Facile and systematic access to the least-coordinating WCA [(RFO)3Al–F–Al(ORF)3]− and its more Lewis-basic brother [F–Al(ORF)3]− (RF = C(CF3)3)

Martens, Arthur; Weis, Philippe; Krummer, Michael; Kreuzer, Marvin; Meierhöfer, Andreas; Meier, Stefan; Bohnenberger, Jan; Scherer, Harald; Riddlestone, Ian M.; Krossing, Ingo

doi:10.1039/c8sc02591f

Cited by 68 publications

(75 citation statements)

References 54 publications

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“…One of the best WCAsi st he [( F RO) 3 Al(m-F)Al(OR F ) 3 ] À ion (R F designates in this section only C(CF 3 ) 3 ). [143] Related bridged anions of the type [( F RO) 3 Al(m-X)Al-(OR F ) 3 ] À (where X = Cl or OH) are also accessible,b ut are more prone to either exchange reactions and/or dissociation to yield the corresponding [XAl(OR F ) 3 ] À and Al(OR F ) 3 species. [142] It shows improved stability against electrophiles and reduced coordinative strength compared to the parent [Al(OR F ) 4 ] À anion.…”

Section: Bridged Wcasmentioning

confidence: 99%

Taming the Cationic Beast: Novel Developments in the Synthesis and Application of Weakly Coordinating Anions

et al. 2018

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This Review gives a comprehensive overview of the most topical weakly coordinating anions (WCAs) and contains information on WCA design, stability, and applications. As an update to the 2004 review, developments in common classes of WCA are included. Methods for the incorporation of WCAs into a given system are discussed and advice given on how to best choose a method for the introduction of a particular WCA. A series of starting materials for a large number of WCA precursors and references are tabulated as a useful resource when looking for procedures to prepare WCAs. Furthermore, a collection of scales that allow the performance of a WCA, or its underlying Lewis acid, to be judged is collated with some advice on how to use them. The examples chosen to illustrate WCA developments are taken from a broad selection of topics where WCAs play a role. In addition a section focusing on transition metal and catalysis applications as well as supporting electrolytes is also included.

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Section: Bridged Wcasmentioning

confidence: 99%

Taming the Cationic Beast: Novel Developments in the Synthesis and Application of Weakly Coordinating Anions

et al. 2018

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“…The aluminate anions [Al(OR F ) 4 ] – and [Al(OR HF ) 4 ] – {where R F = C(CF 3 ) 3 and R HF = C(H)(CF 3 ) 2 }, as well as the related bridged analogue [(R F O) 3 Al‐F‐Al(OR F ) 3 ] – , are some of the most versatile WCAs present in the literature. This is due to their simple preparation and transformation into common reagents used to introduce WCAs to a given system . They also represent some the most weakly coordinating WCAs currently reported.…”

Section: Introductionmentioning

confidence: 99%

Towards Weakly Coordinating Anions with the Extremely Electron Withdrawing Perfluoropyridinoxy Ligand –OC₅F₄N

et al. 2018

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The extreme electron withdrawing properties of the perfluoropyridinoxy ligand –OC5F4N were used for the preparation of new (weakly) coordinating borate and aluminate anions of the type [E(OC5F4N)4]– (E = B or Al). These new anions are based on the potent parent Lewis acids E(OC5F4N)3, which possess exceptionally high calculated fluoride ion affinities (FIAs) of 500 and 587 kJ mol–1 for E = B and Al respectively. For aluminum, this extreme Lewis acidity dominates the chemistry and from mixtures of the neutral polymeric Lewis acid [Al(OC5F4N)3]n, the five‐ and six‐coordinate complexes Al(OC5F4N)3(OEt2)2 (1) and [Al(OC5F4N)2(µ‐OC5F4N) (NCMe)2]2 (2) were crystallized upon addition of ether or MeCN. The aluminate salts M[Al(OC5F4N)4] (M = Li or K) were prepared from the reaction between the alcohol 4‐HO–C5F4N and either LiAlH4 or K[AlEt4] respectively. The aluminate anion [Al(OC5F4N)4]– remains Lewis acidic coordinating small donor molecules forming [Al(OC5F4N)4(L)]– (L = THF or NMe3) and even supports formation and structural characterisation of the aluminum dianion containing salt [Na(OEt2)2][Na][Al(OC5F4N)5] (8). The from NaBH4 and 4‐HO–C5F4N accessible borate salt Na[B(OC5F4N)4] shows increased kinetic stability in comparison to the aluminum analogue.

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“…Compound 3 crystallizes in two modifications with space groups P 2 1 / c ( 3 a ) and P

\overset{1}{true}

( 3 b ). The compounds 3 – 5 include [Co(CO) 5 ] + at ordered positions, whereas some OR F groups of the anions are disordered (not shown), as typical for these types of WCAs . Crystallographic details, including a description of the number and type of disorder present in each of the asymmetric units of compounds 3 – 5 , are included in the Supporting Information.…”

Section: Resultsmentioning

confidence: 99%

“…In compounds 1 , 4 , and 5 , with M−F bonds (M=B, Al) that point towards one of the planes spanned by three carbon atoms, stronger interactions are present with values ranging from 3.2–3.3 Å for Co⋅⋅⋅F contacts and 2.6–2.9 Å for C⋅⋅⋅F contacts. The terminal Al−F bond lengths between 1.66 Å ( 5 ) and 1.67 Å ( 4 ) are similar to reported values …”

Section: Resultsmentioning

confidence: 99%

How does the Environment Influence a Given Cation? A Systematic Investigation of [Co(CO)₅]⁺ in Gas Phase, Solution, and Solid State

Meier

Himmel

Krossing

2018

Chemistry A European J

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IR spectroscopic studies of the gaseous metal carbonyl cations [Co(CO)5]+⋅mCO (m=1–4) indicated that the weakly bound CO molecules in a second coordination sphere perturb the structure of [Co(CO)5]+ causing the CO stretching frequencies ν(CO) to become noticeably redshifted. In this work, we aimed to establish the relationship between such gas phase IR spectra and those recorded in condensed phases, either as a solid salt or as a solution in the weakly basic solvent o‐difluorobenzene. For this purpose, a series of [Co(CO)5]+[WCA]− salts (WCA=weakly coordinating anion), with the counterions varying between more coordinating (WCA=F‐Al(ORF)3, (RFO)3Al‐F‐Al(F)(ORF)2; RF=C(CF3)3) and almost non‐coordinating (WCA=Al(ORF)4, F{Al(ORF)3}2), were synthesized and characterized by vibrational spectroscopy as well as X‐ray structure analysis. The experimental spectra differ considerably from that of the undisturbed gaseous [Co(CO)5]+ ion, as the structural deformation of [Co(CO)5]+ requires very little energy. Together with previously reported data, the perturbed condensed phase [Co(CO)5]+ ions were analyzed and compared with the gaseous [Co(CO)5]+⋅mCO ions. DFT calculations were performed on simply adapted [Co(CO)5]+ structures to allow the assignment of all the ν(CO) modes and a qualitative interpretation of structural deformations by external influences as a function of the environment (ligands, solvation, crystal packing). The analysis showed that especially the degenerate E′ mode νe and the averaged asymmetric equatorial CO stretch trueν‾ e, which originates from a split of the E′ mode, are a function of the interaction with the environment. Whereas for the more coordinating counterions trueν‾ e values of 2112–2120 cm−1 were obtained, for the less coordinating counterions trueν‾ e values of up to 2133 cm−1 were found, which is very close to that of gaseous [Co(CO)5]+⋅4CO, with a trueν‾ e value of 2135 cm−1. This indicates the possibility of approximating the gas phase conditions in the condensed phases with the [Co(CO)5]+ ion probably being the prototypical probe molecule for investigating the strengths of interactions in different environments.

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Facile and systematic access to the least-coordinating WCA [(R^FO)₃Al–F–Al(OR^F)₃]⁻ and its more Lewis-basic brother [F–Al(OR^F)₃]⁻ (R^F = C(CF₃)₃)

Abstract: The least-coordinating anion [(RFO)3Al–F–Al(ORF)3]– and its more Lewis-basic brother [F–Al(ORF)3]– (RF = C(CF3)3).

Cited by 68 publications

References 54 publications

Taming the Cationic Beast: Novel Developments in the Synthesis and Application of Weakly Coordinating Anions

Taming the Cationic Beast: Novel Developments in the Synthesis and Application of Weakly Coordinating Anions

Towards Weakly Coordinating Anions with the Extremely Electron Withdrawing Perfluoropyridinoxy Ligand –OC₅F₄N

How does the Environment Influence a Given Cation? A Systematic Investigation of [Co(CO)₅]⁺ in Gas Phase, Solution, and Solid State

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Facile and systematic access to the least-coordinating WCA [(RFO)3Al–F–Al(ORF)3]− and its more Lewis-basic brother [F–Al(ORF)3]− (RF = C(CF3)3)

Abstract: The least-coordinating anion [(RFO)3Al–F–Al(ORF)3]– and its more Lewis-basic brother [F–Al(ORF)3]– (RF = C(CF3)3).

Cited by 68 publications

References 54 publications

Taming the Cationic Beast: Novel Developments in the Synthesis and Application of Weakly Coordinating Anions

Taming the Cationic Beast: Novel Developments in the Synthesis and Application of Weakly Coordinating Anions

Towards Weakly Coordinating Anions with the Extremely Electron Withdrawing Perfluoropyridinoxy Ligand –OC5F4N

How does the Environment Influence a Given Cation? A Systematic Investigation of [Co(CO)5]+ in Gas Phase, Solution, and Solid State

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Product

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Facile and systematic access to the least-coordinating WCA [(R^FO)₃Al–F–Al(OR^F)₃]⁻ and its more Lewis-basic brother [F–Al(OR^F)₃]⁻ (R^F = C(CF₃)₃)

Towards Weakly Coordinating Anions with the Extremely Electron Withdrawing Perfluoropyridinoxy Ligand –OC₅F₄N

How does the Environment Influence a Given Cation? A Systematic Investigation of [Co(CO)₅]⁺ in Gas Phase, Solution, and Solid State