Generation and Reactivity of Enantiomeric (BINOLato)Ni<sup>+</sup> Complexes with Chiral Secondary Alcohols in the Gas Phase

Novara, Francesca R.; Gruene, Philipp; Schröder, Detlef; Schwarz, Helmut

doi:10.1002/chem.200800090

Cited by 7 publications

(2 citation statements)

References 63 publications

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“…Path A involves the formation of a T-shaped transition state, 5, while Path B involves a side-on S N 2 transition state, 6. Metal alkoxides generated via ESI also fragment to form metal hydrides as demonstrated by a number of studies [75,76]. In contrast, the transition state energies for both pathways for the silver congener are above the energy-separated reactants.…”

Section: Unmasking Reactive Metallic Intermediates Via Collision-indusupporting

confidence: 89%

Gas Phase Ligand Fragmentation to Unmask Reactive Metallic Species

O’Hair

2009

Reactive Intermediates

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The newer ionization methods of electrospray ionization, cold-spray ionization [1], atmospheric pressure chemical ionization [2], and matrix-assisted laser desorption [3] are making possible the mass spectrometry-based analysis of a diverse range of metal-based species [4]. With the very recent coupling of ESI to a glovebox [5], even challenging organometallic and inorganic species should be examinable via MS. Electrospray ionization has been particularly useful in the direct interception of reactive intermediates in solution. Pioneering work in the area includes that of Wilson and Canary in the early 1990s, who studied the intermediates formed in a number of textbook organic reactions including the Wittig, Mitsunobu, and Staudinger reactions [6] and CÀC bond-coupling reactions [7]. Since this topic has been recently reviewed [8,9] and also forms the basis of chapters 3, 4, 5 and 7 of this book, it is not discussed further here.The focus of this chapter is on the combined used of ESI and collision-induced dissociation (CID) as a means of synthesizing reactive intermediates so that their fundamental gas-phase reactivity may be examined via, for example, the use of ion-molecule reactions (IMR) [10] 1) . The motivation for such studies is to gain fundamental insights into metal-containing species that may have relevance to catalysis and metal-mediated reactions [13][14][15][16][17][18]. This field builds upon a wealth of previous metal ion chemistry studies in which other ionization techniques were utilized [14,[19][20][21][22][23][24][25][26][27][28]. Indeed, the potential for using CID to generate important (and sometimes novel) organic, organoelement and transition metal reactive intermediates was recognized some time ago. For example, Squires used decarboxylation of carboxylates and/or loss of aldehydes from alkoxide anions to study the gasphase chemistry of naked alkyl anions [29][30][31][32]. Thus, the prototypical methyl anion, 1) It is worth noting that photolysis [11] and thermolysis of metal complexes have a rich history and have been used as a route to reactive intermediates and new materials [12].

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Section: Unmasking Reactive Metallic Intermediates Via Collision-indusupporting

confidence: 89%

Gas Phase Ligand Fragmentation to Unmask Reactive Metallic Species

O’Hair

2009

Reactive Intermediates

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“…These experiments rest on the comparison between the collision-induced dissociation efficiency of diastereomer complexes, both in a single-collision regime 11 or in a multiple collision regime under ion trap conditions. [12][13][14][15][16][17] Tandem mass spectrometry experiments based on the kinetic method allow quantifying chirality effects. [18][19] The enantioselectivity in the dissociation is related to different binding energies or different barriers to dissociation between enantiomers, 14 or to entropic effects.…”

Section: Introductionmentioning

confidence: 99%

Homochiral vs. heterochiral sodium core dimers of tartaric acid esters: A mass spectrometry and vibrational spectroscopy study

Barbu‐Debus

Scuderi

Lepère

et al. 2020

Journal of Molecular Structure

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The mixed sodium core dimers of dimethyl-L-tartrate (Lmt) and the two enantiomers of diisopropyl tartrate (Lipt and Dipt) are studied by mass spectrometry coupled with laser vibrational spectroscopy. Infra-Red Multiple Photon Dissociation (IRMPD) spectra of the two diastereomer sodium-core dimers, namely, LmtLiptNa + and LmtDiptNa + , are identical in the fingerprint region but show a slight difference in the OH stretch region. Comparison to ab initio calculations indicates that the formed complexes probably reflect the structures preexisting in solution. The difference between LmtLiptNa + and LmtDiptNa + arises from the presence of an additional Na + …O interactions in the homochiral complex. The two complexes also differ in the strength and nature of the OH…OC hydrogen bond. Highlights:  Sodium ion-core dimers of tartaric acid esters are studied by mass spectrometry and laser spectroscopy  Infra-red Multiple photon spectroscopy coupled with quantum chemical calculations aim at explaining the chirality effects observed in these systems. 2  Infra-red spectroscopy shows that the dimer with two monomers of identical absolute configuration possesses one more hydrogen bond relative to the heterochiral dimer.

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Isotope‐Sensitive Degenerate [1,3]‐Hydrogen Migration versus Competitive Enol–Keto Tautomerization

Zhang¹,

Zummack²,

Schröder³

et al. 2009

Chemistry A European J

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The question of intramolecular energy distribution in polyatomic molecules or, more precisely, whether reacting molecules display ergodic or non-ergodic behavior, is of central importance in reaction dynamics.[1] For ionic gas-phase systems, the unimolecular behavior of the enol and keto forms of ionized acetone, 1 and 2, respectively, constitutes one of the best studied systems. [2,3] Detailed 2 H-and 13 C-labeling experiments, energetic measurements, analysis of kinetic energy release distributions as well as electronic-structure calculations of the potential-energy surface with the inclusion of trajectory studies reveal the following (Scheme 1): Direct dissociation of 1 to generate the hydroxyvinyl cation 4 does not occur; rather, irreversible isomerization to a highly excited, short-lived acetone ion 2 takes place, which decomposes to the acylium ion 3 concomitant with loss of a CH 3 radical at a time-scale of 5 10 À13 s. From 2, the newly formed methyl group is eliminated preferentially as compared to the one which is already present in 1, and the kinetic energy release associated with elimination of this process is smaller than that for the loss of the newly generated methyl group. All these findings clearly point to a non-statistical (i.e., "non-ergodic") behavior of the chemically activated acetone ion 2. Inspired by the detailed mechanistic information which can be achieved from kinetic analysis of multiple labeling data, [4] here we report a re-investigation of the dissociation of 1 for a wide set of isotopologues, generated via dissociative electron ionization of the corresponding labeled 2-hexanones in a McLafferty reaction. [5,6] To our surprise, however, it turned out that the unimolecular dissociation of ionized acetone and its enol form offers additional mechanistic puzzles which have not been recognized before. [2,3] The experimentally obtained data for the unimolecular dissociation of the enol ions 1-1 h (Table 1) can be accounted for by a rate-determining, irreversible enol-keto tautomerization 1 ! 2 followed by a rapid dissociation of the latter in which the two methyl groups do not have sufficient time to completely equilibrate their originally different energy content. As a consequence, both CÀCH 3 bonds are cleaved with different rates. This view has been supported by numerous computational studies. [1b,2c,d,f,h,i,j] Further, the analysis of the data for 1-1 h implies that a degenerate [1,3]-hydrogen migration, by which the methyl and the methylene groups of 1 equilibrate, cannot energetically compete with the tautomerization 1 ! 2. This is in line with exploratory, [a] Dr.

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Generation and Reactivity of Enantiomeric (BINOLato)Ni⁺ Complexes with Chiral Secondary Alcohols in the Gas Phase

Cited by 7 publications

References 63 publications

Gas Phase Ligand Fragmentation to Unmask Reactive Metallic Species

Gas Phase Ligand Fragmentation to Unmask Reactive Metallic Species

Homochiral vs. heterochiral sodium core dimers of tartaric acid esters: A mass spectrometry and vibrational spectroscopy study

Isotope‐Sensitive Degenerate [1,3]‐Hydrogen Migration versus Competitive Enol–Keto Tautomerization

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Generation and Reactivity of Enantiomeric (BINOLato)Ni+ Complexes with Chiral Secondary Alcohols in the Gas Phase

Cited by 7 publications

References 63 publications

Gas Phase Ligand Fragmentation to Unmask Reactive Metallic Species

Gas Phase Ligand Fragmentation to Unmask Reactive Metallic Species

Homochiral vs. heterochiral sodium core dimers of tartaric acid esters: A mass spectrometry and vibrational spectroscopy study

Isotope‐Sensitive Degenerate [1,3]‐Hydrogen Migration versus Competitive Enol–Keto Tautomerization

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Generation and Reactivity of Enantiomeric (BINOLato)Ni⁺ Complexes with Chiral Secondary Alcohols in the Gas Phase