{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T04:29:28Z","timestamp":1787027368034,"version":"build-2736575974"},"reference-count":44,"publisher":"MDPI AG","issue":"16","license":[{"start":{"date-parts":[[2026,8,11]],"date-time":"2026-08-11T00:00:00Z","timestamp":1786406400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100003725","name":"National Research Foundation of Korea","doi-asserted-by":"publisher","award":["NRF-2023R1A2C2004993"],"award-info":[{"award-number":["NRF-2023R1A2C2004993"]}],"id":[{"id":"10.13039\/501100003725","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100003725","name":"National Research Foundation of Korea","doi-asserted-by":"publisher","award":["RS-2023-00301938"],"award-info":[{"award-number":["RS-2023-00301938"]}],"id":[{"id":"10.13039\/501100003725","id-type":"DOI","asserted-by":"publisher"}]},{"award":["NRF-2023R1A2C2004993"],"award-info":[{"award-number":["NRF-2023R1A2C2004993"]}],"id":[{"id":"https:\/\/ror.org\/013aysd81","id-type":"ROR","asserted-by":"publisher"}]},{"award":["RS-2023-00301938"],"award-info":[{"award-number":["RS-2023-00301938"]}],"id":[{"id":"https:\/\/ror.org\/013aysd81","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Int. J. Mol. Sci.","IJMS"],"abstract":"<jats:p>The ultrafast photochemical reaction dynamics of a cyclic(alkyl)(amino)carbene\u2013carbon disulfide (CAAC\u2013CS2) dimer containing two adjacent S\u2013S bonds were investigated using femtosecond time-resolved infrared spectroscopy in combination with multireference electronic structure calculations. Time-resolved vibrational spectra and global kinetic analysis reveal that photoexcitation of the S\u2013S n \u2192 \u03c3* transition at 375 nm induces subpicosecond (&lt;0.3 ps) homolytic cleavage of one S\u2013S bond, generating a bis-thiyl diradical intermediate. This intermediate undergoes two competing pathways: recombination to regenerate the parent dimer with a time constant of 5.7\u20138.5 ps, or secondary cleavage of the remaining S\u2013S bond to yield two CAAC\u2013CS2 monomers with a time constant of 30\u201335 ps. Wavelength- and temperature-dependent kinetic measurements demonstrate that the branching between these pathways is governed by excess excitation energy and thermally driven radical-pair fluctuations. Multireference electronic structure calculations support a sequential S\u2013S bond cleavage mechanism, in good agreement with the experimental observations. These findings provide direct spectroscopic evidence for a bis-thiyl diradical intermediate and offer new mechanistic insight into the ultrafast photochemistry of adjacent S\u2013S bonds.<\/jats:p>","DOI":"10.3390\/ijms27167190","type":"journal-article","created":{"date-parts":[[2026,8,11]],"date-time":"2026-08-11T13:46:16Z","timestamp":1786455976000},"page":"7190","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Ultrafast Photochemical Reaction Dynamics of a Cyclic (Alkyl)(Amino)Carbene-Carbon Disulfide Dimer Probed by Femtosecond Infrared Spectroscopy"],"prefix":"10.3390","volume":"27","author":[{"given":"Seongbeom","family":"Jeon","sequence":"first","affiliation":[{"name":"Department of Chemistry, Pusan National University, Busan 46241, Republic of Korea"},{"name":"Chemistry Institute for Functional Materials, Pusan National University, Busan 46241, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2418-8020","authenticated-orcid":false,"given":"Juhyang","family":"Shin","sequence":"additional","affiliation":[{"name":"Department of Chemistry, Pusan National University, Busan 46241, Republic of Korea"},{"name":"Chemistry Institute for Functional Materials, Pusan National University, Busan 46241, Republic of Korea"},{"name":"Institute for Future Earth, Pusan National University, Busan 46241, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jaegeum","family":"Cha","sequence":"additional","affiliation":[{"name":"Department of Chemistry, Pusan National University, Busan 46241, Republic of Korea"},{"name":"Institute for Future Earth, Pusan National University, Busan 46241, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Youngsuk","family":"Kim","sequence":"additional","affiliation":[{"name":"Department of Chemistry, Pusan National University, Busan 46241, Republic of Korea"},{"name":"Chemistry Institute for Functional Materials, Pusan National University, Busan 46241, Republic of Korea"},{"name":"Institute for Future Earth, Pusan National University, Busan 46241, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8920-3458","authenticated-orcid":false,"given":"Manho","family":"Lim","sequence":"additional","affiliation":[{"name":"Department of Chemistry, Pusan National University, Busan 46241, Republic of Korea"},{"name":"Chemistry Institute for Functional Materials, Pusan National University, Busan 46241, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,11]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"485","DOI":"10.1038\/nature13384","article-title":"An overview of N-heterocyclic carbenes","volume":"510","author":"Hopkinson","year":"2014","journal-title":"Nature"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"10046","DOI":"10.1002\/anie.201702148","article-title":"Cyclic (alkyl)(amino)carbenes (CAACs): Recent developments","volume":"56","author":"Melaimi","year":"2017","journal-title":"Angew. 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