Transformations of anionic Cu-II chlorocomplexes have been studied under conditions of catalytic exchange reactions between carbon tetrachloride and n-alkanes. It was shown that chlorocuprates are just, precursors and are easily reduced to the genuine catalysts, that is, to the respective Cut complexes. Both the composition and the geometric structure of the precursor (CuCl42-) and, probably, the active site (CuCl32-) have been investigated by several techniques (UV-vis spectroscopy, electron spin resonance (ESR), extended X-ray absorption fine structure (EXAFS), X-ray absorption near-edge structure (XANES), and static magnetic measurements). The dependence of the metathesis velocity on the [Cl-]/[Cu] ratio was found to exhibit a maximum most likely corresponding to the highest content of trichlorocuprite CuCl32-.