A Highly Lewis Acidic Strontium <i>ansa</i>‐Arene Complex for Lewis Acid Catalysis and Isobutylene Polymerization

Dabringhaus, Philipp; Schorpp, Marcel; Scherer, Harald; Krossing, Ingo

doi:10.1002/ange.202010019

Cited by 9 publications

(4 citation statements)

References 61 publications

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“…To the best of our knowledge, the CIP complexes 4-Ln exhibit the first structurally authenticated examples of κ 1 -F-binding of the [Al{OC(CF3)3}4]anion. [67][68][69][70][71][72][73][74] We attribute the polymorphism-induced structural changes of 3-Dy•C6H6 and 4-Dy to differences in crystal packing forces, 75 which should be energetically similar to the weak coordination of one of the F atoms of a CF3 group in [Al{OC(CF3)3}4]to the {Dy(Cp ttt )(Cp*)} + moiety.…”

Section: Discussionmentioning

confidence: 99%

AtomAccess: A predictive tool for molecular design and its application to the targeted synthesis of dysprosium single-molecule magnets

Gransbury

Corner

Kragskow

et al. 2023

Preprint

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Isolated dysprosocenium cations, [Dy(CpR)2]+ (CpR = substituted cyclopentadienyl), have recently been shown to exhibit superior single-molecule magnet (SMM) properties over closely related complexes with equatorially-bound ligands. However, gauging the crossover point at which the CpR substituents are large enough to prevent equatorial ligand binding, but small enough to approach the metal closely and generate strong crystal field splitting, has required laborious synthetic optimization. We therefore created the computer program, AtomAccess, to predict the accessibility of a metal binding site and its ability to accommodate additional ligands. Here we apply AtomAccess to rapidly screen a series of derivatized dysprosium metallocene fragments of varying steric bulk in silico, allowing us to identify the crossover point for equatorial coordination in [Dy(CpR)2]+ cations, and hence predict a cation that is at the cusp of stability without equatorial interactions, viz. [Dy(Cpttt)(Cp*)]+ (Cpttt = C5H2tBu3-1,2,4, Cp* = C5Me5). Upon synthesizing this cation we found it crystallizes as either a contact ion-pair, [Dy(Cpttt)(Cp*){Al[OC(CF3)3]4-k-F}], or separated ion-pair polymorph, [Dy(Cpttt)(Cp*)][Al{OC(CF3)3}4]C6H6. These complexes, together with their precursors and yttrium analogs, have been characterized by NMR and ATR-IR spectroscopy, elemental analysis, powder and single crystal X-ray diffraction, SQUID magnetometry and ab initio calculations. We find that the contact ion-pair shows inferior SMM properties to the separated ion-pair, as expected, due to faster Raman and quantum tunneling of magnetization relaxation processes. The experimental verification of the predicted crossover point for equatorial coordination in this work indicates that programs like AtomAccess have significant potential to boost efficiency in exploratory synthetic chemistry.

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Section: Discussionmentioning

confidence: 99%

AtomAccess: A predictive tool for molecular design and its application to the targeted synthesis of dysprosium single-molecule magnets

Gransbury

Corner

Kragskow

et al. 2023

Preprint

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“…Similar unsupported binding modes were recently observed in the structurally characterized M(arene) 2+ salts (M = Ca, Sr, Ba; arene = hexamethylbenzene and dixyline). 42 , 43 The electrostatic contribution to the metal–ligand bonds is higher than in classical transition metal complexes of the more electronegative metals but the bonds are otherwise very similar. The transition-metal-like behavior of the heavier alkaline earth metals was supported by a theoretical study of N 2 activation by M = Ca, Sr, Ba.…”

Section: Introductionmentioning

confidence: 95%

Metal–CO Bonding in Mononuclear Transition Metal Carbonyl Complexes

Frenking

Fernández

Holzmann

et al. 2021

JACS Au

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DFT calculations have been carried out for coordinatively saturated neutral and charged carbonyl complexes [M(CO) n ] q where M is a metal atom of groups 2–10. The model compounds M(CO) 2 (M = Ca, Sr, Ba) and the experimentally observed [Ba(CO)] + were also studied. The bonding situation has been analyzed with a variety of charge and energy partitioning approaches. It is shown that the Dewar–Chatt–Duncanson model in terms of M ← CO σ-donation and M → CO π-backdonation is a valid approach to explain the M–CO bonds and the trend of the CO stretching frequencies. The carbonyl ligands of the neutral complexes carry a negative charge, and the polarity of the M–CO bonds increases for the less electronegative metals, which is particularly strong for the group 4 and group 2 atoms. The NBO method delivers an unrealistic charge distribution in the carbonyl complexes, while the AIM approach gives physically reasonable partial charges that are consistent with the EDA-NOCV calculations and with the trend of the C–O stretching frequencies. The AdNDP method provides delocalized MOs which are very useful models for the carbonyl complexes. Deep insight into the nature of the metal–CO bonds and quantitative information about the strength of the [M] ← (CO) 8 σ-donation and [M(d)] → (CO) 8 π-backdonation visualized by the deformation densities are provided by the EDA-NOCV method. The large polarity of the M–CO π orbitals toward the CO end in the alkaline earth octacarbonyls M(CO) 8 (M = Ca, Sr, Ba) leads to small values for the delocalization indices δ(M–C) and δ(M···O) and significant overlap between adjacent CO groups, but the origin of the charge migration and the associated red-shift of the C–O stretching frequencies is the [M(d)] → (CO) 8 π-backdonation. The heavier alkaline earth metals calcium, strontium and barium use their s/d valence orbitals for covalent bonding. They are therefore to be assigned to the transition metals.

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“…When the halogen metathesis is favorable, Li +[1,2] or Na +[3,4] salts are recommended. In more challenging cases, silver salts [5,6] (or thallium salts when redox processes occur with Ag + ), [7,8] are to be employed to precipitate the corresponding metal halide (Scheme 1, top). Krossing et al.…”

Section: Introductionmentioning

confidence: 99%

Taming the Lewis Superacid Al(ORF)₃ (RF=C(CF₃)₃): DFT Guided Identification of the “Stable yet Reactive” Adduct SiPr₂→Al(ORF)₃; Its Use as ORF‐ Abstractor from a “Ni‐ORF” complex

Petit

Babinot

Saffon

et al. 2023

Chemistry A European J

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A DFT study of several L→Al(ORF)3 (L=Lewis bases) adducts allowed the identification of (iPr2S)→Al(ORF)3 1‐SiPr2 as a “stable yet reactive” adduct. 1‐SiPr2 was shown to act as a masked Lewis superacid able to release Al(ORF)3 under mild conditions. It could be used to abstract a ORF− ligand from (bipyMe2)Ni(ORF)2 (bipyMe2 : 6,6’‐dimethyl‐2,2’‐dipyridyl) and generate the nickel alkoxide complex [(bipyMe2)Ni(ORF)(iPr2S)]+[(RFO)3Al−F−Al(ORF)3]− 5. Ligand exchange of iPr2S by Ph3P yielded [(bipyMe2)Ni(ORF)(PPh3)]+[(RFO)3Al−F−Al(ORF)3]− 6.

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A Highly Lewis Acidic Strontium ansa‐Arene Complex for Lewis Acid Catalysis and Isobutylene Polymerization

Cited by 9 publications

References 61 publications

AtomAccess: A predictive tool for molecular design and its application to the targeted synthesis of dysprosium single-molecule magnets

AtomAccess: A predictive tool for molecular design and its application to the targeted synthesis of dysprosium single-molecule magnets

Metal–CO Bonding in Mononuclear Transition Metal Carbonyl Complexes

Taming the Lewis Superacid Al(ORF)₃ (RF=C(CF₃)₃): DFT Guided Identification of the “Stable yet Reactive” Adduct SiPr₂→Al(ORF)₃; Its Use as ORF‐ Abstractor from a “Ni‐ORF” complex

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A Highly Lewis Acidic Strontium ansa‐Arene Complex for Lewis Acid Catalysis and Isobutylene Polymerization

Cited by 9 publications

References 61 publications

AtomAccess: A predictive tool for molecular design and its application to the targeted synthesis of dysprosium single-molecule magnets

AtomAccess: A predictive tool for molecular design and its application to the targeted synthesis of dysprosium single-molecule magnets

Metal–CO Bonding in Mononuclear Transition Metal Carbonyl Complexes

Taming the Lewis Superacid Al(ORF)3 (RF=C(CF3)3): DFT Guided Identification of the “Stable yet Reactive” Adduct SiPr2→Al(ORF)3; Its Use as ORF‐ Abstractor from a “Ni‐ORF” complex

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Product

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Taming the Lewis Superacid Al(ORF)₃ (RF=C(CF₃)₃): DFT Guided Identification of the “Stable yet Reactive” Adduct SiPr₂→Al(ORF)₃; Its Use as ORF‐ Abstractor from a “Ni‐ORF” complex