Triplet (T1) state and radical cation resonance Raman spectroscopy ofN,N,Nprime;,Nprime;hyphen;tetramethylhyphen; andN,N,Nprime;,Nprime;hyphen;tetraethylhyphen;phyphen;phenylenediamines

摘要

The timehyphen;resolved resonance Raman spectra of the first triplet state and the cw resonance Raman spectra of the radical cation are reported for various isotopic derivatives of theN,N,Nprime;,Nprime;hyphen;tetramethylhyphen;phyphen;phenylenediamine (TMPD) and of theN,N,Nprime;,Nprime;hyphen;tetraethylhyphen;phyphen;phenylenediamine (TEPD). Vibrational assignments and structural implications are discussed. The radical cation spectra are consistent with a semiquinoidal conformation of the ionized species. They are characterized by a significant frequency increase of the inhyphen;phase ngr;(Nndash;ring) mode with respect to the ground state spectra (Dgr;ngr;ge;120 cmminus;1) and by the high resonance enhancement of various bands assigned to vibrations of the N(alkyl)2groups, resulting from couplings of these vibrations with modes of the pgr; chromophore. The triplet spectra display almost only bands due to vibrations of the N(alkyl)2groups, implying that similar couplings take place in theT1state. Two signals characterize the Nndash;ringndash;N framework: one is assigned to the Wilson ring mode 9a(CH bending ); the second one, a strong signal around 1500 cmminus;1, corresponds to a vibration involving a large contribution of the Nndash;ring stretching motion and possibly also of the ring mode 8a.