für Naturforschung in cooperation with the Max Planck Society for the Advancement of Science under a Creative Commons Attribution 4.0 International License. Dieses Werk wurde im Jahr 2013 vom Verlag Zeitschrift für Naturforschung in Zusammenarbeit mit der Max-Planck-Gesellschaft zur Förderung der Wissenschaften e.V. digitalisiert und unter folgender Lizenz veröffentlicht: Creative Commons Namensnennung 4.0 Lizenz. Polydeckerkomplexe mit p, i;5-2,3-Dihydro-l,3-diborolylnickel-Fragmenten als Stapeleinheiten Polydecker Complexes with ,«,?75-2,3-Dihydro-l,3-diborolylnickel Fragments as Stacking Units

Reactions of 2,3-dihydro-1,3-diboroles 6a–h with (C3H5)2Νi lead to µ,η5-2,3-dihydro-1,3-diborolylnickel triple-decker complexes 7a –h. By slow heating these oily, diamagnetic complexes in a rotating flask polycondensation with formation of black 8a–h as well as of bis(allyl)nickel and hexadiene occurs. The latter can be removed under reduced pressure. The constitution of the polymeric material follows from EXAFS studies. The Ni–Ni distance is 3,35 A, the ring atom Ni bonds are in the range of 2,13 to 2,15 A. Thermogravimetric measurements between 200 and 400°C show a mass loss of 20-40%, depending of the alkyl substituents of the heterocycle. In dynamic difference calorimetry an endothermic process occurs near 420°C. The powder conductivity of the amorphous, air-sensitive material is in the range of 10-2 S • cm-1. Doping with iodine or oxygen causes a decrease in the conductivity of these semi-conductors.

Reactions of 2,3-dihydro-1,3-diboroles 6a-h with (C3H5)2Ni lead to mu,eta5-2,3-dihydro-1,3-diborolylnickel triple-decker complexes 7a - h. By slow heating these oily, diamagnetic complexes in a rotating flask polycondensation with formation of black 8a-h as well as of bis(allyl)nickel and hexadiene occurs. The latter can be removed under reduced pressure. The constitution of the polymeric material follows from EXAFS studies. The Ni-Ni distance is 3,35 angstrom, the ring atom Ni bonds are in the range of 2,13 to 2,15 angstrom. Thermogravimetric measurements between 200 and 400-degrees-C show a mass loss of 20-40%, depending of the alkyl substituents of the heterocycle. In dynamic difference calorimetry an endothermic process occurs near 420-degrees-C. The powder conductivity of the amorphous, air-sensitive material is in the range of 10(-2) S . cm-1. Doping with iodine or oxygen causes a decrease in the conductivity of these semi-conductors.

AbstractDie Tetra‐ und Pentamethyl‐Derivate 1a, b des 2,3‐Dihydro‐1,3‐diborols reagieren mit überschüssigem Bis(allyl)nickel bei tiefer Temperatur unter Bildung der thermolabilen Tris(allyl)dinickel‐Tripeldeckerkomplexe 2a, b mit dem 2,3‐Dihydro‐1,3‐diborolyl‐Liganden in Brückenstellung. 2a ist reaktiver als 2b hinsichtlich einer Kondensation zu dem Quadrupeldeckerkomplex 4. Die spektroskopischen Daten (1H‐, 13C‐NMR) zeigen, daß eine Allylgruppe π‐statisch an ein Nickel‐Atom gebunden ist, während die beiden anderen am zweiten Nickel‐Atom einem raschen η1,η3‐Austausch unter Ausbildung eines AMNXY‐Spinsystems unterliegen.

AbstractThe known triple‐decker (I) may be cleaved in the presence of cyclooctadiene (II) by chemical (AgBF4) or electrochemical oxidation to form the cationic (η5‐tricarbahexaboranyl)(1,5‐cyclooctadiene)‐Ni complex (III) and the neutral (η5‐tricarbahexaboranyl)(η5‐diborolyl)‐Ni (IV).

Abstract(IIIb) is obtained analogously to (IIIa) in Et2O at ‐40 °C. The bonding in (III) is elucidated by 1H and 13C NMR data.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTRedox chemistry of transition-metal .pi. complexes. 1. Tricarbahexaboranylmetal complexes. 2. Electronic structures and reactivities of .eta.5-2,3,5-tricarbahexaboranylnickel sandwich complexes. A combined electrochemical, preparative, and NMR spectroscopic approachJoachim Zwecker, Thomas Kuhlmann, Hans Pritzkow, Walter Siebert, and Ulrich ZenneckCite this: Organometallics 1988, 7, 11, 2316–2324Publication Date (Print):November 1, 1988Publication History Published online1 May 2002Published inissue 1 November 1988https://doi.org/10.1021/om00101a011RIGHTS & PERMISSIONSArticle Views78Altmetric-Citations24LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-AlertscloseSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

AbstractThe reaction of (I) with excess (II) at low temp. yields the dinuclear.

Two routes have been studied to obtain the first hexadecker sandwich complexes 4. The reaction between the η3-allyl tetradecker 2b and the cobalt sandwich 3b in refluxing mesitylene leads to red-violet diamagnetic 4bb in 7% yield. Bis(allyl)nickel and the cyclopentadienylcobalt(2,3-dihydro-1,3-diborol) 3b form the tripledecker η3-allylnickel(μ, η5-dihydro-1,3-diborolyl)-cobalt(η5-cyclopentadienyl) 9b, which reacts at 160 °C with the bis(2,3-dihydro-1,3-diborol)nickel sandwich 10c to give 4bc (21%) and the tetradecker 7b (69%). The constitution of the new complexes is derived from NMR and mass spectra.

Multilayer sandwich complexes containing the novel ligands 1b and 1c have been obtained by unusual boranediyl transfer and stacking reactions. Reaction of Ni(allyl)2 with 2b leads to formation of trace amounts of the complexes [1b Ni 2b] and [1bNi 2bNi 1b]. Also [1b Ni 2b Ni 2b Ni 1b] could be obtained from the primary product [2b Ni 2b]. [2c Ni 2c] reacts analogously; the ligand 2a in [2a Ni 2a], on the other hand, is sterically too well shielded for boranediyl-transfers.

Abstract Reactions between bis(allyl)nickel complexes and alkyl derivatives of 2,3-dihydro-1,3-diborole (1a, b) in refluxing toluene or mesitylene yield deeply colored solutions. By distillation and chromatography the first η3-allyl tetradecker complexes 8 were obtained in 4 -15% yield. In the violet residues higher molecular species are present, which could not be identified. The red, oily tetradeckers are characterized by NMR and mass spectra; their formation is discussed.

Viellagige Sandwichkomplexe mit den neuen Liganden 1b und 1c wurden durch ungewöhnliche Borandiyl—Übertragung und Aufstockungsreaktionen erhalten. Ni(allyl)2 ergibt mit 2b in Spuren die Komplexe [1b Ni 2b] und [1b Ni 2b Ni 1b]. Aus dem Primärprodukt [2b Ni 2b] konnte außerdem [1b Ni 2b Ni 2b Ni 1b] erhalten werden. [2c Ni 2c] reagiert analog; der Ligand 2a in [2a Ni 2a] ist dagegen für Borandiyl—Übertragungen sterisch zu gut abgeschirmt.