PUMA publications for /user/b_schwederski/pteridinehttps://puma.ub.uni-stuttgart.de/user/b_schwederski/pteridinePUMA RSS feed for /user/b_schwederski/pteridine2024-03-29T12:39:29+01:00Stabilizing biochemically important intermediates through metal coordination. 5,8-Bis(trimethylsilyl)-5,8-dihydropteridine and its deaza derivativehttps://puma.ub.uni-stuttgart.de/bibtex/2c7f76d187ea623ed9dc7e1f8de6f9922/b_schwederskib_schwederski2019-07-15T13:41:23+02:00deazapteridine pteridine reductive silylation <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/1ead6c81788da22e407b815aa2b40104c/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/1ead6c81788da22e407b815aa2b40104c/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">Journal of Organometallic Chemistry</span>, </em> <em><span itemtype="http://schema.org/PublicationVolume" itemscope="itemscope" itemprop="isPartOf"><span itemprop="volumeNumber">362 </span></span>(<span itemprop="issueNumber">1-2</span>):
<span itemprop="pagination">37--51</span></em> </span>(<em><span>1989<meta content="1989" itemprop="datePublished"/></span></em>)</span>Mon Jul 15 13:41:23 CEST 2019Journal of Organometallic Chemistry1-237--51Stabilizing biochemically important intermediates through metal coordination. 5,8-Bis(trimethylsilyl)-5,8-dihydropteridine and its deaza derivative3621989deazapteridine pteridine reductive silylation Reductive trimethylsilylation of pteridine and its deaza derivs. 1,4,6- and 1,4,5-triazanaphthalene and quinoxaline yields the primary reduced forms of these heterocycles, which contain the 1,4-dihydro-1,4-diazine ring with 8 conjugated \textgreek{p}-electrons as the only low mol. wt. products. Although the organometallic substituents stabilize these biochem. important yet normally short-lived dihydro forms and so allow unambiguous characterization by NMR, the non-cryst., colored compds. are still highly reactive. Unexpectedly, the deaza derivs. prove to be less electron-rich than the silylated dihydropteridine despite a clear increase in the electron d. in the arom. ring. The characteristic conformational flexibility of these intermediates is responsible for this inverse annulation effect. Reductive trimethylsilylation of 1,5-naphthyridine yields the 1-trimethylsilyl-1,4-dihydro deriv. as the major product. [on SciFinder(R)]Coordination ambivalence and fluxional behavior in mono- and binuclear pentacarbonyltungsten complexes of pteridine and its deaza derivativeshttps://puma.ub.uni-stuttgart.de/bibtex/2248687dc2e2486673fb2c4a8d5656820/b_schwederskib_schwederski2019-07-15T13:41:23+02:00carbonyl complex;triazanaphthalene complex;tungsten deaza deriv deriv;naphthyridine fluxionality pteridine tungsten <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/1c4ede1b93002d0a9a60a50513eec5f13/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/1c4ede1b93002d0a9a60a50513eec5f13/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">Journal of Organometallic Chemistry</span>, </em> <em><span itemtype="http://schema.org/PublicationVolume" itemscope="itemscope" itemprop="isPartOf"><span itemprop="volumeNumber">369 </span></span>(<span itemprop="issueNumber">1</span>):
<span itemprop="pagination">83--103</span></em> </span>(<em><span>1989<meta content="1989" itemprop="datePublished"/></span></em>)</span>Mon Jul 15 13:41:23 CEST 2019Journal of Organometallic Chemistry183--103Coordination ambivalence and fluxional behavior in mono- and binuclear pentacarbonyltungsten complexes of pteridine and its deaza derivatives3691989carbonyl complex;triazanaphthalene complex;tungsten deaza deriv deriv;naphthyridine fluxionality pteridine tungsten WL(CO)5 (L = pteridine (pte), 1,5-naphthyridine, (npt), 1,4,5-triazanaphthalene (tan), 1,4,6-triazanaphthalene) and W2(CO)10L1 (L1 = pt, npt) were prepd. Unambiguous identification of coordination sites was only possible by use of high-resoln. 1H NMR because the chem. shifts and spin-spin coupling consts. are characteristically affected by W(CO)5-coordination to neighboring N centers. Fluxional behavior with respect to the peri coordination sites was obsd. for W(CO)5(1,4,5-tan) and W(CO)10(pte). Competition between the more basic pyridine or pyrimidine and the better \textgreek{p} backdonating pyrazine N centers leads to various positions for the nondegenerate equil. between linkage isomers. Cyclic voltammetry and solvent-dependent charge transfer absorption spectra of the complexes reveal low-lying \textgreek{p}* levels which can become populated after chem. or electrochem. redn., the spin distribution in the centrosym. binuclear complex of 1,5-naphthyridine anion radical was fully characterized using ESR and results from MO calcns. [on SciFinder(R)]