Selbstorganisation von Chinodimethanen über kovalente Bindungen,Mitteilung III,Untersuchungen zur Herstellung von Nanostrukturen

Self‐Assembly of Quinodimethanes through Covalent Bonds. Part III. Investigations on the Preparation of Nanostructures As part of our studies on the tetramerization of quinodimethane 1 to the macrocyclic compound 2 , the influence of substituents on this reaction was investigated. It was found that a large range of substituents such as 2‐phenylethyl, 2‐(4‐methoxyphenyl)ethyl, 2‐(4‐fluorophenyl)ethyl, 2‐[4‐(tert‐butyl)phenyl]ethyl, and 2‐[4‐(2‐phenylethyl)phenyl]ethyl, attached at positions 2 and 7 of 9H‐fluorene, do not prevent the tetramerization. The key step in the formation of the macrocylic compounds 13a – e is the debromination of 12a – e with mercury to the corresponding quinodimethanes which undergo a self‐assembly forming 13a – e in high yields. To study the conjugative influence of substituents on tetramerization, the effect of the hex‐1‐ynyl groups at positions 3 and 6 of the 9H‐fluorene rings was investigated. In this case, the corresponding macrocycle 17 was generated by the reaction of diol 16a with SnCl₂. Although the expected tetramerization to 17 occurred, the yield was lower than in the case of 13a – e , due to the sensitivity of the product.     

Selbstorganisation von Molekülen über kovalente Bindungen: Selektive Tetramerisierung eines p-Chinodimethans

Self-Organization of Molecules by Covalent Bonds: Selective Tetramerization of a p -Quinodimethane A simple and efficient synthesis of paracyclophane derivatives based on self-organization of a quinodimethane is described. Treatment of dibromides 5a – d with mercury afforded in high yield the macrocyclic compounds 6a – d . Interestingly, these compounds change the color on grinding and heating, from colorless to violet. The structure of 6a – d was determined by spectroscopic analyses. Single-crystal structure analysis of 6b and 6c confirmed the proposed structure.     

Self-Assembly of Quinodimethanes through Covalent Bonds: A Novel Principle for the Synthesis of Functional Macrocycles

A multiplication of functional units was accomplished in a simple fashion by the tetramerization of a quinodimethane. This principle is demonstrated by the convergent construction of a macrocyclic molecule with 16 ferrocenes and a macrocyclic molecule with 16 dendritic units at the periphery of the molecule (see scheme). FG=functional group     

η-Alkynyl and vinylidene transition metal complexes: 10. Reaction of the metal-acetylide [(η-C5H5)(CO)(NO)W---CC---C(CH3)3]Li with 1,2-diiodoethane as electrophile and with various nucleophiles

Treatment of the η¹-acetylide complex [(η⁵-C₅H₅)(CO)(NO)W---CC---C(CH₃)₃]Li (4) with 1,2-diiodoethane in THF at −78 °C, followed by the addition of Li---CC---R [R=C(CH₃)₃, C₆H₅, Si(CH₃)₃, 6a–6c] or n-C₄H₉Li and protonation with H₂O, afforded the corresponding oxametallacyclopentadienyl complexes (η⁵-C₅H₅)W(I)(NO)[η²-O=C(CC---R)CH=CC(CH₃)₃] (7a–7c), 8c and (η⁵-C₅H₅)W(I)(NO)[η²-O=C(n-C₄H₉)CH=CC(CH₃)₃] (9). The formation of these metallafuran derivatives is rationalized by the electrophilic attack of 1,2-diiodoethane onto the metal center of 4 to form first the neutral complex [(η⁵-C₅H₅)(I)(CO)(NO)W---CC---C(CH₃)₃] (5). Subsequent nucleophilic addition of Li---CC---R 6a–6c or n-C₄H₉Li and a reductive elimination step followed by protonation leads to the products 7a–7c and 9. One reaction intermediate could be trapped with CF₃SO₃CH₃ and characterized by a crystal structure analysis. The identity of another intermediate was established by infrared spectroscopic data. The oxametallacyclopentadienyl complex 10 forms in the presence of excess 1,2-diiodoethane through an alternative pathway and crystallizes as a clathrate containing iodine.