10.1021/jo052026k.s002 Mauricio F. Erben Mauricio F. Erben Roland Boese Roland Boese Carlos O. Della Védova Carlos O. Della Védova Heinz Oberhammer Heinz Oberhammer Helge Willner Helge Willner Toward an Intimate Understanding of the Structural Properties and Conformational Preference of Oxoesters and Thioesters:  Gas and Crystal Structure and Conformational Analysis of Dimethyl Monothiocarbonate, CH<sub>3</sub>OC(O)SCH<sub>3</sub> American Chemical Society 2006 term OC bond r hl values GED synperiplanar conformation gas phase MP quantum chemical calculations 3LYP CH Conformational parameter molecule gas electron diffraction analysis 2006-01-20 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Toward_an_Intimate_Understanding_of_the_Structural_Properties_and_Conformational_Preference_of_Oxoesters_and_Thioesters_Gas_and_Crystal_Structure_and_Conformational_Analysis_of_Dimethyl_Monothiocarbonate_CH_sub_3_sub_OC_O_SCH_sub_3_sub_/3242842 The molecular structure and conformational properties of dimethyl monothiocarbonate, CH<sub>3</sub>OC(O)SCH<sub>3</sub>, have been studied in the gas phase by gas electron diffraction (GED) and vibrational spectroscopy and in the solid state by X-ray crystallography. The experimental investigations were supplemented by quantum chemical calculations at the B3LYP/6-311++G(3df,2p) and MP2/6-311++G(2df,p) levels of approximation. The gaseous molecule exhibits only one conformation having <i>C</i><i><sub>s</sub></i> symmetry with synperiplanar orientation of both the CS and the CO single bonds relative to the CO double bond. The following skeletal geometric parameters were derived from the GED analysis (<i>r</i><sub>hl</sub> values with 3σ uncertainties):  CO = 1.203(4) Å, C(sp<sup>2</sup>)O = 1.335(5) Å, C(sp<sup>3</sup>)O = 1.437(5) Å, C(sp<sup>2</sup>)S = 1.763(5) Å, and C(sp<sup>3</sup>)S = 1.803(5) Å; OCO = 125.9(8)°, OCS = 125.7(7)°, OCS = 108.4(9)°, and COC = 113.4(15)°. The structure of a single crystal, grown by a miniature zone-melting procedure, was determined by X-ray diffraction analysis at a low temperature. The crystalline solid [monoclinic, <i>P</i>2<sub>1</sub>/<i>n</i>, <i>a </i>= 12.6409(9) Å, <i>b </i>= 4.1678(3) Å, and <i>c </i>= 19.940(1) Å, β = 98.164(1)°] exists exclusively as molecules in the synperiplanar conformation and with geometrical parameters that agree with those of the molecule in the gas phase. The results are discussed in terms of anomeric and mesomeric effects and in terms of a natural bond orbital analysis.