Vibrational studies of ground state 4-dimethylaminobenzonitrile (DMABN) and its ring deuterated isotopomer DMABN-d₄

IR and Raman spectra of DMABN (4-dimethylaminobenzonitrile) and its ring deuterated isotopomer DMABN-d4have been measured. Hartree-Fock (HF/6-31G*) and density function theory (DFT, B3LYP/6-31G*) ab initio calculations have been performed to interpret the observed vibrational spectra and isotopic shifts. Assignments of several controversial bands have been made. A large change of vibrational composition and mode pattern upon ring deuteration has been found for bands that have dominant contributions from the Wilson 19a, 19b, v(Ph-N) and v(Ph-CN) vibrations in DMABN.