Thiaplatinacycles Derived from Dibenzothiophene-Containing Phosphites as Auxiliary Ligands and Their Role in Homogeneous Desulfurization Reactions

The reaction of complex [Pt(η2-C,S-C12H8)(PEt3)2], 1, with a variety of phosphites afforded compounds of the type [Pt(η2-C,S-C12H8)(PEt3)(P(OR)3)], where R = Et, iPr, and Ph (2a, 2b, 3, and 4, respectively) and [Pt(η2-C,S-C12H8)(P(OR)3)2], where R = Et (5). Compounds 2−4 were used to model a desulfurization process and were compared with 1 and other similar compounds. Under comparable conditions, the amount of desulfurization depended on the σ-donor/π-acceptor properties and the steric effects of the ligands and of the use of alumina in the reaction media. X-ray crystal structures are reported for 2b and 3.