For each system, the geometry was optimized and the molecular Hessian and the rotational constants were computed using the Dalton2013 program package.64,65 The other relevant molecular properties were computed at the optimized geometry using the recursive response property implementation, and the Coriolis coupling constants have been implemented in a development version of Dalton2013. The molecular Hessian was then used in a vibrational analysis to find the harmonic vibrational frequencies and to transform the geometric differentiation in the property tensors from a Cartesian basis to a reduced normal coordinate basis73 to calculate anharmonic frequencies and spectral intensities.