ELECTRON TRANSFER AND ION-PAIR FORMATION .46. TITRATIONS OF TETRACYANOETHENE BY ALKALINE AND ALKALINE EARTH METALS IN APROTIC SOLUTION [German]

摘要

For alkaline and earth alkaline metal 'titrations' of the pi-acceptor tetracyanoethene in aprotic (c(H+) < 0.1 ppm) solution, UV/VIS and ESR spectra have been measured in a scaled glas apparatus. Isosbestic points prove uniform but differing metal-mirror reduction processes for [Li](x), [Na](x), and [K](x) vs. [Cs](x). The formation of solvent-shared or solvent-separated contact ion pairs detected is supported by subsequent crystallization and structure determination. For the tetracyanoethene radical anion, semiempirical PM3 calculations with limited configuration interaction allow to reproduce the structural data as well as the long-wavelength charge-transfer excitation. [References: 47]