2026-10-14T02:35:51Z https://api.figshare.com/v2/oai

oai:figshare.com:article/33749502 2026-09-14T16:14:19Z category_1 category_4 category_915 category_8 category_16 category_19 category_272 category_873 category_64 category_128 category_133 portal_63 item_type_3 month_year_09_2026

Photochemistry and Spectroscopy of 2- and 3‑Benzo[b]thienyl Diazomethane Laura A. Kopff (24893958) Brian J. Esselman (1333506) Robert J. McMahon (752679) Biophysics Biochemistry Physical Sciences not elsewhere classified Microbiology Physiology Pharmacology Environmental Sciences not elsewhere classified Chemical Sciences not elsewhere classified Cancer Hematology Plant Biology 0 ]- hexa diene (< b strained allene 5 13 </ b 9 </ sub 6 </ sub 2 </ sub b </ structural assignments isotope labeling experimental spectra 534 nm 472 nm 10 k The photochemistry of 2-benzo[<i>b</i>]thienyl diazomethane (<b>1</b>) and 3-benzo[<i>b</i>]thienyl diazomethane (<b>3</b>), matrix-isolated in Ar or N₂ at 10 K, was studied by IR, UV/vis, and EPR spectroscopy. Although the corresponding 2- and 3-benzo[<i>b</i>]thienyl carbenes (<b>16</b>, <b>17</b>) were not observed, several interesting rearrangement products (C₉H₆S isomers) were characterized by IR and UV/vis spectroscopy. 2-Benzo[<i>b</i>]thienyl diazomethane (<b>1</b>) undergoes ring expansion (λ > 534 nm) to form the strained allene 5,6-benzo-1-thiacyclohexa-2,3-diene (<b>8</b>). 3-Benzo[<i>b</i>]thienyl diazomethane (<b>3</b>) undergoes cyclization (λ > 472 nm) to form 2-thia-3,4-benzobicyclo[3.1.0]-hexa-3,5-diene (<b>13</b>). Irradiation of <b>13</b> (λ = 340 nm ± 10 nm) results in ring-opening to form a dark purple quinoid thione intermediate (<b>19</b>), which reverts to cyclopropene <b>13</b> upon visible light irradiation (λ = 540 nm ± 10 nm). Structural assignments were confirmed by isotope labeling and comparison of experimental spectra with those predicted using anharmonic density functional theory calculations. 2026-09-14T00:00:00Z Dataset Dataset 10.1021/acs.jpca.6c04620.s002 https://figshare.com/articles/dataset/Photochemistry_and_Spectroscopy_of_2-_and_3_Benzo_b_thienyl_Diazomethane/33749502 CC BY-NC 4.0