Rolf Gleiter

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Organization: Universit?t Heidelberg , Germany

Department: Organisch-Chemisches Institut

Title: Emeritus Professor(PhD)

TOPICS

Organic Chemistry

Chemicals
References

Au(I)-Catalyzed Dimerization of Two Alkyne Units—Interplay between Butadienyl and Cyclopropenylmethyl Cation: Model Studies and Trapping Experiments

Co-reporter:Mathis Kreuzahler, Sven Fabig, Gebhard Haberhauer, and Rolf Gleiter

The Journal of Organic Chemistry December 15, 2017 Volume 82(Issue 24) pp:13572-13572

Publication Date(Web):November 17, 2017

DOI:10.1021/acs.joc.7b02843

In recent years, Au(I)-catalyzed reactions proved to be a valuable tool for the synthesis of substituted cycles by cycloaromatization and cycloisomerization starting from alkynes. Despite the myriad of Au(I)-catalyzed reactions of alkynes, the mono Au(I)-catalyzed pendant to the radical dimerization of nonconjugated alkyne units has not been investigated by quantum chemical calculations. Herein, by means of quantum chemical calculations, we describe the mono Au(I)-catalyzed dimerization of two alkyne units as well as the transannular ring closure reaction of a nonconjugated diyne. We found that depending on the system and the method used either the corresponding cyclopropenylmethyl cation or the butadienyl cation represents the stable intermediate. This circumstance could be explained by different stabilizing effects. Moreover, the calculation reveals a dramatic (>1012-fold) acceleration of the Au(I)-catalyzed reaction compared to that of the noncatalyzed radical variant. Trapping experiments with a substituted 1,6-cyclodecadiyne using benzene as a solvent at room temperature as well as studies with deuterated solvents confirm the calculations. In this context, we also demonstrate that trapping of the cationic intermediate with benzene does not proceed via a Friedel–Crafts-type reaction.

Electron-rich two-, three- and four-center bonds between chalcogens – New prospects for old molecules

Co-reporter:Rolf Gleiter, Gebhard Haberhauer

Coordination Chemistry Reviews 2017 Volume 344(Volume 344) pp:

Publication Date(Web):1 August 2017

DOI:10.1016/j.ccr.2017.03.003

•Bonding models for trithiapentalene and related species.•Rules to rationalize the structures of polycyclic systems with NSN bridges.•Combination of π and σ aromaticity to a three dimensional σ/π-aromaticity.•Double pancake versus long chalcogen-chalcogen bonds in dimeric C,N,S-heterocycles.•Qualitative concept for predicting the length of long chalcogen-chalcogen bonds.The focus of this review is the nature of a third covalent bond between two divalent chalcogen centers. This bond is longer than a single bond and less than the van der Waals distance between two chalcogen atoms. Such a bond is only possible when electron density is withdrawn from the divalent chalcogens. For two sulfur centers this means S⋯S bond lengths between 2.3 Å and 3.1 Å. Our discussion is based on model systems, such as various trithiapentalene derivatives, 1,5-dithia-2,4,6,8-tetrazocine and related SN cage systems, the dimers of a 1,3-dithia-2,4,6-triazine radical, and systems adopting 2-center-3-electron and 4-center-6-electron bonds, respectively, between two or four sulfur centers. The leitmotiv of this review is that the loss of electron density at the divalent sulfides can lead to trivalent sulfur centers. This behavior is first rationalized qualitatively by simple MO models. The properties of the models are reproduced by high level quantum chemical methods.Download high-res image (96KB)Download full-size image

Dimerization of Two Alkyne Units: Model Studies, Intermediate Trapping Experiments, and Kinetic Studies

Co-reporter:Sven Fabig; Gebhard Haberhauer

Journal of the American Chemical Society 2015 Volume 137(Issue 5) pp:1833-1843

Publication Date(Web):January 16, 2015

DOI:10.1021/ja510699b

By means of high level quantum chemical calculations (B2PLYPD and CCSD(T)), the dimerization of alkynes substituted with different groups such as F, Cl, OH, SH, NH2, and CN to the corresponding diradicals and dicarbenes was investigated. We found that in case of monosubstituted alkynes the formation of a bond at the nonsubstituted carbon centers is favored in general. Furthermore, substituents attached to the reacting centers reduce the activation energies and the reaction energies with increasing electronegativity of the substituent (F > OH > NH2, Cl > SH, H, CN). This effect was explained by a stabilizing hyperconjugative interaction between the σ* orbitals of the carbon-substituent bond and the occupied antibonding linear combination of the radical centers. The formation of dicarbenes is only found if strong π donors like NH2 and OH as substituents are attached to the carbene centers. The extension of the model calculations to substituted phenylacetylenes (Ph–C≡C–Y) predicts a similar reactivity of the phenylacetylenes: F > OCH3 > Cl > H. Trapping experiments of the proposed cyclobutadiene intermediates using maleic anhydride as dienophile as well as kinetic studies confirm the calculations. In the case of phenylmethoxyacetylene (Ph–C≡C–OCH3) the good yield of the corresponding cycloaddition product makes this cyclization reaction attractive for a synthetic route to cyclohexadiene derivatives from alkynes.

Enediyne Dimerization vs Bergman Cyclization

Co-reporter:Gebhard Haberhauer, Rolf Gleiter, and Sven Fabig

Organic Letters 2015 Volume 17(Issue 6) pp:1425-1428

Publication Date(Web):March 10, 2015

DOI:10.1021/acs.orglett.5b00296

High-level quantum chemical calculations reveal that the dimerization of enediynes to 1,3-butadiene-1,4-diyl diradicals is energetically more favored than the corresponding Bergman cyclization of enediynes. Moreover, the activation barrier of both reactions can be drastically reduced by the introduction of electron-withdrawing substituents like fluoro groups at the reacting carbon centers of the triple bonds.

anti-Diradical Formation in 1,3-Dipolar Cycloadditions of Nitrile Oxides to Acetylenes

Co-reporter:Gebhard Haberhauer, Rolf Gleiter, and Sascha Woitschetzki

The Journal of Organic Chemistry 2015 Volume 80(Issue 24) pp:12321-12332

Publication Date(Web):November 11, 2015

DOI:10.1021/acs.joc.5b02230

By means of high level quantum chemical calculations (B2PLYPD and CCSD(T)), the mechanisms of the reaction of nitrile oxides with alkenes and alkynes were investigated. We were able to show that in the case of alkenes, regardless of the chosen substituents, the concerted mechanism is always energetically favored as compared to a two-step process, which runs through an anti-diradical species. In the case of alkynes, the concerted mechanism is favored only for the reaction of alkyl-substituted acetylenes. For aryl-substituted acetylenes, the activation barrier toward the anti-diradical is equal to or lower than the activation barrier of the concerted reaction. This reversal of the reaction paths is not only limited to nitrile oxides as dipolarophiles. Conditions favoring the anti-diradical path are the presence of a triple bond in both the 1,3-dipole and the dipolarophile and additionally an aryl substituent attached to the alkyne. The featured energy relationships between the reaction paths are able to explain the experimentally observed byproducts of the reaction of nitrile oxides with arylacetylenes. The discovered differences for the preferred reaction path of 1,3-dipolar cycloadditions to acetylenes should be of considerable interest to a broader field of chemists.

Model Studies on the Dimerization of 1,3-Diacetylenes

Co-reporter:Gebhard Haberhauer, Rolf Gleiter, and Sven Fabig

The Journal of Organic Chemistry 2015 Volume 80(Issue 10) pp:5077-5083

Publication Date(Web):April 22, 2015

DOI:10.1021/acs.joc.5b00461

By means of high-level quantum chemical calculations (B2PLYPD and CCSD(T)), the dimerization of 1,3-diacetylenes was studied and compared to the dimerization of acetylene. We found that substituted 1,3-diacetylenes are more reactive than the corresponding substituted acetylenes having an isolated triple bond. The most reactive centers for a dimerization are always the terminal carbon atoms. The introduction of a test reaction allows the calculation of the relative reactivity of individual carbon centers in phenylacetylene, phenylbutadiyne, and phenylhexatriyne. A comparison shows that the reactivity of the terminal carbon atoms increases with increasing numbers of alkyne units, whereas the reactivity of the internal carbon atoms remains very low independent of the number of alkyne units.

Long Chalcogen–Chalcogen Bonds in Electron-Rich Two and Four Center Bonds: Combination of π- and σ-Aromaticity to a Three-Dimensional σ/π-Aromaticity

Co-reporter:Rolf Gleiter and Gebhard Haberhauer

The Journal of Organic Chemistry 2014 Volume 79(Issue 16) pp:7543-7552

Publication Date(Web):July 10, 2014

DOI:10.1021/jo501277h

Quantum chemical calculations were carried out by applying density functional theory to study the two center-three electron (2c-3e) bonds between the sulfur centers of cyclic dithioethers. Calculated were the S–S distance, the stabilization energy, and the energy of the σ → σ* transition. The extension of the calculations to two (2c-3e) bonds in one molecule shows that a rearrangement to one σ bond and two lone pairs on sulfur is usually more favorable. Exceptions are [H2S2+]2, the dimer of the 1,2-dithia-3,5-diazolyl radical (27a), the dimer of the 1,2,4-trithia-3,5-diazolyl radical cation (26a2+), and its Selena congeners and derivatives. In the case of [H2S2+]2, the (4c-6e) bond between the chalcogen centers is a good description of this dimer. To describe the binding situation in the dimer 26a2+ and 27a, the concept of a “simple” (4c-6e) bond was extended. Our calculations reveal a strong σ-aromaticity within the plane of the four sulfur centers in addition to a strong π-conjugation within the five-membered rings. The whole phenomenon can best be described as a three-dimensional σ/π-aromaticity within the 14π dimers.

From Eight-Membered 10 Electron SulfurNitrogen Cycles to Bicycles and Cages: A Theoretical Approach

Co-reporter:Dr. Rolf Gleiter;Dr. Gebhard Haberhauer;Sascha Woitschetzki

Chemistry - A European Journal 2014 Volume 20( Issue 42) pp:13801-13810

Publication Date(Web):

DOI:10.1002/chem.201402481

Abstract

A simple way of rationalizing the structures of cyclic, bicyclic, and tricyclic sulfur–nitrogen species and their congeners is presented. Starting from a planar tetrasulfur tetranitride with 12π electrons, we formally derived on paper a number of heterocyclic eight-membered 10π electron species by reacting the 3p orbitals of two opposite sulfur centers with one radical each, or by replacing these centers by other atoms with five (P) or four (Si, C) valence electrons. This led to planar aromatic 10π electron systems, nonplanar bicyclic structures with a transannular SS bond, and tricyclic structures by bridging the planar rings with an acceptor or donor unit. The final structures depend on the number of π electrons in the bridges. Intermediate biradicals are stabilized by Jahn–Teller distortion, giving transannular SS bonds between the NSN units. This procedure may be summarized by two rules, which provide a rationale for the structures of a large number of sulfur–nitrogen-based molecules. The long bonds between the NSN units show a p character of >95 %. The qualitative results have been compared with known molecular structures and the results of B3LYP/cc-pVTZ calculations as well as CASSCF and CASVB calculations. B3LYP/cc-pVTZ calculations have also provided the UV/Vis spectra and the NICS values of the planar 10π systems.

Interplay between 1,3-Butadien-1,4-diyl and 2-Buten-1,4-dicarbene Derivatives: The Quest for Nucleophilic Carbenes

Co-reporter:Gebhard Haberhauer

Journal of the American Chemical Society 2013 Volume 135(Issue 21) pp:8022-8030

Publication Date(Web):April 28, 2013

DOI:10.1021/ja4020937

By means of high level quantum chemical calculations, the influence of electron-donating heteroatomic groups (O, NH) was investigated on the 1,6-transannular ring closure of 1,6-cyclodecadiyne (8a). In the case of 8a, the bicyclo[4.4.0]deca-1,6-dien-2,7-diyl biradical 12 is generated. It was found that oxygen centers or NH groups next to the triple bond reduce the activation energy of the ring closure considerably. For the intermediate, a 2-buten-1,4-dicarbene derivative is predicted. The extension of the model calculations to two hydroxyl- or aminoacetylenes predicts the formation of the corresponding 1,3-butadien-1,4-diyl intermediates or the 2-buten-1,4-dicarbene derivatives, a member of the nucleophilic carbene family. Moreover, the calculations predict that two separated dimethoxyacetylenes are more than 7 kcal/mol less stable than the corresponding biradical and dicarbene, respectively. Possible reactions of the dicarbenes with transition metal compounds are discussed.

Alkynes Between Main Group Elements: From Dumbbells via Rods to Squares and Tubes

Co-reporter:Rolf Gleiter and Daniel B. Werz

Chemical Reviews 2010 Volume 110(Issue 7) pp:4447

Publication Date(Web):April 14, 2010

DOI:10.1021/cr9003727

Cyclacenes: Hoop-Shaped Systems Composed of Conjugated Rings

Co-reporter:Rolf Gleiter, Birgit Esser and Stefan C. Kornmayer

Accounts of Chemical Research 2009 Volume 42(Issue 8) pp:1108

Publication Date(Web):May 26, 2009

DOI:10.1021/ar9000179

A carbon nanotube, if it could be cut sideways at the end like a pipe, would yield beltlike structures. These subunits of carbon nanotubes, in their simplest manifestation as the [6]ncyclacenes, are composed of conjugated six-membered rings that are annelated, that is, made of a series of consecutively fused ring structures. These seemingly simple “one-benzene-thick” slices are of considerable interest as models—for electronic structure and spectroscopic properties, for example—for carbon nanotubes. In the late 1980s Stoddart and co-workers, soon to be followed by other groups, embarked on the synthesis of [6]ncyclacenes. The necessary curved shape of the belt was achieved with boat-shaped precursors for Diels−Alder reactions, namely, 7-oxanorbornene derivatives. The preferred endo-addition in Diels−Alder reactions assured an efficient synthesis of beltlike systems containing 12 to 18 six-membered rings. However, the removal of the auxiliary oxygen centers to achieve [6]ncyclacenes as fully conjugated systems has failed so far: they remain an inaccessible target despite some 25 years of synthetic effort. Concurrently, theoretical studies revealed that [6]ncyclacenes as linearly annelated systems show small energy gaps between triplet and singlet states; they can thus be expected to be unstable species. Angularly annelated systems, on the other hand, were predicted to have large singlet−triplet splittings. Nakamura and co-workers and our laboratory have found ways around the obstacles to create cyclacenes. Nakamura and co-workers prepared the first angular annelated cyclacene by selective reduction of the north and south poles of C60. We used a cyclic system that is fully conjugated and also adopts a boat conformation: cyclooctatetraene. By following this principle, we synthesized two types of linearly annelated cyclacenes: metal-stabilized four-membered rings alternating with eight-membered rings ([4.8]ncyclacenes), and six-membered rings alternating with eight-membered rings ([6.8]ncyclacenes). These new scaffolds, if extended along the molecular axis, would represent as-yet unknown forms of carbon nanotubes and are thus inviting synthetic targets. Calculations show that the incorporation of heteroatoms (S and NH) into these scaffolds is promising, encouraging the synthetic pursuit of thia- and azacyclacenes.

Transannular Ring Closure of a 1,8-Diazacyclotetradeca-3,5,10,12-tetrayne to a Tricyclic System with a Central Cyclooctatetraene Ring

Co-reporter:Rolf Gleiter;Kirstin Hövermann;Birgit Esser;Arkasish Byopadhyay

European Journal of Organic Chemistry 2009 Volume 2009( Issue 18) pp:3006-3010

Publication Date(Web):

DOI:10.1002/ejoc.200900193

Abstract

The addition of two equivalents of hydrochloric acid to N,N′-diisopropyl-1,8-diazacyclotetradeca-3,5,10,12-tetrayne (13) afforded a tricyclic scaffold in which a central dichloro-substituted cyclooctatetraene ring is annelated by two N-isopropyl-2,5-dihydropyrrole rings (14). Three other minor products were congeners of 14 in which one (15, 16) or both (17) of the 2,5-dihydropyrrole rings are oxidized. In 16 the chlorine atoms adopt different positions.The assignment of the structures of 14–17 is based on the result of an X-ray investigation on single crystals of 16 and NMR studies. The structural assignments of 14 and 15 were corroborated by labeling experiments with DCl. The regiochemistry in the addition of the second equivalent of hydrochloric acid to 13 was illuminated by DFT calculations. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Intramolecular Nonbonded Interactions Between Divalent Selenium Centers with Donor and Acceptor Substituents

Co-reporter:Alberth Lari;Christian Bleiholder;Frank Rominger

European Journal of Organic Chemistry 2009 Volume 2009( Issue 17) pp:2765-2774

Publication Date(Web):

DOI:10.1002/ejoc.200900108

Abstract

To investigate the intramolecular van der Waals interactions between two divalent selenium centers in the solid state and in solution, we have prepared methyl 2-(methylselenyl)benzyl selenide (1), ethynyl 2-(methylselenyl)benzyl selenide (2), and 2-(methylselenyl)benzyl selenocyanate (3). By means of NMR spectroscopic studies we have determined the ⁷⁷Se NMR chemical shifts of the signals of the Se centers of 1–3 and their long-range ⁴J_Se,Se coupling constants. These results, and the X-ray structural studies of single crystals of 3 and 11, a quasi-dimer of 2, point to an Se···Se van der Waals interaction and short Se···H distances in 1–3. These measurements were supported by quantum chemical calculations on 1–3 at the MP2/6-311+g(d)//B98/6-311+g(d) level of theory, which showed a preference for the endo_X and endo_H conformations of 1–3. This finding was confirmed by calculations of the ⁷⁷Se NMR chemical shifts of 1–3 by GIAO-B98 and GIAO-PBE calculations.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Supramolecular Organization Based on van der Waals Forces: Syntheses and Solid State Structures of Isomeric [6.6]Cyclophanes with 2,5-Diselenahex-3-yne Bridges

Co-reporter:Alberth Lari, ;Frank Rominger

European Journal of Organic Chemistry 2009 Volume 2009( Issue 14) pp:2267-2274

Publication Date(Web):

DOI:10.1002/ejoc.200900106

Abstract

The ortho, meta, and para isomers 4–6 of [6.6]cyclophanes with 2,5-diselenahex-3-yne bridges were synthesized by reacting the bis(selenocyanatomethyl)benzene derivatives 8a–8c with the lithium salt of trimethylsilylethyne to yield 9a–9c, deprotection of which afforded the bis(ethynylselenylmethyl)benzenes 10a–10c. The condensation of the bis-lithium salts of 10a–10c with 8a–8c yielded the target compounds 4–6. X-ray investigations on single crystals of 4–6 revealed intermolecular Se···Se interactions which contribute significantly to the solid-state structures of these species. In the case of the orthocyclophane 4, we found short distances between one Se–C≡C–Se unit of each molecule leading to a linear chain of orthocyclophane rings. In the metacyclophane, 5, the rings adopt a chair conformation and are piled on top of each other. The resulting molecular channels are connected with each other by intermolecular Se···Se interactions. For 6 also a chair conformation of the [6.6]paracyclophane unit was encountered. In the solid state the rings of 6 are connected by intermolecular Se···Se bridges.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Novel Photochemical Reactions of Phosphonium-Iodonium Ylides: Synthesis of Phosphonium-Substituted Oxazoles

Co-reporter:Elena D. Matveeva;Tatyana A. Podrugina;Anna S. Pavlova;Andrey V. Mironov;Nikolai S. Zefirov

European Journal of Organic Chemistry 2009 Volume 2009( Issue 14) pp:2323-2327

Publication Date(Web):

DOI:10.1002/ejoc.200801251

Abstract

Irradiation of the mixed phosphonium-iodonium ylides 4–6 in the presence of acetonitrile, propionitrile, and benzonitrile yielded the oxazole derivatives 9a–9c, 10a–10c, and 11a–11c in 30 %–50 % yields. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

α-Metallocenylmethylium Ions and Their Isoelectronic Congeners: A Comparison Based on DFT Calculations

Co-reporter:Christian Bleiholder, Frank Rominger and Rolf Gleiter

Organometallics 2009 Volume 28(Issue 4) pp:1014-1017

Publication Date(Web):January 21, 2009

DOI:10.1021/om800573u

The geometrical parameters, net natural charges, and Wiberg bond indices of a series of α-metallocenylmethylium ions with 18 valence electrons were calculated using density functional theory. The transition metals considered were Cr, Mn, Fe, Mo, Re, W, Ru, and Os. As coligands to the fulvene-metal fragment we used benzene, cyclopentadienyl, and three CO units. We also examined the fulvene-metal fragments for Co, Rh, and Ir using a cyclobutadiene coligand. Trends in bond order between the exo-carbon atom of the fulvene unit (C6) and the metal atom as well as the bending angle of C6, α, and the net charges at C6 and the metal centers were analyzed. We found good correlation between α and the metal−C6 distance (d1). A comparison of the calculated values of α and d1 with experimental data shows good agreement in cases where steric effects do not hamper the C6−metal interaction.

CpCo-Mediated Reactions of Cyclopropenones: A DFT Study

Co-reporter:Daniel B. Werz, Günter Klatt, Jevgenij A. Raskatov, Horst Köppel and Rolf Gleiter

Organometallics 2009 Volume 28(Issue 6) pp:1675-1682

Publication Date(Web):February 19, 2009

DOI:10.1021/om800685t

Quantum chemical calculations using density functional theory at the B3LYP/6-311G(d)/Wachters+f level have been carried out to model possible pathways for the reaction of CpCo(CO)2 (15) with cyclopropenone to yield CpCo-capped p-benzoquinone complexes. For a number of intermediates, including all relevant 16-electron species, energies and geometries of the triplet electronic state were also obtained, which permitted us to locate four crossings of the singlet and triplet potential surfaces. It was found that first a metallacyclobutenone complex (21) is formed. Our calculations indicate a dissociative mechanism; the previously observed associative mechanism in ligand substitution reactions of 15 is shown to be a consequence of lower reaction temperatures. The addition of a second cyclopropenone unit to 21 reveals a higher energy path (path I) than does the addition of CO to 21, followed by acetylene addition (path II). The latter path is favored, which has already been shown by labeling and trapping experiments. Despite favorable energetics, the paths involving the triplet surface have not been observed experimentally; we tentatively attribute this to the very short lifetime of the initially formed triplet.

From Metacyclophanes to Cyclacenes: Synthesis and Properties of [6.8]3Cyclacene

Co-reporter:Birgit Esser Dr.;Arkasish Byopadhyay Dr.;Frank Rominger Dr. Dr.

Chemistry - A European Journal 2009 Volume 15( Issue 14) pp:3368-3379

Publication Date(Web):

DOI:10.1002/chem.200802297

Synthesis, Properties and Formation of (RCp)Co- and (RCp)Rh-Stabilized[4.8]3Cyclacene Derivatives

Co-reporter:StefanC. Kornmayer Dr.;Björn Hellbach Dr.;Frank Rominger Dr. Dr.

Chemistry - A European Journal 2009 Volume 15( Issue 14) pp:3380-3389

Publication Date(Web):

DOI:10.1002/chem.200802455

CpCo-Mediated Reactions of Cyclopropenones: Access to CpCo-Capped Benzoquinone Complexes

Co-reporter:Andreea Schuster-Haberhauer, Rolf Gleiter, Olivia Körner, Adriane Leskovar, Daniel B. Werz, Felix R. Fischer and Frank Rominger

Organometallics 2008 Volume 27(Issue 7) pp:1361-1366

Publication Date(Web):March 1, 2008

DOI:10.1021/om701115w

The reaction of di(n-propyl)cyclopropenone (7), di(n-butyl)cyclopropenone (16), and bicyclo[12.1.0]pentadeca-1(14)-en-7-yn-15-one (21) with CpCo(CO)2 and CpCo(cod) yielded CpCo-complexed benzoquinone and cyclopentadienone derivatives. When 16 was reacted with CpCo(CO)2 and a 10-fold surplus of 4-octyne, a mixture of CpCo-capped benzoquinone 25 and cyclopentadienone 26 was isolated. The reaction of cyclopropenone 16 containing a 13C-labeled CO group with CpCo(CO)2 yielded a CpCo-capped tetrakis(n-butyl)-p-benzoquinone with one 13C nucleus per molecule as the main product. The mechanism of the formation of p-benzoquinone is discussed on the basis of the results of trapping and labeling experiments.

π-Prismands – Flexible Hosts for Metal Ions

Co-reporter:Andreas Kunze;Saeed Balalaie;Frank Rominger

European Journal of Organic Chemistry 2006 Volume 2006(Issue 13) pp:

Publication Date(Web):2 MAY 2006

DOI:10.1002/ejoc.200600100

The π-prismands dealt with in this paper are: 1,8-diazabicyclo[6.6.6]eicosa-4,11,17-triyne (6), 1,8-diazabicyclo[6.6.5]nonadeca-4,11-diyne (7), 1,8-diazabicyclo[6.6.6]eicosa-4,11-diyne (8), 1,10-diazabicyclo[8.6.6]docosa-5,13,19-triyne (9), 17-(1,4)benzena-1,8-diazabicyclo[6.6.5]nonadecaphane-4,11-diyne (10), 11,16-(1,4)dibenzena-1,8-diazabicyclo[6.5.5]octadecaphane-4-yne (11) and 4,10,15-(1,4)tribenzena-1,7-diazabicyclo[5.5.5]heptadecaphane (12). The synthesis of 9 is reported. The molecular parameters obtained from X-ray investigations on single crystals of 6–9 as well as of 10–12 are compared with each other. Also discussed are the structures of the monoprotonated forms of 6 and 12. The π-prismands 6–12 form stable complexes with Ag⁺ and Cu⁺. The crystal structures of the metal complexes as well as their spectroscopic properties are reported. Both reveal that the metal center interacts with the nitrogen atoms and the π-systems of the bridges.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Tripodands with Phenyl and Thiophenyl Rings and Nitrogen Bridgehead Atoms

Co-reporter:Martin Baier;Frank Rominger

European Journal of Organic Chemistry 2006 Volume 2006(Issue 23) pp:

Publication Date(Web):10 OCT 2006

DOI:10.1002/ejoc.200600512

The flexible tripodands 7–9 and 15 with phenyl and thiophenyl rings as “legs” and nitrogen as bridgehead atoms have been synthesized by three-component condensation reactions of the corresponding amine with the aryl halide. The more rigid species 10–14 and 17 were built up from the podands 7–9 as well as from their iodine substitution products 33–35 by a sequence of ethynylation and C–C coupling reactions. Podand 16 was prepared from tris-iodide 36 by Sonogashira coupling with phenylacetylene. In the cases of 7, 12, 15–17, 22, 24, 35, 36, and 41 the structural parameters were determined by X-ray studies. With the exception of 7, 12, and 17, all structures show either close intermolecular contacts between heteroatoms (15, 22, 24, 35, and 36), C–H···N hydrogen bonding (41), or are closely packed as a result of π···π stacking (16). We were able to isolate silver triflate complexes of 9, 10, and 16, and in the case of 9 we obtained crystals suitable for X-ray diffraction studies. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)