Conjugation between σ- and π-Aromaticity in 1-<i>C</i>-Arylated Monocarba-<i>closo</i>-dodecaborate Anions

Otsuka, Mai; Takita, Ryo; Kanazawa, Junichiro; Miyamoto, Kazunori; Muranaka, Atsuya; Uchiyama, Masanobu

doi:10.1021/jacs.5b10321

Cited by 35 publications

(18 citation statements)

References 24 publications

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“…3−5 It has to do with the extra stability or instability of a cyclic yet planar structure because of the additional delocalization of electrons, 6 either π or σ, leading to the redistribution of the electron density of the system. 7−10 The controversy about aromaticity lies in the fact that many different categories of aromaticity have been unveiled in the literature, 3,11,12 lots of descriptors to characterize it have been proposed as well, 13 but there exists no single descriptor that can be used as the general quantitative measure. 14 The culprit is the fact that these descriptors are often measures of one property only from its many manifestations of the phenomenon, such as energetics, 6 geometry, 3 ring current, 15 and so forth, which are the consequences of the aromaticity phenomenon, not its root cause.…”

Section: Introductionmentioning

confidence: 99%

Baird’s Rule in Substituted Fulvene Derivatives: An Information-Theoretic Study on Triplet-State Aromaticity and Antiaromaticity

Rong

Tian³

et al. 2018

ACS Omega

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Originated from the cyclic delocalization of electrons resulting in extra stability and instability, aromaticity and antiaromaticity are important chemical concepts whose appreciation and quantification are still much of recent interest in the literature. Employing information-theoretic quantities can provide us with more insights and better understanding about them, as we have previously demonstrated. In this work, we examine the triplet-state aromaticity and antiaromaticity, which are governed by Baird’s 4 n rule, instead of Hückel’s 4 n + 2 rule for the singlet state. To this end, we have made use of 4 different aromaticity indexes and 8 information-theoretic quantities, examined a total of 22 substituted fulvene derivatives, and compared the results both in singlet and triplet states. It is found that cross-correlations of these two categories of molecular property descriptors enable us to better understand the nature and propensity of aromaticity and antiaromaticity for the triplet state. Our results have not only demonstrated the existence and validity of Baird’s rule but also shown that Hückel’s rule and Baird’s rule indeed share the same theoretical foundation because with these cross-correlation patterns we are able to distinguish them from each other simultaneously in both singlet and triplet states. Our results should provide new insights into the nature of aromaticity and antiaromaticity in the triplet state and pave the road toward new ways to quantify this pair of important chemical concepts.

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Section: Introductionmentioning

confidence: 99%

Baird’s Rule in Substituted Fulvene Derivatives: An Information-Theoretic Study on Triplet-State Aromaticity and Antiaromaticity

Rong

Tian³

et al. 2018

ACS Omega

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“…We found that the reaction rate was affected by distal substituents on the benzene ring connected at the antipodal carbon vertex. Hammett and Yukawa–Tsuno plots indicated that substantial resonance effects are involved (Figure ) …”

Section: Recent Advances In Synthetic Chemistry At the Carbon Vertex:mentioning

confidence: 99%

“…Hammett and Yukawa-Tsuno plots indicated that substantial resonance effects are involved (Figure 8). [18] Furthermore, density functional theory (DFT) calculations at the B3LYP/6-31 + G* level revealed ar ather strong orbital interaction between one of the degenerate HOMO-1so f1 and one of the HOMOs of the benzene ring 19 (shownw ith red lines). Out-of-phase interaction at the carbon vertex forms the HOMO of 10 a,w hich appears to show a p-conjugation-like interaction over the whole molecule, while the in-phase interaction provides the more stable HOMO-5 ( Figure 9).…”

Section: Introductionmentioning

confidence: 99%

“…Out-of-phase interaction at the carbon vertex forms the HOMO of 10 a,w hich appears to show a p-conjugation-like interaction over the whole molecule, while the in-phase interaction provides the more stable HOMO-5 ( Figure 9). [18] Thus, our cross-coupling reaction at the carbon vertex has made it possible to introduce aw ide range of aromatic rings, overcoming perhaps oneo ft he biggest lacuna in the synthetic chemistry of 1,a nd making it possible to develop functional molecules, and to investigate the conjugation between s-aromatic and p-aromatic structures. In the next part, we would like to introduce recent developments in synthetic chemistry at the boron vertices.…”

Section: Introductionmentioning

confidence: 99%

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Recent Progress in the Synthesis of the Monocarba‐closo‐dodecaborate(−) Anions

Kanazawa

Kitazawa

Uchiyama

2019

Chemistry A European J

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This Concept article focuses on the rapid growth in studies of the chemistry of the monocarba‐closo‐dodecaborate(−) anion (C1 carborane anion). As one of the most stable anions known, the C1 carborane anion has been useful for exploring the chemistry of highly reactive cations. On the other hand, development of novel functional molecules utilizing the unique properties of C1 carborane anion (e.g., σ‐aromaticity, rigid spherical skeleton) has progressed more slowly. The main reason for this is the relatively undeveloped state of synthetic chemistry in this area. Recent advances in the synthetic chemistry of C1 carborane anion are highlighted in this Concept article, focusing on cross‐coupling reactions at the carbon vertex, direct conversion of B−H bonds, and the synthesis of multivalent weakly coordinating anions. These progressions move this species beyond its well‐established role of highly stable “counter” monocharged anion.

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“…1 ) is a spherical compound formed by one or more boron peaks of polyhedral boron compounds, which is formed by carbon atoms. The volume is similar to that of a benzene ring [ 1 – 5 ]. This is a special large steric skeleton with a very strong hydrophobic structure.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and biological evaluation of a new series of ortho-carboranyl biphenyloxime derivatives

Jin

Xiao

Liu

2018

Chemistry Central Journal

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(Z,Z’)-1,1′-(4-ortho-Caboranyldimethyl)-bis(2-methoxyphenylethan-1-oxime) intermediate 3 was synthesized by a three-step reaction with a final treatment with base to give a new series of ortho-carboranyl biphenyloxime derivatives (4–8). Compounds 7 and 8 showed high solubility and the in vitro study results revealed high levels of accumulation in HeLa cells with higher cytotoxicity and boron uptake compared to l-boronphenylalanine. Electronic supplementary materialThe online version of this article (10.1186/s13065-018-0444-z) contains supplementary material, which is available to authorized users.

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Conjugation between σ- and π-Aromaticity in 1-C-Arylated Monocarba-closo-dodecaborate Anions

Cited by 35 publications

References 24 publications

Baird’s Rule in Substituted Fulvene Derivatives: An Information-Theoretic Study on Triplet-State Aromaticity and Antiaromaticity

Baird’s Rule in Substituted Fulvene Derivatives: An Information-Theoretic Study on Triplet-State Aromaticity and Antiaromaticity

Recent Progress in the Synthesis of the Monocarba‐closo‐dodecaborate(−) Anions

Synthesis and biological evaluation of a new series of ortho-carboranyl biphenyloxime derivatives

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