Probing London Dispersion in Proton-Bound Onium Ions: Are Alkyl–Alkyl Steric Interactions Reliably Modeled?

Journal of the American Chemical Society, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 28, 2025

We report spectroscopic and spectrometric experiments that probe the London dispersion interaction between tert-butyl substituents in three series of covalently linked, protonated bis-pyridines gas phase. Molecular ions test series, along with several reference molecules for control, were electrosprayed from solution into phase then probed by infrared multiphoton dissociation spectroscopy trapped ion mobility spectrometry. The observed N-H stretching frequencies provided an experimental readout diagnostic ground-state geometry each ion, which could be furthermore compared to a second, independent structural via collision cross section. In strength modulated systematically progressive increase size H Me tert-Bu. Parallel study, extensive dispersion-corrected density functional theory (DFT-D3BJ) calculations performed range exchange correlation functionals. A full analysis conformational space flexible members vibrational spectra context general double-well potential, finds DFT-D3BJ appears significantly overbind alkyl-alkyl interactions, specifically interactions tert-Bu groups, even failing predict minimum energy structures reliably case competes other noncovalent such as hydrogen bonding.

Language: Английский

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Advances and Prospects in Understanding London Dispersion Interactions in Molecular Chemistry

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 63(12)

Published: Dec. 5, 2023

London dispersion (LD) interactions are the main contribution of attractive part van der Waals potential. Even though LD effects driving force for molecular aggregation and recognition, role these omnipresent in structure reactivity had been largely underappreciated over decades. However, recent years considerable efforts have made to thoroughly study their potential as a chemical design element structures catalysis. This was possible through fruitful interplay theory experiment. review highlights results advances utilizing structural motif understand utilize intra- intermolecularly LD-stabilized systems. Additionally, we focus on quantification fundamental reactions.

Language: Английский

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An Isolable One‐Coordinate Lead(I) Radical with Strong g‐Factor Anisotropy

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(20)

Published: March 5, 2024

Abstract Lead‐based radicals in the oxidation state of +1 are elusive species and highly challenging to isolate condensed phase. In this study, we present synthesis characterization first isolable free plumbylyne radical 2 bearing a one‐coordinate Pb(I) atom. It reacts with an N ‐heterocyclic carbene (NHC) afford two‐coordinate NHC‐ligated 3 . represent Pb(I)‐based radicals. Theoretical calculations electron paramagnetic resonance analysis revealed that unpaired mainly resides at Pb 6p orbital both Owing unique nature atom , it possesses two‐fold pseudo‐degeneracy substantial unquenched angular momentum, exhibits hitherto strongest g ‐factor anisotropy ( x,y,z =1.496, 1.166, 0.683) amongst main group Preliminary investigations into reactivity unveiled its Pb‐centered nature, plumbylenes were isolated as products.

Language: Английский

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Synthesis of Crystallographically Characterizable Bis(cyclopentadienyl) Sc(II) Complexes: (C₅H₂^tBu₃)₂Sc and {[C₅H₃(SiMe₃)₂]₂ScI}^1–

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(5), P. 3279 - 3292

Published: Jan. 24, 2024

The synthesis of previously unknown bis(cyclopentadienyl) complexes the first transition metal, i.e., Sc(II) scandocene complexes, has been investigated using C

Language: Английский

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Lewis Structures and the Bonding Classification of End-on Bridging Dinitrogen Transition Metal Complexes

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(8), P. 4326 - 4342

Published: Feb. 16, 2023

The activation of dinitrogen by coordination to transition metal ions is a widely used and promising approach the utilization Earth's most abundant nitrogen source for chemical synthesis. End-on bridging N2 complexes (μ-η1:η1-N2) are key species in fixation chemistry, but lack consensus on seemingly simple task assigning Lewis structure such has prevented application valence electron counting other tools understanding predicting reactivity trends. structures have traditionally been determined comparing experimentally observed NN distance bond lengths free N2, diazene, hydrazine. We introduce an alternative here argue that should be assigned based total π-bond order MNNM core (number π-bonds), which derives from character (bonding or antibonding) occupancy delocalized π-symmetry molecular orbitals (π-MOs) MNNM. To illustrate this approach, cis,cis-[(iPr4PONOP)MCl2]2(μ-N2) (M = W, Re, Os) examined detail. Each complex shown different number nitrogen–nitrogen metal–nitrogen π-bonds, indicated as, respectively: W≡N–N≡W, Re═N═N═Re, Os–N≡N–Os. It follows each these represents distinct class (diazanyl, diazenyl, dinitrogen, respectively), μ-N2 ligand donor (total 8e–, 6e–, 4e–, respectively). show how classification can greatly aid properties patterns complexes.

Language: Английский

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Chiral Bismuth‐Rhodium Paddlewheel Complexes Empowered by London Dispersion: The C−H Functionalization Nexus

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 61(45)

Published: Sept. 14, 2022

Heterobimetallic [BiRh] tetracarboxylate catalysts endowed with 1,3-disilylated phenylglycine paddlewheels benefit from interligand London dispersion. They were originally designed for asymmetric cyclopropanation but are now shown to perform very well in C-H functionalization reactions too. Because of the confined ligand sphere about derived donor/acceptor carbenes, insertions into unhindered methyl groups kinetically favored, although methylene units also react excellent levels induction; even gaseous ethane is a suitable substrate. Moreover, many functional both partners tolerated. The resulting products synthetically equivalent outcome traditional ester alkylation, allylation, benzylation, propargylation and aldol therefore constitute valuable nexus more conventional chemical logic.

Language: Английский

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Boosting Energy‐Transfer Processes via Dispersion Interactions

Chemistry - A European Journal, Journal Year: 2024, Volume and Issue: 30(15)

Published: Jan. 15, 2024

Abstract The generation of open‐shell intermediates under mild conditions has opened broad synthetic opportunities during this century. However, these reactive species often require a case specific and tailored tuning experimental parameters in order to efficiently convert substrates into products. We report general approach that can overcome ubiquitous limitations for several visible‐light promoted energy‐transfer processes. use either naphthalene (5–20 equiv.) or simple binaphthyl derivatives (10–30 mol %) greatly increases their efficiency, giving rise new strategy catalysis. trend is consistent among different media, photocatalysts, light sources substrates, allowing one improve existing methods, more easily optimize ones, and, moreover, disclose otherwise inaccessible reaction pathways.

Language: Английский

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Investigating Steric and Electronic Effects in the Synthesis of Square Planar 6d¹ Th(III) Complexes

Inorganic Chemistry, Journal Year: 2024, Volume and Issue: 63(14), P. 6217 - 6230

Published: March 19, 2024

The factors affecting the formation and crystal structures of unusual 6d1 Th(III) square planar aryloxide complexes, as exemplified by [Th(OArMe)4]1– (OArMe = OC6H2tBu2-2,6-Me-4), were explored synthetic reduction studies a series related Th(IV) tetrakis(aryloxide) Th(OArR)4 (OArR OC6H2tBu2-2,6-R-4). Specifically, electronic, steric, countercation effects varying ligand, alkali metal reducing agent, chelating agent. Salt metathesis reactions between ThBr4(DME)2 (DME 1,2-dimethoxyethane) 4 equiv appropriate potassium salt used to prepare complexes in high yields: Th(OArH)4 (OArH OC6H3tBu2-2,6), Th(OArtBu)4 (OArtBu OC6H2tBu3-2,4,6), Th(OArOMe)4 (OArOMe OC6H2tBu2-2,6-OMe-4), Th(OArPh)4 (OArPh OC6H2tBu2-2,6-Ph-4). can be reduced KC8, Na, or Li absence presence 2.2.2-cryptand (crypt) 18-crown-6 (crown) form dark purple solutions that have EPR UV–visible spectra similar those complex, [Th(OArMe)4]1–. Hence, para position ligand does not alkylated obtain complexes. Furthermore, Th(OArOMe)4, Th(OArtBu)4, with KC8 THF generated are previously reported anion, Although many these did produce single crystals suitable for study X-ray diffraction, Th(OArH)4, provided quality whose had coordination geometries. Reduction also gave product matched [Th(OArMe)4]1–, but too unstable provide data. Neither Th(Odipp)4(THF)2 (Odipp OC6H3iPr2-2,6) nor Th(Odmp)4(THF)2 (Odmp OC6H3Me2-2,6) could products under conditions. U(OArH)3(THF) was examined comparison formed [K(crypt)][U(OArH)4], which has tetrahedral arrangement ligands. Moreover, no further observed when either [K(crypt)][U(OArH)4] [K(crown)(THF)2][U(OArH)4] treated Li.

Language: Английский

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On the reliability of atoms in molecules, noncovalent index, and natural bond orbital to identify and quantify noncovalent bonds

Journal of Computational Chemistry, Journal Year: 2022, Volume and Issue: 43(26), P. 1814 - 1824

Published: Aug. 26, 2022

Abstract Atoms in molecules, noncovalent index, and natural bond orbital methods are commonly invoked to identify the presence of various bonds measure their strength. However, there numerous instances literature where these provide contradictory or apparently erroneous interpretations bonding. The range reliability is assessed by calculations a variety systems, which include an H‐bond, halogen bond, π‐tetrel CH··HC interaction, pairing two anions. While results appear be meaningful for equilibrium geometries, those subunits progressively pulled apart, techniques erroneously predict stronger bonding interaction as units compressed becomes clearly repulsive. falsely indicate arrangement, incorrectly mimic behavior energy when anions approach. These approaches also unreliable understanding angular deformations.

Language: Английский

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EtIDip (EtIPr)—Synthesis, Characterisation and Reactivity of a Robust, Backbone-Modified N-Heterocyclic Carbene and Group 13 Element Complexes

Inorganics, Journal Year: 2025, Volume and Issue: 13(1), P. 27 - 27

Published: Jan. 17, 2025

We report the synthesis, characterisation and reactivity of stable imidazol-2-ylidene EtIDip (EtIPr), {EtCN(Dip)}2C:, Dip = 2,6-iPr2C6H3, as a chemically robust alternative to IDip (IPr), {HCN(Dip)}2C:. The N-heterocyclic carbene could be further converted oxidised species [EtIDipCl]Cl, EtIDipF2, EtIDipO, EtIDipSe, group 13 element complexes EtIDipEX3, with E B, X Br; Al, I; Ga, H. properties ligands are compared molecular structures (DipNCEt)2, [EtIDipH]Cl, [EtIDipH]I, EtIDip, EtIDipBBr3, EtIDipAlI3, EtIDipGaI3, EtIDipAlH3 have been determined.

Language: Английский

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