Tricyclo[5.3.0.02,8]deca-3,5,9-triene

Abstract

kcahmol'1)16 is slightly less stable than 3 (AH°= 74.6 kcal• mol-1)16 but certainly much more stable than 4 (AH°= 102.7 kcahmoL1). We consider it likely that lc is indeed formed on irradiation of 3 but that the photostationary state is even more unfavorable than in the case of 2b where 6-7% of 2b are in photoequilibrium with its Dewar isomer.5

Thermochemical and X-ray Crystallographic Investigations of Some (CH)10 Hydrocarbons: Basketene, Nenitzescu’s Hydrocarbon, and Snoutene

“…These values and the strain energies (SEs) [SE(9) = 110.3 kcal·mol −1 , SE (14) = 78.4 kcal·mol −1 ] derived from them were compared with values obtained from MM2/ MM3 calculations. The enthalpy of isomerization of 9 to tricyclo[4.2.2.0 2,5 ]deca-3,7,9-triene (8, Nenitzescu's hydrocarbon) was measured by differential scanning calorimetry (DSC) as −20.7 ± 0.3 kcal·mol −1 (384.1 K), corresponding to a strain energy SE(8) of 44.6 kcal·mol −1 .…”

“…The obtained strain energies and the derived heats of isomerization to 9,10-dihydronaphthalene (7) did not correlate in any way either with the activation energies of the thermal isomerizations of these Families of (CH) n hydrocarbons are characterized by the multiple rearrangements into one another that their members can undergo. [1] These rearrangements can be initiated (CH) 10 hydrocarbons or with the structural features determined experimentally for basketene (9) and computationally (DFT at the B3LYP/6-311+G* level) for snoutene (14). Compounds 8, 9, 10, and 14 exhibited solid-state phase transitions in a narrow temperature range (−55 to −70°C), whereas the melting points or rearrangement temperatures varied to a much greater extent (in the 0−126°C range).…”

“…Basketene (9), for example, is known to rearrange to Nenitzescu's hydrocarbon 8 upon heating [3] and under rhodium(I) [4a] and LiCB 11 Me 12 catalysis conditions, [4b] while unScheme 1. Interconversions of (CH) 10 hydrocarbons der silver(I) catalysis conditions it rearranges to snoutene (14). [4a,5] In the presence of gold (Au 0 or Au I ), however, snoutene (14) rearranges to basketene (9), [6] a fact that apparently has to do with the relative stabilities of the intermediate metal complexes.…”

“…Interconversions of (CH) 10 hydrocarbons der silver(I) catalysis conditions it rearranges to snoutene (14). [4a,5] In the presence of gold (Au 0 or Au I ), however, snoutene (14) rearranges to basketene (9), [6] a fact that apparently has to do with the relative stabilities of the intermediate metal complexes. Upon heating to 500°C, snoutene (14) undergoes an interesting automerization, detectable by appropriate labelling, which interchanges the two vinylic and the cyclopropyl methyne positions.…”

“…[4a,5] In the presence of gold (Au 0 or Au I ), however, snoutene (14) rearranges to basketene (9), [6] a fact that apparently has to do with the relative stabilities of the intermediate metal complexes. Upon heating to 500°C, snoutene (14) undergoes an interesting automerization, detectable by appropriate labelling, which interchanges the two vinylic and the cyclopropyl methyne positions. [7] When irradiated with UV light, snoutene (14) reversibly rearranges to diademane (10).…”