The thiocarbonyl-bridged complex Cp 2Fe 2(CO) 3CS is obtained by the reaction of CpFe(CO) 2 − and (PhO) 2CS in THF. Infrared and NMR spectra show that the compound exists in solution in interconverting cis and trans forms, but that the isomerization occurs more slowly than for the carbonyl analog [CpFe(CO) 2] 2. Most reagents which cleave [CpFe(CO) 2] 2, such as Br 2, HgCl 2, and O 2/HBF 4, do not give simple cleavage reactions with Cp 2Fe 2(CO) 3CS. Reductive cleavage of Cp 2Fe 2(CO) 3CS with Na(Hg) gives the thiocarbonyl anion CpFe(CO)(CS) −, which reacts with Ph 3SnCl to form CpFe(CO)(CS)SnPh 3. Methylamine reacts with CpFe(CO)(CS)SnPh 3 to give CpFe(CO)(CNMe)SnPh 3, while ethylenediamine gives the carbene complexes CpFe(CO)C(N 2C 2H 6)SnPh 3. The preparation of another new carbene complex, [CpFe(CO) 2C(OMe) 2]PF 6, is also described.