1972 Volume 45 Issue 7 Pages 1947-1950
The 2-methyltetrahydrofuran solutions of several alkali tetracyanoethylenides (M+, TCNE−, where M=Na, K, Rb, and Cs) show strong visible absorption spectra at low temperature which might be considered to be charge-transfer bands between two TCNE anions. Temperature dependence of the electronic absorption and ESR spectra of TCNE− in solution yields the monomer-dimer equilibrium of the TCNE anion. The heat of dimer formation of the anion was found to decrease in the order Na+>K+>Rb+>Cs+ with the size of the counter ions. The heat of dimer formation in Na+(TCNE)− also depends considerably on the solvent system. The absorption spectra of the solid TCNE anions were found to resemble the spectrum of the TCNE anion dimer (TCNE−)2 in solution to a great extent. A comparison of the electronic absorption and ESR spectra of M+(TCNE)− in solution and in solid demonstrates that the solid TCNE− is almost diamagnetic, and the anion dimer can be the unit of structure in the solid salts.
This article cannot obtain the latest cited-by information.