Intramolecular sulphur(II)—oxygen interaction in sulphides and disulphides with 2-methoxycarbonylphenyl and 2-nitrophenyl groups: an X-ray study

Abstract

The molecular structures of methyl 2-(methylthio)benzoate, dimethyl 2,2′-dithiodibenzoate, dimethyl 2,2′-thiodibenzoate, methyl 2-(2-nitrophenylthio)benzoate, 2,2′-dinitrodiphenyl sulphide and methyl 2-(2-nitrophenylthio)phenylacetate exhibiting S(II)⋯O(carbonyl) or S(II)⋯O—(nitro) close contact have been investigated by X-ray diffreaction. Planar (ArSMe), equatorial (Ar 2S 2) and skew (Ar 2S) conformations are explained by steric and conjugative effects and sulphur(II)—oxygen interaction. Linear and non-linear X—S⋯O close contacts resulting from favourable “bond direction” and unfavouralbe “lone-pair direction” approaches (2.619–2.722 and 2.900–3.402 Å, respectively) are discussed in detail. Possible aryl ring positions, the geometry of rings with S⋯O contact and the nature of counter-atom (X = C, S) are considered as decisive factors. The results are consistent with different neighbouring group effects found earlier for o-CO 2Me, o-CH 2CO 2Me and o-NO 2 groups. Data support the mutual dependence of S—S and S⋯O distances in compounds with a linear S—S⋯O arrangement. Other bond lenghts, e.g. CO, NO and S(II)—C ar are not affected significantly by sulphur—oxygen interaction.