Dieter Hellwinkel

Die stereochemie ortho-substituierter triphenylamin-derivate

Zusammenfassung Nach den Ergebnissen dynamischer NMR-Untersuchungen liegen die Titelverbindungen in Form chiraler Propellerpyramiden vor, in denen vielfaltige Rotationen der Phenylgruppen mehr oder weniger leicht anregbar sind. Es werden zwei Energiebereiche der Positionenaquilibrierung bei ΔGc‡ ∼ 12/2-13 und ∼ 18–19 kcal/mol beobachtet. Die hierfur verantwortlichen Mechanismen vom Ein-, Zwei- und eventuell Drei-Ring-Flip-Typ werden anhand eines topologischen Schemas analysiert.

Bis-2,2′-biphenylylenarsen(V)-hydrid und seine folgeprodukte

Abstract While reacting bis-2,2′-biphenylylenearsonium iodide(II) with lithiumalanat, varying amounts of bis-2,2′-biphenylylene[2′-(2,2′-biphenylylenearsino)-2-biphenylyl]arsenic(IV) and 2-biphenylyl-2,2′-biphenylylenearsine(XII) are formed, depending on the conditions of the reactions. Beginning from primarily formed, unstable bis-2,2′biphenylylenearsenic hydride (I), complex reaction sequences appear to occur. With regard to comparable reactions of corresponding phosphorus compounds, the arsenic radical(XVII), the red arsenic anion(IX) and the colorless carbanionic arsine [(VIII) = (XX)] are discussed as intermediates.

Inverse Triphenylmethylium-Farbstoffe / Inverse Triphenylmethylium Dyes

Keywords When in the conventional triphenylmethylium dye systems of the crystal violet and malachit green type, 6 and 7, the N̈ -donor and C⊕ -acceptor centers are interchanged , the “Inverse Triphenylmethylium Dye Types” 4 and 5 are obtained , showing very similar colors. The stable models with R = phenyl (8-10) and R = p-tolyl (11-13) were investigated in more detail. The visual observations were supported by the VIS spectra which show ed nearly the same longest wavelength absorption maxim a for corresponding pairs of inverse and conventional dye representatives. The experimental results can be interpreted with a simple HMO -model according to which the longest wavelength absorptions correspond here to transitions of equal energy from weakly bonding to nonbonding and from nonbonding to weakly antibonding molecular orbitals, respectively. On the same basis numerous isoelectronic variants of that dye type can be envisaged. In the N M R -spectra of the new dyes, characteristically increasing deshieldings of nearly all positions are observed in going from the mono- (10+, 13+) through the di- (9++, 12++) to the trications (8+++, 11+++).

Nucleophile substitutionsreaktionen an Spirocyclen des pentakoordinierten Antimons

Abstract Phenylbis-2,2′-biphenylyleneantimony (III) reacts with η-butyllithium to give pentabutylantimony (IV), which, after cleavage by acid is identified as the tetrabutylantimony cation. Phenyllithium reacts with the spirocycles (III) and (XII) cleaving one ring and giving products with one more phenyl group. The mixed cyclic derivative (XVI) reacts with phenyllithium and its six-membered ring is cleaved. With lithium alanate and with alkali metals the spiro compound (III) is decomposed to the 2,2′-biphenylyleneantimony anion (XXV).

On the 1H-NMR spectra of highly charged multi-triphenylmethylium ions

Abstract Relative to their neutral precursors, higly charged multi-tritylium ions show typical downfield 1 H-NMR shifts, whereas the corresponding phenylfluorenylium ions show upfield shifts. A Huckel based model is presented that accounts for this contrasting behavior in terms of antiaromatic ring current in the five-membered ring of the fluorenyl system with essentially null ring currents in the two six-membered rings.

Chalcogeno-substituierte Triphenylmethylium-Ionen vom inversen Malachitgrün-Typ / Chalcogeno-Substituted Bis-triphenylmethylium Ions of the Inverse Malachite Green Type

The longest wavelength VIS absorptions of the deeply colored CF3CO,H solutions of the 4,4′-chalcogenobis-(triphenylmethylium) ions 4++, Y[C6H4C(C6H5)2]2 (Y = O,S,Se,Te) resemble closely those of the corresponding monocationic 4-arylchalcogenotriphenylmethylium systems 5+, ArYC6H4C(C6H5)2, and not those of the structurally directly related 4,4′-bis(arylchalcogeno)triphenylmethylium ions 3+, C6H5C(C6H4YAr)2. This is in striking contrast to the results obtained previously for analogous nitrogen systems, where “inverse”, 2++, RN[C6H4C(C6H5)2], and “conventional” malachite green systems 1+, (Ar2NC6H4)2CR, yield almost indentical Amax values. A rationalization of these observations can be achieved based on the assumption of largely delocalized dications 2++ versus more or less orthogonal “double monocationic” systems 4B++ separated due to torsional twist. Whereas the formal push-pull systems 6+, ArSC6H4YC6H4C(C6H5)2 (Y = O,S,Se) behaved practically like the corresponding standard systems 5+, the mono- and bis-triphenylmethylio-substituted dibenzofurane, dibenzothiophene and thioxanthene derivatives 8+, 9++, 10+ and 11++ displayed hypsocromic shifts of their color bands relative to their noncyclic analogues which are only partly in accordance with predictions based on a simple frontier orbital Hückel model. The 1H and 13C NMR spectra of all these cationic species comply with their respective charges.

Novel Colored Systems of the “Inverted Triphenylmethylium Dye” Type Containing Nitrogen, Phosphorus, Sulfur and Congeneric Donor Centers

Abstract In the course of a fundamental study relating to the question of color and constitution it was found, that a simple HMO-treatment of the isoconjugate resonance system of triphenylmethylium (TPM) dyes1 provides a very variegated scenery for imagining some novel dye systems. Thus, for the archetype of all TPM-dyes, crystal violet, the spectroscopically relevant frontier orbitals show above a core of nine bonding MOs with a limiting energy of s, two nonbonding levels (nb), one slightly bonding (b) and one slightly antibonding (ab) MO, respectively. The occupancy of the frontier orbitals is 6, so that the longest wavelength absorption corresponds to an excitation from a nb-MO to the weakly antibonding MO. One sees at once, that diminuation of the frontier orbital occupancy by 4, leaving only 2 electrons, should generate a new dye system presenting approximatly the same color as crystal violet, since now the longest wavelength absorption would correspond to a transition from the (symmetrically situat...

Die Konstruktion der Namen komplexer Verbindungen

Nachdem in den Teilen 1 und 2 dieses Buches die Nomenklaturregeln fur Stammsysteme sowie fur die verschiedenen funktionellen Verbindungsklassen ausfuhrlich abgehandelt worden sind, sollen in diesem abschliesenden Kapitel die Anleitungen zur Bildung der vollstandigen Namen komplizierter Verbindungen gegeben werden. Hierbei mussen wir uns erneut mit der Frage der Prioritaten bei Ketten- und Ringsystemen befassen, die bereits in den entsprechenden Sektionen des Teils 1 zur Sprache gekommen waren. Da aber nun die funktionellen Gruppen in die Uberlegungen mit einbezogen werden mussen, ist eine Erweiterung der Prioritatsregeln unerlaslich, wie die folgenden Abschnitte zeigen werden.

Anhang I: Tabellen beizubehaltender Trivialnamen (und Semitrivialnamen)

Bereits in Teil 1 dieses Buches sind grosere Serien beizubehaltender Trivialnamen in Tabellenform zusammengestellt worden (Kondensierte Polycyclen: Tabelle 1, S. 13–17; Heterocyclen: Tabellen 2 und 3, S. 37–43). Fur die zahlreichen Trivialnamen der funktionellen Verbindungsklassen des Teils 2 hat es sich als zweckmasiger erwiesen, diese nicht direkt in den Text einzuarbeiten, sondern sie in einem Tabellenanhang zu vereinen. Auch spezielle Kohlenwasserstoff-Systeme wie Terpene und Steroide, deren Nomenklatur weitestgehend von Trivialbezeichnungen beherrscht wird, sind in diesen Anhang aufgenommen.