Spectroscopic properties of praseodymium perchlorates in alcohols and 2-halogeno derivatives of ethanol. Part III

Abstract

1. The oscillator strength values of Pr(ClO4)3 in 2-chloroderivatives of ethyl alcohol vs. solvent polarizability exhibit a different relation than that observed in neodymium perchlorate solutions. 2. The energies of f-d transitions for the above series shift to higher energies, indicating the expected effects of changes in electron densities in oxygen atoms of the solvent molecules. On the other hand, a shift energy of3P0 bands towards the IR can be caused by nephelauxetic effects and is not realized for the CCl3CH2OH solution. Moreover, the f-d transition of the Pr3+ ion in the latter solution appears at drastically low energies. This may indicate a decrease in the C-N and M-L distance in this system. 3. The strange results of f-f transition-intensity variation in the series CH2FCH2OH, CH2ClCH2OH, CH2BrCH2OH, CH2ICH2OH indicate the competition of three factors: a/ changes in the composition of the immediate environment of the Pr3+ ion; b/ changes in the dimerization or polymerisation of the solvent molecules caused by hydrogen bonding, which leads to polarizability of solvent molecule changes [2]; c/ splitting of d-orbitals of low-laying configuration and their shifts caused by the nephelauxetic effect [9]. 4. A decrease in the temperature of the solution leads to an effect close to the pressure one: as a result, a significant increase in the intensity of the f-f transition is observed, which is caused by shortening of Me−O distance.