New and effective routes to synthesize 2-trimethylsilylmethyl-3-trimethylsilyl-1-propene and its 1,1-d(2)- and 1,1,1',1',3,3-d(6)-isotopomers have been developed, using the displacement reaction of lithium trimethylsilylcyanocuprate with allylic halides and tosylates. These compounds are pivotal precursors for the gas-phase synthesis and characterization of the trimethylenemethane anion, and for negative ion photoelectron spectroscopic investigations of the singlet-triplet splitting in trimethylenemethane. Copyright (C) 2001 John Wiley & Sons, Ltd.

The gas phase synthesis, structure, and reactivity of distonic negative ions of the “ate” class are described. “Ate”-class negative ions are readily prepared in the gas phase by addition of neutral Lewis acids, such as BF 3 , BH 3 , and AlMe 3 , to molecular anions, carbene negative ions, and radical anions of biradicals. The ions contain either localized σ - or delocalized π -type radical moieties remote from relatively inert borate and aluminate charge sites. The free radical reactivity displayed by these ions appears to be independent of the charge site. As an example, the distonic alkynyl radical (·C≡CBF 3 − ) is highly reactive and undergoes radical coupling reactions with NO 2 , NO, H 2 C=CH-CN, and H 2 C=CH-CH 3 . Radical-mediated group and atom transfers are observed with O 2 , CS 2 , and CH 3 SSCH 3 . Furthermore, H-atom abstraction reactions are observed, in accordance with the predicted high C-H bond strength of this species [DH 298 (H-C 2 BF 3 − )=130.8 kcal mol −1 ]. High level ab initio molecular orbital calculations on the prototype “ate”-class distonic ion · CH 2 BH 3 − and its conventional isomer CH 3 BH 2 ·− reveal that CH 3 BH 2 ·− is 3.2 kcal/mol more stable than the α -distonic form. However, the calculations also show that CH 3 BH 2 ·− is unstable with respect to electron detachment, and only the α -distonic form ·CH 2 BH 3 − should be experimentally observed in the gas phase.

The gas-phase negative ion chemistry of molecular fluorine is described, with an emphasis on its use in the regiospecific synthesis of distonic radical anions and related species. Sequential reaction of organic compounds containing two trimethylsilyl (TMS) substituents with F− followed by F2 produces distonic radical anions with the negatively charged and odd-spin sites determined by the locations of the TMS groups. The mechanism of the F2 reaction involves dissociative electron transfer from the TMS-substituted carbanion to F2, yielding an F−/radical complex; subsequent attack by F− on the TMS group of the radical produces the distonic radical anion product. Experimental evidence in support of the proposed mechanism is presented, including the dependence of the efficiency of radical anion formation on both the electron binding energy of the reactant carbanion and the leaving-group ability of the radical anion product. Selected applications of the F2 method for distonic anion synthesis are described, including formation of the negative ions of trimethylene methane, the benzynes, oxyallyl and acetoxyl biradicals and α,3-dehydrotoluene. Mechanistic variations in the F2 reactions with carbanions are described in which the transient F− ion produced by dissociative electron transfer to F2 reacts with the organic radical in the long-lived complex by proton transfer, nucleophilic substitution at carbon, and elimination. Formation of distonic biradical anions (ionized triradicals) from neutral precursors containing three TMS groups is described, along with the rational gas-phase synthesis using F2 of distonic carbene and nitrene anions.

The reactions of o-, m- and p-benzyne anions and the phenide ion with a series of neutral reagents are described. The m- and p-benzyne anions display similar behavior towards Bronsted acids, CS2, N2O, NO and O-2, which is analogous to that of phenide ion but clearly different from that of o-benzyne anion. The strongly basic and nucleophilic character of m- and p-benzyne anions dominates their reactivity, and radical-type reactions are generally not observed. Novel bifunctional reactions between m- and p-benzyne anions and both CS, and NO are observed in which two sequential S-atom abstractions and two NO additions, respectively, take place. (C) 1998 John Wiley & Sons, Ltd.

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTNew Approach to Carbene Chemistry via Distonic Carbene Ions. A Case of Spin-Forbidden Proton Transfer and Carbene−Biradical TautomerismJun Hu, Brian T. Hill, and Robert R. SquiresView Author Information The Department of Chemistry, Purdue University West Lafayette, Indiana 47907 Cite this: J. Am. Chem. Soc. 1997, 119, 48, 11699–11700Publication Date (Web):December 3, 1997Publication History Received5 August 1997Published online3 December 1997Published inissue 1 December 1997https://pubs.acs.org/doi/10.1021/ja9727070https://doi.org/10.1021/ja9727070rapid-communicationACS PublicationsCopyright © 1997 American Chemical SocietyRequest reuse permissionsArticle Views313Altmetric-Citations19LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose SUBJECTS:Anions,Carbene compounds,Cluster ions,Ions,Reaction mechanisms Get e-Alerts

The design and implementation of a simple electrospray ionization source for a flowing afterglow/triple quadrupole device are described. Ions can be electrosprayed directly into the room temperature flow tube through a heated capillary without the need for differential pumping or ion focusing. Detected ion currents at the detector sampling orifice as high as 3 pA have been achieved, and the mass spectra indicate little or no re-clustering of the desolvated ions with the background solvent vapor in the flow tube. Spatially and temporally resolved ion/molecule reactions of electrosprayed ions can be carried out in the flow reactor under thermal energy conditions. Sufficient ion densities can be achieved for tandem mass spectrometric experiments in the triple quadrupole analyzer, including energy-resolved collision-induced dissociation. Selected chemical applications illustrating these features are described, including proton transfer reactions with aromatic polysulfonate dianions and multiply protonated polypeptides and threshold CID of a doubly charged transition metal coordination complex.

The isomeric m- and p-benzyne anions have been generated in the gas phase in a flowing afterglow-triple quadrupole instrument from the reactions of molecular fluorine (F2) with m- and p-(trimethylsilyl)phenyl anions. The mechanism of the F2 reaction involves electron transfer from the (trimethylsilyl)phenyl anion to F2, followed by nucleophilic attack on the resulting (trimethylsilyl)phenyl radical by the nascent F- formed within the intermediate ion/molecule complex. The structures of o-, m-, and p-benzyne anion are unambiguously identified by a classical derivatization scheme wherein the ions are first converted to the corresponding o-, m-, and p-nitrobenzoates by stepwise addition of CO2 and NO2. These derivatives are then identified by forming proton-bound dimers of each ion with CHF2CO2H, and comparing the O2NC6H4CO2-/CHF2CO2- yield ratios obtained by collision-induced dissociation (CID) with those obtained from analogous experiments with the authentic nitrobenzoate ions. Estimates of the electron af...

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTDistonic Biradical Anions. Synthesis and Characterization of the 3,5-Dehydrophenyl and 1,3,5-Trimethylenebenzene Negative IonsJun Hu and Robert R. SquiresView Author Information Department of Chemistry, Purdue University West Lafayette, Indiana 47907 Cite this: J. Am. Chem. Soc. 1996, 118, 24, 5816–5817Publication Date (Web):June 19, 1996Publication History Received8 March 1996Published online19 June 1996Published inissue 1 January 1996https://doi.org/10.1021/ja960756rCopyright © 1996 American Chemical SocietyRequest reuse permissionsArticle Views201Altmetric-Citations23LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit Read OnlinePDF (136 KB) Get e-AlertscloseSUBJECTS:Anions,Ions,Quantum mechanics,Reaction products,Reactivity Get e-Alerts

The photoelectron spectrum of the trimethylenemethane (TMM) negative ion is described. The electron affinity of TMM is found from the spectrum to be 0. 431±0.006 eV, and the energy difference between the \(\tilde X^3 A'_2 \)3A′2 and \(\tilde b^1 A_1 \)1A1 states of TMM is determined to be 16.1±0.2 kcal/mol. The energy difference between the lowest energy triplet and singlet states is estimated to be 13–16 kcal/mol. The enthalpy of formation of TMM is measured to be 70±3 kcal/mol, and the C-H bond enthalpy in 2-methylallyl radical is 90±2 kcal/mol. Previously unobserved vibrational frequencies of 425, 915, and 1310 cm−1 are found for the triplet state of TMM, whereas a frequency of 325 cm−1 is found for the singlet state. In addition, an overtone peak is observed for the triplet state at 1455 cm−1, and both states contain peaks that are assigned to bands arising from excited vibrational levels of the ion.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTRegioselective Synthesis of Biradical Negative Ions in the Gas Phase. Generation of Trimethylenemethane, m-Benzyne, and p-Benzyne AnionsPaul G. Wenthold, Jun Hu, and Robert R. SquiresCite this: J. Am. Chem. Soc. 1994, 116, 15, 6961–6962Publication Date (Print):July 1, 1994Publication History Published online1 May 2002Published inissue 1 July 1994https://pubs.acs.org/doi/10.1021/ja00094a071https://doi.org/10.1021/ja00094a071research-articleACS PublicationsRequest reuse permissionsArticle Views170Altmetric-Citations77LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts