428483-32-3Relevant academic research and scientific papers
Computational and experimental studies of the effect of substituents on the singlet-triplet energy gap in phenyl(carbomethoxy)carbene
Geise, C. Michael,Wang, Yuhong,Mykhaylova, Olena,Frink, Brian T.,Toscano, John P.,Hadad, Christopher M.
, p. 3079 - 3088 (2007/10/03)
The effect of aromatic substitution on the singlet-triplet energy gap in substituted phenyl-(carbomethoxy)carbene (X-Ph-C-CO2CH3, PCC) has been explored by time-resolved infrared (TRIR) spectroscopy and gas-phase computational methods. The ground state of para-substituted PCC is calculated to change from the triplet state in p-NO2-PCC (AGST = 6.1 kcal/mol) to the singlet state in p-NH2-PCC (AGST = -2.81kcal/mol). The absence of solvent perturbation in the TRIR spectra of p-N(CH3)2-PCC (which should have electronic properties similar to p-NH2-PCC) and parent PCC is consistent with their ground states lying >±2 kcal/mol from the next available electronic state, in line with the computational results. The observation of solvent perturbation in the TRIR spectra ofp-OCH3-PCC and p-CH3-PCC implies that their ground states lie ST values of -3.9 and -1.3 kcal/mol from polarizable continuum model (PCM) calculations with acetonitrile as a solvent. Gas-phase computational results for the meta- and ortho-substituted PCC species are also presented, along with selected linear free energy (LFE) relationships for the para and meta species.
