Jörg Grunenberg

Technische Universität Braunschweig, Brunswyck, Lower Saxony, Germany

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Publications (90)393.27 Total impact

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    ABSTRACT: A novel type of π-helicenes is reported, in which the π-system is truncated to an all-s-cis all-Z oligoene chain. A domino sequence was developed, consisting of up to four consecutive carbopalladation reactions and a terminal Stille cross-coupling, to generate these entities in one step from the respective linear oligoynes. Despite the minimal π-system, very high optical rotation values were encountered for the single enantiomers. X-ray crystallography confirmed their screw-shaped structure.
    Angewandte Chemie International Edition 12/2014; 54(4). DOI:10.1002/anie.201408637 · 11.34 Impact Factor
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    ABSTRACT: Ein neuartiger Typ von π-Helicenen, deren π-System auf eine all-s-cis-Z,Z,…-Oligoenkette reduziert ist, wird vorgestellt. Eine Dominosequenz aus bis zu vier aufeinanderfolgenden Carbopalladierungen und einer abschließenden Stille-Kreuzkupplung wurde entwickelt, um den einstufigen Aufbau dieser Einheiten ausgehend von den jeweiligen linearen Oligoinen zu ermöglichen. Trotz des minimalen π-Systems wurden für die einzelnen Enantiomere sehr hohe Werte ihrer optischen Rotation festgestellt. Die schraubenförmigen Strukturen wurden durch Röntgenstrukturanalyse zweifelsfrei nachgewiesen.
    Angewandte Chemie 12/2014; 127(4). DOI:10.1002/ange.201408637
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    ABSTRACT: The [2.2]paracyclophane moiety is used as a spacer to connect the ends of a hex-3-ene-1,5-diyne unit, a π-system that on thermolysis usually cycloaromatizes to a benzene ring (Bergman cyclization). For the preparation of the pseudo-geminally-bridged system 9, the diacetylene 3 was chain-extended to the diol 16, which after conversion to the pseudo-geminal dibromide 17 was ring-closed by treatment with LiHMDS/HMPA to the [2.2]paracyclophane enediyne 9. Whereas the McMurry coupling of the pseudo-ortho bisaldehyde 24 resulted in the formation of the hexadienyne-bridged cyclophane 27, the pseudo-ortho-bridged hydrocarbon 11 was obtained by preparing first the diol 28 from 24, converting the latter into the dioxolane 29, which in the last step furnished the olefin 11 by treatment with Tf2O/EtN(iPr)2. The authentic Bergman product 10 of the pseudo-gem-bridged hexenediyne 9 was synthesized by a conventional sequence starting from the ethynyl formyl substrate 18. Since the pseudo-ortho-enediyne-bridged hydrocarbon 11 is thermally labile, its benzannelated derivate 34 was prepared. No classical Bergman cyclization reactions could be observed for any of the [2.2]paracyclophane-bridged hexenediynes prepared here. In the pseudo-gem-series the fulvenes 14 and 15 were the only products that could be identified under thermal conditions (McMurry coupling); the benzannelated substrate 34 gave the benzofulvene-bridged cyclophane 36 on photolysis. Bergman cyclizations yielding fulvene derivatives are extremely rare. The mechanism of the cyclization of 9 and 34 is discussed, using compliance constants. The structure assignments of the hydrocarbons synthesized in this study are based on spectroscopic studies as well as X-ray structural analyses for 9, 10, 11, 27, and 34.
    Chemistry - A European Journal 12/2014; 20(49):16360-16376. DOI:10.1002/chem.201403122 · 5.70 Impact Factor
  • Jörg Grunenberg, Giampaolo Barone, Angelo Spinello
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    ABSTRACT: Different force fields and approximate density functional theory were applied in order to study the rotamer space of the telomeric G-quadruplex DNA. While some force fields show an erratic behavior when it comes to the reproduction of the higher-order DNA conformer space, OPLS and MMFF implementations are able to reproduce the experimentally known energy order. The stabilizing effect of the AA (anti−anti) versus SA (syn−anti) conformer is analyzed applying mechanical bond strength descriptors (compliance constants). The fact that we observe the correct energy order using appropriate force fields is in contrast with results previously reported, which suggested the general inappropriateness of force fields for the description of G-quadruplex structures.
    Journal of Chemical Theory and Computation 08/2014; 10(8). DOI:10.1021/ct500329f · 5.31 Impact Factor
  • Christian Kleeberg, Jörg Grunenberg, Xiulan Xie
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    ABSTRACT: A series of trimethylstannyl potassium complexes [K(L)SnMe3] with different auxiliary ligands L (L = 18-C-6, (TMEDA)2 (TMEDA = tetramethylethylenediamine), and (12-C-4)2) were synthesized by alkoxide-induced B-Sn bond cleavage. X-ray structure determinations were performed for all these complexes, and the structural chemistry was studied in detail. For L = 18-C-6 and (TMEDA)2 the solid state structures comprise polymeric [K(L)SnMe3]n chains containing bidentate trimethylstannyl anions bridging two [K(L)](+) ions, featuring unsymmetrical coordination of the [K(L)](+) ion by K-Sn and K-H3C interactions as a central structural motif. In contrast, for L = (12-C-4)2, separated [K(12-C-4)2](+) and [SnMe3](-) ions are observed. Unexpectedly, in the presence of tetrahydrofuran (THF), [K(18-C-6)SnMe3]n forms upon crystallization a new species consisting of separated [K(18-C-6)(THF)2](+) and [(Me2SnCH3)K(18-C-6)SnMe3](-) ions. In this unsymmetrical anion two trimethylstannyl anions coordinate a single [K(18-C-6)](+) ion; one trimethylstannyl anion coordinates via a K-Sn interaction, and the second coordinates via a K-H3C interaction. Simulations of the mechanochemical properties (compliance constants) applying approximated density functional theory revealed that both interactions are very soft and are of comparable strength. Moreover, according to our gas phase simulations the unsymmetrically coordinated [(Me2SnCH3)K(18-C-6)SnMe3](-) is indeed thermodynamically favored over both possible symmetrical isomers with either K-Sn or K-H3C coordination. Furthermore, the existence of multiple species due to the two coordination modes and aggregates of [K(18-C-6)SnMe3] in solution is suggested by NMR spectroscopic studies using (1)H, NOESY/ROESY, and (1)H pulsed field gradient diffusion experiments.
    Inorganic Chemistry 04/2014; 53(9). DOI:10.1021/ic500065s · 4.79 Impact Factor
  • Georgios Markopoulos, Jörg Grunenberg
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    ABSTRACT: Determining the weakest link: A simple analysis pinpoints kinetically unstable carbon-carbon bonds. No prior knowledge of reaction pathways is necessary and the approach is particularly helpful for the prediction of novel molecules. krel =relaxed force constant, req =bond length.
    Angewandte Chemie International Edition 09/2013; 52(40). DOI:10.1002/anie.201303821 · 11.34 Impact Factor
  • Georgios Markopoulos, Jörg Grunenberg
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    ABSTRACT: Achillessehne auf den ersten Blick: Wir stellen eine einfache Analyse vor, die kinetisch labile Kohlenstoff‐Kohlenstoff‐Bindungen anzeigt. Detaillierte Kenntnisse über Reaktionsmechanismen sind a priori nicht notwendig, und die Methode ist besonders nützlich bei der Vorhersage von neuen Molekülen. k rel=relaxierte Kraftkonstante, r eq=Bindungslänge.
    Angewandte Chemie 09/2013; 125(40). DOI:10.1002/ange.201303821
  • Holger F. Bettinger, Sarah Brough, Jörg Grunenberg
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    ABSTRACT: The interaction of methyl(oxo)borane, CH3BO, with typical Lewis bases (nitrogen based and N‐heterocyclic carbenes) was investigated using density functional theory (B97‐D, TPSS‐D3), double hybrid density functionals (PWPB95‐D3, B2PLYP‐D3) in conjunction with empirical dispersion corrections, and coupled cluster theory involving singles, doubles, and a perturbative estimate of triple excitations [CCSD(T)]. A polarized quadruple‐zeta basis set was used throughout. The interaction energies computed with the double‐hybrid methods agree very well with CCSD(T). Compared to typical boron Lewis acids, the interaction energies are much smaller for methyl(oxo)borane, indicating that the BO triple bond results in significantly reduced Lewis acidity. An analysis of the mechanical bond strengths in CH3BO and its complexes indicates that the relaxed BO force constants (compliance constants) and the stretching vibrations decrease with increasing strengths of the dative interactions.
    Zeitschrift für anorganische und allgemeine Chemie 06/2013; 639(7). DOI:10.1002/zaac.201200557 · 1.25 Impact Factor
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    ABSTRACT: A bridging chloride anion between two electrophilic phosphorus centers was observed for the first time in the molecular structure of the novel P–P bonded cation [LDipp2P2Cl3]+ (2+; LDipp = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene). Cation 2+ is prepared by the reduction of the monophosphorus species [LDippPCl2]+ (1+) with sodium. DFT calculations, AIM and mechanochemical (compliance constants) analyses are used to examine the bonding situation of this unusual species. The monochloro-substituted cation [LDipp2P2Cl]+ (3+) was likewise observed as a reduction product of 1+.
    Organometallics 04/2013; 32(22). DOI:10.1021/om4002268 · 4.25 Impact Factor
  • Thies M. Schulze, Jörg Grunenberg, Stefan Schulz
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    ABSTRACT: The synthesis of α-methyl-β-hydroxy-δ-trichloromethyl-δ-valerolactone was achieved by an intramolecular Reformatsky reaction. The cyclisation was effected by samarium diiodide or (for the first time) ytterbium diiodide. The diastereoselectivity of the reaction corresponds to earlier investigations by Molander. Consecutive stereoselective reactions during the esterification to the Reformatsky precursor 1,1,1-trichloropent-4-en-2-yl 2-bromopropanoate and in the Reformatsky reaction itself led to (3RS,4RS,6SR)-4-hydroxy-3-methyl-6-(trichloromethyl)tetrahydro-2H-pyran-2-one (3a) as the major formed diastereomer. The influence of the orientation of the substituents in the transition state is discussed.
    Tetrahedron Letters 02/2013; 54(8):921–924. DOI:10.1016/j.tetlet.2012.11.146 · 2.39 Impact Factor
  • Jörg Grunenberg, Giampaolo Barone
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    ABSTRACT: Just as the potential energy can be written as a quadratic form in internal coordinates, so it can also be expanded in terms of generalized forces. The resulting coefficients are termed compliance constants. In this article, the suitability of compliance constants as non-covalent bond strength descriptors is studied (a) for a series of weakly bound hydrogen halide–rare gas complexes applying a configuration interaction theory, (b) for a double stranded DNA 4-mer using approximate density functional methods and finally (c) for a double stranded DNA 20-mer using empirical force fields. Our results challenge earlier studies, which concluded the inappropriateness of compliance constants as soft matter descriptors. The discrepancy may be ascribed, inter alia, to the application of an oversimplified potential function in these earlier studies, assuming a central forces approximation.
    RSC Advances 01/2013; 3(14). DOI:10.1039/c3ra22866e · 3.71 Impact Factor
  • Jörg Grunenberg
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    ABSTRACT: Determining molecular bond orders can be a delicate and sophisticated task, especially if the electronic structure of the studied system is complex. Now, two different ab initio methods have revealed that C2 and analogous species have a fourth bond, rather than the previously assumed maximum of three.
    Nature Chemistry 02/2012; 4(3):154-5. DOI:10.1038/nchem.1274 · 23.30 Impact Factor
  • Marc D. Walter, Jörg Grunenberg, Peter S. White
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    ABSTRACT: Metathesis of [Cp′FeI]2 (1) with KHBEt3 affords the polyhydride iron complexes [Cp′FeH2]2 (2) and [Cp′2Fe2H3] (3). The ratio in which both 2 and 3 are obtained correlates to the applied H2 pressure during synthesis. Complex 2 activates CH- or CD- bonds in aromatic compounds and shows slow H/D exchange in the presence of D2 at room temperature in cyclohexanesolvent. [Cp′FeH2]2 acts as a Cp′Fe(I)-synthon when reacted with white phosphorus (P4) to give [Cp′Fe]2(μ-P4) (4) as the only P-containing product. This complex is best described as a triple-decker complex with a planar arrangement of a severely distorted kite-like cyclo-P4 unit. This distortion persists in solution and solid state as evidenced by a small PP coupling constant in the 31P{1H} NMR spectrum and a long P–P distance of 2.53 Å. Complex 4 is an isomer to the long-known [{Cp′Fe}2(μ-η4:η4-P4)] (5) with a cis-tetraphosphabutadiene moiety and it thermally rearranges to 5, [{Cp′Fe}2(μ-η3:η3-P3)] and [Cp′Fe(P5)]. All complexes described in this paper have been completely characterized including X-ray crystallography, variable temperature NMR studies and DFT calculations. Relaxed force constants (inverse compliance constants) are used as bond strength descriptors.
    Chemical Science 10/2011; 2(11):2120-2130. DOI:10.1039/C1SC00413A · 8.60 Impact Factor
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    ABSTRACT: Experimental Fourier-transform infrared spectra and DFT calculated infrared spectra are compared to investigate the effect of adsorbed nitrogen on the OH-stretch band complex of water clusters. Using a collisional cooling experiment, pure as well as partially and completely N(2)-covered water clusters consisting of 20-200 water molecules have been generated in thermal equilibrium in the aerosol phase within the temperature range of 5-80 K. Computational IR-spectra simulations have been performed for discrete pure and N(2)-covered water clusters including 10, 15, 20, and 30 water molecules. The adsorbed N(2) molecules especially affect the three-coordinated water molecules at the cluster surface which could be observed as a blue shift of the companion O-H band at 2900 cm(-1) and a red shift of the dangling O-H band at 3700 cm(-1) by about 20 cm(-1) in both cases. The most striking effect of the N(2) adsorbate is an intensity increase of the dangling O-H band by a factor of 3-5. Furthermore, the onset temperature of nitrogen adsorption at the water cluster surface was experimentally found to be roughly 30 K for cluster sizes of about 100 water molecules. Experimental and computational results are in good agreement. The presented results are based on and support the work of V. Buch, J. P. Devlin, and co-workers (e.g., J. Phys. Chem. B, 1997; J. Phys. Chem. A, 2003; Int. Rev. Phys. Chem., 2004).
    The Journal of Physical Chemistry A 06/2011; 115(23):6218-25. DOI:10.1021/jp111481q · 2.78 Impact Factor
  • Jörg Grunenberg
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    ABSTRACT: The anomer selectivity of artificial carbohydrate receptors was studied using in silico methods in order to shed light on the thermodynamic driving forces at work during molecular recognition in general. The contributions of relevant intermolecular hydrogen bonds were investigated by means of generalized compliance constants in order to dissect important from less important non-covalent interactions. Even at this moderately low rung on the ladder of complexity essential aspects of molecular recognition are not explainable in terms of additive intermolecular interactions. Though molecular recognition seems to be a complex and emergent property, a rationale for the diastereoselectivity of carbohydrate receptors was obtained by a combination of experimental data, free energy simulations and ab initio calculations.
    Physical Chemistry Chemical Physics 06/2011; 13(21):10136-46. DOI:10.1039/c1cp20097f · 4.20 Impact Factor
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    ABSTRACT: We report the structure and spectroscopic characteristics for the Xe:HI van der Waals binary isomers determined from variational solutions of two-dimensional and three-dimensional (3D) vibrational Schrödinger equations. The solutions are based on a potential energy surface computed at the coupled-cluster level of theory including single and double excitations and a non-iterative perturbation treatment of triple excitations [CCSD(T)]. The dipole moment surface was calculated using quadratic configuration interaction (QCISD). The global potential minimum is shown to be located at the anti-hydrogen-bonded Xe-IH isomer, 21 cm(-1) below the secondary local minimum associated with the hydrogen-bonded Xe-HI isomeric form. The dissociation energy from the global minimum is 245.9 cm(-1). 3D Schrödinger equations are solved for the rotational quantum numbers J = k = 0, 1, and 2, without invoking an adiabatic separation of high- and low-frequency degrees of freedom. The vibrational ground state resides in the Xe-HI potential well, while the first excited state, 8.59 cm(-1) above the ground, occupies the Xe-IH well. We find that intra-complex dynamics exhibits a sudden transformation upon increase of the r(HI) bond length, accompanied by abrupt changes in the geometric and dipole parameters. A similar chaotic behavior is predicted to occur for Xe:DI at a shorter r(DI) bond length, which implies stronger coupling between low- and high-frequency motions in the heavier complex. Our calculations confirm a strong enhancement for the r(HI) stretch fundamental and a significant weakening for the first overtone vibrational transitions in Xe:HI, as compared to those in the free HI molecule. A qualitative explanation of this, earlier experimentally detected effect is suggested.
    The Journal of Chemical Physics 05/2011; 134(17):174302. DOI:10.1063/1.3583817 · 3.12 Impact Factor
  • Friedhelm Lehrich, Henning Hopf, Jörg Grunenberg
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    ABSTRACT: The cross-conjugated allenes ("allenic dendralenes") 2-allenylbuta-1,3-diene (2), 1,1-divinylallene (3, prepared here as the methyl derivative 49), and 1,1-diallenylethene (4) are prepared either by S(N)2'-substitution processes from appropriate allenic or acetylenic precursors or by base-catalyzed isomerizations of propargylic substrates. Thermal elimination/isomerization routes to these highly unsaturated hydrocarbons require reaction conditions under which these allenes undergo secondary transformations. The new oligoolefins, the structures of which have been calculated by MP2 methods, are interesting substrates for addition and isomerization reactions.
    European Journal of Organic Chemistry 05/2011; 2011(14):2705 - 2718. DOI:10.1002/ejoc.201001508 · 3.15 Impact Factor
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    ABSTRACT: The reaction of bis(pentafluorophenyl)borane, HB(C(6)F(5))(2), with 3,5-di-tert-butyl-1H-pyrazole (3) affords the zwitterionic pyrazolium-borate trans-5 and, after dehydrogenation by use of the frustrated carbene-borane Lewis pair 1/B(C(6)F(5))(3), the bifunctional pyrazolylborane 6, which is able to cleave dihydrogen heterolytically with the formation of a mixture of cis-5 and trans-5.
    Chemical Communications 10/2010; 46(45):8561-3. DOI:10.1039/c0cc03474f · 6.72 Impact Factor
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    ABSTRACT: The reaction of [PhC[triple bond]MBr(3)(dme)] (dme=1,2-dimethoxyethane) with the hexafluoro-tert-butoxides LiX or KX [X=OC(CF(3))(2)Me] afforded the benzylidyne complexes [PhC[triple bond]MX(3)(dme)] (2a: M=W, 2b: M=Mo), which further reacted with the lithium reagent Li(Im(tBu)N), generated with MeLi from 1,3-di-tert-butylimidazolin-2-imine (Im(tBu)NH), to form the imidazolin-2-iminato complexes [PhC[triple bond]MX(2)(Im(tBu)N)] (3a: M=W, 3b: M=Mo). The propylidyne complex [EtC[triple bond]MoX(2)(NIm(tBu))] (4) was obtained by treatment of 3b with an excess of 3-hexyne. Complexes 3a and 3b are able to efficiently catalyse alkyne cross metathesis of various 3-pentynyl benzyl ethers 5 and benzoic esters 7 at room temperature, to afford 2-butyne and the corresponding diethers 6 and diesters 8. The tungsten complex 3a proved to be a superior catalyst for ring-closing alkyne metathesis, and the [10]cyclophanes 10 and 12 were synthesised in high yield from 1,3-bis(3-pentynyloxymethyl)benzene (9) and bis(3-pentynyl) phthalate (11), respectively. The molecular structures of compounds 2a, 2b, 3a, 3b, 4, and 12 were determined by single-crystal X-ray diffraction. DFT calculations have been carried out for catalyst systems based on the imidazolin-2-iminato tungsten and molybdenum complexes 3a and 3b by choosing the alkyne metathesis of 2-butyne as the model reaction; the studies revealed a lower activation barrier for the tungsten system.
    Chemistry - A European Journal 08/2010; 16(29):8868-77. DOI:10.1002/chem.201000597 · 5.70 Impact Factor
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    ABSTRACT: The title compound 3,4-benzocycloocten-1,5-diyne (1) is a highly reactive hydrocarbon that has been shown to undergo addition reactions with tetraphenyl-cyclopentadienone(tetracyclone) to the 2:1 adduct 6, with octacarbonyldicobalt to the bis metal complex 7, with lithium aluminium hydride to the bis diene 9, and with various electrophilic reagents. In these latter cases cationic intermediates are generated from 1 and a transannular cyclization takes place leading to novel derivatives of 1,2-dihydropentalene (31, 32, 35, 36, 43, 44).
    European Journal of Organic Chemistry 07/2010; 2010(21). DOI:10.1002/ejoc.200901371 · 3.15 Impact Factor

Publication Stats

903 Citations
393.27 Total Impact Points

Institutions

  • 1997–2014
    • Technische Universität Braunschweig
      • Institute of Organic Chemistry
      Brunswyck, Lower Saxony, Germany
  • 2005
    • University of Bonn
      Bonn, North Rhine-Westphalia, Germany
    • Universität Heidelberg
      • Institute of Organic Chemistry
      Heidelburg, Baden-Württemberg, Germany
    • Deutsches Herzzentrum München
      München, Bavaria, Germany
  • 1999
    • Klinikum Braunschweig
      Brunswyck, Lower Saxony, Germany