{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,20]],"date-time":"2026-10-20T07:17:16Z","timestamp":1792480636339,"version":"4.5.0"},"reference-count":129,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2021,12,24]],"date-time":"2021-12-24T00:00:00Z","timestamp":1640304000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001659","name":"Deutsche Forschungsgemeinschaft","doi-asserted-by":"publisher","award":["271107160\/SPP1807"],"award-info":[{"award-number":["271107160\/SPP1807"]}],"id":[{"id":"10.13039\/501100001659","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001659","name":"Deutsche Forschungsgemeinschaft","doi-asserted-by":"publisher","award":["405832858\/INST 186\/1294-1 FUGG"],"award-info":[{"award-number":["405832858\/INST 186\/1294-1 FUGG"]}],"id":[{"id":"10.13039\/501100001659","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001659","name":"Deutsche Forschungsgemeinschaft","doi-asserted-by":"publisher","award":["389479699\/GRK2455"],"award-info":[{"award-number":["389479699\/GRK2455"]}],"id":[{"id":"10.13039\/501100001659","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>Rotational microwave jet spectroscopy studies of the monoterpenol \u03b1-fenchol have so far failed to identify its second most stable torsional conformer, despite computational predictions that it is only very slightly higher in energy than the global minimum. Vibrational FTIR and Raman jet spectroscopy investigations reveal unusually complex OH and OD stretching spectra compared to other alcohols. Via modeling of the torsional states, observed spectral splittings are explained by delocalization of the hydroxy hydrogen atom through quantum tunneling between the two non-equivalent but accidentally near-degenerate conformers separated by a low and narrow barrier. The energy differences between the torsional states are determined to be only 16(1) and 7(1) cm\u22121hc for the protiated and deuterated alcohol, respectively, which further shrink to 9(1) and 3(1) cm\u22121hc upon OH or OD stretch excitation. Comparisons are made with the more strongly asymmetric monoterpenols borneol and isopinocampheol as well as with the symmetric, rapidly tunneling propargyl alcohol. In addition, the third\u2014in contrast localized\u2014torsional conformer and the most stable dimer are assigned for \u03b1-fenchol, as well as the two most stable dimers for propargyl alcohol.<\/jats:p>","DOI":"10.3390\/molecules27010101","type":"journal-article","created":{"date-parts":[[2021,12,27]],"date-time":"2021-12-27T01:06:54Z","timestamp":1640567214000},"page":"101","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Hydrogen Delocalization in an Asymmetric Biomolecule: The Curious Case of Alpha-Fenchol"],"prefix":"10.3390","volume":"27","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6134-0437","authenticated-orcid":false,"given":"Robert","family":"Medel","sequence":"first","affiliation":[{"name":"Institut f\u00fcr Physikalische Chemie, Georg-August-Universit\u00e4t G\u00f6ttingen, Tammannstr. 6, 37077 Goettingen, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3937-9233","authenticated-orcid":false,"given":"Johann R.","family":"Springborn","sequence":"additional","affiliation":[{"name":"Institut f\u00fcr Physikalische Chemie, Georg-August-Universit\u00e4t G\u00f6ttingen, Tammannstr. 6, 37077 Goettingen, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6740-0477","authenticated-orcid":false,"given":"Deborah L.","family":"Crittenden","sequence":"additional","affiliation":[{"name":"School of Physical and Chemical Sciences, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8841-7705","authenticated-orcid":false,"given":"Martin A.","family":"Suhm","sequence":"additional","affiliation":[{"name":"Institut f\u00fcr Physikalische Chemie, Georg-August-Universit\u00e4t G\u00f6ttingen, Tammannstr. 6, 37077 Goettingen, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2021,12,24]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"980","DOI":"10.1016\/j.trechm.2020.08.006","article-title":"Quantum Mechanical Tunneling Is Essential to Understanding Chemical Reactivity","volume":"2","author":"Schreiner","year":"2020","journal-title":"Trends Chem."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Quack, M., and Seyfang, G. 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