Synthesis of a new bowl-shaped polyarene aiming

Efficient hydrogen storage is one of the major hurdles towards a potential hydrogen economy. Curved molecules are very interesting for this purpose because of their permanent electrical dipole moment, which can induce a dipole moment on H2 molecules increasing therefore the dipole-dipole interaction and so their adsorption. This work presents the synthesis of a new bowl-shaped polyarene based on curved corannulene’s motive. Since corannulene is known for its ability to adsorb hydrogen, the greater surface and curvature of our target molecule is assumed to increase the hydrogen adsorption. The plan was to start from phenanthrene-9,10-dione and 1-phenylpropan-2-one to obtain a planar polycyclic aromatic hydrocarbon (PAH) containing a five-membered ring. Then, via a crosscoupling reaction and a classical Scholl reaction under Kovacic conditions, it would have been possible to obtain the bowl-shaped molecule. Unfortunately, the synthesis of the first precursor presented obstacles and, from three proposed strategies, only one allowed the obtainment of the planar PAH in acceptable yield. Moreover, only one attempt for the coupling reaction was made and, because of the small amount and the impurity of the obtained product, no Scholl reaction was performed. Therefore, the desired bowl-shaped polyaromatic compound has not been obtained and the efficacy of the Scholl reaction for this synthesis has not been tested

Dialoging A Successful Pedagogy for Embedded Tutors

Over the past three years, Rider University’s Student Success Center Writing Lab has implemented an embedded tutor program for composition courses. Tutors attend class, participate in class discussions, facilitate writing workshops in class, and hold drop-in hours for students (in addition to tutors’ Writing Lab hours). The Embedded Tutor (ET) program, facilitated by Jenny Scudder (who is also the Writing Lab Director), has been successful in helping students complete skills-based courses and connect to academic support services. Initial assessment of the ET program supports the inclusion of the tutor in a skills-based course. While an ET’s training is similar to a tutor who works solely in the Writing Lab, there are key additions that are vital to the tutors’—and the program’s—succesUniversity Writing Cente

Development of iron catalysts for hydrogenation and polymerization

Im Rahmen der vorliegenden Arbeit wurden eine Reihe von neuen, einfach herzustellenden Eisenhydrierkatalysatoren eingeführt. Verschiedenste Aspekte dieser neuen Hydrierkatalysatoren wie Eisenquelle, Aktivierungsmittel, Substrate und Effizienz wurden untersucht. Ein ligandfreier Katalysator, hergestellt aus einer Eisen(II)chlorid-Suspension aktiviert mit Diisobutylaluminiumhydrid (DIBAH), weist die grösste Aktivität auf. Alle Arten von C-C-Doppelbindungen wie mono-, di- oder trisubstituierte, acyclische oder cyclische, isolierte oder konjugierte Doppelbindungen sowie Alkine werden von diesem Katalysator unter milden Bedingungen (3 bar Wasserstoffdruck, Raumtemperatur) in kurzer Zeit quantitativ hydriert. Sowohl TON wie auch TOF steigen mit zunehmender Menge Aktivierungsmittel, bis bei einem Verhältnis FeCl2/DIBAH 1:8 mit TON = 1900 und TOF = 125 h-1 der effizienteste Katalysator erhalten wird. Mit Ausnahme von Ethern und Aminen verhindert die Verwendung eines starken Reduktionsmittels zur Aktivierung die Hydrierung von funktionalisierten Olefinen. In Abwesenheit von Wasserstoff H2 konnte katalytische Aktivität für Alkinpolymerisierungs- und Alkincyclotrimerisierungsreaktionen nachgewiesen werden. Ferner kann dieser Katalysator zur Polymerisierung von Acetylen eingesetzt werden. Bei dem Versuch, die in diesen Fällen katalytisch aktive Spezies zu identifizieren fand man einen homogenen Präkatalysator, welcher erstaunliche Effizienz aufweist (TOF > 340 h-1). Abgeleitet von der angenommenen Struktur dieses Präkatalysators wurden eine Reihe von Allylbenzylether synthetisiert, welche als Liganden getestet wurden. Die entsprechenden Katalysatoren, erhalten durch Aktivierung mit Alkyllithiumreagenzien, weisen Alkenhydrier- und Ethylenoligomerisierungsaktivität auf.In the scope of this work, a series of new, easy to prepare iron hydrogenation catalysts have been introduced. Different aspects of this new hydrogenation catalysts such as iron source, activation reagent, substrates and efficiency were investigated. A ligand-free catalyst, prepared from an iron(II) chloride suspension activated with diisobutylaluminiumhydride (DIBAH), showed the highest activity. With this catalyst all kind of C-C double bonds like mono-, di- or trisubstituted, acyclic or cyclic, isolated or conjugated double bonds as well as alkynes were hydrogenated quantitatively under mild conditions (3 bar hydrogen pressure, room temperature) within short time. Both TON and TOF scale with the added amount of activation reagent up to a 1:8 FeCl2/DIBAH ratio furnishing the most active catalyst with TON = 1900 and TOF = 125 in this case. With the exception of ethers and amines, the use of strong reducing agents as activators prevents the hydrogenation of functionalized olefins. In absence of hydrogen H2, catalytic activity for alkyne polymerization and cyclotrimerization was observed. Furthermore, this catalyst is able to promote the polymerization of acetylene. Attempts to identify the catalytic active species led to the development of a homogeneous precatalyst showing an amazing efficiency (TOF > 340 h-1). Derived from the assumed structure of this precatalyst, a series of allylbenzylethers were synthesized and tested as ligands. The corresponding catalysts, obtained by activation with alkyllithium reagents, display alkene hydrogenation and ethylene oligomerization activity

Hexa-peri-hexabenzocoronenes – Controlling their Self-Assembly by Engineering the Lateral Substituents

Polycondensed aromatic hydrocarbons (PAH), which can be regarded as two-dimensional subsections of graphite, have begun to attract increasing interest in supramolecular chemistry. Substituted hexa-peri-hexabenzocoronenes (HBC), an outstanding class of PAH, are well-known to self-organize in solution into highly ordered columnar molecular stacks. The formed structures are very sensitive to any variation of the medium as well as the lateral substituents of the HBC derivatives. Various perfluoroalkylated HBC compounds have been prepared and investigated by powder XRD, DSC, fluorescence and cryo-SEM in order to gain certain control over the self-assembling behavior of this class of compounds

Reactivity of Allenes towards Iron Carbonyl Complexes

A series of monosubstituted allenes was reacted with Fe2(CO)9 to give dinuclear iron-carbonyl complexes containing organic ligands derived either from monomeric or dimerized allene. A mechanism of formation is proposed based on isolated intermediates. These intermediates point to an allene dimerization via addition of a reactive allene iron complex to free allene. Unusual chemical shifts were observed for many resonances in the 1H- and 13C-NMR spectra of the new compounds

Synthesis of perfluoroalkylated bulky triarylamines

The synthesis of two new triarylamine compounds bearing perfluoroalkylated side chains is described. Good thermal stabilities combined with a blue emission make these compounds promising candidates for materials applications

Crystal structures of <i>trans</i>-di­chlorido­tetra­kis­[1-(2,6-diiso­propyl­phen­yl)-1<i>H</i>-imidazole-Κ<i>N</i>³]iron(II), <i>trans</i>-di­bromido­tetra­kis­[1-(2,6-diiso­propyl­phen­yl)-1<i>H</i>-imidazole-Κ<i>N</i>³]iron(II) and <i>trans</i>-di­bromido­tetra­kis­[1-(2,6-diiso­propyl­phen­yl)-1<i>H</i>-imidazole-Κ<i>N</i>³]iron(II) diethyl ether disolvate

The title compounds, [FeCl₂(C₁₅H₂₀N₂)₄], (I), [FeBr₂(C₁₅H₂₀N₂)₄], (II), and [FeBr₂(C₁₅H₂₀N₂)₄]·2C₄H₁₀O, (IIb), respectively, all have triclinic symmetry, with (I) and (II) being isotypic. The FeII atoms in each of the structures are located on an inversion center. They have octa­hedral FeX₂N₄ (X = Cl and Br, respectively) coordination spheres with the FeII atom coordinated by two halide ions in a trans arrangement and by the tertiary N atom of four aryl­imidazole ligands [1-(2,6-diiso­propyl­phen­yl)-1H-imidazole] in the equatorial plane. In the two independent ligands, the benzene and imidazole rings are almost normal to one another, with dihedral angles of 88.19 (15) and 79.26 (14)° in (I), 87.0 (3) and 79.2 (3)° in (II), and 84.71 (11) and 80.58 (13)° in (IIb). The imidazole rings of the two independent ligand mol­ecules are inclined to one another by 70.04 (15), 69.3 (3) and 61.55 (12)° in (I), (II) and (IIb), respectively, while the benzene rings are inclined to one another by 82.83 (13), 83.0 (2) and 88.16 (12)°, respectively. The various dihedral angles involving (IIb) differ slightly from those in (I) and (II), probably due to the close proximity of the diethyl ether solvent mol­ecule. There are a number of C-H***Missing image substitution***halide hydrogen bonds in each mol­ecule involving the CH groups of the imidazole units. In the structures of compounds (I) and (II), mol­ecules are linked via pairs of C-H...halogen hydrogen bonds, forming chains along the a axis that enclose R₂²(12) ring motifs. The chains are linked by C-H...π inter­actions, forming sheets parallel to (001). In the structure of compound (IIb), mol­ecules are linked via pairs of C-H...halogen hydrogen bonds, forming chains along the b axis, and the diethyl ether solvent mol­ecules are attached to the chains via C-H...O hydrogen bonds. The chains are linked by C-H...π inter­actions, forming sheets parallel to (001). In (I) and (II), the methyl groups of an isopropyl group are disordered over two positions [occupancy ratio = 0.727 (13):0.273 (13) and 0.5:0.5, respectively]. In (IIb), one of the ethyl groups of the diethyl ether solvent mol­ecule is disordered over two positions (occupancy ratio = 0.5:0.5)

Novel iron tweezers complexes for hydrogenation and polymerization of olefins

L’utilisation des complexes organométalliques comme catalyseurs est devenu un domaine très important de la chimie des matériaux. Cependant et malgré ce développement, les catalyseurs à base de fer(II) sont peu employés dans la polymérisation d’oléfines. Un de rares catalyseur utilisé dans ce contexte est le complexe tridenté diimine pyridine développé par Gibson et Brookhart. Cependant ce modèle souffre par son manque de tolérance envers le moindre changement effectué dans son enveloppe, résultant par une diminution drastique de son activité catalytique. Le but de ce travail est de synthétiser des catalyseurs de fer(II) contenant des ligands chelates et d’étudier leur utilisation dans la polymérisation d’oléfines. Il est important de signaler que des travaux précédents dans notre groupe on montré une très bonne corrélation entre la polymérisation et l’hydrogénation d’oléfines. Ainsi nous avons aussi exploité l’habilité de nos complexes dans l’hydrogénation. Deux projets ont été menés en parallèle : il s’agit de la synthèse de complexes de fer(II) contenant d’un côté le ligand benzylétherfurane et de l’autre côté les ligands carbenes bisimidazol-2-ylidene. Le complexe de fer(II) benzyletherfurane a été employé avec succès dans l’hydrogénation d’oléfines sous des conditions très douces (1-3 bar d’hydrogène et à température ambiante), cependant son emploi comme catalyseur de polymérisation d’oléfines n’a pas donné les résultats escomptés. Compte tenu de ceci, ce projet à été mis à côté au profit des complexes de fer(II) bisimidazol-2-ylidene qui eux ont montré une bonne activité dans les deux réactions, polymérisation et hydrogénation des oléfines sous des conditions douces. Durant la préparation de ces précatalyseurs, plusieurs autres complexes de fer(II) et fer(III) ont été isolé comme étant des produits secondaires de la réaction. Dans le but de caractériser les produits obtenus, nous avons aussi préparé plusieurs dérivés en introduisant des ligands supplémentaires dans la sphère de coordination; c’est ainsi que des dérivés formiate, carboxylate, triflate et cyclopentadiényle ont été synthétisés. Plusieurs voies ont été exploitées pour synthétiser les complexes fer(II) bisimidazol-2-ylidene, une d’elles, la transmetallation, nous a conduit à préparer des nouveaux complexes d’argent; ces complexes ont été caractérisés entre autre par diffraction de rayons – X. Enfin dans une démarche purement comparative, deux complexes nickel bisimidazol-2-ylidene ont été préparés et leur activité catalytique dans la polymérisation d’éthylène a été sommairement étudiée, donnant de très bons résultats.The use of organometallic complexes as catalysts became a very significant topic in the field of material chemistry. However, despite of this development, only few of them contain iron(II), except the tridentate complex diimine pyridine developed by Gibson and Brookhart and employed in the olefin polymerization. Unfortunately, this model suffers by its lack of tolerance towards the minor changes carried out in its envelope, resulting by a drastic reduction from its catalytic activity. The goal of this work is to synthesize iron(II) complexes containing pincer ligands and to study their use as catalyst for polymerization of olefins. It has to be noted that previous work in our group showed a very good correlation between the polymerization and the hydrogenation of olefin. Thus, we have also exploited the ability of our news complexes in hydrogenation. Two projects were carried out in parallel: one was the synthesis of iron(II) complexes containing benzyletherfuran ligand and the second one was the preparation of iron(II) bisimidazol-2-ylidene complexes. First project : The prepared iron(II) benzyletherfuran complex was successfully tested in the hydrogenation of olefin under very mild conditions (1-3 bar of hydrogen at room temperature); however, its employment as catalyst for olefin polymerization did not give the expected results. Thus, this project was left aside with the profit of the second one. Second project : The prepared iron(II) bisimidazol-2-ylidene complexes showed a good activity in both reactions, polymerization and hydrogenation of olefins under mild conditions. During the preparation of these complexes, several other complexes of iron(II) and iron(III) were isolated as secondary products from the reaction. With the purpose of characterizing the obtained products, we also prepared several derivatives by introducing additional ligands into the coordination sphere of iron(II) bisimidazol-2- ylidene complexes. Thus, formiate, carboxylate, triflate and cyclopentadienyl derivatives were synthesized. Several ways were exploited to synthesize the iron(II) bisimidazol-2-ylidenes complexes, one of them was the transmetallation which led us to prepare new silver complexes. These complexes were characterized amongst other analytical tools by X-ray diffraction. Finally, in a purely comparative approach, two nickel bisimidazol-2-ylidene complexes were prepared and their catalytic activity in the ethylene polymerization was studied, giving very good results