[Si(O2C6F4)2]14: Self‐Assembly of a Giant Perfluorinated Macrocyclic Host by Low‐Barrier Si−O Bond Metathesis

Hartmann, Deborah; Greb, Lutz

doi:10.1002/anie.202009942

Cited by 17 publications

(10 citation statements)

References 56 publications

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“…Unfortunately, the application of the entire class of Si(cat X ) 2 in catalysis was hampered by its very poor solubility and unidentified deactivation channels. Recent and ongoing studies on the structure of bis(catecholato)silanes suggest covalent oligomerization as the cause [5] . Thus, we considered addressing these issues by suitable substitution of the catecholates with sufficiently large yet electron‐withdrawing groups.…”

Section: Introductionmentioning

confidence: 99%

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Bis(pertrifluoromethylcatecholato)silane: Extreme Lewis Acidity Broadens the Catalytic Portfolio of Silicon

Thorwart

Roth

Greb

2021

Chemistry A European J

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Given its earth abundance, silicon is ideal for constructing Lewis acids of use in catalysis or materials science. Neutral silanes were limited to moderate Lewis acidity, until halogenated catecholato ligands provoked a significant boost. However, catalytic applications of bis (perhalocatecholato)silanes were suffering from very poor solubility and unknown deactivation pathways. In this work, the novel per(trifluoromethyl)catechol, H 2 cat CF3 , and adducts of its silicon complex Si(cat CF3 ) 2 (1) are described. According to the computed fluoride ion affinity, 1 ranks among the strongest neutral Lewis acids currently accessible in the condensed phase. The improved robustness and affinity of 1 enable deoxygenations of aldehydes, ketones, amides, or phosphine oxides, and a carbonyl-olefin metathesis. All those transformations have never been catalyzed by a neutral silane. Attempts to obtain donor-free 1 attest to the extreme Lewis acidity by stabilizing adducts with even the weakest donors, such as benzophenone or hexaethyl disiloxane.

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Section: Introductionmentioning

confidence: 99%

“…Recent and ongoing studies on the structure of bis(catecholato)silanes suggest covalent oligomerization as the cause. [5] Thus, we considered addressing these issues by suitable substitution of the catecholates with sufficiently large yet electron‐withdrawing groups.…”

Section: Introductionmentioning

confidence: 99%

Bis(pertrifluoromethylcatecholato)silane: Extreme Lewis Acidity Broadens the Catalytic Portfolio of Silicon

Thorwart

Roth

Greb

2021

Chemistry A European J

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“…A first insight was provided upon sublimation of Si(cat F )2 from its bis(acetonitrile) adduct and crystallization of the sublimate in CH2Cl2. [28] Dynamic constitutional self-assembly of 14 units of Si(cat F )2 led to [Si(O2C6F4)2]14 -the first giant perfluorinated macrocycle (Figure 4a). The oligomerization process was monitored spectroscopically, and the macrocycle was analyzed by single-crystal X-ray diffraction.…”

Section: Constitutional Dynamics Cause a Structural Mysterymentioning

confidence: 99%

p-Block Element Catecholates: Lewis Superacidic, Constitutionally Dynamic, and Redox Active

Greb

2023

Synlett

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Numerous strategies for enhancing the reactivity and properties of p-block elements have been devised in the past decades. The present Account article discusses our approaches by a distinct ligand control on p-block elements in their normal (group) oxidation states. Catecholato ligands at silicon, germanium, and phosphorous enable a range of rewarding properties. Substantial electron withdrawal paired with structural constraint effects (influence of deformation energy) impart Lewis superacidity to these abundant elements. The ease of synthesis of such species facilitates screening in catalysis, promising a range of applications by powerful bond activation. Low barrier Si-O/Si-O bond metathesis imposes the most abundant bond in our Earth’s crust with adaptive features under mild conditions and establishes a new branch of constitutional dynamic chemistry. The redox-active character of catecholates grants access to novel compounds with tunable open-shell features. Overall, p-block catecholates offer unique opportunities due to the versatile features that will enrich the chemistry of the main group elements.

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“…The group of von Hänisch reported elegant syntheses of dialkoxysilane analogues of cryptands and crown ethers, [62–64] which in the most recent work was facilitated by a template effect [63] . Earlier this year, Johnson made use of mild reaction conditions to facilitate the dynamic covalent synthesis of thermosets based on dialkoxysilanes (Figure 1a, center) [65] and one of us used Si−O bond metathesis to prepare large, catechol‐bridged macrocycles under thermodynamic control (Figure 1a, right) [66] . While these and other reports highlight the value of the dynamic Si−O bond for polymers and macrocycles, [67–70] the exploitation of trialkoxysilanes in host‐guest chemistry is elusive.…”

Section: Introductionmentioning

confidence: 99%

Trialkoxysilane Exchange: Scope, Mechanism, Cryptates and pH‐Response

et al. 2023

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The dynamic covalent chemistry (DCvC) of the Si−O bond holds unique opportunities, but has rarely been employed to assemble discrete molecular architectures. This may be due to the harsh conditions required to initiate exchange reactions at silicon in aprotic solvents. Herein, we provide a comprehensive experimental and computational account on the reaction of trialkoxysilanes with alcohols and identify mild conditions for rapid exchange in aprotic solvents. Substituent, solvent and salt effects are uncovered, understood and exploited for the construction of sila‐orthoester cryptates. A sharp, divergent pH‐response of the obtained cages renders this substance class attractive for future applications well beyond host‐guest chemistry, for instance, in drug delivery.

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[Si(O₂C₆F₄)₂]₁₄: Self‐Assembly of a Giant Perfluorinated Macrocyclic Host by Low‐Barrier Si−O Bond Metathesis

Cited by 17 publications

References 56 publications

Bis(pertrifluoromethylcatecholato)silane: Extreme Lewis Acidity Broadens the Catalytic Portfolio of Silicon

Bis(pertrifluoromethylcatecholato)silane: Extreme Lewis Acidity Broadens the Catalytic Portfolio of Silicon

p-Block Element Catecholates: Lewis Superacidic, Constitutionally Dynamic, and Redox Active

Trialkoxysilane Exchange: Scope, Mechanism, Cryptates and pH‐Response

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