Triplet electronic ground state of trimethylenemethane

Yarkony, David R.; Schaefer, Henry F.

doi:10.1021/ja00819a007

Cited by 82 publications

(23 citation statements)

References 9 publications

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“…The 2/3 of an unpaired electron on each terminal site cannot be paired to one another under the alternancy-pairing condition (0) of pairing solely between sites of the same type (starred or unstarred), so that there are 2 fully unpaired spins and the ground state is a spin triplet. The result here also agrees largely with numerous ab initio quantum-chemical computations 39,40,41,42,43,44,45 , as well as experiment 46,47,48 .…”

Section: Application To Small Moleculessupporting

confidence: 89%

Mean-field resonance-theoretic view of benzenoid networks

Klein¹,

Ivanciuc²

2005

Arkivoc

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A simple classically based "mean field" resonance-theoretic approach is described to anticipate the effects of various modes of electron pairing (as in π-bond formation) for general "alternant" benzenoid conjugated π-networks. This simplified approach avoids generation and manipulation of individual resonance structures, whence application is facilitated, even for very large systems -so large that there might be hundreds or millions or moles or even substantially greater numbers of resonance structures. Some of the predictions so facilitated for several general circumstances are conveniently manifested as explicit algebraic formulas for numbers of unpaired electrons. The simplicity (and apparent reliability) of these algebraic formulas is emphasized; they involve no more than counts of different "kinds" of π-center carbons, e.g., the numbers of π-centers of different functionalities (primary, secondary, or tertiary) which are "starred" (in an "alternant" system) as well as those which are "unstarred". The argumentation also provides some information about rough locations for the (unpaired) spin densities, and ultimately also about the presence of low-lying excited states, magnetic moments, reactivities, and more. In particular these easily used ideas, which are extensions of those already familiar in "classical" organic chemistry should then aid in nano-technological developments.

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Section: Application To Small Moleculessupporting

confidence: 89%

Mean-field resonance-theoretic view of benzenoid networks

Klein¹,

Ivanciuc²

2005

Arkivoc

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“…These two states have been characterized in several previous studies. 11,24,29,30 The second closed-shell singlet, 2 1 A 1 , 14 is composed of the same determinants as the 1 1 A 1 state ͓this is the ⌿ 2 s state from Eq. ͑2͔͒.…”

Section: A Low-lying Excited States Of Tmmmentioning

confidence: 99%

Electronic structure of the trimethylenemethane diradical in its ground and electronically excited states: Bonding, equilibrium geometries, and vibrational frequencies

Slipchenko

Krylov

2003

The Journal of Chemical Physics

109

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Accurate equilibrium properties of the ground and the three lowest excited states of the trimethylenemethane ͑TMM͒ diradical are calculated by using the novel spin-flip electronic structure method. Changes in structures and vibrational frequencies upon excitation are analyzed. The bonding picture in different states of TMM is derived from wave function analysis and comparison of equilibrium structures with typical values of coupled-cluster ͑CC͒ bond lengths, e.g., a double CC bond in ethylene, a single CC bond in twisted ethylene, and a bond in the allyl radical.

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“…28 Several theoretical studies on TMM had appeared following Dowd's synthesis, and all of them predicted the triplet to be the ground state by a comfortable margin. [29][30][31] Experimental confirmation was accomplished by the observation of a linear relationship between ESR signal intensity and inverse temperature over the range 20-80 K. Such Curie law behavior sets an upper limit on the singlet-triplet splitting from solution of eqn. (1) where I is…”

Section: The Pittsburgh Yearsmentioning

confidence: 99%

Paul Dowd and diradicals

Cramer¹

1998

J. Chem. Soc., Perkin Trans. 2

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Triplet electronic ground state of trimethylenemethane

Cited by 82 publications

References 9 publications

Mean-field resonance-theoretic view of benzenoid networks

Mean-field resonance-theoretic view of benzenoid networks

Electronic structure of the trimethylenemethane diradical in its ground and electronically excited states: Bonding, equilibrium geometries, and vibrational frequencies

Paul Dowd and diradicals

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