Tris(perfluorotolyl)borane—A Boron Lewis Superacid

Körte, Leif Arne; Schwabedissen, Jan; Soffner, Marcel; Blomeyer, Sebastian; Reuter, Christian G.; Vishnevskiy, Yury V.; Neumann, Beate; Stammler, Hans‐Georg; Mitzel, Norbert W.

doi:10.1002/anie.201704097

Cited by 75 publications

(76 citation statements)

References 70 publications

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“…Hence, the large EA of the ligand and the positive charge on the B center in B[C 2 BNO(CN) 3 ] 3 and B[C 2 BNS(CN) 3 ] 3 confirm that these are stronger Lewis acids than B(C 6 F 5 ) 3 . To see if these can be classified as super Lewis acids, we have calculated their fluoride ion affinities (FIA) . A super Lewis acid is one whose FIA is larger than that of SbF 5 /SbF 6 − , namely >495–501 kJ mol −1 .…”

Section: Resultsmentioning

confidence: 99%

Superhalogens as Building Blocks of Super Lewis Acids

et al. 2019

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Lewis acids play an important role in synthetic chemistry. Using first‐principle calculations on some newly designed molecules containing boron and organic heterocyclic superhalogen ligands, we show that the acid strength depends on the charge of the central atom as well as on the ligands attached to it. In particular, the strength of the Lewis acid increases with increasing electron withdrawing power of the ligand. With this insight, we highlight the importance of superhalogen‐based ligands in the design of strong Lewis acids. Calculated fluoride ion affinity (FIA) values of B[C2BNO(CN)3]3 and B[C2BNS(CN)3]3 show that these are super Lewis acids.

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Section: Resultsmentioning

confidence: 99%

Superhalogens as Building Blocks of Super Lewis Acids

et al. 2019

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“…The considerably higher Lewis acidity of 9‐boratriptycene 6 than of BPh 3 3 and of boraadamantane 8 (CBC angles 116°) is linked with the stronger pyramidalization of its boron atom environment (CBC angles 113° in 6 ). The neutral boratriptycenes 6 and 10 are even more Lewis acidic than B(C 6 F 5 ) 3 when considering their FIAs and is approaching that of SbF 5 (536 kJ mol −1 ) and of the “super‐B(C 6 F 5 ) 3 ” 30 in the gas phase …”

Section: Methodsmentioning

confidence: 98%

“…The 31 P NMR chemical shift of 79.3 ppm for PO(Et) 3 in 29 corresponded to an Acceptor Number of 84.7 showing that the Lewis acidity of tris(perfluorotolyl)borane 30 (AN=85.0) is reached when considering PO(Et) 3 as a reference Lewis base.…”

Section: Methodsmentioning

confidence: 99%

“…Trivalent organoboron compounds are readily available Lewis acids of importance in academia and industry . In contrast to triphenylborane ( 3 ), which has a propeller‐like structure, enforced planarization of the aryl rings with three linkers results in air and water stable planar boranes 1 – 2 , which are unreactive towards most Lewis bases (Scheme )…”

Section: Methodsmentioning

confidence: 99%

“…Since the synthesis of B(C 6 F 5 ) 3 4 by Massey et al. in 1963, the main approaches for increasing the acidity strength of boron Lewis acids essentially remained to use electron‐withdrawing groups ( p ‐C 6 F 4 CF 3 , OC(CF 3 )),– cationic substituents (NR 3 + , PR 3 + , SMe 2 + , BR 2 + ), or anti‐aromatic borole rings…”

Section: Methodsmentioning

confidence: 99%

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Pushing the Lewis Acidity Boundaries of Boron Compounds With Non‐Planar Triarylboranes Derived from Triptycenes

et al. 2019

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Bending the planar trigonal boron center of triphenylborane by connecting its aryl rings with carbon or phosphorus linkers gave access to a series of 9‐boratriptycene derivatives with unprecedented structures and reactivities. NMR spectroscopy and X‐ray diffraction of the Lewis adducts of these non‐planar boron Lewis acids with weak Lewis base revealed particularly strong covalent bond formation. The first Lewis adduct of a trivalent boron compounds with the Tf2N− anion illustrates the unrivaled Lewis acidity of these species. Increasing the pyramidalization of the boron center and using a cationic phosphonium linker resulted in an exceptional enhancement of Lewis acidity. Introduction of a phosphorus and a boron atom at each edge of a triptycene framework, allowed access to new bifunctional Lewis acid‐base 9‐phospha‐10‐boratriptycenes featuring promising reactivity for the activation of carbon‐halogen bonds.

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Lewis Superacids

Thorwart

Greb

2021

Encyclopedia of Inorganic and Bioinorganic Chemistry

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Lewis acids (LAs) play a prominent role in all domains of chemistry. The present contribution deals with a “super” class of LAs. As a starting point for a meaningful discussion, a more general treatise of the concept of Lewis acidity is required. Lewis acidity is a multi‐dimensional property that depends on a delicate interplay of steric and electronic factors during the interaction with a reference Lewis base or a substrate. Accordingly, various methods that gauge the strength and effectiveness of LAs on various grounds have been developed, as will be discussed in the first part of this work. Different scaling methods do not necessarily show the same trend. In turn, there is no reason to believe that one single parameter is sufficient to describe the full character of a LA. Based on the nature of the Lewis acidity scaling methods and the factors that cause the computed or measured output, a classification into “global”, “effective”, and “intrinsic” groups is made. With this framework in mind, the fluoride ion affinity (FIA) is chosen as a firm “global” parameter to discuss a broad range of LAs within the second part of this contribution. LAs that exceed the FIA of SbF 5 are termed Lewis superacids (LSAs). Accordingly, LAs that reach or exceed this threshold are collected and discussed. The clear focus is on neutral LAs of the p‐block elements, but reference will also be given for cationic Lewis acidic compounds. The majority of those compounds can be found in group 13 and for the heavier group 15 elements. Beyond, this summary touches strong Lewis acidity of d‐block metals and Lewis acidity in alternative media.

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Tris(perfluorotolyl)borane—A Boron Lewis Superacid

Cited by 75 publications

References 70 publications

Superhalogens as Building Blocks of Super Lewis Acids

Superhalogens as Building Blocks of Super Lewis Acids

Pushing the Lewis Acidity Boundaries of Boron Compounds With Non‐Planar Triarylboranes Derived from Triptycenes

Lewis Superacids

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