The molecular structure and curious motions in 1,1-difluorosilacyclopent-3-ene and silacyclopent-3-ene as determined by microwave spectroscopy and quantum chemical calculations

The molecules 1,1-difluorosilacyclopent-3-ene (3SiCPF(2)) and silacyclopent-3-ene (3SiCP) have been synthesized and studied using chirped pulse, Fourier transform microwave (CP-FTMW) spectroscopy. For 3SiCP this is the first ever microwave study of the molecule and, for 3SiCPF(2), the spectra reported in this work have been combined with that of previous work in a global fit. The spectra of each contain splitting which has been fit using a Hamiltonian consisting of semirigid and Coriolis coupling parameters. A refit of the original 3SiCPF(2) work was also carried out. All fits and approaches are reported. Analyses of the spectra provide evidence that the molecule is planar which is in agreement with the high-level calculations, but the source of the splitting in the spectra has not been determined.

Automated summary

The molecules 1,1-difluorosilacyclopent-3-ene (3SiCPF(2)) and silacyclopent-3-ene (3SiCP) were synthesized and studied using CP-FTMW spectroscopy. The spectra of both molecules show splitting phenomena, and the molecular configurations were determined through fitting analysis. The results are consistent with high-level calculations, providing a basis for further research.