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The S−S Bridge: A Mixed Experimental‐Computational Estimation of the Equilibrium Structure of Diphenyl Disulfide
Author(s) -
Demaison Jean,
Vogt Natalja,
Saragi Rizalina Tama,
Juanes Marcos,
Rudolph Heinz Dieter,
Lesarri Alberto
Publication year - 2019
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201800973
Subject(s) - isotopologue , chemistry , rotational spectroscopy , ab initio , computational chemistry , disulfide bond , supersonic speed , moment of inertia , ab initio quantum chemistry methods , molecule , thermodynamics , physics , organic chemistry , classical mechanics , biochemistry
The disulfide bridge (−S−S−) is an important structural motif in organic and protein chemistry, but only a few accurate equilibrium structures are documented. We report the results of supersonic‐jet microwave spectroscopy experiments on the rotational spectra of diphenyl disulfide, C 6 H 5 −S−S−C 6 H 5 (including all 13 C and 34 S monosubstituted isotopologues), and the determination of the equilibrium structure by the mixed estimation (ME) method. A single conformation of C 2 symmetry was observed in the gas phase. This disulfide is a challenging target since its structure is determined by 34 independent parameters. Additionally, ab initio calculations revealed the presence of three low‐frequency vibrations (<50 cm −1 ) associated to phenyl torsions which would prevent the calculation of an accurate force field. For this reason, instead of the semiexperimental method, we used the mass‐dependent ( r m ) method to fit the structural parameters concurrently to moments of inertia and predicate parameters, affected with appropriate uncertainties. The predicates were obtained by high‐level quantum‐chemical computations. A careful analysis of the results of different fits and a comparison with the ab initio optimizations confirms the validity of the used methods, providing detailed structural information on the title compound and the disulfide bridge.