Evidence for Charge Transfer (CT) Complexes involving Aniline Trimers

Fig. 4 - UV-Vis spectrum of 1:1 complex of 2,6-dimnethylaniline trimer and TCNE in acetonitrile. The strongest evidence for complex formation is the preseence of two bumps at 395 and 415 nm., which correspond to TCNE anion.

These peaks are easily predicted using the Delta SCF method on TCNE anion, optimizing at B3LYP/6-31G(d'), and using single point orbital energies at B3LYP/6-311G(2d,p). Or, one can simply consult the exerimental literature. A subtle point here is that pure TCNE does not form anions in acetonitrile solution; impure TCNE is frequently contaminated by anions, and so must be studiously avoided. Since pure TCNE does not form anions simply by being in acetonitrile solution, there must be some other electron donor. The donor, is, in this case, 2,6-dimethyl aniline trimer. This conjecture, that substituted aniline trimers are capable of efficient electron transfer, will be considerably strengthened in the next few frames.

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