On the conformational preference of chlorothioformates species: molecular structure of ethyl chlorothioformate (ClC(O)SCH2CH3) in the solid phase and NBO analysis

RODRGÍGUEZ PIRANI, LUCAS S; ERBEN, MAURICIO F.; BOESE, ROLAND; DELLA VÉDOVA, CARLOS O.

ACTA CRYSTALLOGRAPHICA SECTION B-STRUCTURAL SCIENCE

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2011 vol. 67 p. 350 - 356

0108-7681

The molecular structure of ethyl chlorothioformate, ClC(O)SCH2CH3, has been investigated in the solid phase by X-ray diffraction analysis at low temperature using a miniature zone melting procedure using infrared laser radiation. The crystalline solid (monoclinic, P21/c, a = 9.4763 (6) Å, b = 5.8288 (4) Å, c = 11.0764 (7) Å, β = 112.8530 (10) ˚ and Z = 4) consists exclusively of molecules with the synperiplanar conformation with respect to the C=O double bond and the S?C single bond, and gauche orientation of the ethyl group (syn-gauche). These results coincide with previous studies devoted to the gas-phase conformational properties. The conformational preference for the ClC(O)SY (Y = Cl, CF3, CH3 and CH2CH3) series of molecules was rationalized by using the natural bond orbital (NBO) scheme. It was found that both resonance (mesomeric) and anomeric (hyperconjugation) intermolecular charge transfer interactions are important for describing the syn↔anti equilibrium, illustrating also the effect of the electronegativity of the substituent in the conformation preference of the ClC(O)S? moiety. On the basis of the AIM theory, intermolecular interactions have been characterized in the B3LYP/6‑31G** periodic boundary electron density.