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>
Mauricio F. Erben
Roland Boese
Carlos O. Della Védova
Heinz Oberhammer
Helge Willner
10.1021/jo052026k.s002
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 CS and the CO single bonds relative to the CO double bond. The following
skeletal geometric parameters were derived from the GED analysis (<i>r</i><sub>hl</sub> values with 3σ uncertainties):
CO = 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; OCO = 125.9(8)°, OCS = 125.7(7)°, OCS = 108.4(9)°, and COC = 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.
2006-01-20 00:00:00
term
OC
bond
r hl values
GED
synperiplanar
conformation
gas phase
MP
quantum chemical calculations
3LYP
CH
Conformational
parameter
molecule
gas electron diffraction
analysis