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oai:figshare.com:article/33868072 2026-09-16T19:07:56Z category_1 category_4 category_7 category_272 category_873 category_734 category_64 category_122 portal_63 item_type_3 month_year_09_2026

Structure of Furan from 44 IsotopologuesResolving Differences in the Theoretical (r_e) and Semi-Experimental Equilibrium (r_e^SE) Structures Kolton T. Mehalko (24999154) Brian J. Esselman (1333506) Peter R. Franke (4490539) Martin S. Holdren (10811336) Gabi Wenzel (21074372) D. Archie Stewart (21173563) Zachary P. Burke (11938344) Brett A. McGuire (1278318) R. Claude Woods (2043850) Robert J. McMahon (752679) Biophysics Biochemistry Medicine Environmental Sciences not elsewhere classified Chemical Sciences not elsewhere classified Biological Sciences not elsewhere classified Cancer Mental Health theoretical (< italic experimental equilibrium (< 0003 å uncertainties >< sub >< precision (≤ 0 bond angles ). experimental rotational constants se </ sup principal axis rotation possible furan -< level electron correlation 44 furan isotopologues ></ sub ≤ 0 bond distances rotational spectra x </ e </ r </ two structures previously reported previously determined pcv5z geometry mass distribution large number first time determined using containing analogue catalyzed h 750 ghz 02 ° )/ cc The rotational spectra of furan and numerous isotopologues were recorded and analyzed between 6 and 750 GHz. High-temperature, high-pressure, base-catalyzed H/D exchange was employed to create a mixture of all possible furan-<i>d</i>_<i>x</i> isotopologues, allowing for the measurement and analysis of the rotational spectra of 44 furan isotopologues. The experimental rotational constants of these isotopologues, combined with CCSD(T)/cc-pCVTZ corrections for the effects of vibration–rotation interaction and the electron-mass distribution, were used to determine a semi-experimental equilibrium (<i>r</i>_<i>e</i>^SE) structure of furan. The large number of isotopologues used, including 35 isotopologues observed for the first time, allowed for the determination of the <i>r</i>_<i>e</i>^SE structure to a high level of accuracy and precision (≤0.0003 Å uncertainties in bond distances and ≤0.02° in bond angles). The current study additionally corrects for differences in principal axis rotation between the structure at which the vibration–rotation interaction constants were evaluated (CCSD(T)/cc-pCVTZ) and the <i>r</i>_<i>e</i>^SE structure. The difference in rotation between these two structures had been previously reported, but not addressed. The “best theoretical estimate” (BTE) for the structure of furan was determined using a CCSD(T)/cc-pCV5Z geometry, with additional corrections addressing finite basis set, higher-level electron correlation, and relativistic effects, as well as the diagonal Born–Oppenheimer correction. The BTE structure of furan is compared to the <i>r</i>_<i>e</i>^SE structure of furan, which is also compared to the previously determined <i>r</i>_<i>e</i>^SE structure of its sulfur-containing analogue, thiophene. 2026-09-16T00:00:00Z Dataset Dataset 10.1021/acs.jpca.6c04036.s002 https://figshare.com/articles/dataset/Structure_of_Furan_from_44_Isotopologues_Resolving_Differences_in_the_Theoretical_r_sub_e_sub_and_Semi-Experimental_Equilibrium_r_sub_e_sub_sup_SE_sup_Structures/33868072 CC BY-NC 4.0