MO CALCULATIONS TO INTERPRET OPTICAL-SPECTRA OF MV - AND RELATED SPECIES

The higher reduction products of dications of methyl viologen (MV2+), diquat (DQ(2+)) and n-butyl viologen (BV2+) i.e. MV; DO; and BV; respe ctively were prepared and their spectra recorded. MO calculation have been carried out to interpret the optical spectra of MV; and DQ:. A go od agreement was obtained between experimental and predicted singlet t ransitions for MV: while in case of DQ: the agreement for singlet rans ition at longer wave length was at variance. In case of MV:(I) the obs erved transition are 3.1307 and 3.3056 eV while calculated one are 3.1 352 (B-2u) and 3.4006 (B-3u) eV respectively where as in case of DQ: ( II) the observed transitions are 3.0228 and 3.1307 eV while the calcul ated one are 2.6032 (B-1) and 3.0873 (A(1)) eV respectively.