Abstract <p>Chromato-mass spectrometry has been used to study the reactions of coordinated ligands in chromium and boron difluoride acetylacetonate complexes. It has been established that bromine- and thiophenyl-substituted acetylacetonates of boron difluoride, unlike chromium complexes, do not react with thiophenol. The reaction of thio-substituted chelates with SO₂Cl₂ also proceeds differently. In chromium complexes, the reaction involves the substitution of the thioalkyl or thioaryl group with a chlorine atom. Thioethyl-substituted boron difluoride acetylacetonate reacts with SO₂Cl₂ similarly to aromatic analogs, leading to chlorination of the ethyl group. However, thioaryl-substituted boron difluoride acetylacetonate does not react with SO₂Cl₂. Additionally, it was found that bromine- and thio-substituted chromium acetylacetonates react with sulfenyl chlorides, replacing the α-substituent with a chlorine atom. It is suggested that the difference in the reactivity of chromium and boron difluoride acetylacetonates is due to the different charge distribution in the chelate cycle. The strong electron-accepting nature of the BF₂ group leads to a positive charge on the substituent attached to the chelate ring in boron complexes.</p>