Synthesis, structures and ab initio studies of selenium and tellurium bis(carbodithioates and carbothioates)

Abstract

A series of selenium and tellurium bis(carbodithioates and carbothioates) were synthesized. X-Ray structure analysis revealed that Se(SSCC₆H₄OMe-2)₂, Te(SSCC₆H₄OMe-2)₂ and Te(SSCC₆H₄Me-4)₂ have trapezoidal-planar configuration of ES₄ (E = Se, Te) and despite the larger atomic radii, the CS⋯Te distances in Te(SSCC₆H₄OMe-2)₂ are comparable to those in the corresponding selenium derivatives Se(SSCC₆H₄OMe-2)₂. Molecular-orbital calculations performed on compounds E(E′SCR)₂ (E = S, Se, Te; E′ = O, S; R = Me, Ph, C₆H₄OMe-2) showed that the syn-conformers of Se(SSCR)₂ and Te(SSCR)₂ are more stable than the corresponding anti-ones, while, in the case of carbothioic acid derivatives, E(SOCR)₂ showed that their anti-conformers are all more stable than the corresponding syn-ones. Natural bond orbital (NBO) analyses of these dithio-compounds revealed that two types of orbital interactions, n_S(1)→σ*_E–S(2) and n_O→σ*_E–S(2), play a role in the bonding of E[S(2)S(1)CC₆H₄OMe-2]₂ (E = Se, Te) and the former play a particularly predominant role.