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Mono-and dibenzoannelated [2.2]paracyclophanes 12 and 1 were synthesized by palladium-catalyzed twoand four-fold alkenylation of vicinal di-and tetrabromides 5 and 6, respectively, and subsequent electrocyclization/ dehydrogenation of the resulting (E,Z,E)-trienes. Further extensions of the annelated ring systems, leading to the tetrahydronaphthalene derivative 15, the bis-terphenylene derivative 16, and the benzobis[2.2]paracyclophane 18, were achieved through derivatization of suitable substituents introduced with the alkene coupling component. Mono-and polyanions of some derivatives were generated and studied by ESR, E N D O R , and N M R spectroscopy, as well as by cyclic voltammetry. The assembly of mutually orthogonal r-systems in arene annelated [2.2]paracyclophanes allows the reversible incorporation of up to six additional electrons per molecule, which is the upper limit for hydrocarbons reported to date. Recently, we developed a general method for annelating sixmembered carbocycles onto 1 ,2-dibromocycloalkenes1 ' by Heck-type12 alkenylation and subsequent cyclization/dehydrogenation of the resulting (E,Z,E)-1,3,5-trienes. Preliminary studied3 had previously established that this protocol is applicable to vicinal dibromoalkenes derived from (3) Jacobson, N.; Boekelheide, V.

Si-B bonds in commo-3,3'-Si(3,1,2-SiC2B9Hl 1)2, which contains a single silicon atom bonded within a 12-atom boroncontaining cluster: 2.05(1) and 2.14(1)The 'H, 13C, 29Si, and "B NMR spectra of 1 were recorded.[*] The "B NMR spectrum (160.367 MHz, [D,]acetone, 25 "C, external BF, . OEt,) was in agreement with the 1,2disila-closo-dodecaborane(l2) cage structure, showing four doublets in 2:2:2:4 intensity ratio at 6 = -11.2 (d, (d, J = 152 Hz, B3,6), J = 147 Hz, B4,5,7, 11). The assignments are based on a 2D proton-decoupled ' B-' ' B NMR spectrum. The CH, resonance was observed at 6 = -0.07 in the 'H NMR spectrum of 1 in C6D6 solution. The proton-decoupled 29SiNMR spectrum of 1 in C6D6 solution at 50 "C showed a singlet at 6 = -37.77, the proton-decoupled 13C NMR spectrum, also in C,D6 at 40 "C, a singlet at 6 = -12.80. The upfield shifts observed in the 13C and 29Si spectra of 1 taken in C6D6 solution, as compared with TMS, are consistent with the well-documented electron-deficient nature of boron cages.Compound 1 is less stable than the o-carboranes. It melts at 201 -203 "C (sealed capillary) and decomposes with gas evolution above 230 "C. It remains undecomposed when heated at reflux in wet tetrahydrofuran solution for several days. It was unaffected when treated with an excess of CF,CO,H in THF at room temperature and remained largely undecomposed when this solution was heated at reflux for 14 hours. It was found to be stable toward AlCl, in refluxing benzene. It reacts with and is degraded by alcoholic KOH in THF at room temperature within minutes and it decolorizes a solution of bromine in carbon tetrachloride after several hours at reflux. Now that the first member of this new class of boron cluster compounds has been isolated, it may be expected that other 1 ,2-R,Si,B,oH,o compounds can be prepared. The development of their chemical reactivity at silicon and at boron will be of some interest as will a comparison of their chemistry with that of the o-carboranes. Angew. Chem. Int. Ed. Engl. 29 (1990) No. 8 0 VCH Verlagsgesellschafi mbH, 0-4940 Weinheim, 1990 0570-0833/90/0808-0919 S 3.50+.25/0 0.24 A, to 3.641(1) A.

The article contains sections titled: 1. Organic Bromine Compounds 1.1. Physical Properties 1.2. Chemical Properties 1.2.1. Nucleophilic Displacement of Bromine 1.2.2. Displacement of Bromine by Metals 1.3. Production 1.3.1. Addition Reactions 1.3.2. Substitution Reactions 1.4. Commercial Products 1.4.1. 1,2‐Dibromoethane 1.4.2. 1‐Bromo‐3‐chloropropane 1.4.3. 1‐Bromo‐2‐phenylethane 1.4.4. 1‐(Bromomethyl)‐3‐phenoxybenzene 1.4.5. Bromoacetic Acid 1.4.6. Bromomethane 1.4.7. 3‐Bromo‐1‐propene 1.4.8. Bromochloromethane and Dibromomethane 1.4.9. Trifluorobromomethane and Difluorobromochloromethane 1.4.10. Flame Retardants 1.4.11. Biocides 1.4.12. Pharmaceuticals 1.4.13. Dyes and Indicators 1.5. Manufacturers 1.6. Toxicology and Occupational Health 2. Inorganic Bromine Compounds 2.1. Hydrogen Bromide and Bromides 2.1.1. Hydrogen Bromide 2.1.2. Bromides 2.2. Hypobromous Acid, Hypobromites 2.3. Bromous Acid, Bromites 2.4. Bromic Acid, Bromates

Helicene dianions, e.g. phenanthrene derivatives, once believed t o be non-helical, maintain their chirality as 4nn dianions. Phenanthrene 5, as well as substituted phenanthrene derivatives, undergo a two-electron reduction to form the respective 4nn: dianion e.g., 5'-/2Li+. Phenanthrene derivatives substituted at the 4and 5-positions (bay substituents) e.g. 6-11, which are helical, afford stable dianions. These dianions are also prepared by a two-electron reduction of the (4n + 2 ) n electron hydrocarbons and show, in their 'H N M R spectra, a quench of the paratropicity compared t o 5'as well as a line shape dependence on their twist angle. The quench of paratropicity was also observed in the closely related charged helicenes derived from the benzo[g]chrysene system, i.e. anions 122and 132-. The twist angles were calculated by M M X and M N D O calculations for the neutral systems, i,e., 5-11, and b y M N D O for the dianions. M N D O calculations also included the preferred location of the counter cation. A dynamic NMR spectroscopic study proves experimentally the helicity of anion 11'thus shedding light on the behaviour of this novel class of dianions.

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A common feature of the "stacked" molecules [2.2]paracyclophane 1 and ferrocene 2 is that there is electronic communication between the two remote aromatic decksr2'. For the last few years, we have been investigating systems in which these two structural units have been united, e.g. 3, with the ultimate goal of preparing molecules which exhibit very-long-range comm~nication [~]. The first synthesis of 3[41 was accomplished via the [2]paracyclo[2]indenophane 4 and its anion 5 which are interesting molecules in their own right. We recently showed ['] that, by comparison of their NMR data with that of related compounds, it was possible to separate-charge transfer from anisotropic effects. ing the structural elements of 2 and 6 it should be possible to gauge the degree to which the remote aromatic systems communicate. We now describe our initial efforts towards this goal and present the preparation of the first member of this series, the metallocenophane 7 and the precursor molecules 8 -10. It has been reportedP1 that treatment of 6 with Lewis acids gives rise to ring closure at C-8 and -16. This would apparently rule out the synthetic methodology used for the preparation of 4, in which two of the steps are Lewis acid catalyzed electrophilic aromatic substitutions. However, the

2.2]Paracyclophane sind aromatische Kohlenwasserstoffe mit besonderen sterischen und elektronischen Eigenschaften. Die beiden x-Elektronensysteme durchdringen sich gegenseitig, so da13 sich diese Arene verhalten, als hatten sie nur ein einziges x-Sy~teml'-~~. Paracyclophan-Anionen sind wegen der elektronischen Wechselwirkung zwischen eng benachbarten anionischen Untereinheiten gleichfalls von Interesse. Anionische Paracyclophane sind bereits friiher studiert ~o r d e n '~' ; insbesondere hat Haener" Darstellung und 'H-NMR-Spektren von synund anri-[2.2](2,7)Fluorenophanen beschrieben. Uber I3C-NMR-Spektren dieser Spezies ist hingegen nichts bekanntl"'. Wir berichten hier iiber Darstellung sowie 'Hund '%-NMR-Spektren des Dianions des [2.2]Indenophans 5 sowie des Monoanions des [2.2]Benzoindenophans 7. Dies ist die erste detaillierte Untersuchung der Eigenschaften von doppellagigen Mono-und Dianionen. Die Synthese des [2.2]Indenophans 4 geht vom Dialdehyd 1[") aus, der durch Wittig-Horner-Kettenverlangerung, Verseifung und katalytische Hydrierung in die Dicarbonsaure 2 iibergefuhrt wurde. Deren Cyclisierung ergab das ,,Indanonophan" 3, das zum entsprechenden Diol reduziert wurde. Saure-katalysierte Dehydratisierung lieferte schliefllich das Indenophan qC7l. Analog wurde aus 4-Formyl[2.2]paracyclophan das Benzoindenophan 6 herge-~t e I I t [~~.