Bond stretch isomerism in Be<sub>3</sub><sup>2−</sup>driven by the Renner–Teller effect

Homray, Manoswita; Mondal, Sukanta; Misra, Anirban; Chattaraj, Pratim Kumar

doi:10.1039/c9cp00643e

Cited by 12 publications

(9 citation statements)

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“…Our complex PECs directly contradict the real-valued PEC from ref that suggests the presence of two D 3 h symmetrical minima with bond lengths close to 2.078 and 2.156 Å. We cannot directly comment on these density functional results, but it seems likely that the two identified minima can be understood in the Weisskopf–Fano–Feshbach picture (see section ): One may assume that one minimum corresponds to a state showing essentially discrete state character, while the other minimum corresponds to a state showing essentially discretized-continuum state character.…”

Section: Resultscontrasting

confidence: 64%

“…We focus primarily on D 3 h symmetrical structures at geometries between the neutral and the anion as the lowest electronic states of both neutral Be 3 and Be 3 – are trigonal planar and the same is true for the corresponding Mg species. Moreover, we investigate the symmetric breathing mode of Be 3 , Be 3 – , and Be 3 2– over a range that covers some of the structures discussed in refs − and .…”

Section: Resultsmentioning

confidence: 99%

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Lifetimes of Be₃^2– and Mg₃^2– Cluster Dianions

et al. 2021

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The alkaline earth metal trimer cluster dianions Be 3 2− and Mg 3 2− lie energetically above their respective monoanions and can therefore decay by electron autodetachment. Consequently, these dianions possess only short-lived resonance states, and here we study these states using regularized analytic continuation as well as complex absorbing potentials combined with a wide a variety of quantum chemistry methods including CCSD(T), SACCI, EOM-CCSD, CASPT2, and NEVPT2. For both Be 3 2− and Mg 3 2− , four low-energy resonance states corresponding to different occupation patterns of the two excess electrons in the two lowest p−σ and p−π orbitals are identified: Two states are dominated by doubly occupied configurations and can be characterized as showing σ and π aromatic character. The other two states correspond to the open-shell singlet/triplet pair. All dianion states are found to be highly unstable and to possess short lifetimes: They show resonance positions in the energy range 2.3−4.3 eV above the ground states of their respective monoanions and broad widths between 1 and 1.5 eV translating into femtosecond lifetimes. For both Be 3 2− and Mg 3 2− , the differences between the four states are small, but the triplet states tend to be slightly more stable than the three singlet states. Thus, in the case of the multicharged ion aromatic character of the excess electrons takes second stage while Coulomb repulsion takes front and center. In addition to the two isolated cluster dianions, model stabilization by small water clusters is explored. Our results show a dramatic drop in resonance position and width corresponding to a lifetime increase by 2 orders of magnitude. However, the "solvated" clusters are still resonances, and a more pronounced perturbation by, for example, yet larger water clusters or a ligand environment providing larger bond dipoles will be needed to fully stabilize two excess electrons localized on a small system such as an alkaline metal trimer.

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Section: Resultscontrasting

confidence: 64%

Section: Resultsmentioning

confidence: 99%

Lifetimes of Be₃^2– and Mg₃^2– Cluster Dianions

et al. 2021

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“…This in turn confirms Dressler and Ramsay's attributing of the absorption spectrum to transitions between two real compo-nents of the Π state (Figure 1c). Other illustrations, where the RT effect plays an important role, include enhancement of magnetism of luminescence properties by suppressing RT vibronic coupling or restriction of RT distortion, 10 bond stretch isomerism, 11 chemistry involving continuum processes, 12 or anomaly dynamic behaviors. 13 Intuitively, different molecules would exhibit different behaviors when experiencing the RT distortion.…”

Section: ■ Introductionmentioning

confidence: 99%

Neglected Importance of Anharmonicity in Quantifying the Renner–Teller Effect

2022

ACS Omega

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Linear molecules in degenerate electronic states are influenced by the Renner–Teller (RT) effect. Currently the formula to quantify this vibronic interaction only considers the harmonic term. However, such a harmonic formula cannot well describe molecules that have double-well potential along the bending coordinate. In this work, we propose a new formula to quantify the RT effect by explicitly including the anharmonic term. A sign function and a delta function are additionally included to distinguish different scenarios. It is mathematically proved that the new formula is capable of differentiating different degrees of RT splitting. Representative molecules of different types are calculated. According to the new formula, molecules experiencing a weak RT effect have a positive parameter smaller than 1. For those experiencing a medium RT effect, the parameter will be negative. For others experiencing a large RT effect, the parameter will be larger than 1.

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“…One of such phenomena is the bond stretch isomerism, the isomer where more than one stable configuration of the same molecule exists with only major distinct difference in the bond length. Many instances of bond stretch isomerization have been theorized or reported for organic, main group elements, and transition metal compounds . Among such structures is the silicon analogues of bicyclo[1.1.0]butane (Scheme a).…”

Section: Introductionmentioning

confidence: 99%

Switchable dual bonding nature in silabicyclo[1.1.0]butanes that exhibit bond stretch isomerism

Chinaroj

Iwamoto

2019

J of Physical Organic Chem

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Silicon analogues of bicyclo[1.1.0]butanes are known to exhibit a bond stretch isomerism where the bridgehead Si Si bond changes in both length and geometry. The bridgehead silicon atom of long bond (lb) isomers exhibits an unusual geometry where all the bonds are located on the same hemisphere, making the geometry of the bridgehead Si Si bond the so-called inverted σ bond in contrast with the typical σ bond geometry found in the short bond (sb) isomers. Herein, the bonding nature of bridgehead Si Si bonds was theoretically investigated in detail using valence bond theory calculation at SL-BOVB/6-31G(d) level of theory. Our calculation demonstrates that the bond type of the bridgehead bond depends on the geometry around the bridgehead atoms with those in sb and lb isomers classified as covalent (COV) and chargeshift (CS) bonds, respectively. The different bond types between two bond stretch isomer indicate that the bonding nature is switchable in one molecule. The detailed examination of the bond stretch isomerization in parent 1,3-disilabicyclo[1.1.0]butane demonstrated that the enhanced CS bond nature in the lb isomer is mainly attributed to the geometry inversion of the σ bond rather than the bond elongation. This switchable dual bonding nature provides an important platform to compare covalent and CS bond on equal footing for both theoretical and experimental investigations. K E Y W O R D Sbicyclo[1.1.0]butane, bond theory, charge shift bond, covalent bond, silicon

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Bond stretch isomerism in Be₃²⁻driven by the Renner–Teller effect

Cited by 12 publications

References 61 publications

Lifetimes of Be₃^2– and Mg₃^2– Cluster Dianions

Lifetimes of Be₃^2– and Mg₃^2– Cluster Dianions

Neglected Importance of Anharmonicity in Quantifying the Renner–Teller Effect

Switchable dual bonding nature in silabicyclo[1.1.0]butanes that exhibit bond stretch isomerism

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Bond stretch isomerism in Be32−driven by the Renner–Teller effect

Cited by 12 publications

References 61 publications

Lifetimes of Be32– and Mg32– Cluster Dianions

Lifetimes of Be32– and Mg32– Cluster Dianions

Neglected Importance of Anharmonicity in Quantifying the Renner–Teller Effect

Switchable dual bonding nature in silabicyclo[1.1.0]butanes that exhibit bond stretch isomerism

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Bond stretch isomerism in Be₃²⁻driven by the Renner–Teller effect

Lifetimes of Be₃^2– and Mg₃^2– Cluster Dianions

Lifetimes of Be₃^2– and Mg₃^2– Cluster Dianions