traveled the world and had my own off Broadway run in NYC. I combine magic with art, creating and designing all of my own illusions.
Proof: https://www.instagram.com/p/CNsrAgZH0bT
My recent Fool Us appearance was just aired on the CW: https://www.youtube.com/watch?v=ojLBGSnej_U
My first Fool Us appearance: https://www.youtube.com/watch?v=1I0UTKsRYLg
If you want to learn more about me, check out the recent MSN story: https://www.msn.com/en-ca/entertainment/news/vancouver-based-magician-vitaly-beckman-fools-penn-andamp-teller-for-second-time/ar-BB1eUIgB
Watch my promo video: https://www.youtube.com/watch?v=X9L5Qu_8kYM
Or learn more about me on my website: http://www.eveningofwonders.com
I love to talk about art, magic, movies, stage performance, creativity & invention. Ask me anything! (almost)
Update:
Thank you so much for the great questions everyone! I really enjoyed this AMA and would love to do it again sometime in the future! Till then, stay safe and healthy, and have a wonderful day / night!
Journal of the American Chemical SocietyDOI: 10.1021/jacs.9b13269
https://ift.tt/2u4bU54
Came up with this while sitting at a thesis defense yesterday:
There once was Jahn-Teller Distortion
With d-orbitals filled just a portion
When an Oh point group
To D4h does droop:
Anisotropic MO contortion
Edit: Formatting was screwy
I'm working with a copper complex that seems to prefer a square planar geometry, and I'm having a hard time understanding why that is. I've been told that Jahn-Teller distortion causes copper(II) ions to prefer the square planar.
I'm having a hard time finding good places to learn about Jahn-Teller distortion, and I'm having difficulty understanding the sources I do find.
Could someone explain Jahn-Teller distortion and how it applies to copper? Any good basic level articles would be helpful as well. Thanks r/chemistry
http://www.azom.com/news.aspx?newsID=43656
I'm trying to go through articles about it but everything that I find is either simplified to the point of being useless or so complex that I cannot fathom the first few sentences. Please help!
The Jahn‐Teller (JT) theorem constitutes one of the most fundamental and stringent concepts in chemistry. In transition elements chemistry, the 3 d 4 , 3 d 9 , and 3 d 7 configurations in octahedral complexes are particularly illustrative, where a distortion in local geometry is associated to a reduction of electronic energy. However, there has been a lasting debate about the fact that the octahedra are found to exclusively elongate. In contrast, for Na 9 Bi 5 Os 3 O 24 , the octahedron around Os 6+ (5 d 2 ) is heavily compressed, and the splitting of the t 2g set of 5 d orbitals induced by this compression is extreme, such that a diamagnetic ground state results. Both these issues are extremely rare. The splitting into a lower d xy (hosting two d electrons with opposite spin) and two higher d xz and d yz orbitals is so large that the Hund´s coupling for t 2g electrons is overcome. These effects are not forced by structural constraints, the structure offers sufficient space for osmium to shift the apical oxygen atoms to a standard distance. The relevance of these findings is far reaching, since they provide insights in the hierarchy of perturbations defining ground states of open shell electronic systems.
https://ift.tt/3tSDbRA
