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Blue Ruthenium Chloride Complexes where is the primary quantum yield for reaction 1 and Ia is the absorbed light intensity. If it is assumed that all the incident light is absorbed, which is a good approximation for the first 10-20% reaction where the product quantum yields were generally measured, it is seen that the rates and thus (product quantum yield) are independent of initial concentration of Mo-(CN)s3-and that the expression leads to zero-order kinetics, in agreement with the experimental results. Furthermore, consideration of the expressions indicates must also be independent of light intensity, also in agreement with the results. The rate expressions indicate the product quantum yield in acidic solution must lie between 1 and 2 and in basic solution between 4 and 5, depending on the values of ki and k%, again in agreement with the results. Finally, if the mechanism is valid, the primary quantum yield, , using the

The polymerization of racemic methylthiirane in homogeneous phase, initiated by bis(isopropy1-S-cysteinato) cadmium is a living process. The resulting polymers are isotactic and optically active at partial conversion. The optical purity of the residual monomer may reach 27% at half conversion. The propagation occurs mainly on one valency of Cd, however oligomers grow slowly on the second valency. The stereoregularity of the polymer chain appears only when the length of the oligomer becomes high enough, making possible a bicoordination of the Cd counterions. The stereoregularity of the polymer is characterized by the molar fraction G of isotactic diads which varies from 0.5 for atactic chains-formed at the beginning-to about one for isotactic segments formed for longer chains. The stereospecificity also depends on temperature of propagation and on initiator concentration. The kinetics observed (zero order in monomer and one-half in Cd) are explained by monomer coordination before insertion and dimeric association of the thiolate end groups. The enantioasymmetric process observed results from an unbalance in the number of the two different types of active sites and possibly from a difference in their reactivities. Enantioasymmetry has been found to decrease significantly when the dielectric constant E of the medium increases.