Investigation of structural trends in difluoropyridine rings using chirped-pulse Fourier transform microwave spectroscopy and ab initio calculations

► Pure rotational spectra of difluoropyridines and the 13C and 15N isotopologues. ► Accurate rotational, centrifugal and 14N hyperfine constants are derived. ► rs and ro structural parameters in agreement with ab initio calculations. ► Fluorination at ortho carbon has greater effect on ring geometry.