Centrifugal distortion constants and force field of HClCO

Abstract Measurement of the a - and b -type rotational transitions of formyl chloride, HClCO, was extended up to J = 50 and k a = 5 ← 4 in the frequency range of 8 to 200 GHz. Accurate rotational parameters including the sextic centrifugal distortion constants were determined from the observed spectrum for the 35 Cl and 37 Cl species. The τ defect in the planarity relations of the quartic centrifugal distortion constants was found to be negligibly small. From the quartic centrifugal distortion constants and the previously reported fundamental vibrational frequencies, force constants of formyl chloride were calculated by assuming the Urey-Bradley force field.