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Calculations were performed using strictly atomic benzene-p-orbitals and p-orbitals that are allowed to delocalize, on naphthalene, acenaphthylene, pyracylene and many organic compounds. The results show that cyclopenta-fusion does not extend the pie system in the ground state and the five-membered rings act as peri-substituents.

3-Ferrocenyl-2,4,5-tri-([beta]-naphthyl)cyclopentadienone undergoes a Diels--Alder reaction with di-([beta]-naphthyl)acetylene to yield, after elimination of carbon monoxide, ferrocenyl-penta-([beta]-naphthyl)benzene (4). [sup.1]H and [sup.13]C variable-temperature NMR studies on 4 reveal the existence of multiple diastereoisomers at low temperature. These data are interpreted in terms of slowed rotation of the naphthyl groups, and are supported by the X-ray crystal structure of 4, which exhibits disorder at three of the naphthyl sites. Key words: sterically crowded molecules, hindered rotations, crystallography, NMR.

The introduction of a nitrogen atom at one of the acetylenic termini of 10-, 11-, 12-, and 13-membered benzannulated cyclic enediynes has resulted in the complete suppression of the conventional radical Bergman reaction in favor of a polar cycloaromatization. The latter reaction is catalyzed by acids and has proceeded by initial protonation of an ynamide fragment, where the resulting ketenimmonium cation has cyclized to produce naphthyl cation, which has reacted with nucleophiles or undergoes Friedel-Crafts addition to aromatic compounds.

The reduction of the steric interaction between the upper-half and the lower-half of a light-driven rotary molecular motor by decreasing the size of the aromatic moiety in the upper-half from naphthalene to a benzothiophene has resulted in a much faster rotation.

The dearomatization reaction of benzylic chlorides, chloromethylnaphthalenes, and naphthalene allyl chlorides with allenyltributyltin was performed in presence of Pd[(P[Ph.sub.3]).sub.4] catalyst at room temperature to yield the corresponding propargylated and/or allenylated dearomatization products. The reactions provide a new and efficient method for the synthesis of propargylic and allenic carbocycles.

Nuclear magnetic resonance (NMR), absorption, and emission spectroscopy as well as electrochemical techniques are employed to study the complex formation between dendritic guests and a molecular tweezer host. The dependence of the rate constants for the formation and dissociation of the complexes upon addition of N[Bu.sub.4]P[F.sub.6] are also discussed.

Competition experiments are performed to determine the relative reactivities of substituted bromobenzenes, bromonaphthalenes and 9-bromoanthracene toward i-PrMgCl.LiCl in THF. The second-order rate constants with the [k.sub.rel] values from competition experiments have helped in calculating the reaction times for the bromine-magnesium exchange reactions of a large variety of bromoarenes.

The density functional calculations at B3LYP/6-31G(d) level with free energy estimates at 625 degree Celsius is used to study the mechanistic pathways for high-temperature rearrangement of 2-ethynylbiphenyl. The results offer insight into the significance of isophenanthrene, isobenzene (1,2,4-cyclohexatriene) and several isonaphthalenes with low C-H bond dissociation energies as a source of aryl radicals in high temperature and combustion chemistry.

Research has been conducted on 1,2-benzo-1,3-cycloalkadienes. The authors describe the amination of these compounds by application of redox photosensitization via 2,2'-methylenedioxy-1,1'-binaphthalene and polyphenylbenzenes.

Seven substituted benzene and naphthalene derivatives seeded in a supersonic jet are studied. Laser-induced fluorescence (LIF) is used for this purpose.

The structure and the properties of a structure-modified naphthalene, which is obtained by one-electron oxidation of benzene is reported. It is concluded that the six-membered ring of an isolated naphthalene annelated with bicyclo[2.1.1]hexene (BCH) units is made more aromatic by the bond-length equalization and it has become more reactive than the other ring because of increased strain.

The polymers prepared by a kumada coupling and the Bergman cyclization is structurally distinct. Spectroscopic and spectrometric data indicate that the poly(1,4-dibromonaphthalene) is a poly(1,4-naphthalene), whereas the poly(o-diethynylbenzene) contains five-membered rings.