PUMA publications for /tag/conjugationhttps://puma.ub.uni-stuttgart.de/tag/conjugationPUMA RSS feed for /tag/conjugation2024-03-28T09:53:12+01:00Effects of cyclic 8p-electron conjugation in reductively silylated nitrogen heterocycleshttps://puma.ub.uni-stuttgart.de/bibtex/2a3e31762ee93b14c4b267bda7acc33a4/huebleriachuebleriac2022-06-15T11:26:56+02:00antiaromaticity conjugation heterocycle;dihydropyrazine nitrogen silyl silylated <span data-person-type="author" class="authorEditorList "><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Wolfgang. Kaim" itemprop="url" href="/person/1bba34322f4187365bf9c012743fa0243/author/0"><span itemprop="name">W. Kaim</span></a></span></span>. </span><span class="additional-entrytype-information"><span itemtype="http://schema.org/PublicationIssue" itemscope="itemscope" itemprop="isPartOf"><em><span itemprop="journal">Journal of the American Chemical Society</span>, </em> <em><span itemtype="http://schema.org/PublicationVolume" itemscope="itemscope" itemprop="isPartOf"><span itemprop="volumeNumber">105 </span></span>(<span itemprop="issueNumber">4</span>):
<span itemprop="pagination">707--713</span></em> </span>(<em><span>1983<meta content="1983" itemprop="datePublished"/></span></em>)</span>Wed Jun 15 11:26:56 CEST 2022Journal of the American Chemical Society4707--713Effects of cyclic 8\textgreek{p}-electron conjugation in reductively silylated nitrogen heterocycles1051983antiaromaticity conjugation heterocycle;dihydropyrazine nitrogen silyl silylated A no. of partly reduced N-heterocycles ,e.g., I [R = H (II), 2-Me, 2,3,5-Me3, etc.), III, have been prepd. by reductive silylation of arom. precursors. The N-silyl substituents stabilize unusual electronic structures such as the 1,4-dihydropyrazine system toward rearrangements. In addn., Me3Si substitution is likely to cause planarization at the amino N atoms. This may lead to cyclic 8\textgreek{p}-electron conjugation, as has been established, e.g., for II. The exptl. results obtained for II by comparative 1H NMR and photoelectron spectroscopic studies are a distinct paratropism, an exceptionally low ionization potential, and an enormous difference between the first and second ionization energies. These effects confirm the predictions made for planar 1,4-dihydropyrazine on the basis of HMO calcns. Corresponding to the very low ionization potentials of most of the reduced compds., persistent radical cations such as II+.bul. have been readily obtained (ESR). Modification of II by Me substitution or by extension of the \textgreek{p} system results in an attenuation of the 8\textgreek{p}-electron conjugation through steric and/or electronic factors. [on SciFinder(R)]Ruthenium complexes with vinyl, styryl, and vinylpyrenyl ligands: A case of non-innocence in organometallic chemistryhttps://puma.ub.uni-stuttgart.de/bibtex/2ffc8ac9ac6e5c7681f8e0ed77243b8c9/huebleriachuebleriac2022-06-15T11:26:56+02:00ESR carbonyl complex complex;crystal complex;mol complex;ruthenium conjugated conjugation effect electrooxidn;spectroelectrochem hexenyl oxidn phosphine pi potential prepn pyrenylethenyl pyridine ruthenium spectra structure styryl vinyl vinylruthenium <span data-person-type="author" class="authorEditorList "><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Joerg Maurer" itemprop="url" href="/person/19784e4c65bc618f661506a3660a9a016/author/0"><span itemprop="name">J. Maurer</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Michael Linseis" itemprop="url" href="/person/19784e4c65bc618f661506a3660a9a016/author/1"><span itemprop="name">M. Linseis</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Biprajit Sarkar" itemprop="url" href="/person/19784e4c65bc618f661506a3660a9a016/author/2"><span itemprop="name">B. Sarkar</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Brigitte Schwederski" itemprop="url" href="/person/19784e4c65bc618f661506a3660a9a016/author/3"><span itemprop="name">B. Schwederski</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Mark Niemeyer" itemprop="url" href="/person/19784e4c65bc618f661506a3660a9a016/author/4"><span itemprop="name">M. Niemeyer</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Wolfgang Kaim" itemprop="url" href="/person/19784e4c65bc618f661506a3660a9a016/author/5"><span itemprop="name">W. Kaim</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Stanislav Zalis" itemprop="url" href="/person/19784e4c65bc618f661506a3660a9a016/author/6"><span itemprop="name">S. Zalis</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Chris Anson" itemprop="url" href="/person/19784e4c65bc618f661506a3660a9a016/author/7"><span itemprop="name">C. Anson</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Manfred Zabel" itemprop="url" href="/person/19784e4c65bc618f661506a3660a9a016/author/8"><span itemprop="name">M. Zabel</span></a></span>, </span> and <span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Rainer F. Winter" itemprop="url" href="/person/19784e4c65bc618f661506a3660a9a016/author/9"><span itemprop="name">R. Winter</span></a></span></span>. </span><span class="additional-entrytype-information"><span itemtype="http://schema.org/PublicationIssue" itemscope="itemscope" itemprop="isPartOf"><em><span itemprop="journal">Journal of the American Chemical Society</span>, </em> <em><span itemtype="http://schema.org/PublicationVolume" itemscope="itemscope" itemprop="isPartOf"><span itemprop="volumeNumber">130 </span></span>(<span itemprop="issueNumber">1</span>):
<span itemprop="pagination">259--268</span></em> </span>(<em><span>2008<meta content="2008" itemprop="datePublished"/></span></em>)</span>Wed Jun 15 11:26:56 CEST 2022Journal of the American Chemical Society1259--268Ruthenium complexes with vinyl, styryl, and vinylpyrenyl ligands: A case of non-innocence in organometallic chemistry1302008ESR carbonyl complex complex;crystal complex;mol complex;ruthenium conjugated conjugation effect electrooxidn;spectroelectrochem hexenyl oxidn phosphine pi potential prepn pyrenylethenyl pyridine ruthenium spectra structure styryl vinyl vinylruthenium A series of vinylruthenium bis-phosphine five- and six-coordinated complexes with non-conjugated 1-hexenyl, conjugated styryl and pyrenylethenyl ligands were prepd.; the effects of conjugation of the arom. system with vinyl \textgreek{p}-bond on oxidn. potential, stability of the oxidated species, ESR spectra and IR CO-stretching bands were systematically explored by IR-spectroelectrochem. and DFT calcns. Hydrometalation of 1-hexyne, phenylacetylene and 1-ethynylpyrene affords the corresponding five-coordinated ruthenium complexes [(PR3)2Cl(CO)RuCH:CHR1] (1a-3a; R = Ph, R1 = Bu, Ph, 1-pyrenyl; 1c-3c; R = iPr, same R1) and their octahedral pyridine adducts [(PPh3)2Cl(CO)(4-EtO2CC5H4N-\textgreek{k}N)RuCH:CHR1] (1b-3b; same R1). Crystal structures of 1b, 1c, 3c and 3a·PPh3 and enynyl complex [Ru(CO)Cl(PPh3)2(\textgreek{h}1:\textgreek{h}2-nBuHC:CHC$\equiv$CnBu)], the result of coupling of the hexenyl ligand of complex 1a with another mol. of 1-hexyne, are reported. All vinyl complexes undergo a one-electron oxidn. at fairly low potentials and a second oxidn. at more pos. potentials. Anodic half-wave or peak potentials show a progressive shift to lower values as \textgreek{p}-conjugation within the vinyl ligand increases. Carbonyl band shifts of the metal-bonded CO ligand upon monooxidn. are significantly smaller than is expected of a metal-centered oxidn. process and are further diminished as the vinyl CH:CH entity is incorporated into a more extended \textgreek{p}-system. ESR spectra of the electrogenerated radical cations display negligible g-value anisotropies and small deviations of the av. g-value from that of the free electron. The vinyl ligands thus strongly contribute to or even dominate the anodic oxidn. processes. This renders them a class of truly {\dq}non-innocent{\dq} ligands in organometallic ruthenium chem. Exptl. findings are fully supported by quantum chem. calcns. The contribution of the vinyl ligand to the HOMO increases from 46{\%} (Ru-vinyl delocalized) to 84{\%} (vinyl dominated) as R changes from Bu to 1-pyrenyl. [on SciFinder(R)]Electron-rich olefins. 3. Formation of the first N,N'-persilylated 1,4-diaminoethene via a 1,2,3-triazoline(4) intermediate with 8 cyclically conjugated p electrons and 3 neighboring nitrogen electron pairshttps://puma.ub.uni-stuttgart.de/bibtex/20a341a252e531881c17054ad94bdee91/huebleriachuebleriac2022-06-15T11:26:56+02:00ESR;conformation cation cleavage conformation;ring conjugation intermediate mechanism;triazole mechanism;triazoline photoelectron prepn radical reductive silyl silylation silyltriazole silyltriazole;silylation spectra;ethenediamine tetrasilyl tetrasilylethenediamine trisilyl <span data-person-type="author" class="authorEditorList "><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Christian Bessenbacher" itemprop="url" href="/person/1c65d3ac595830d6ecadf2484822935b4/author/0"><span itemprop="name">C. Bessenbacher</span></a></span>, </span> and <span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Wolfgang. Kaim" itemprop="url" href="/person/1c65d3ac595830d6ecadf2484822935b4/author/1"><span itemprop="name">W. Kaim</span></a></span></span>. </span><span class="additional-entrytype-information"><span itemtype="http://schema.org/PublicationIssue" itemscope="itemscope" itemprop="isPartOf"><em><span itemprop="journal">Zeitschrift fuer Naturforschung, B: A Journal of Chemical Sciences</span>, </em> <em><span itemtype="http://schema.org/PublicationVolume" itemscope="itemscope" itemprop="isPartOf"><span itemprop="volumeNumber">44 </span></span>(<span itemprop="issueNumber">5</span>):
<span itemprop="pagination">511--518</span></em> </span>(<em><span>1989<meta content="1989" itemprop="datePublished"/></span></em>)</span>Wed Jun 15 11:26:56 CEST 2022Zeitschrift fuer Naturforschung, B: A Journal of Chemical Sciences5511--518Electron-rich olefins. 3. Formation of the first N,N'-persilylated 1,4-diaminoethene via a 1,2,3-triazoline(4) intermediate with 8 cyclically conjugated \textgreek{p} electrons and 3 neighboring nitrogen electron pairs441989ESR;conformation cation cleavage conformation;ring conjugation intermediate mechanism;triazole mechanism;triazoline photoelectron prepn radical reductive silyl silylation silyltriazole silyltriazole;silylation spectra;ethenediamine tetrasilyl tetrasilylethenediamine trisilyl Exhaustive reductive silylation of 2-(trimethylsilyl)-1,2,3-triazole (I) using Me3SiCl/K yields (E)-(Me3Si)2NCH:CHN(SiMe3)2 (II) and N(SiMe3)3. Initial reductive 1,4-addn. to I leads to 1,2,3-tris(trimethylsilyl)-1,2,3-triazoline (III) as an intermediate, which is rapidly reduced and silylated further to give II. Partial \textgreek{p} overlap within the five-membered ring of III is evident from NMR shifts and electron-transfer reaction with TCNE. Photoelectron spectroscopy of II and the lability of its radical cation, as studied by ESR, show that this system cannot adopt a planar conformation, in contrast to the tetrazene(2) analog. [on SciFinder(R)]Charge delocalization in a heterobimetallic ferrocene-(vinyl)Ru(CO)Cl(PiPr3)2 systemhttps://puma.ub.uni-stuttgart.de/bibtex/23022d0ef889737bdfeee3ee620ceb5f0/huebleriachuebleriac2022-06-15T11:26:56+02:00calcn communication complex complex;frontier complex;mixed complex;solvent complex;vinylferrocene conjugation crystal effect electronic electrooxidn;mol ethenylruthenium ferrocenyl mixed orbital oxidn prepn ruthenium sigma spectra structure valence <span data-person-type="author" class="authorEditorList "><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Konrad Kowalski" itemprop="url" href="/person/120994018d1f362552dbbc54ec04c1a86/author/0"><span itemprop="name">K. Kowalski</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Michael Linseis" itemprop="url" href="/person/120994018d1f362552dbbc54ec04c1a86/author/1"><span itemprop="name">M. Linseis</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Rainer F. Winter" itemprop="url" href="/person/120994018d1f362552dbbc54ec04c1a86/author/2"><span itemprop="name">R. Winter</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Manfred Zabel" itemprop="url" href="/person/120994018d1f362552dbbc54ec04c1a86/author/3"><span itemprop="name">M. Zabel</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Stanislav Zalis" itemprop="url" href="/person/120994018d1f362552dbbc54ec04c1a86/author/4"><span itemprop="name">S. Zalis</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Harald Kelm" itemprop="url" href="/person/120994018d1f362552dbbc54ec04c1a86/author/5"><span itemprop="name">H. Kelm</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Hans-Jorg Kruger" itemprop="url" href="/person/120994018d1f362552dbbc54ec04c1a86/author/6"><span itemprop="name">H. Kruger</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Biprajit Sarkar" itemprop="url" href="/person/120994018d1f362552dbbc54ec04c1a86/author/7"><span itemprop="name">B. Sarkar</span></a></span>, </span> and <span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Wolfgang. Kaim" itemprop="url" href="/person/120994018d1f362552dbbc54ec04c1a86/author/8"><span itemprop="name">W. Kaim</span></a></span></span>. </span><span class="additional-entrytype-information"><span itemtype="http://schema.org/PublicationIssue" itemscope="itemscope" itemprop="isPartOf"><em><span itemprop="journal">Organometallics</span>, </em> <em><span itemtype="http://schema.org/PublicationVolume" itemscope="itemscope" itemprop="isPartOf"><span itemprop="volumeNumber">28 </span></span>(<span itemprop="issueNumber">14</span>):
<span itemprop="pagination">4196--4209</span></em> </span>(<em><span>2009<meta content="2009" itemprop="datePublished"/></span></em>)</span>Wed Jun 15 11:26:56 CEST 2022Organometallics144196--4209Charge delocalization in a heterobimetallic ferrocene-(vinyl)Ru(CO)Cl(PiPr3)2 system282009calcn communication complex complex;frontier complex;mixed complex;solvent complex;vinylferrocene conjugation crystal effect electronic electrooxidn;mol ethenylruthenium ferrocenyl mixed orbital oxidn prepn ruthenium sigma spectra structure valence Ruthenium \textgreek{s}-vinylferrocene electronically conjugated redox-active complex was prepd.; mixed-valence cationic states were explored by spectroelectrochem., IR, NIR, ESR spectra, and DFT calcns. Addn. of ruthenium hydride [RuH(CO)Cl(iPr3)2] to ethynylferrocene gave \textgreek{s}-vinylruthenium complex [Cl(CO)(PiPr3)2RuCH:CHFc] (1, Fc = ferrocenyl), which was characterized by NMR, IR, ESI-MS, and Moessbauer spectroscopy and by x-ray crystallog. Complex 1 features conjoined ferrocene and (vinyl)ruthenium redox sites and undergoes two consecutive reversible oxidns. Pure samples of cryst., monooxidized [1·+][PF6] were prepd. by chem. oxidn. of 1 with the ferrocenium hexafluorophosphate. Structural comparison with 1 reveals an increase of Fe-C and Fe-Cp bond lengths and ring tilting of the Cp decks, as is typical of ferrocenium ions, but also a discernible lengthening of the Ru-C(CO) and Ru-P bonds and a shortening of the Ru-C(vinyl) bond upon oxidn. This supports the general idea of charge delocalization over both redox sites in 1·+. Band shifts of the charge-sensitive IR labels (\textgreek{n}(CO) for Ru, \textgreek{n}(C-H, Cp) for Fc), the rather small g-anisotropy in the ESR spectrum of 1·+, and the results of quantum chem. calcns. indicate that in soln. the pos. charge partly resides on the vinyl ruthenium moiety. Comparison of IR shifts in the solid state and in soln. and the quadrupole splitting in the Moessbauer spectrum of powd. 1·+ point to a larger extent of charge localization on the ferrocenyl site in solid samples. This is probably due to CH···F hydrogen bonding interactions between the cyclopentadienyl hydrogen atoms of the radical cations and the PF6- counterions. Monooxidized 1·+ displays low-energy electronic absorption bands at 1370 and 2150 nm. According to quantum chem. calcns., the underlying transitions are largely localized on the ferrocene part of the mol. with only little charge transfer into the vinyl ruthenium subunit. The second oxidn. is more biased toward the (vinyl)ruthenium site. [on SciFinder(R)]Charge delocalization in a heterobimetallic ferrocene-(vinyl)Ru(CO)Cl(PiPr3)2 systemhttps://puma.ub.uni-stuttgart.de/bibtex/23022d0ef889737bdfeee3ee620ceb5f0/b_schwederskib_schwederski2019-07-15T13:41:23+02:00calcn communication complex complex;frontier complex;mixed complex;solvent complex;vinylferrocene conjugation crystal effect electronic electrooxidn;mol ethenylruthenium ferrocenyl mixed orbital oxidn prepn ruthenium sigma spectra structure valence <span data-person-type="author" class="authorEditorList "><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Konrad Kowalski" itemprop="url" href="/person/120994018d1f362552dbbc54ec04c1a86/author/0"><span itemprop="name">K. Kowalski</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Michael Linseis" itemprop="url" href="/person/120994018d1f362552dbbc54ec04c1a86/author/1"><span itemprop="name">M. Linseis</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Rainer F. Winter" itemprop="url" href="/person/120994018d1f362552dbbc54ec04c1a86/author/2"><span itemprop="name">R. Winter</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Manfred Zabel" itemprop="url" href="/person/120994018d1f362552dbbc54ec04c1a86/author/3"><span itemprop="name">M. Zabel</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Stanislav Zalis" itemprop="url" href="/person/120994018d1f362552dbbc54ec04c1a86/author/4"><span itemprop="name">S. Zalis</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Harald Kelm" itemprop="url" href="/person/120994018d1f362552dbbc54ec04c1a86/author/5"><span itemprop="name">H. Kelm</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Hans-Jorg Kruger" itemprop="url" href="/person/120994018d1f362552dbbc54ec04c1a86/author/6"><span itemprop="name">H. Kruger</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Biprajit Sarkar" itemprop="url" href="/person/120994018d1f362552dbbc54ec04c1a86/author/7"><span itemprop="name">B. Sarkar</span></a></span>, </span> and <span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Wolfgang. Kaim" itemprop="url" href="/person/120994018d1f362552dbbc54ec04c1a86/author/8"><span itemprop="name">W. Kaim</span></a></span></span>. </span><span class="additional-entrytype-information"><span itemtype="http://schema.org/PublicationIssue" itemscope="itemscope" itemprop="isPartOf"><em><span itemprop="journal">Organometallics</span>, </em> <em><span itemtype="http://schema.org/PublicationVolume" itemscope="itemscope" itemprop="isPartOf"><span itemprop="volumeNumber">28 </span></span>(<span itemprop="issueNumber">14</span>):
<span itemprop="pagination">4196--4209</span></em> </span>(<em><span>2009<meta content="2009" itemprop="datePublished"/></span></em>)</span>Mon Jul 15 13:41:23 CEST 2019Organometallics144196--4209Charge delocalization in a heterobimetallic ferrocene-(vinyl)Ru(CO)Cl(PiPr3)2 system282009calcn communication complex complex;frontier complex;mixed complex;solvent complex;vinylferrocene conjugation crystal effect electronic electrooxidn;mol ethenylruthenium ferrocenyl mixed orbital oxidn prepn ruthenium sigma spectra structure valence Ruthenium \textgreek{s}-vinylferrocene electronically conjugated redox-active complex was prepd.; mixed-valence cationic states were explored by spectroelectrochem., IR, NIR, ESR spectra, and DFT calcns. Addn. of ruthenium hydride [RuH(CO)Cl(iPr3)2] to ethynylferrocene gave \textgreek{s}-vinylruthenium complex [Cl(CO)(PiPr3)2RuCH:CHFc] (1, Fc = ferrocenyl), which was characterized by NMR, IR, ESI-MS, and Moessbauer spectroscopy and by x-ray crystallog. Complex 1 features conjoined ferrocene and (vinyl)ruthenium redox sites and undergoes two consecutive reversible oxidns. Pure samples of cryst., monooxidized [1·+][PF6] were prepd. by chem. oxidn. of 1 with the ferrocenium hexafluorophosphate. Structural comparison with 1 reveals an increase of Fe-C and Fe-Cp bond lengths and ring tilting of the Cp decks, as is typical of ferrocenium ions, but also a discernible lengthening of the Ru-C(CO) and Ru-P bonds and a shortening of the Ru-C(vinyl) bond upon oxidn. This supports the general idea of charge delocalization over both redox sites in 1·+. Band shifts of the charge-sensitive IR labels (\textgreek{n}(CO) for Ru, \textgreek{n}(C-H, Cp) for Fc), the rather small g-anisotropy in the ESR spectrum of 1·+, and the results of quantum chem. calcns. indicate that in soln. the pos. charge partly resides on the vinyl ruthenium moiety. Comparison of IR shifts in the solid state and in soln. and the quadrupole splitting in the Moessbauer spectrum of powd. 1·+ point to a larger extent of charge localization on the ferrocenyl site in solid samples. This is probably due to CH···F hydrogen bonding interactions between the cyclopentadienyl hydrogen atoms of the radical cations and the PF6- counterions. Monooxidized 1·+ displays low-energy electronic absorption bands at 1370 and 2150 nm. According to quantum chem. calcns., the underlying transitions are largely localized on the ferrocene part of the mol. with only little charge transfer into the vinyl ruthenium subunit. The second oxidn. is more biased toward the (vinyl)ruthenium site. [on SciFinder(R)]Electron-rich olefins. 3. Formation of the first N,N'-persilylated 1,4-diaminoethene via a 1,2,3-triazoline(4) intermediate with 8 cyclically conjugated p electrons and 3 neighboring nitrogen electron pairshttps://puma.ub.uni-stuttgart.de/bibtex/20a341a252e531881c17054ad94bdee91/b_schwederskib_schwederski2019-07-15T13:41:23+02:00ESR;conformation cation cleavage conformation;ring conjugation intermediate mechanism;triazole mechanism;triazoline photoelectron prepn radical reductive silyl silylation silyltriazole silyltriazole;silylation spectra;ethenediamine tetrasilyl tetrasilylethenediamine trisilyl <span data-person-type="author" class="authorEditorList "><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Christian Bessenbacher" itemprop="url" href="/person/1c65d3ac595830d6ecadf2484822935b4/author/0"><span itemprop="name">C. Bessenbacher</span></a></span>, </span> and <span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Wolfgang. Kaim" itemprop="url" href="/person/1c65d3ac595830d6ecadf2484822935b4/author/1"><span itemprop="name">W. Kaim</span></a></span></span>. </span><span class="additional-entrytype-information"><span itemtype="http://schema.org/PublicationIssue" itemscope="itemscope" itemprop="isPartOf"><em><span itemprop="journal">Zeitschrift fuer Naturforschung, B: A Journal of Chemical Sciences</span>, </em> <em><span itemtype="http://schema.org/PublicationVolume" itemscope="itemscope" itemprop="isPartOf"><span itemprop="volumeNumber">44 </span></span>(<span itemprop="issueNumber">5</span>):
<span itemprop="pagination">511--518</span></em> </span>(<em><span>1989<meta content="1989" itemprop="datePublished"/></span></em>)</span>Mon Jul 15 13:41:23 CEST 2019Zeitschrift fuer Naturforschung, B: A Journal of Chemical Sciences5511--518Electron-rich olefins. 3. Formation of the first N,N'-persilylated 1,4-diaminoethene via a 1,2,3-triazoline(4) intermediate with 8 cyclically conjugated \textgreek{p} electrons and 3 neighboring nitrogen electron pairs441989ESR;conformation cation cleavage conformation;ring conjugation intermediate mechanism;triazole mechanism;triazoline photoelectron prepn radical reductive silyl silylation silyltriazole silyltriazole;silylation spectra;ethenediamine tetrasilyl tetrasilylethenediamine trisilyl Exhaustive reductive silylation of 2-(trimethylsilyl)-1,2,3-triazole (I) using Me3SiCl/K yields (E)-(Me3Si)2NCH:CHN(SiMe3)2 (II) and N(SiMe3)3. Initial reductive 1,4-addn. to I leads to 1,2,3-tris(trimethylsilyl)-1,2,3-triazoline (III) as an intermediate, which is rapidly reduced and silylated further to give II. Partial \textgreek{p} overlap within the five-membered ring of III is evident from NMR shifts and electron-transfer reaction with TCNE. Photoelectron spectroscopy of II and the lability of its radical cation, as studied by ESR, show that this system cannot adopt a planar conformation, in contrast to the tetrazene(2) analog. [on SciFinder(R)]Ruthenium complexes with vinyl, styryl, and vinylpyrenyl ligands: A case of non-innocence in organometallic chemistryhttps://puma.ub.uni-stuttgart.de/bibtex/2ffc8ac9ac6e5c7681f8e0ed77243b8c9/b_schwederskib_schwederski2019-07-15T13:41:23+02:00ESR carbonyl complex complex;crystal complex;mol complex;ruthenium conjugated conjugation effect electrooxidn;spectroelectrochem hexenyl oxidn phosphine pi potential prepn pyrenylethenyl pyridine ruthenium spectra structure styryl vinyl vinylruthenium <span data-person-type="author" class="authorEditorList "><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Joerg Maurer" itemprop="url" href="/person/19784e4c65bc618f661506a3660a9a016/author/0"><span itemprop="name">J. Maurer</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Michael Linseis" itemprop="url" href="/person/19784e4c65bc618f661506a3660a9a016/author/1"><span itemprop="name">M. Linseis</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Biprajit Sarkar" itemprop="url" href="/person/19784e4c65bc618f661506a3660a9a016/author/2"><span itemprop="name">B. Sarkar</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Brigitte Schwederski" itemprop="url" href="/person/19784e4c65bc618f661506a3660a9a016/author/3"><span itemprop="name">B. Schwederski</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Mark Niemeyer" itemprop="url" href="/person/19784e4c65bc618f661506a3660a9a016/author/4"><span itemprop="name">M. Niemeyer</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Wolfgang Kaim" itemprop="url" href="/person/19784e4c65bc618f661506a3660a9a016/author/5"><span itemprop="name">W. Kaim</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Stanislav Zalis" itemprop="url" href="/person/19784e4c65bc618f661506a3660a9a016/author/6"><span itemprop="name">S. Zalis</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Chris Anson" itemprop="url" href="/person/19784e4c65bc618f661506a3660a9a016/author/7"><span itemprop="name">C. Anson</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Manfred Zabel" itemprop="url" href="/person/19784e4c65bc618f661506a3660a9a016/author/8"><span itemprop="name">M. Zabel</span></a></span>, </span> and <span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Rainer F. Winter" itemprop="url" href="/person/19784e4c65bc618f661506a3660a9a016/author/9"><span itemprop="name">R. Winter</span></a></span></span>. </span><span class="additional-entrytype-information"><span itemtype="http://schema.org/PublicationIssue" itemscope="itemscope" itemprop="isPartOf"><em><span itemprop="journal">Journal of the American Chemical Society</span>, </em> <em><span itemtype="http://schema.org/PublicationVolume" itemscope="itemscope" itemprop="isPartOf"><span itemprop="volumeNumber">130 </span></span>(<span itemprop="issueNumber">1</span>):
<span itemprop="pagination">259--268</span></em> </span>(<em><span>2008<meta content="2008" itemprop="datePublished"/></span></em>)</span>Mon Jul 15 13:41:23 CEST 2019Journal of the American Chemical Society1259--268Ruthenium complexes with vinyl, styryl, and vinylpyrenyl ligands: A case of non-innocence in organometallic chemistry1302008ESR carbonyl complex complex;crystal complex;mol complex;ruthenium conjugated conjugation effect electrooxidn;spectroelectrochem hexenyl oxidn phosphine pi potential prepn pyrenylethenyl pyridine ruthenium spectra structure styryl vinyl vinylruthenium A series of vinylruthenium bis-phosphine five- and six-coordinated complexes with non-conjugated 1-hexenyl, conjugated styryl and pyrenylethenyl ligands were prepd.; the effects of conjugation of the arom. system with vinyl \textgreek{p}-bond on oxidn. potential, stability of the oxidated species, ESR spectra and IR CO-stretching bands were systematically explored by IR-spectroelectrochem. and DFT calcns. Hydrometalation of 1-hexyne, phenylacetylene and 1-ethynylpyrene affords the corresponding five-coordinated ruthenium complexes [(PR3)2Cl(CO)RuCH:CHR1] (1a-3a; R = Ph, R1 = Bu, Ph, 1-pyrenyl; 1c-3c; R = iPr, same R1) and their octahedral pyridine adducts [(PPh3)2Cl(CO)(4-EtO2CC5H4N-\textgreek{k}N)RuCH:CHR1] (1b-3b; same R1). Crystal structures of 1b, 1c, 3c and 3a·PPh3 and enynyl complex [Ru(CO)Cl(PPh3)2(\textgreek{h}1:\textgreek{h}2-nBuHC:CHC$\equiv$CnBu)], the result of coupling of the hexenyl ligand of complex 1a with another mol. of 1-hexyne, are reported. All vinyl complexes undergo a one-electron oxidn. at fairly low potentials and a second oxidn. at more pos. potentials. Anodic half-wave or peak potentials show a progressive shift to lower values as \textgreek{p}-conjugation within the vinyl ligand increases. Carbonyl band shifts of the metal-bonded CO ligand upon monooxidn. are significantly smaller than is expected of a metal-centered oxidn. process and are further diminished as the vinyl CH:CH entity is incorporated into a more extended \textgreek{p}-system. ESR spectra of the electrogenerated radical cations display negligible g-value anisotropies and small deviations of the av. g-value from that of the free electron. The vinyl ligands thus strongly contribute to or even dominate the anodic oxidn. processes. This renders them a class of truly {\dq}non-innocent{\dq} ligands in organometallic ruthenium chem. Exptl. findings are fully supported by quantum chem. calcns. The contribution of the vinyl ligand to the HOMO increases from 46{\%} (Ru-vinyl delocalized) to 84{\%} (vinyl dominated) as R changes from Bu to 1-pyrenyl. [on SciFinder(R)]Effects of cyclic 8p-electron conjugation in reductively silylated nitrogen heterocycleshttps://puma.ub.uni-stuttgart.de/bibtex/2a3e31762ee93b14c4b267bda7acc33a4/b_schwederskib_schwederski2019-07-15T13:41:23+02:00antiaromaticity conjugation heterocycle;dihydropyrazine nitrogen silyl silylated <span data-person-type="author" class="authorEditorList "><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Wolfgang. Kaim" itemprop="url" href="/person/1bba34322f4187365bf9c012743fa0243/author/0"><span itemprop="name">W. Kaim</span></a></span></span>. </span><span class="additional-entrytype-information"><span itemtype="http://schema.org/PublicationIssue" itemscope="itemscope" itemprop="isPartOf"><em><span itemprop="journal">Journal of the American Chemical Society</span>, </em> <em><span itemtype="http://schema.org/PublicationVolume" itemscope="itemscope" itemprop="isPartOf"><span itemprop="volumeNumber">105 </span></span>(<span itemprop="issueNumber">4</span>):
<span itemprop="pagination">707--713</span></em> </span>(<em><span>1983<meta content="1983" itemprop="datePublished"/></span></em>)</span>Mon Jul 15 13:41:23 CEST 2019Journal of the American Chemical Society4707--713Effects of cyclic 8\textgreek{p}-electron conjugation in reductively silylated nitrogen heterocycles1051983antiaromaticity conjugation heterocycle;dihydropyrazine nitrogen silyl silylated A no. of partly reduced N-heterocycles ,e.g., I [R = H (II), 2-Me, 2,3,5-Me3, etc.), III, have been prepd. by reductive silylation of arom. precursors. The N-silyl substituents stabilize unusual electronic structures such as the 1,4-dihydropyrazine system toward rearrangements. In addn., Me3Si substitution is likely to cause planarization at the amino N atoms. This may lead to cyclic 8\textgreek{p}-electron conjugation, as has been established, e.g., for II. The exptl. results obtained for II by comparative 1H NMR and photoelectron spectroscopic studies are a distinct paratropism, an exceptionally low ionization potential, and an enormous difference between the first and second ionization energies. These effects confirm the predictions made for planar 1,4-dihydropyrazine on the basis of HMO calcns. Corresponding to the very low ionization potentials of most of the reduced compds., persistent radical cations such as II+.bul. have been readily obtained (ESR). Modification of II by Me substitution or by extension of the \textgreek{p} system results in an attenuation of the 8\textgreek{p}-electron conjugation through steric and/or electronic factors. [on SciFinder(R)]