Cyclynes. Part 4. Pericyclynes of the order [5], [6], [7], and [8]. Simple convergent syntheses and chemical reactions of the first homoconjugated cyclic polyacetylenes

A Photophysical and Electrochemical Investigation on a Phenylacetylene Macrocycle Containing Two 2,2′‐Bipyridine Units, Its Protonated Forms, and RuII and OsII Complexes

“…The potential value at which the two Os ions are simultaneously oxidized is identical to that obtained for the metal oxidation in [Os(bpy) 3 ] 2ϩ (Table 2). On reduction, two reversible bielectronic processes are observed in the accessible potential window.…”

“…Consistently with the dinuclear Ru-based complex discussed above, the first process at Ϫ1.06 V vs. SCE can be assigned to the reduction of ligand 1, while the second process at Ϫ1.35 V vs. SCE concerns the simultaneous reduction of two bpy ligands, one for each Os(bpy) 2 moiety. The fact that these processes occur at the same potential values as observed for [Os(bpy) 3 ] 2ϩ (Table 2) can be explained by considering that the Os ion to be capable of delocalising the introduced charges better than the Ru ion. [14] …”

“…Table 2), these processes can be easily assigned as follows: (i) the first process at Ϫ1.13 V vs. SCE concerns the simultaneous reduction of the two bpy units of the ligand 1, considering that such a ligand is easier to reduce than the bpy ligand, and (ii) the second process at Ϫ1.43 V vs. SCE involves two bpy ligands, one for each Ru(bpy) 2 moiety, which are reduced simultaneously at the same potential. This process occurs at a potential value: (a) more negative than that of the first reduction of [Ru(bpy) 3 ] 2ϩ , because in undergoes a reversible bielectronic oxidation at ϩ1.03 V vs. SCE ( Figure 5, Table 2), which can be assigned to the concomitant oxidation of the two metal centres.…”

“…Particularly interesting are shape-persistent macrocycles incorporating coordination units such as 2,2Ј-bipyridines (bpy). endo-Cyclic metal-ion coordination may be exploited to generate nanowires, [3] whereas exo-cyclic coordination can be used of the macrocyclic ligand 1 and the dinuclear complexes at 77 K has also been investigated. The electrochemical properties of 1, the model compound ligand 3 and bpy ligand were investigated in purified tetrahydrofuran under vacuum conditions.…”

Functional [6]Pericyclynes: Synthesis through [14+4] and [8+10] Cyclization Strategies

“…[7] In contrast, the first hexaoxy [6]pericyclynes were prepared through a cyclization strategy in which the 18 carbon atoms of the ring were brought together from either two C 9 w-ynal moieties [4] or from a C 7 w-dialdehyde 5 a-b and a C 11 w-diyne 6 a-b (Scheme 1). [5,8] The latter [11 + 7] strategy afforded the pivotal hexaoxy [6]pericyclynes 2 d and 2 e in 13 steps (2 a-c were obtained from 2 e via the pericyclynetrione 2 f).…”