Molecule 1,5-C10H6(SO2Cl)2 as prototype of conformational properties of naphthalene sulfonyl derivatives

Abstract

Conformational composition of the vapor (T = 413(5) K) and the conformer structures of 1,5-naphthalenedisulfonylchloride (1,5-NaphDSC) have been studied by a combined gas-phase electron diffraction and mass spectrometry (GED/MS) method complemented by quantum chemical calculations. According to quantum chemical calculations at DFT/B3LYP/cc-pVTZ and MP2/cc-pVTZ theory levels, the molecule 1,5-NaphDSC possesses four conformers differing mutual orientation of the two SO2Cl groups.GED data clearly indicate that only two conformers, whose structures are characterized by deviation of two SCl bonds from perpendicular position relative to the plane of the naphthalene skeleton (syn-symmetry C2 and anti-symmetry Ci), are present in vapor at 413 K.The following geometrical parameters of these conformers were obtained from the experiment (Å and degrees; uncertainties are in parentheses): rh1(CH) = 1.098(9), rh1(CC) = 1.405(3), rh1(CS) = 1.781(4), rh1(SO) = 1.426(3), rh1(SCl) = 2.056(4), ∠CCSC = 122.9(1), ∠CSSCl = 101.8(6); C9C1SCl = 71.2(12), C10C5SCl = 71.2(12)-syn conformer; C9C1SCl = 71.2(12), C10C5SCl = −71.2(12) -anti-conformer.The presence of C9Hn+ ions in the mass spectra of naphthalenesulfonyl chlorides, which are absent in the mass spectrum of naphthalene, may be attributed to the weakening of two CC bonds adjacent to the substituent of the naphthalene skeleton. This reflects in the geometric parameters of 1,5-NaphDSC.The barriers to internal rotation of sulfonyl chloride groups were calculated. It is shown that the low-energy syn- and anti-conformers are structurally rigid, in contrast to high-energy conformers with one or two SCl bonds, lying in the plane of the naphthalene skeleton.The dependence of C1C2, CS, SCl bond lengths from SO2Cl groups orientation relative to naphthalene skeleton is discussed in terms of NBO-analysis of electron density distribution.The relationship between conformational properties of molecule and some physicochemical characteristics of the 1,5-NaphDSC compound is discussed.