The reaction of the perfluorosulfanylvinyldiiron(I) complex [_Fe(CO)3₂_μ-C(SMe)(CF3)-C β(CαF2)_] (1) with secondary mono- and diamines (L = Me2NH, (CH2)4NH, HN(CH2)4NH) in a 1:1 ratio in dichloromethane at room temperature led in a multistep reaction to the new monoaminocycloferrathiapentadiene compounds [_Fe(CO)3₂_μ-S(Me)C(CF3)CFCX_] (X = NMe2 (2), N(CH2)4 (3), N(CH2)4NH (4)) and [[_Fe(CO)3₂_μ-S(Me)C(CF3)CFC] 2(μ-N(CH2)4N_] (5). However, when the reaction of 1 was conducted in THF with a large excess of amine, the diaminocycloferrathiabutene complexes [_Fe(CO)3₂_μ-S(Me)C(CF3)C(CX2)_] (X = NMe2 (6), N(CH2)4 (7)) and [_Fe(CO)3₂_μ-S(Me)C(CF3)C(CX)_] (X = MeN(CH2)2NMe (8), HN(CH2)2 NH (9)) were formed. It is suggested that these compounds form via initial nucleophilic attack at Cα to give the common zwitterionic intermediate [_Fe(CO)3₂_μ-S(Me)C-(CF3)C(CFNX 2)] (C). Thermally induced C-F bond activation is a feature of these reactions. Thermolysis of diaminocycloferrathiabutene compounds (6-9) in tetrahydrofuran gave the amidinium-substituted μpar;-alkyne derivatives [_Fe(CO)3₂(μ-SMe)_μ-(CF3)C=C(CX 2)_] (X = NMe2 (10), N(CH2)4 (11)) and [_Fe(CO)3₂(μS-SMe)_μ-(CF3)C=C(CX)_] (X = MeN(CH2)2 NMe (12), NH(CH2)2NH (13)), in quantitative yields via C-S bond scission. The molecular structures of 6, 8, and 10 have been established by X-ray diffraction studies.