Depending on ratios of starting materials and reaction conditions, treatment of sodium indenide (NaInd) with C6F6 and NaH in THF afforded 3-(pentafluorophenyl)indene (1) or 1,3-bis(pentafluorophenyl)indene (2) in 65% and 80% yields, respectively, after aqueous workup and recrystallization from methanol. Both 1 and 2 reacted quantitatively with NaH to afford the corresponding mono- and diarylated sodium indenides (3 and 4), respectively. The monoarylated ligand (3) reacted with Re(CO)5Br in THF at 65 °C for 2 h to afford pentacarbonyl(η1-3-(pentafluorophenyl)-1-indenyl]rhenium(I) (5, 57%), which was thermally decarbonylated in decane to afford tricarbonyl[η5-1-(pentafluorophenyl)indenyl]rhenium(I) (6, 85%). An analogous reaction of the diarylated ligand (4) with Re(CO)5Br in THF at 65 °C directly gave tricarbonyl[η5-1,3-bis(pentafluorophenyl)indenyl]rhenium(I) (7) in 67% yield. All three rhenium carbonyl complexes were characterized by IR, NMR, elemental analysis, and single-crystal X-ray diffraction. Infrared spectroscopic measurements showed that each C6F5 substituent increases νCO of η5-indenylrhenium tricarbonyl complexes by 4 cm-1 relative to the unsubstituted parent, demonstrating the strong electron-withdrawing capabilities of the C6F5 group. Distinct, intermolecular C−H···F−C interactions were identified in the crystal packing diagrams of 5−7.
The image shows that single electron transfer is “back on the menu” as a possible mechanism for catalysis by monoamine oxidase B (MAO-B). By using a chemical model for MAO-B, a compelling evidence that the initial chemical step of the oxidation of certain tertiary amines involves proton-coupled electron transfer (PCET) is provided. Molecular oxygen is found to play a key, hitherto unrecognized role in the early steps of the catalysis. The structural/electronic properties of the substrates that provide entry into the electron transfer pathway have been identified and are presented in the Full Paper by J. M. Tanko et al. on page 823 ff.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
The reaction of CpNa (Cp = C5H5) with C6F6 (diglyme, 110 °C, 14 h) afforded a mixture of products, from which two new triarylated cyclopentadienes, 1,2,4-Ar3C5H3 (3) and 1,2,3-Ar3C5H3 (4), were separated by silica gel chromatography (Ar = C6F5). The dienes 3 and 4 were readily converted (NaH, THF) to the corresponding triarylated sodium cyclopentadienides, (1,2,4-Ar3C5H2)Na (7) and (1,2,3-Ar3C5H2)Na (8). Reactions of the ligands 7 and 8 with FeBr2 afforded the ferrocenes (1,2,4-Ar3C5H2)2Fe (11) and (1,2,3-Ar3C5H2)2Fe (12), respectively. The cobaltocenes (ArC5H4)2Co (13), (1,3-Ar2C5H3)2Co (14), (1,2,4-Ar3C5H2)2Co (15), and (1,2,3-Ar3C5H2)2Co (16) were prepared from CoBr2 and (ArC5H4)Na (5), (1,3-Ar2C5H3)Na (6), 7, and 8, respectively. Oxidation of 13 (air, dilute aqueous HCl) followed by precipitation with KPF6 afforded [(ArC5H4)2Co]+PF6- (17). The homologous cobaltocenium ions [1,3-Ar2C5H3]2Co+ (18), (1,2,4- Ar3C5H2)2Co+ (19), and (1,2,3-Ar3C5H2)2Co+ (20) were observed (NMR) only after dissolving the corresponding CoII species 14−16 in D2SO4; efforts to isolate 18−20 as hexafluorophosphates failed. Reactions of the ligands 5−8 with M(CO)5Br (M = Mn, Re) afforded the piano stool complexes (ArCp)Mn(CO)3 (21), (1,3-Ar2Cp)Mn(CO)3 (22), (1,2,4-Ar3C5H2)M(CO)3 (23, M = Mn; 27, M = Re), and (1,2,3-Ar3C5H2)M(CO)3 (24, M = Mn; 28, M = Re). Both the voltammetric oxidation potentials (E1/2) of the substituted metallocenes 9−16 and the carbonyl stretching wavenumbers of the substituted piano stool complexes 21−24 and 25−28 increased linearly with increasing number of C6F5 substituents. Crystal structures were obtained for 2 (two polymorphs), 4, 11, 16, 23, 26, and 27. Noteworthy features of these structures include C6F5−C6F5 arene stacking, C6F5 stacking with benzene solvate molecules, C6F5···O⋮C−M interactions, and extensive C−H···F−C interactions. Barriers toward Cp−C6F5 rotation and Cp−Fe−Cp rotation were quantified for several of the complexes using dynamic 19F and 1H NMR spectroscopy.
NMR-scale reactions of several group 4 metallocene dimethyls with either trityl chloride or benzyl bromide gave the corresponding L2M(Me)X complexes selectively. Five reactions, including syntheses of Cp2Zr(Me)Cl and Ind2Zr(Me)Cl, were conducted on a preparative scale to afford useful isolated yields of L2M(Me)Cl complexes.
ADVERTISEMENT RETURN TO ISSUEPREVArticleCompetitive intramolecular cyclizations of epoxides to aromatic and double bond positions [Erratum to document cited in CA113(3):23551w]Stephen K. Taylor, David S. Bischoff, Curtis L. Blankespoor, Paul A. Deck, Suzanne M. Harvey, Patricia L. Johnson, Ariane E. Marolewski, Steven W. Mork, Douglas H. Motry, and Ronald Van EenenaamCite this: J. Org. Chem. 1991, 56, 19, 5736Publication Date (Print):September 1, 1991Publication History Published online1 May 2002Published inissue 1 September 1991https://pubs.acs.org/doi/10.1021/jo00019a059https://doi.org/10.1021/jo00019a059research-articleACS PublicationsRequest reuse permissionsArticle Views44Altmetric-Citations2LEARN 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
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectronic Effects of Arene Substituents in (.eta.6-Arene)(.eta.5-cyclopentadienyl)iron(II) HexafluorophosphatesPaul G. Gassman and Paul A. DeckCite this: Organometallics 1994, 13, 7, 2890–2894Publication Date (Print):July 1, 1994Publication History Published online1 May 2002Published inissue 1 July 1994https://pubs.acs.org/doi/10.1021/om00019a052https://doi.org/10.1021/om00019a052research-articleACS PublicationsRequest reuse permissionsArticle Views306Altmetric-Citations7LEARN 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
The reaction of decafluorobiphenyl with 10 equiv of sodium cyclopentadienide (NaCp) in THF (65 °C, 2 h) afforded 4,4'-bis(cyclopentadienyl)octafluorobiphenyl (1) as a mixture of double-bond isomers in 72% yield after workup and purification. Subsequent treatment with sodium hydride in THF (25 °C, 6 h) afforded disodium 4,4'-bis(cyclopentadienyl)octafluorobiphenyl (2). Reaction of NaCp, ligand 2, and FeBr2 (21:1:10 mol ratio) in THF afforded mostly ferrocene as well as the diiron complex CpFe(η5-C5H4-4,4'-C6F4C6F4-η5-C5H4)FeCp (3), the linear triiron complex Cp[Fe(η5-C5H4-4,4'-C6F4C6F4-η5-C5H4)]2FeCp (4), and the linear tetrairon complex Cp[Fe(η5-C5H4-4,4'-C6F4C6F4-η5-C5H4)]3FeCp (5), which were isolated by liquid chromatography. Solution voltammetric analysis of 3 showed a single, reversible two-electron oxidation at +200 mV, 4 showed two reversible oxidations (2:1 ratio) at +180 and +372 mV, respectively, and 5 showed two reversible oxidations (2:2 ratio) at +192 and +382 mV, respectively (all vs Cp2Fe|Cp2Fe+). A similar reaction of NaCp, ligand 2, and CoBr2 in THF was worked up with air and dilute aqueous HCl followed by aqueous KPF6 to afford a mixture of cobaltocenium hexafluorophosphates, from which [Cp2Co]+PF6- and the dicobalt complex [CpCo(η5-C5H4-4,4'-C6F4C6F4-η5-C5H4)CoCp]2+[PF6-]2 (6) were isolated by liquid chromatography. CV analysis of 6 showed a single, reversible CoII|CoIII wave at +232 mV relative to Cp2Co|Cp2Co+. These voltammetric data suggest that no significant electronic communication exists between two metals bridged by this conjugated dibasic ligand (2). A crystal structure of diiron complex 3 demonstrated the conformational preferences of the CpC6F4C6F4Cp ligand in the solid state with respective torsional angles of 37.5°, 50.1°, and 32.1°.
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