calculated and observed wavenumbers (Table V) must be somewhat arbitrary and we make no claim to uniqueness. However, again the force-constant values all are physically reasonable and, in addition to providing a description of the normal modes in MV+., they provide an indication of the way in which the chemical bonding has changed from that in MV2+. This change is illustrated in Figure 2. The nature of the bonding in MV+. thus suggests that an electron added to MV2+ goes to a molecular orbital which has strong bonding character in the inter-ring region.In Table VI the observed and calculated wavenumber values for MV2+ and MV+. are compared in full. In addition to the points made above, it may be seen that a surprisingly large change in the CH3 symmetric deformation accompanies the transformation from MV2+ to MV+.. Since this motion is essentially uncoupled from the rest of the molecular motion (see Tables I11 and V), it is not at all clear what causes this effect.In conclusion, we offer this admittedly crude approximation to a description of the normal modes of vibration in methylviologen and its radical ion as an aid to the interpretation of experimental spectra. While we recognize fully its defects, the description seems to us to be very much better than anything else we have seen! In the preceding study of the radiolysis of concentrated aqueous LiCl solutions (ref 6), one of the hypotheses used to explain the apparent inefficacy of C12-formation by the direct effect was that molecular chlorine, not detectable by spectrophotometry, could be formed during the early stages of water radiolysis. Such an hypothesis is confirmed here for pulse and 7-radiolysis of concentrated aqueous neutral LiI solutions. Indeed, it is shown that, 10 ns after the pulse, molecular iodine, detected as 13-, is formed with a yield that increases with the LiI concentration. The experimental results yields values of 4.8 and 7.3 respectively for the indirect and direct effects of total oxidation GI,-+ 2GI,-. This last high value is discussed.

No abstract

No abstract

No abstract

No abstract