REACTIONS OF BENZO[B]THIOPHENE WITH SOME AQUEOUS PLATINUM METAL SPECIES AT ELEVATED-TEMPERATURES

The desulfurization of benzo[b]thiophene 1 with aqueous transition metal species in the presence of various hydrocarbons at elevated temperatures is described. Mechanistic studies have shown that treatment of 1 with solutions of RuCl3 and other platinum metal species results in the formation of 2,3-dihydrobenzo[b]thiophene 2 and ethylbenzene 3 as major products. Metal coordinated species are probable intermediates in the formation of 2 and hydrocarbon products. 2 readily coordinates to PdCl2 to form square-planar trans-dichlorobis(2,3-dihydrobanzo[b]thiophene) palladium(II), which decomposes to ethylbenzene at 300-degrees-C. The crystal structure of the complex was determined by a single crystal X-ray diffraction study. The complex crystallized in the monoclinic space group C 2/c with Z = 8 in a cell of dimensions a = 23.057 (3), b = 9.711 (1), c = 15.227 (2) angstrom and beta = 99.74(1)-degrees. The structure was solved by the Fourier method and was refined by full-matrix least-squares calculations to R = 0.042 for 2537 observed data with I > 2.5-sigma-(I).