A 15‐Vertex Heteroborane

McIntosh, Ruaraidh D.; Ellis, David; Rosair, Georgina M.; Welch, Alan J.

doi:10.1002/ange.200601266

Cited by 17 publications

(5 citation statements)

References 39 publications

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“…Instead, it affords a structural isomer of CAd 14-vertex closo -carborane. On the other hand, both 13- and 14-vertex nido -carborane dianions are a class of useful synthons for the preparation of 14- and 15-vertex metallacarboranes via polyhedral expansion methodology. − Thus, 14-vertex closo -carboranes and 15-vertex metallacarboranes represent the largest carboranes and metallacarboranes known so far.…”

Section: Conclusion and Summarymentioning

confidence: 99%

Synthesis, Structure, and Reactivity of 13- and 14-Vertex Carboranes

Zhang

Xie

2014

Acc. Chem. Res.

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Carboranes are a class of polyhedral boron hydride clusters in which one or more of the BH vertices are replaced by CH units. Their chemistry has been dominated by 12-vertex carboranes for over half a century. In contrast, knowledge regarding supercarboranes (carboranes with more than 12 vertices) had been limited merely to possible cage geometries predicted by theoretical work before 2003. Only in recent years has significant progress been made in synthesizing supercarboranes. Such a breakthrough relied on the use of Carbon-Atoms-Adjacent (CAd) nido-carborane dianions or arachno-carborane tetraanions as starting materials. In this Account, we describe our work on constructing and elucidating the chemistry of supercarboranes. Earlier attempted insertions of the formal [BR](2+) unit into Carbon-Atoms-Apart (CAp) 12-vertex nido-[7,9-C2B10H12](2-) did not produce the desired 13-vertex carboranes. Such failure is often attributed to the extraordinary stability of the B12 icosahedron (the "icosahedral barrier"). However, the difference in reducing power between CAp and CAd 12-vertex nido-carborane dianions had been overlooked. Our results have shown that CAd nido-carborane dianions are weaker reducing agents than the CAp isomers, allowing a capitation to prevail over a redox reactivity. This finding provides an entry point to the synthesis of supercarboranes and a series of 13- and 14-vertex closo-carboranes have been prepared and structurally characterized. They share some chemical properties with those of 12-vertex carboranes; on the other hand, they have their own unique characteristics. For example, a 13- vertex closo-carborane can undergo single electron reduction to give a stable carborane radical anion with [2n + 3] framework electrons, which can accept one additional electron to form a 13-vertex CAd nido-carborane dianion. 13-Vertex closo-carborane can also react with various nucleophiles to afford the cage carbon and/or boron extrusion products closo-CB11(-), nido-CB10(-), closo-CB10(-), and closo-C2B10, depending on the nature of the nucleophiles. Studies of supercarboranes remain a relative young research area, particularly in comparison to the rich literature of icosahedral carboranes with 12-vertices. Other supercarboranes are expected to be prepared and structurally characterized as the field progresses, and the results detailed here will further these efforts.

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Section: Conclusion and Summarymentioning

confidence: 99%

Synthesis, Structure, and Reactivity of 13- and 14-Vertex Carboranes

Zhang

Xie

2014

Acc. Chem. Res.

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“…[6] A number of 13-and 14-vertex carboranes have been synthesized and structurally characterized. [7][8][9][10][11][12] These compounds can be reduced by Group 1 metals to afford their corresponding nido-supercarborane dianions. [8][9][10][11][12] The 13-vertex carborane 1,2-(CH 2 ) 3 -1,2-C 2 B 11 H 11 can even undergo single-electron reduction to give a stable carborane radical anion with [2n+3] framework electrons.…”

Section: Introductionmentioning

confidence: 99%

“…[7][8][9][10][11][12] These compounds can be reduced by Group 1 metals to afford their corresponding nido-supercarborane dianions. [8][9][10][11][12] The 13-vertex carborane 1,2-(CH 2 ) 3 -1,2-C 2 B 11 H 11 can even undergo single-electron reduction to give a stable carborane radical anion with [2n+3] framework electrons. [13] This 13-vertex carborane can also react with various nucleophiles to give cage-boron-or cage-carbon-extrusion products nido-CB 10 , closo-CB 10 , closo-CB 11 , or closo-C 2 B 10 , depending on the nature of the nucleophile.…”

Section: Introductionmentioning

confidence: 99%

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Reactions of 13‐Vertex Carboranes with Strong Bases: Synthesis and Structural Characterization of Carborane Monoanions with exo‐π Bonding

Zheng

Zhang

et al. 2013

Chemistry An Asian Journal

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Several monoanions of 13-vertex carboranes were prepared in high yields from the reactions of C,C'-linked 13-vertex carboranes with tBuOK or NaH in dry THF at room temperature. These monoanions were characterized by various spectroscopic methods, elemental analysis, and single-crystal X-ray diffraction. The results showed substantial double-bond character between the cage-carbon atom and the exo vicinal carbon atom, thus leading to charge delocalization into the cage. As a result, the atom-atom distances within the cage were elongated, with one broken C-B bond. However, the cage geometry of the monoanions remained very similar to that of their corresponding neutral 13-vertex closo-carboranes. These monoanions represent the first examples of 13-vertex carboranes with exo-π bonding to hypercarbon atoms.

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“…Such a breakthrough relied on the use of relatively weaker reducing compounds, CAd (carbon atoms-adjacent) nido-carborane dianions or arachno-carborane tetraanions 17 , as starting materials for polyhedral expansion reactions 18,19 . A number of 13-and 14vertex closo-carboranes were prepared and structurally characterized [20][21][22][23][24][25][26][27][28][29] . They showed some unique characteristics.…”

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confidence: 99%

Synthesis and X-ray characterization of 15- and 16-vertex closo-carboranes

et al. 2020

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Carboranes are a class of carbon-boron molecular clusters with three-dimensional aromaticity, and inherent robustness. These endowments enable carboranes as valuable building blocks for applications ranging from functional materials to pharmaceuticals. Thus, the chemistry of carboranes has received tremendous research interest, and significant progress has been made in the past decades. However, many attempts to the synthesis of carboranes with more than 14 vertices had been unsuccessful since the report of a 14-vertex carborane in 2005. The question arises as to whether these long sought-after molecules exist. We describe in this article the synthesis and structural characterization of 15- and 16-vertex closo-carboranes as well as 16-vertex ruthenacarborane. Such a success relies on the introduction of silyl groups to both cage carbons, stabilizing the corresponding nido-carborane dianions and promoting the capitation reaction with HBBr2·SMe2. This work would shed some light on the preparation of carboranes with 17 vertices or more, and open the door for studying supercarborane chemistry.

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A 15‐Vertex Heteroborane

Cited by 17 publications

References 39 publications

Synthesis, Structure, and Reactivity of 13- and 14-Vertex Carboranes

Synthesis, Structure, and Reactivity of 13- and 14-Vertex Carboranes

Reactions of 13‐Vertex Carboranes with Strong Bases: Synthesis and Structural Characterization of Carborane Monoanions with exo‐π Bonding

Synthesis and X-ray characterization of 15- and 16-vertex closo-carboranes

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