Zero field splitting parameter of trimethylenemethane

Gold, Avram

doi:10.1021/ja01046a003

Cited by 11 publications

(2 citation statements)

References 6 publications

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“…Since in naive MO theory the proton and carbon atoms lie in the nodal plane of the π orbital containing the unpaired electron, the hyperfine interaction might be expected to be zero. McConnell [6][7][8][9] showed how exchange interactions with the σ bond electrons could lead to a non-zero negative value at the proton which was proportional to the population of unpaired π electrons on the neighboring carbon. The empirical proportionality factor, commonly called Q, varies somewhat between molecules.…”

Section: Introductionmentioning

confidence: 99%

The benzene radical anion: A computationally demanding prototype for aromatic anions

Bazanté

Davidson

Bartlett

2015

The Journal of Chemical Physics

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The benzene radical anion is studied with ab initio coupled-cluster theory in large basis sets. Unlike the usual assumption, we find that, at the level of theory investigated, the minimum energy geometry is non-planar with tetrahedral distortion at two opposite carbon atoms. The anion is well known for its instability to auto-ionization which poses computational challenges to determine its properties. Despite the importance of the benzene radical anion, the considerable attention it has received in the literature so far has failed to address the details of its structure and shape-resonance character at a high level of theory. Here, we examine the dynamic Jahn-Teller effect and its impact on the anion potential energy surface. We find that a minimum energy geometry of C2 symmetry is located below one D2h stationary point on a C2h pseudo-rotation surface. The applicability of standard wave function methods to an unbound anion is assessed with the stabilization method. The isotropic hyperfine splitting constants (Aiso) are computed and compared to data obtained from experimental electron spin resonance experiments. Satisfactory agreement with experiment is obtained with coupled-cluster theory and large basis sets such as cc-pCVQZ.

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Section: Introductionmentioning

confidence: 99%

The benzene radical anion: A computationally demanding prototype for aromatic anions

Bazanté

Davidson

Bartlett

2015

The Journal of Chemical Physics

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“…One might think that the total self-consistent-field (SCF) energy of the IE' state should be the same whether it is obtained using configuration (4), configuration (5)~ or the antisymmetric combination of configurations (6 Therefore the C 2v ~ C 2 state correlation is…”

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confidence: 99%

Triplet electronic ground state of trimethylenemethane

Yarkony¹,

Schaefer²

1974

J. Am. Chem. Soc.

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A Stable Trimethylenemethane Triplet Diradical Based on a Trimeric Porphyrin Fused π‐System

2018

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Trimethylenemethane (TMM) diradical is the simplest non-KekulØ non-disjoint molecule with the triplet ground state (DE ST =+16.1 kcal mol À1 )a nd is extremely reactive.I tis ac hallenge to design and synthesize as table TMM diradical with key properties,s uch as actual aliphatic TMM diradical centers and the triplet ground state with al arge positive DE ST value,s ince such species provide detailed information on the electronic structure of TMM diradical. Herein we report aT MM derivative,i nw hicht he TMM segment is fused with three Ni II meso-triarylporphyrins,t hat satisfies the above criteria. The diradical shows delocalized spin density on the propeller-like porphyrin p-network and the triplet ground state owingt ot he strong ferromagnetic interaction. Despite the apparent TMM structure,t he diradical can be handled under ambient conditions and can be stored for months in the solid state,t hus allowing its X-raydiffraction structural analysis.Trimethylenemethane (TMM, 1 in Figure 1) is arepresentative non-KekulØ and non-disjoint diradical possessing intrinsic opposed spin-pairing tendency. [1] Its abnormal electronic structure and reactivity have provided fundamental understanding in theoretical chemistry [2] and have promoted various useful synthetic methods. [3] TMM usually behaves as an extremely reactive species that can survive only at cryogenic temperatures and displays ad istinct ah igh-spin ground state with alarge singlet-triplet energy gap of DE ST = + 16.1(1) kcal mol À1 ,a so ne of the largest values for organic diradicals. [4] Stabilization of these TMM-related high-spin species will allow detailed understanding of the relationship of the electronic properties with regard to their thermal stability,which is important for the development of moleculebased magnetic materials and spintronics. [5] Thus,i ti s ac hallenge to realize as table TMM diradical that holds key properties such as actual aliphatic TMM radical centers and atriplet ground state with alarge positive DE ST value.Along this line,s everal TMM-based stable high-spin molecules have been developed to date. [6,7] As as uccessful example,t he Yang diradical 2 [6a-d] showed both strong ferromagnetic coupling and stability similar to other typical phenoxy radicals.However,its methylene ends of TMM were located as parts of aromatic rings,h ence significantly contributing to improvement of the chemical stability.O nt he other hand, TMM derivatives without such structural features were highly reactive. [7] In fact, 3 was generated in situ by reduction of the corresponding dication and directly subjected to characterization by ESR spectroscopy under inert conditions. [7b] In recent years,w eh ave explored stable porphyrinoid radicals,i nw hich as pin is delocalized over the large pelectronic networks of porphyrinoids. [8,9] Reported examples include meso-oxy radicals, [8b-d] meso-aminyl radicals, [8e,f] and meso-ammoniumyl cation radicals [8g] that can be handled and stored under ambient conditions.Amethyl radical was also stabilized at...

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Zero field splitting parameter of trimethylenemethane

Cited by 11 publications

References 6 publications

The benzene radical anion: A computationally demanding prototype for aromatic anions

The benzene radical anion: A computationally demanding prototype for aromatic anions

Triplet electronic ground state of trimethylenemethane

A Stable Trimethylenemethane Triplet Diradical Based on a Trimeric Porphyrin Fused π‐System

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