Effects of ring tilting on rates of intramolecular electron transfer in mixed-valence 1',2',1'',2''-tetraethyl-, 1',3',1'',3''-tetraethyl-, and 1',2',4',1'',2'',4''-hexaethylbiferrocenium triiodides

Relatively minor perturbations caused by Cp ring substituents in a series of mixed-valence biferrocenium cations have pronounced effects on the electronic structure and rate of intramolecular electron transfer. The X-ray structure of 1',2',1'',2'''-tetraethylbiferrocene has been determined at 298 K: C2/c, a=18.760(3) A, b=9.568(3) A, c=16.441 (3) A, β=130.494(13) o , Z=4, D calcd =1.42 g cm -1 , R f =0.038, and R wf =0.041