Synthese von Beltenen durch Umsetzung von 5,6,11,12‐Tetradehydrodibenzo[a,e]cycloocten mit Derivaten von [CpCo(CO)₂]

1,1,8,8‐Tetramethyl[8](2,11)teropyrenophane: Half of an Aromatic Belt and a Segment of an (8,8) Single‐Walled Carbon Nanotube

“…[7] Of particular interest to us are the Vögtle belts, [8] for example, 3, which are armchair SWCNT segments having a pyrenoid or rylenoid motif, depending upon ones perspective.A recurring theme in the numerous unsuccessful attempts to synthesize aromatic belts is the inability to aromatize partially saturated belt precursors. The interplay of two major energetic factors, strain and aromaticity, is at the heart of the problem.…”

Synthesis, Properties and Formation of (RCp)Co‐ and (RCp)Rh‐Stabilized[4.8]3Cyclacene Derivatives

“…The irradiation of 10 at l = 254 nm in the presence of [CpCo(CO) 2 ] (11) [15] in decalin for three days gave a yellow colored product in 14 % yield (Scheme 3). [10] The assignment of the structure to the trimer 12 is based on its spectroscopic data and the results of a X-ray study on single crystals (see below). The NMR data of 12 (three singlets in the 1 H NMR spectrum, five in the 13 C NMR spectrum) suggest D 3h symmetry for 12 in solution.…”

“…All reactions were carried out in dried glassware under argon atmosphere using dried and oxygen-free solvents. The reagents 5,6,11,12-tetradehydro-dibenzeno-A C H T U N G T R E N N U N G [a,e]cyclooctene (10), [14] [(h 5 -cyclopentadienyl)(dicarbonyl)cobalt] (11), [15] [(h 5 -methoxycarbonylcyclopentadienyl)(dicarbonyl)cobalt] (13), [15,30] [(h 5 -cyclopentadienyl)(diethenyl)rhodium] (18), [16,17,18] [(h 5 -methylcarbonyl- (14), [31] [(h 5 -trimethylsilylcyclopentadienyl)(dicarbonyl)cobalt](15), [32] [(h 5 -pentamethyl-cyclopentadienyl)-(dicarbonyl)cobalt](16), [33] [(h 5 -ethyltetramethylcyclopentadienyl)(dicarbonyl)cobalt] (17), [34] [(h 5 -methoxycarbonylcyclopentadienyl)(diethenyl)-A C H T U N G T R E N N U N G rhodium] (19), [35,36,37] [(h (20), [35,36,37] [(h 5 -chlorocyclopentadienyl)(diethenyl)rhodium]-A C H T U N G T R E N N U N G (21), [38] [(h 5 -pentamethylcyclopentadienyl)(diethenyl)rhodium] (22) [39] and several cyclacenes (12, 23, 25 and 26) [10] were prepared according to literature procedures.…”

“…[3] It has been predicted that the even membered species, such as 2, should show rather small energy differences between the singlet and triplet states, [3e] which is indicative for a high reactivity and low stability at room temperature. For other cyclacenes, such as cyclo [10]phenacene (3), the singlet-triplet splitting is predicted to be high and, therefore, this species is expected to be stable at room temperature.…”

“…[10,11] In the case of 6 we used a stepwise approach whereas derivatives of [4.8] n cyclacenes were achieved in a rather simple way. In this paper we report the preparation and properties of (RCp)Co-and (RCp)Rh-capped derivatives of 5 as well as the isolation of an intermediate, which allows to decipher the reaction mechanism.…”