Low resolution microwave spectra and indo calculations of phenylisothiocyanate and phenylisocyanate

Rotational Spectra and Structures of Phenyl Isocyanate and Phenyl Isothiocyanate

“…The spectroscopic parameters for PhNCO and PhNCS are well-determined and are compared with the calculated values at the MP2/aug-cc-pVTZ and B3LYP-D3BJ/aug-cc-pVTZ levels of theory in Table 4. For the rotational and 14 N quadrupole coupling constants, both methods provide reasonable agreement to the experimental values, but the MP2 derived parameters yield a closer match for the rotational constants and χ aa . The experimental values of χ bb and χ cc seemingly align better with the B3LYP-D3BJ estimates, but one should make this comparison with caution as the actual fit parameter (0.25(χ bb − χ cc )) was a small number.…”

“…The experimentally derived 14 N quadrupole coupling constants of PhNCO and PhNCS can be used to derive an independent estimate of the electronic structure at that site using a Townes−Dailey analysis as described in detail by Gordy and Cook 37 and as applied to other nitrogen-containing species such as the fluoropyridines. 38,39 To obtain the quadrupole coupling constants in the quadrupole tensor frame (x, y, z), the principal inertial system was rotated by 7.3°and 3.3°(a → x, b → z, c → y) through the QDIAG program 34 for PhNCO and PhNCS, respectively.…”

“…A 140 MHz portion of the broadband spectrum of PhNCO is provided in Figure 1 as an example. Next, with an aim to achieve higher resolution and sensitivity and in order to analyze the hyperfine structure due to the presence of the 14…”

“…The rotational, centrifugal distortion, and 14 N nuclear quadrupole coupling constants were determined for each species by fitting the observed rotational transitions using Pickett's SPFIT program 28 set to Watson's A-reduced Hamiltonian. 29 The results for PhNCO and PhNCS are shown in Tables 1 and 2, respectively.…”

“…The phenyl-substituted versions are excellent prototypes as the molecules are planar with only one stable conformer. The ground state microwave spectra of the normal isotopologues of phenyl isocyanate (PhNCO) 14,15 and phenyl isothiocyanate (PhNCS) 14,16 have been previously reported including investigation of the 14 N nuclear quadrupole hyperfine structure. 17 These studies have confirmed that the molecules are planar with C s symmetry in contrast to infrared spectra which were interpreted based on the assumption of C 2v symmetry.…”