Ferrocenyl triflate and 1,1'-ferrocenediyl ditriflate are known to undergo anionic thia-Fries rearrangements in high yields at low temperature. The double rearrangement of 1,1'-ferrocenediyl ditriflate leads in an intriguing manner exclusively to the meso diastereomer.Through experimental and theoretical research using DFT calculations, the understanding of the mechanism of the anionic thia-Fries rearrangement was expanded, and the use of this reaction and its product was broadened. The rearrangement product before hydrolysis was isolated and crystallized, and the crystal structure analysis was used as a benchmark for the selection of functionals, basis sets, and pseudopotentials. This thesis demonstrates the mechanism of the anionic thia-Fries rearrangement for ferrocenyl triflate and 1,1'-ferrocenediyl ditriflate and explains the reason for the unprecedent meso diastereoselectivity of the double anionic thia-Fries rearrangement of the latter. The scope of the reaction was expanded to ferrocenyl fluorosulfonate, and for the first time, to a cobalt complex. The anionic thia-Fries rearrangement product of the cobaltocenium salts proved more stable than the corresponding ferrocene derivative. The investigation of the reactivity of new ferrocenyl sulfonates also led to the synthesis of a rare ferrocene annellated oxathiine derivative. The mono anionic thia-Fries rearrangement product was explored as a new electrophilic partner for Suzuki-Miyaura cross-coupling, and the investigation around it gave rise to the syntheses of fluorosulfonylferrocene in addition to (trifluoromethylsulfonyl)ferrocene. These two new ferrocene derivatives were investigated as ortho metalating groups at ferrocene, and they performed very well as such.