Theoretical Models of Low-Resolution Microwave Rotational Spectra of Ethane- and Propanethiol

Conformational and structural stability of n and 2-propylthiols: a revisit

“…Experimental measurements reported T–G as the global minimum (although one earlier experiment based on IR absorption identified T–T as the global minimum) with one local minimum conformer G–T or T–T conformers, respectively. 2–8 The scan with initial geometry as the optimized G–G conformer resulted in T–G as the global minimum conformer and G–G as the local minimum which is similar to the prediction by Gorai et al 1 and Choi et al 9 Furthermore, the results reported herein match exceedingly well with the experimental results. Table ST2† summarizes all conformational scans for the nP molecule at the CCSD/cc-pVDZ level of theory with a step size of 5°.…”

“…Our results support all previous experimental measurements. [2][3][4][5][6][7] In the case of the 2-propanethiol (2P) molecule, a homologue of the nP molecule, no change in conformation was observed even aer revisiting the calculations with higher levels of theory compared to the ones reported earlier. Similar to earlier reports, 12,13 only two low-energy conformers were observed, with the anti conformer being the global minimum and the gauche conformer being the local minimum, as shown in Fig.…”

“…In experiments, not all these conformers are found, though. Different researchers reported varying numbers and structures of conformers using different spectroscopic techniques like microwave, 2–5 infrared, 6,7 Raman, 8 and vacuum ultraviolet mass-analyzed threshold ionization spectroscopy. 9 On the other hand, literature pertaining to computational research using methods such as Urey–Bradley force field theory, 10 quantum molecular force field theory, 11 MP2/cc-pVTZ, and B3LYP/6-311++G(2df, 2pd) 9 differed significantly among each other as well as from the experiments.…”