Pyrolysis of ortho-cyanotoluene and PCl3 mixtures: the millimeter and submillimeter-wave spectrum of NCCCCP

The unstable NCCCCP molecule has been detected in the pyrolysis products of phosphorus trichloride and ortho-cyanotoluene mixtures. Its rotational spectrum has been investigated in the millimeter and submillimeter-wave regions for the ground and various vibrationally excited states which approximately lie below 400 cm⁻¹, namely (v₈,v₉)=(0,1),(0,2),(0,3),(0,4),(1,0), and (1,1). Transitions up to J=241←240 were measured for the ground state, making a precise evaluation of the sextic centrifugal distortion constant possible. The l-type resonances between the different sublevels of the bending states have been taken into account in the analysis of the spectra, which yielded accurate determinations of the x_L(99) and x_L(89) anharmonicity constants.