Phosphanyl-substituted siloles: synthesis, structural characterization and an unexpected secondary isotope effect in the 31P NMR spectrum at room temperature

We report the synthesis and characterization of a series of phosphanyl-substituted siloles, in which the effects of substituents at the phosphanyl units were examined, including both electronic and steric factors. The structural features of these new siloles were investigated using NMR spectroscopy, single-crystal X-ray diffraction and DFT calculations. For the halogen-substituted derivatives, an unexpected 35Cl/37Cl secondary isotope effect is observed in the 31P{1H} NMR spectra even at room temperature.