PUMA publications for /tag/bidiazinehttps://puma.ub.uni-stuttgart.de/tag/bidiazinePUMA RSS feed for /tag/bidiazine2024-03-28T13:49:29+01:00Coordination characteristics of four isomeric a-diimine ligands. p Molecular orbital perturbation calculations for the bidiazines and their correlation with the properties of group 6 metal carbonyl complexeshttps://puma.ub.uni-stuttgart.de/bibtex/24f6433f1ea46898fc234a4249fcfb849/huebleriachuebleriac2022-06-15T11:26:56+02:00Group VIB basicity bidiazine bidiazine;Group bidiazine;bipyrazine bidiazine;electron bidiazine;molybdenum bidiazine;redox bidiazine;tungsten carbonyl carbonyl;bipyridazine carbonyl;bipyrimidine carbonyl;chromium configuration potential <span data-person-type="author" class="authorEditorList "><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Sylvia Ernst" itemprop="url" href="/person/13efa3bf4b2b2a9ad87713cc0b5dd3acf/author/0"><span itemprop="name">S. Ernst</span></a></span>, </span> and <span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Wolfgang. Kaim" itemprop="url" href="/person/13efa3bf4b2b2a9ad87713cc0b5dd3acf/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 the American Chemical Society</span>, </em> <em><span itemtype="http://schema.org/PublicationVolume" itemscope="itemscope" itemprop="isPartOf"><span itemprop="volumeNumber">108 </span></span>(<span itemprop="issueNumber">13</span>):
<span itemprop="pagination">3578--3586</span></em> </span>(<em><span>1986<meta content="1986" itemprop="datePublished"/></span></em>)</span>Wed Jun 15 11:26:56 CEST 2022Journal of the American Chemical Society133578--3586Coordination characteristics of four isomeric \textgreek{a}-diimine ligands. \textgreek{p} Molecular orbital perturbation calculations for the bidiazines and their correlation with the properties of group 6 metal carbonyl complexes1081986Group VIB basicity bidiazine bidiazine;Group bidiazine;bipyrazine bidiazine;electron bidiazine;molybdenum bidiazine;redox bidiazine;tungsten carbonyl carbonyl;bipyridazine carbonyl;bipyrimidine carbonyl;chromium configuration potential Energies and charge distributions of the lower unoccupied \textgreek{p} MO's were detd. for the isomeric bidiazine ligands 3,3'-bipyridazine (bpdz), 4,4'-bipyrimidine (bpm), 2,2'-bipyrazine (bpz), and 2,2'-bipyrimidine (bpym) as well as for 2,2'-bipyridine (bpy) by Gueckel MO perturbation calcns. In conjunction with exptl. pKa values, the calcn. results are related to the different stabilities, redox potentials, and various spectroscopic properties of Cr, Mo, and W tetracarbonyl complexes with these ligands. W(CO)5L (L = bpdz, bpm) were isolated as intermediates in the reactions between W(THF)(CO)5 and L.. Each of the 4 isomeric ligands exhibits very characteristic features, and the potential uses of the individual systems for different purposes in coordination chem. are discussed. Whereas bpdz is the strongest base in that series, thus compensating for a rather high-lying \textgreek{p}* level, the bpm complexes exhibit the strongest back-bonding interaction because of a very low-lying \textgreek{p}* level and sufficient ligand basicity. The bpz system is distinguished by acquiring high amts. of addnl. charge at both sets of N centers upon redn., and finally, the otherwise less outstanding bpym ligand is unique among the bidiazine isomers by forming binuclear bischelate complexes on 2nd coordination. [on SciFinder(R)]Electron transfer catalyzed carbonyl substitution. I. Synthesis and spectroscopy of phosphine tricarbonyl metal complexes of bidiazinehttps://puma.ub.uni-stuttgart.de/bibtex/2ee7f09d3a85a797ccd3162d82db70658/huebleriachuebleriac2022-06-15T11:26:56+02:00bidiazine carbonyl catalysis molybdenum phosphine;bipyrazine phosphine;bipyridazine phosphine;bipyrimidine phosphine;electron substitution;spectra transfer tungsten <span data-person-type="author" class="authorEditorList "><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Barbara Olbrich-Deussner" itemprop="url" href="/person/1ad374c12725cb6450afdfaacb7ed8426/author/0"><span itemprop="name">B. Olbrich-Deussner</span></a></span>, </span> and <span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Wolfgang. Kaim" itemprop="url" href="/person/1ad374c12725cb6450afdfaacb7ed8426/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">340 </span></span>(<span itemprop="issueNumber">1</span>):
<span itemprop="pagination">71--91</span></em> </span>(<em><span>1988<meta content="1988" itemprop="datePublished"/></span></em>)</span>Wed Jun 15 11:26:56 CEST 2022Journal of Organometallic Chemistry171--91Electron transfer catalyzed carbonyl substitution. I. Synthesis and spectroscopy of phosphine tricarbonyl metal complexes of bidiazine3401988bidiazine carbonyl catalysis molybdenum phosphine;bipyrazine phosphine;bipyridazine phosphine;bipyrimidine phosphine;electron substitution;spectra transfer tungsten fac-M(R3P)(CO)3(bdz) (R = Bu, CHMe2; M = Mo, W; dbz = 3,3'-bipyridazine, 2,2'-bipyrazine, 2,2'- and 4,4'-bipyrimidine) were obtained via electron transfer catalyzed CO substitution of M(CO)4(bdz) in good yields. The preparative procedure involves the use of substoichiometric amts. (10-20 mol{\%}) of K metal to generate ESR-detectable anion radical intermediates, which then undergo selective substitution of 1 cis carbonyl group by way of hyperconjugative charge transfer from the reduced bidiazine ligand to the metal fragment. A catalytic cycle results because the ESR-detectable tricarbonyl anion radical complexes can reduced M(CO)4(bdz), seen from electrochem. Ligand-centered electron transfer-catalyzed substitution is fairly slow but proceeds by $\geq$1 order of magnitude faster than the daylight-induced process which can lead to dissocn. of the partially sensitive tricarbonyls. The compds. are distinguished by long-wavelength metal-to-ligand charge transfer absorption bands resulting from transitions between the electron-rich metal and the low-lying \textgreek{p}* orbitals of the bidiazines. Advantages and disadvantages of the anion radical ligand-induced activation of metal fragments are discussed. [on SciFinder(R)]ESR and ENDOR study of three isomeric bidiazine anion radicals and of their Group 6 metal carbonyl complexes. Coordinative effects on the spin distributionhttps://puma.ub.uni-stuttgart.de/bibtex/2837a37967d54ce99fda5678b8ae289a9/huebleriachuebleriac2022-06-15T11:26:56+02:00ESR VIB bidiazine carbonyl complex <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/16ae1b4e1b030fbc3f8e90f5e08a8a558/author/0"><span itemprop="name">W. Kaim</span></a></span>, </span> and <span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Sylvia. Ernst" itemprop="url" href="/person/16ae1b4e1b030fbc3f8e90f5e08a8a558/author/1"><span itemprop="name">S. Ernst</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 Physical Chemistry</span>, </em> <em><span itemtype="http://schema.org/PublicationVolume" itemscope="itemscope" itemprop="isPartOf"><span itemprop="volumeNumber">90 </span></span>(<span itemprop="issueNumber">21</span>):
<span itemprop="pagination">5010--5014</span></em> </span>(<em><span>1986<meta content="1986" itemprop="datePublished"/></span></em>)</span>Wed Jun 15 11:26:56 CEST 2022Journal of Physical Chemistry215010--5014ESR and ENDOR study of three isomeric bidiazine anion radicals and of their Group 6 metal carbonyl complexes. Coordinative effects on the spin distribution901986ESR VIB bidiazine carbonyl complex Hyperfine coupling consts. and g values were detd. for the anion radicals of 3,3'-bipyridazine (bpdz), 4,4'-bipyrimidine (bpm), and 2,2'-bipyrazine (bpz) and for several of their penta- and tetracarbonylchromium(0), -molybdenum(0), and -tungsten(0) complexes. Analyses of the ESR spectra and assignments of the coupling consts. were accomplished with the help of ENDOR spectroscopy, by relating data of the free anion radicals with those of their various complexes and by using \textgreek{p} MO perturbation calcns. of spin densities at the McLachlan level. Large 14N splittings at the \textgreek{a}-diimine centers were obsd. for the bpdz and bpz anion radical systems, whereas the thermodynamically most stable bpm.bul. complexes display a rather balanced spin distribution. Calcns. and exptl. results demonstrate a very strong response of the bpdz.bul. ligand toward coordination at the \textgreek{a}-diimine N centers. The bis(pentacarbonyltungsten) complexes of bpdz.bul. and bpm.bul. are persistent at ambient temp. and show distinctly higher g value sthan their tetracarbonyltungsten analogs. Inclusion of the previously studied 2,2'-bipyridine and 2,2'-bipyrimidine systems yields a set of structurally very similar yet electronically quite variegated anion radicals of \textgreek{p} acceptor ligands. [on SciFinder(R)]Spectroscopic and electrochemical properties of the isomeric bidiazine complexes (C5Me5)ClRh(bdz)+ and (C5Me5)Rh(bdz) and their relevance to the catalysis of the 2 H+ $\rightarrow$ H2 reaction by 2,2'-bipyridine analogshttps://puma.ub.uni-stuttgart.de/bibtex/2e7360ef339fe90b319c5d6d3e26505a7/huebleriachuebleriac2022-06-15T11:26:56+02:00MO bidiazine bidiazinerhodium;rhodium catalyst electrochem extn hydrogen isomer redox water <span data-person-type="author" class="authorEditorList "><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Monika Ladwig" itemprop="url" href="/person/1081b27b5376b1c39cf14460e67cbeed1/author/0"><span itemprop="name">M. Ladwig</span></a></span>, </span> and <span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Wolfgang. Kaim" itemprop="url" href="/person/1081b27b5376b1c39cf14460e67cbeed1/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">419 </span></span>(<span itemprop="issueNumber">1-2</span>):
<span itemprop="pagination">233--243</span></em> </span>(<em><span>1991<meta content="1991" itemprop="datePublished"/></span></em>)</span>Wed Jun 15 11:26:56 CEST 2022Journal of Organometallic Chemistry1-2233--243Spectroscopic and electrochemical properties of the isomeric bidiazine complexes [(C5Me5)ClRh(bdz)]+ and (C5Me5)Rh(bdz) and their relevance to the catalysis of the 2 H+ $\rightarrow$ H2 reaction by 2,2'-bipyridine analogs4191991MO bidiazine bidiazinerhodium;rhodium catalyst electrochem extn hydrogen isomer redox water Electronic structures and ligand effects were studied for the isomeric Rh(III/I) complexes [(C5Me5)ClRh(bdz)](X) (X- = Cl-, PF6-; bdz = 3,3'-bipyridazine, 2,2'-bipyrazine, 2,2'- and 4,4'-bipyrimidine) and (C5Me5)Rh(bdz). Comparative NMR and UV-visible spectroscopic and cyclic-voltammetry measurements in aprotic solvents allowed definition of a frontier-MO situation that was correlated with the reactivity of the [(C5Me5)ClRh(bpy)]+ system as a catalyst for H evolution from H2O. Thus, while the potential for the 2-electron redn. of the Rh(III) halide precursor depends on the ligand basicity, the MO description shows that there is extremely strong \textgreek{p}-back donation and orbital mixing between the d orbitals of the H+-accepting (C5Me5)Rh(I) fragment and the acceptor level of the heterocyclic ligand. [on SciFinder(R)]Mononuclear bis(triphenylphosphine)copper(I) complexes of bidiazineshttps://puma.ub.uni-stuttgart.de/bibtex/2d75fbe06a3a5153515364ec5fc976c6f/huebleriachuebleriac2022-06-15T11:26:56+02:00bidiazine bipyrazine bipyridazine bipyrimidine;redn charge complex complex;copper copper potential transfer <span data-person-type="author" class="authorEditorList "><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Conny Vogler" itemprop="url" href="/person/11fd28c76f69600debe6737326a6d0182/author/0"><span itemprop="name">C. Vogler</span></a></span>, </span> and <span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Wolfgang. Kaim" itemprop="url" href="/person/11fd28c76f69600debe6737326a6d0182/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">47 </span></span>(<span itemprop="issueNumber">8</span>):
<span itemprop="pagination">1057--1062</span></em> </span>(<em><span>1992<meta content="1992" itemprop="datePublished"/></span></em>)</span>Wed Jun 15 11:26:56 CEST 2022Zeitschrift fuer Naturforschung, B: A Journal of Chemical Sciences81057--1062Mononuclear bis(triphenylphosphine)copper(I) complexes of bidiazines471992bidiazine bipyrazine bipyridazine bipyrimidine;redn charge complex complex;copper copper potential transfer The cationic d10 metal complexes [(bdz)Cu(PPh3)2]+ of the \textgreek{p} accepting bidiazine (bdz) chelate ligands 3,3'-bipyridazine, 2,2'-bipyrazine, 2,2'- and 4,4'-bipyrimidine were prepd. and compared with the analogous complex of 2,2'-bipyridine. The long wavelength metal-to-ligand charge-transfer (MLCT) absorption max. and the redn. potentials indicate relatively little \textgreek{p}* orbital stabilization by +Cu(PPh3)2. The particular d orbital splitting in a tetrahedral ligand field results in an addnl. contribution from \textgreek{D}t to the energy difference between the 1st and 2nd MLCT band. Only the most easily reduced complexes of 4,4'-bipyrimidine and 2,2'-bipyrazine yield neutral radical complexes (Cu(0)) which were characterized by ESR spectroscopy. [on SciFinder(R)]cis-Bis(tributylphosphine)molybdenum dicarbonyl complexes with four isomeric bidiazine ligandshttps://puma.ub.uni-stuttgart.de/bibtex/2b6a49182236dc1aac21334202b2e3c38/huebleriachuebleriac2022-06-15T11:26:56+02:00bidiazine bipyrazine carbonyl complex complex;electrochem complex;molybdenum molybdenum phosphine;bipyridazine phosphine;bipyrimidine phosphine;charge phosphine;photosensitivity redox transfer <span data-person-type="author" class="authorEditorList "><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Sylvia Ernst" itemprop="url" href="/person/141a1f335298e2f5d973b4202db7a9386/author/0"><span itemprop="name">S. Ernst</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Stephan Kohlmann" itemprop="url" href="/person/141a1f335298e2f5d973b4202db7a9386/author/1"><span itemprop="name">S. Kohlmann</span></a></span>, </span> and <span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Wolfgang. Kaim" itemprop="url" href="/person/141a1f335298e2f5d973b4202db7a9386/author/2"><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">354 </span></span>(<span itemprop="issueNumber">2</span>):
<span itemprop="pagination">177--192</span></em> </span>(<em><span>1988<meta content="1988" itemprop="datePublished"/></span></em>)</span>Wed Jun 15 11:26:56 CEST 2022Journal of Organometallic Chemistry2177--192cis-Bis(tributylphosphine)molybdenum dicarbonyl complexes with four isomeric bidiazine ligands3541988bidiazine bipyrazine carbonyl complex complex;electrochem complex;molybdenum molybdenum phosphine;bipyridazine phosphine;bipyrimidine phosphine;charge phosphine;photosensitivity redox transfer cis-Mo(CO)2(PBu3)2(bdz) (bdz = 3,3'-bipyridazine, 2,2'-bipyrazine, 2,2'- and 4,4'-bipyrimidine) were prepd. They can undergo reversible 1-electron oxidn. and redn. and show small redox potential differences {\textless}1.5 V. The small HOMO-LUMO gap gives rise to long-wavelength metal-to-ligand charge transfer absorptions, an assignment which is supported by ESR studies. Guidelines for the construction of complexes with small charge-transfer absorption energies by CO/PR3 exchange are presented. Although a ligand-centered MO is occupied during redn., the small g factors of the radical complexes indicate low-lying ligand-field-excited states which are believed to be responsible for the pronounced light-sensitivity of the compds. cis-Mo(CO)2(PBu3)2(bdz) were also characterized by IR and 1H NMR spectral methods. [on SciFinder(R)]The d in 18 + d Electron Complexes: Importance of the Metal/Ligand Interface for the Substitutional Reactivity of \dqRe(0)\dq Complexes (a-diimine-)ReI(CO)3(X)https://puma.ub.uni-stuttgart.de/bibtex/2c2afe89097e7e022d3ddf6134369d15c/huebleriachuebleriac2022-06-15T11:26:56+02:00bidiazine bromo chloro complex complex;EPR diimine halo redn rhenium substitution;electrochem substitution;rhenium substitution;substitution <span data-person-type="author" class="authorEditorList "><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Axel Klein" itemprop="url" href="/person/176dec298f33b43d8af8dc010eb221bf0/author/0"><span itemprop="name">A. Klein</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Conny Vogler" itemprop="url" href="/person/176dec298f33b43d8af8dc010eb221bf0/author/1"><span itemprop="name">C. Vogler</span></a></span>, </span> and <span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Wolfgang. Kaim" itemprop="url" href="/person/176dec298f33b43d8af8dc010eb221bf0/author/2"><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">15 </span></span>(<span itemprop="issueNumber">1</span>):
<span itemprop="pagination">236--244</span></em> </span>(<em><span>1996<meta content="1996" itemprop="datePublished"/></span></em>)</span>Wed Jun 15 11:26:56 CEST 2022Organometallics1236--244The \textgreek{d} in 18 + \textgreek{d} Electron Complexes: Importance of the Metal/Ligand Interface for the Substitutional Reactivity of {\dq}Re(0){\dq} Complexes (\textgreek{a}-diimine-)ReI(CO)3(X)151996bidiazine bromo chloro complex complex;EPR diimine halo redn rhenium substitution;electrochem substitution;rhenium substitution;substitution The factors detg. the electron transfer-induced halide labilization in complexes (\textgreek{a}-diimine)Re(CO)3(Hal), Hal = Cl and Br, were systematically studied via EPR and cyclic voltammetry in the presence of substituting ligands such as triphenylphosphine, cyanide, or acetonitrile. The \textgreek{a}-diimines employed were the four isomeric bidiazines (bdz) 3,3'-bipyridazine, 2,2'-bipyrazine, and 2,2'- and 4,4'-bipyrimidine and the nonarom. \textgreek{a}-diimines 1,4-di-tert-butyl-1,4-diaza-1,3-butadiene (dab) and 1,3-di-tert-butylsulfurdiimine (sdi). For comparison, (L)Re(CO3)Cl (L = 2,2'-bipyridine, 1,4,7,10-tetraazaphenanthrene, and \textgreek{h}2-2,2',2''-terpyridine) and the new cationic species [(bdz)Re(CO)3(CH3CN)]+ were also studied. In a further expt., in situ EPR spectroelectrochem. was employed to study the primary paramagnetic intermediates during the redn. of the prototype compd., (bpy)Re(CO)3Cl, under a CO2 atmosphere. The susceptibility to substitution is dependent not on the redox potential but on the \textgreek{p} MO coeffs. at the metal-coordinating nitrogen centers which are reflected by 14N, 185,187Re, and 31P EPR coupling consts. The most labile systems were thus found among the complexes of the small dab and sdi ligands, despite their facile redn. In contrast, the complexes of these nonarom. compds. showed an electrochem. reversible 1-electron oxidn. which, in comparison to the absorption max., allowed the authors to est. contributions to the reorganization energy of the MLCT excited state in two cases. For the reductive labilization, it is primarily the small but variable and EPR-detectable ligand-to-metal electron (spin) transfer at the metal/ligand interface which dets. the extent of activation in 18 + \textgreek{d} valence electron intermediates. [on SciFinder(R)]A study of the reduced states of four isomeric bidiazines (diaza-2,2'-bipyridines) by UV-VIS/NIR-spectroelectrochemistryhttps://puma.ub.uni-stuttgart.de/bibtex/29b4fd11b0ed6cea75e9fce6ff49c1d3e/huebleriachuebleriac2022-06-15T11:26:56+02:00IR IR;reduced UV bidiazine bipyrazine bipyridazine bipyrimidine isomer reduced <span data-person-type="author" class="authorEditorList "><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Michael Krejcik" itemprop="url" href="/person/1809254d9aa5ddb13f9c21edfb5048cbc/author/0"><span itemprop="name">M. Krejcik</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Stanislav Zalis" itemprop="url" href="/person/1809254d9aa5ddb13f9c21edfb5048cbc/author/1"><span itemprop="name">S. Zalis</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Monika Ladwig" itemprop="url" href="/person/1809254d9aa5ddb13f9c21edfb5048cbc/author/2"><span itemprop="name">M. Ladwig</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Walter Matheis" itemprop="url" href="/person/1809254d9aa5ddb13f9c21edfb5048cbc/author/3"><span itemprop="name">W. Matheis</span></a></span>, </span> and <span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Wolfgang. Kaim" itemprop="url" href="/person/1809254d9aa5ddb13f9c21edfb5048cbc/author/4"><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 Chemical Society, Perkin Transactions 2: Physical Organic Chemistry</span>, </em> </span>(<em><span>1992<meta content="1992" itemprop="datePublished"/></span></em>)</span>Wed Jun 15 11:26:56 CEST 2022Journal of the Chemical Society, Perkin Transactions 2: Physical Organic Chemistry112007--2010A study of the reduced states of four isomeric bidiazines (diaza-2,2'-bipyridines) by UV-VIS/NIR-spectroelectrochemistry1992IR IR;reduced UV bidiazine bipyrazine bipyridazine bipyrimidine isomer reduced Singly and doubly reduced forms of the four isomeric bidiazines 2,2'-bipyrazine, 3,3'-bipyridazine, 2,2'- and 4,4'-bipyrimidine have been generated in a spectroelectrochem. cell and studied by UV-visible/near-IR spectroscopy. As derivs. of 2,2'-bipyridine the compds. exhibit several groups of vibrationally structured long-wavelength bands in the paramagnetic anion radical state. The assignments and variations of transition energies depending on the diaza perturbation may be rationalized using CNDO/S CI calcns. [on SciFinder(R)]A study of the reduced states of four isomeric bidiazines (diaza-2,2'-bipyridines) by UV-VIS/NIR-spectroelectrochemistryhttps://puma.ub.uni-stuttgart.de/bibtex/29b4fd11b0ed6cea75e9fce6ff49c1d3e/b_schwederskib_schwederski2019-07-15T13:41:23+02:00IR IR;reduced UV bidiazine bipyrazine bipyridazine bipyrimidine isomer reduced <span data-person-type="author" class="authorEditorList "><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Michael Krejcik" itemprop="url" href="/person/1809254d9aa5ddb13f9c21edfb5048cbc/author/0"><span itemprop="name">M. Krejcik</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Stanislav Zalis" itemprop="url" href="/person/1809254d9aa5ddb13f9c21edfb5048cbc/author/1"><span itemprop="name">S. Zalis</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Monika Ladwig" itemprop="url" href="/person/1809254d9aa5ddb13f9c21edfb5048cbc/author/2"><span itemprop="name">M. Ladwig</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Walter Matheis" itemprop="url" href="/person/1809254d9aa5ddb13f9c21edfb5048cbc/author/3"><span itemprop="name">W. Matheis</span></a></span>, </span> and <span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Wolfgang. Kaim" itemprop="url" href="/person/1809254d9aa5ddb13f9c21edfb5048cbc/author/4"><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 Chemical Society, Perkin Transactions 2: Physical Organic Chemistry</span>, </em> </span>(<em><span>1992<meta content="1992" itemprop="datePublished"/></span></em>)</span>Mon Jul 15 13:41:23 CEST 2019Journal of the Chemical Society, Perkin Transactions 2: Physical Organic Chemistry112007--2010A study of the reduced states of four isomeric bidiazines (diaza-2,2'-bipyridines) by UV-VIS/NIR-spectroelectrochemistry1992IR IR;reduced UV bidiazine bipyrazine bipyridazine bipyrimidine isomer reduced Singly and doubly reduced forms of the four isomeric bidiazines 2,2'-bipyrazine, 3,3'-bipyridazine, 2,2'- and 4,4'-bipyrimidine have been generated in a spectroelectrochem. cell and studied by UV-visible/near-IR spectroscopy. As derivs. of 2,2'-bipyridine the compds. exhibit several groups of vibrationally structured long-wavelength bands in the paramagnetic anion radical state. The assignments and variations of transition energies depending on the diaza perturbation may be rationalized using CNDO/S CI calcns. [on SciFinder(R)]The d in 18 + d Electron Complexes: Importance of the Metal/Ligand Interface for the Substitutional Reactivity of \dqRe(0)\dq Complexes (a-diimine-)ReI(CO)3(X)https://puma.ub.uni-stuttgart.de/bibtex/2c2afe89097e7e022d3ddf6134369d15c/b_schwederskib_schwederski2019-07-15T13:41:23+02:00bidiazine bromo chloro complex complex;EPR diimine halo redn rhenium substitution;electrochem substitution;rhenium substitution;substitution <span data-person-type="author" class="authorEditorList "><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Axel Klein" itemprop="url" href="/person/176dec298f33b43d8af8dc010eb221bf0/author/0"><span itemprop="name">A. Klein</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Conny Vogler" itemprop="url" href="/person/176dec298f33b43d8af8dc010eb221bf0/author/1"><span itemprop="name">C. Vogler</span></a></span>, </span> and <span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Wolfgang. Kaim" itemprop="url" href="/person/176dec298f33b43d8af8dc010eb221bf0/author/2"><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">15 </span></span>(<span itemprop="issueNumber">1</span>):
<span itemprop="pagination">236--244</span></em> </span>(<em><span>1996<meta content="1996" itemprop="datePublished"/></span></em>)</span>Mon Jul 15 13:41:23 CEST 2019Organometallics1236--244The \textgreek{d} in 18 + \textgreek{d} Electron Complexes: Importance of the Metal/Ligand Interface for the Substitutional Reactivity of {\dq}Re(0){\dq} Complexes (\textgreek{a}-diimine-)ReI(CO)3(X)151996bidiazine bromo chloro complex complex;EPR diimine halo redn rhenium substitution;electrochem substitution;rhenium substitution;substitution The factors detg. the electron transfer-induced halide labilization in complexes (\textgreek{a}-diimine)Re(CO)3(Hal), Hal = Cl and Br, were systematically studied via EPR and cyclic voltammetry in the presence of substituting ligands such as triphenylphosphine, cyanide, or acetonitrile. The \textgreek{a}-diimines employed were the four isomeric bidiazines (bdz) 3,3'-bipyridazine, 2,2'-bipyrazine, and 2,2'- and 4,4'-bipyrimidine and the nonarom. \textgreek{a}-diimines 1,4-di-tert-butyl-1,4-diaza-1,3-butadiene (dab) and 1,3-di-tert-butylsulfurdiimine (sdi). For comparison, (L)Re(CO3)Cl (L = 2,2'-bipyridine, 1,4,7,10-tetraazaphenanthrene, and \textgreek{h}2-2,2',2''-terpyridine) and the new cationic species [(bdz)Re(CO)3(CH3CN)]+ were also studied. In a further expt., in situ EPR spectroelectrochem. was employed to study the primary paramagnetic intermediates during the redn. of the prototype compd., (bpy)Re(CO)3Cl, under a CO2 atmosphere. The susceptibility to substitution is dependent not on the redox potential but on the \textgreek{p} MO coeffs. at the metal-coordinating nitrogen centers which are reflected by 14N, 185,187Re, and 31P EPR coupling consts. The most labile systems were thus found among the complexes of the small dab and sdi ligands, despite their facile redn. In contrast, the complexes of these nonarom. compds. showed an electrochem. reversible 1-electron oxidn. which, in comparison to the absorption max., allowed the authors to est. contributions to the reorganization energy of the MLCT excited state in two cases. For the reductive labilization, it is primarily the small but variable and EPR-detectable ligand-to-metal electron (spin) transfer at the metal/ligand interface which dets. the extent of activation in 18 + \textgreek{d} valence electron intermediates. [on SciFinder(R)]cis-Bis(tributylphosphine)molybdenum dicarbonyl complexes with four isomeric bidiazine ligandshttps://puma.ub.uni-stuttgart.de/bibtex/2b6a49182236dc1aac21334202b2e3c38/b_schwederskib_schwederski2019-07-15T13:41:23+02:00bidiazine bipyrazine carbonyl complex complex;electrochem complex;molybdenum molybdenum phosphine;bipyridazine phosphine;bipyrimidine phosphine;charge phosphine;photosensitivity redox transfer <span data-person-type="author" class="authorEditorList "><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Sylvia Ernst" itemprop="url" href="/person/141a1f335298e2f5d973b4202db7a9386/author/0"><span itemprop="name">S. Ernst</span></a></span>, </span><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Stephan Kohlmann" itemprop="url" href="/person/141a1f335298e2f5d973b4202db7a9386/author/1"><span itemprop="name">S. Kohlmann</span></a></span>, </span> and <span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Wolfgang. Kaim" itemprop="url" href="/person/141a1f335298e2f5d973b4202db7a9386/author/2"><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">354 </span></span>(<span itemprop="issueNumber">2</span>):
<span itemprop="pagination">177--192</span></em> </span>(<em><span>1988<meta content="1988" itemprop="datePublished"/></span></em>)</span>Mon Jul 15 13:41:23 CEST 2019Journal of Organometallic Chemistry2177--192cis-Bis(tributylphosphine)molybdenum dicarbonyl complexes with four isomeric bidiazine ligands3541988bidiazine bipyrazine carbonyl complex complex;electrochem complex;molybdenum molybdenum phosphine;bipyridazine phosphine;bipyrimidine phosphine;charge phosphine;photosensitivity redox transfer cis-Mo(CO)2(PBu3)2(bdz) (bdz = 3,3'-bipyridazine, 2,2'-bipyrazine, 2,2'- and 4,4'-bipyrimidine) were prepd. They can undergo reversible 1-electron oxidn. and redn. and show small redox potential differences {\textless}1.5 V. The small HOMO-LUMO gap gives rise to long-wavelength metal-to-ligand charge transfer absorptions, an assignment which is supported by ESR studies. Guidelines for the construction of complexes with small charge-transfer absorption energies by CO/PR3 exchange are presented. Although a ligand-centered MO is occupied during redn., the small g factors of the radical complexes indicate low-lying ligand-field-excited states which are believed to be responsible for the pronounced light-sensitivity of the compds. cis-Mo(CO)2(PBu3)2(bdz) were also characterized by IR and 1H NMR spectral methods. [on SciFinder(R)]Mononuclear bis(triphenylphosphine)copper(I) complexes of bidiazineshttps://puma.ub.uni-stuttgart.de/bibtex/2d75fbe06a3a5153515364ec5fc976c6f/b_schwederskib_schwederski2019-07-15T13:41:23+02:00bidiazine bipyrazine bipyridazine bipyrimidine;redn charge complex complex;copper copper potential transfer <span data-person-type="author" class="authorEditorList "><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Conny Vogler" itemprop="url" href="/person/11fd28c76f69600debe6737326a6d0182/author/0"><span itemprop="name">C. Vogler</span></a></span>, </span> and <span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Wolfgang. Kaim" itemprop="url" href="/person/11fd28c76f69600debe6737326a6d0182/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">47 </span></span>(<span itemprop="issueNumber">8</span>):
<span itemprop="pagination">1057--1062</span></em> </span>(<em><span>1992<meta content="1992" itemprop="datePublished"/></span></em>)</span>Mon Jul 15 13:41:23 CEST 2019Zeitschrift fuer Naturforschung, B: A Journal of Chemical Sciences81057--1062Mononuclear bis(triphenylphosphine)copper(I) complexes of bidiazines471992bidiazine bipyrazine bipyridazine bipyrimidine;redn charge complex complex;copper copper potential transfer The cationic d10 metal complexes [(bdz)Cu(PPh3)2]+ of the \textgreek{p} accepting bidiazine (bdz) chelate ligands 3,3'-bipyridazine, 2,2'-bipyrazine, 2,2'- and 4,4'-bipyrimidine were prepd. and compared with the analogous complex of 2,2'-bipyridine. The long wavelength metal-to-ligand charge-transfer (MLCT) absorption max. and the redn. potentials indicate relatively little \textgreek{p}* orbital stabilization by +Cu(PPh3)2. The particular d orbital splitting in a tetrahedral ligand field results in an addnl. contribution from \textgreek{D}t to the energy difference between the 1st and 2nd MLCT band. Only the most easily reduced complexes of 4,4'-bipyrimidine and 2,2'-bipyrazine yield neutral radical complexes (Cu(0)) which were characterized by ESR spectroscopy. [on SciFinder(R)]Spectroscopic and electrochemical properties of the isomeric bidiazine complexes (C5Me5)ClRh(bdz)+ and (C5Me5)Rh(bdz) and their relevance to the catalysis of the 2 H+ $\rightarrow$ H2 reaction by 2,2'-bipyridine analogshttps://puma.ub.uni-stuttgart.de/bibtex/2e7360ef339fe90b319c5d6d3e26505a7/b_schwederskib_schwederski2019-07-15T13:41:23+02:00MO bidiazine bidiazinerhodium;rhodium catalyst electrochem extn hydrogen isomer redox water <span data-person-type="author" class="authorEditorList "><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Monika Ladwig" itemprop="url" href="/person/1081b27b5376b1c39cf14460e67cbeed1/author/0"><span itemprop="name">M. Ladwig</span></a></span>, </span> and <span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Wolfgang. Kaim" itemprop="url" href="/person/1081b27b5376b1c39cf14460e67cbeed1/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">419 </span></span>(<span itemprop="issueNumber">1-2</span>):
<span itemprop="pagination">233--243</span></em> </span>(<em><span>1991<meta content="1991" itemprop="datePublished"/></span></em>)</span>Mon Jul 15 13:41:23 CEST 2019Journal of Organometallic Chemistry1-2233--243Spectroscopic and electrochemical properties of the isomeric bidiazine complexes [(C5Me5)ClRh(bdz)]+ and (C5Me5)Rh(bdz) and their relevance to the catalysis of the 2 H+ $\rightarrow$ H2 reaction by 2,2'-bipyridine analogs4191991MO bidiazine bidiazinerhodium;rhodium catalyst electrochem extn hydrogen isomer redox water Electronic structures and ligand effects were studied for the isomeric Rh(III/I) complexes [(C5Me5)ClRh(bdz)](X) (X- = Cl-, PF6-; bdz = 3,3'-bipyridazine, 2,2'-bipyrazine, 2,2'- and 4,4'-bipyrimidine) and (C5Me5)Rh(bdz). Comparative NMR and UV-visible spectroscopic and cyclic-voltammetry measurements in aprotic solvents allowed definition of a frontier-MO situation that was correlated with the reactivity of the [(C5Me5)ClRh(bpy)]+ system as a catalyst for H evolution from H2O. Thus, while the potential for the 2-electron redn. of the Rh(III) halide precursor depends on the ligand basicity, the MO description shows that there is extremely strong \textgreek{p}-back donation and orbital mixing between the d orbitals of the H+-accepting (C5Me5)Rh(I) fragment and the acceptor level of the heterocyclic ligand. [on SciFinder(R)]ESR and ENDOR study of three isomeric bidiazine anion radicals and of their Group 6 metal carbonyl complexes. Coordinative effects on the spin distributionhttps://puma.ub.uni-stuttgart.de/bibtex/2837a37967d54ce99fda5678b8ae289a9/b_schwederskib_schwederski2019-07-15T13:41:23+02:00ESR VIB bidiazine carbonyl complex <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/16ae1b4e1b030fbc3f8e90f5e08a8a558/author/0"><span itemprop="name">W. Kaim</span></a></span>, </span> and <span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Sylvia. Ernst" itemprop="url" href="/person/16ae1b4e1b030fbc3f8e90f5e08a8a558/author/1"><span itemprop="name">S. Ernst</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 Physical Chemistry</span>, </em> <em><span itemtype="http://schema.org/PublicationVolume" itemscope="itemscope" itemprop="isPartOf"><span itemprop="volumeNumber">90 </span></span>(<span itemprop="issueNumber">21</span>):
<span itemprop="pagination">5010--5014</span></em> </span>(<em><span>1986<meta content="1986" itemprop="datePublished"/></span></em>)</span>Mon Jul 15 13:41:23 CEST 2019Journal of Physical Chemistry215010--5014ESR and ENDOR study of three isomeric bidiazine anion radicals and of their Group 6 metal carbonyl complexes. Coordinative effects on the spin distribution901986ESR VIB bidiazine carbonyl complex Hyperfine coupling consts. and g values were detd. for the anion radicals of 3,3'-bipyridazine (bpdz), 4,4'-bipyrimidine (bpm), and 2,2'-bipyrazine (bpz) and for several of their penta- and tetracarbonylchromium(0), -molybdenum(0), and -tungsten(0) complexes. Analyses of the ESR spectra and assignments of the coupling consts. were accomplished with the help of ENDOR spectroscopy, by relating data of the free anion radicals with those of their various complexes and by using \textgreek{p} MO perturbation calcns. of spin densities at the McLachlan level. Large 14N splittings at the \textgreek{a}-diimine centers were obsd. for the bpdz and bpz anion radical systems, whereas the thermodynamically most stable bpm.bul. complexes display a rather balanced spin distribution. Calcns. and exptl. results demonstrate a very strong response of the bpdz.bul. ligand toward coordination at the \textgreek{a}-diimine N centers. The bis(pentacarbonyltungsten) complexes of bpdz.bul. and bpm.bul. are persistent at ambient temp. and show distinctly higher g value sthan their tetracarbonyltungsten analogs. Inclusion of the previously studied 2,2'-bipyridine and 2,2'-bipyrimidine systems yields a set of structurally very similar yet electronically quite variegated anion radicals of \textgreek{p} acceptor ligands. [on SciFinder(R)]Electron transfer catalyzed carbonyl substitution. I. Synthesis and spectroscopy of phosphine tricarbonyl metal complexes of bidiazinehttps://puma.ub.uni-stuttgart.de/bibtex/2ee7f09d3a85a797ccd3162d82db70658/b_schwederskib_schwederski2019-07-15T13:41:23+02:00bidiazine carbonyl catalysis molybdenum phosphine;bipyrazine phosphine;bipyridazine phosphine;bipyrimidine phosphine;electron substitution;spectra transfer tungsten <span data-person-type="author" class="authorEditorList "><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Barbara Olbrich-Deussner" itemprop="url" href="/person/1ad374c12725cb6450afdfaacb7ed8426/author/0"><span itemprop="name">B. Olbrich-Deussner</span></a></span>, </span> and <span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Wolfgang. Kaim" itemprop="url" href="/person/1ad374c12725cb6450afdfaacb7ed8426/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">340 </span></span>(<span itemprop="issueNumber">1</span>):
<span itemprop="pagination">71--91</span></em> </span>(<em><span>1988<meta content="1988" itemprop="datePublished"/></span></em>)</span>Mon Jul 15 13:41:23 CEST 2019Journal of Organometallic Chemistry171--91Electron transfer catalyzed carbonyl substitution. I. Synthesis and spectroscopy of phosphine tricarbonyl metal complexes of bidiazine3401988bidiazine carbonyl catalysis molybdenum phosphine;bipyrazine phosphine;bipyridazine phosphine;bipyrimidine phosphine;electron substitution;spectra transfer tungsten fac-M(R3P)(CO)3(bdz) (R = Bu, CHMe2; M = Mo, W; dbz = 3,3'-bipyridazine, 2,2'-bipyrazine, 2,2'- and 4,4'-bipyrimidine) were obtained via electron transfer catalyzed CO substitution of M(CO)4(bdz) in good yields. The preparative procedure involves the use of substoichiometric amts. (10-20 mol{\%}) of K metal to generate ESR-detectable anion radical intermediates, which then undergo selective substitution of 1 cis carbonyl group by way of hyperconjugative charge transfer from the reduced bidiazine ligand to the metal fragment. A catalytic cycle results because the ESR-detectable tricarbonyl anion radical complexes can reduced M(CO)4(bdz), seen from electrochem. Ligand-centered electron transfer-catalyzed substitution is fairly slow but proceeds by $\geq$1 order of magnitude faster than the daylight-induced process which can lead to dissocn. of the partially sensitive tricarbonyls. The compds. are distinguished by long-wavelength metal-to-ligand charge transfer absorption bands resulting from transitions between the electron-rich metal and the low-lying \textgreek{p}* orbitals of the bidiazines. Advantages and disadvantages of the anion radical ligand-induced activation of metal fragments are discussed. [on SciFinder(R)]Coordination characteristics of four isomeric a-diimine ligands. p Molecular orbital perturbation calculations for the bidiazines and their correlation with the properties of group 6 metal carbonyl complexeshttps://puma.ub.uni-stuttgart.de/bibtex/24f6433f1ea46898fc234a4249fcfb849/b_schwederskib_schwederski2019-07-15T13:41:23+02:00Group VIB basicity bidiazine bidiazine;Group bidiazine;bipyrazine bidiazine;electron bidiazine;molybdenum bidiazine;redox bidiazine;tungsten carbonyl carbonyl;bipyridazine carbonyl;bipyrimidine carbonyl;chromium configuration potential <span data-person-type="author" class="authorEditorList "><span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Sylvia Ernst" itemprop="url" href="/person/13efa3bf4b2b2a9ad87713cc0b5dd3acf/author/0"><span itemprop="name">S. Ernst</span></a></span>, </span> and <span><span itemtype="http://schema.org/Person" itemscope="itemscope" itemprop="author"><a title="Wolfgang. Kaim" itemprop="url" href="/person/13efa3bf4b2b2a9ad87713cc0b5dd3acf/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 the American Chemical Society</span>, </em> <em><span itemtype="http://schema.org/PublicationVolume" itemscope="itemscope" itemprop="isPartOf"><span itemprop="volumeNumber">108 </span></span>(<span itemprop="issueNumber">13</span>):
<span itemprop="pagination">3578--3586</span></em> </span>(<em><span>1986<meta content="1986" itemprop="datePublished"/></span></em>)</span>Mon Jul 15 13:41:23 CEST 2019Journal of the American Chemical Society133578--3586Coordination characteristics of four isomeric \textgreek{a}-diimine ligands. \textgreek{p} Molecular orbital perturbation calculations for the bidiazines and their correlation with the properties of group 6 metal carbonyl complexes1081986Group VIB basicity bidiazine bidiazine;Group bidiazine;bipyrazine bidiazine;electron bidiazine;molybdenum bidiazine;redox bidiazine;tungsten carbonyl carbonyl;bipyridazine carbonyl;bipyrimidine carbonyl;chromium configuration potential Energies and charge distributions of the lower unoccupied \textgreek{p} MO's were detd. for the isomeric bidiazine ligands 3,3'-bipyridazine (bpdz), 4,4'-bipyrimidine (bpm), 2,2'-bipyrazine (bpz), and 2,2'-bipyrimidine (bpym) as well as for 2,2'-bipyridine (bpy) by Gueckel MO perturbation calcns. In conjunction with exptl. pKa values, the calcn. results are related to the different stabilities, redox potentials, and various spectroscopic properties of Cr, Mo, and W tetracarbonyl complexes with these ligands. W(CO)5L (L = bpdz, bpm) were isolated as intermediates in the reactions between W(THF)(CO)5 and L.. Each of the 4 isomeric ligands exhibits very characteristic features, and the potential uses of the individual systems for different purposes in coordination chem. are discussed. Whereas bpdz is the strongest base in that series, thus compensating for a rather high-lying \textgreek{p}* level, the bpm complexes exhibit the strongest back-bonding interaction because of a very low-lying \textgreek{p}* level and sufficient ligand basicity. The bpz system is distinguished by acquiring high amts. of addnl. charge at both sets of N centers upon redn., and finally, the otherwise less outstanding bpym ligand is unique among the bidiazine isomers by forming binuclear bischelate complexes on 2nd coordination. [on SciFinder(R)]