The 13C NMR spectrum of tetraphenylethylene (Ø2, C:C Ø), of its dilithium salt (Ø2, C.C Ø2.2Li+), and of their mixtureszin C6D6 were recorded. The spectta of The mixture consist of two sets of The hydrocarbon and the lithium salt lines each. This demonstrates that the Ø2C:C Ø2 + Ø2C.CØ2, 2 Li exchange is very slow, even on NMR scale an its ytmolefular rate constant has, therefore, to be smaller than 100M-1- sec-1