Structure of O-alkyl-N-ethoxycarbonyl thiocarbamate and imidothiocarbonate derivatives

Abstract

O-methyl-N-ethoxycarbonylthiocarbamate, CH3CH2OC(O)N(H)C(S)OCH3 (I), and O-ethyl-N-ethoxycarbonylthiocarbamate, CH3CH2OC(O)N(H)(S)OCH2CH3 (II), were prepared by the addition reaction between CH3CH2OC(O)NCS and the corresponding alcohols. Their structural and conformational properties were studied using lowtemperature single crystal X-ray diffraction and vibrational spectroscopy assisted by quantum chemical calculations. Compound I crystallizes in the monoclinic space group P21/n with lattice parameters a = 4.2450(1), b = 18.4992(5), c = 9.8759(3) Å, β = 95.887(3)° and 4 molecules per unit cell (Z=4), and II in the triclinic space group P1 with parameters a = 4.1771(8), b = 9.235(2), c = 11.804(2) Å and values angles α = 98.17(1),β = 98.62(1), γ = 102.29(2)°, and Z = 2. In the crystal, the conformation around the thiocarbamate group-N(H)C(S)O- is characterized by a synperiplanar orientation of the C=S double with respect to the N-H single bond, while the methoxycarbonyl C=O double bond is in antiperiplanar orientation with respect to the N-H bond. Both species form dimersl linked by NH???S=C hydrogen bond, the N???S non-bonding distance being 3.352(2) Å in compound I. Furthermore, ethoxycarbonylimidothiocarbonatespecies were obtained by the addition of methyl and n-butyl groups to the C=S double bond of I and II. Thus, species with formula CH3CH2OC(O)N=C(SCH3)OCH3 (III), CH3CH2OC(O)N=C(SCH3)OCH2CH3 (IV), as well as the novel compounds CH3CH2OC(O)N=C(SC4H9)OCH3 (V) and CH3CH2OC(O)N=C(SC4H9)OCH2CH3 (VI), were alsoprepared and fully characterized by spectroscopic methods.