Potential scans for X–MO 2–NCO (M=S and Se and X=F and Cl) and vibrational assignments of haloselenonyl isocyanates

Abstract

The structural stability of halosulfonyl isocyanate X–SO 2–NCO and haloselenonyl isocyanate X–SeO 2–NCO (X is F and Cl) was investigated by density functional DFT-B3LYP/6-311+G** and ab initio MP2/6-311+G** calculations. The potential scans for the rotation of the –NCO rotor were calculated and found to be consistent with a single minimum that corresponds to a gauche conformation (–NCO moiety nearly eclipses one of the two MO bonds). The vibrational frequencies, infrared intensities as well as depolarization ratios were calculated at DFT-B3LYP/6-311+G** level for the two selenides at their gauche conformation. The potential energy distributions among symmetry coordinates of the normal modes of both F–SeO 2–NCO and Cl–SeO 2–NCO in their gauche conformation were then computed from normal coordinate analyses.