Microwave Spectrum of IOF5

The microwave spectrum of iodenyl pentafluoride IOF₅ shows it to be a symmetric rotor with ${\mathcal{C}}_{\text{4v}}$ symmetry. Rotational constants are B(I¹⁶OF₅) =2131.09±0.01 Mc/sec and B(I¹⁸OF₅) =2073.15±0.02 Mc/sec. The iodine nuclear quadrupole coupling constant is +552.9±0.6 Mc/sec, and the molecular dipole moment is 1.08±0.10 D. The coupling constant is discussed in terms of a simple molecular‐orbital model.