Structure and dynamics of bis(organothiophosphoryl) disulfides in the solid state. X-Ray diffraction and cross-polarization magic angle spinning nuclear magnetic resonance studies

Abstract

The structure and dynamics of selected bis(organothiophosphoryl) disulfides have been studied by single-crystal X-ray diffraction and high-resolution solid-state NMR spectroscopy. The crystal and molecular structures of bis[tert-butyl(phenyl)thiophosphoryl] disulfide 1, bis-(diphenoxythiophosphoryl) disulfide 2 and bis[tert-butyl(methoxy)thiophosphoryl] disulfide 3 were determined, giving space groups of C2/c, P2₁2₁2₁ and P for 1, 2 and 3, respectively. Both phosphorus centres of the disulfide 1 have the same absolute configuration, as have those of the disulfide 3, although their environments were significantly different. It has been unambiguously proved that the S–S disulfide bond length varies as a function of the PSSP torsional angle. Moreover the influence the S–S–PS conformation has on the P–S bond length is discussed. Carbon-13 NMR dipolar-dephasing experiments, using powdered samples, indicated that both the tert-butyl and methoxy groups attached to the phosphorus atom were in a fast regime exchange.