The reaction of [Fe~3(CO)~1~2] with four S, N-substituted heterocyclic thioamides [SCSC(SR)NNPh(SL~n, where SL~1:R=Me; SL~2: R=ET; SL~3:R=n-pr; SL~4:R=i-Bu)] yields new open triangelar iron carbonyl clusters [Fe~3(CO)~3(μ~3-S)~2L] 1～4. It was found that the coordinated ligands in the product clusters were two sulfito S atoms and a heterocyclic carbene L which was formed from the cleavage of the ligand precursor SL~n. The formulas and structures of these clusters were characterized by elemental analysis, IR, ^1H NMR, and MS techniques and the molecular structures of 2 was determined by X- ray diffraction analysis. The sp^2 bonding character of the carbon (carbene) atom of fragmental S, N-substituted heterocyclic thioamides CSC(SEt)NNPh(L~2) is showed clearly in 2 and the C~c~a~r~b~e~n~e-Fe bond length of 0.1960nm corresponds to other iron stabilized carbenes. This carbene ligand displaces a terminal radial CO of the basal Fe(3) atom and locates in an essentially coplanar position to the Fe(1)S(1) Fe(3)S(2) distorted basal plane. The open triangular geometry of the matrix cluster [Fe~3(CO)~9(μ~3-S)~2] with a distorted Fe~3S~2 square pyramidal framework has been maintained in 2.

Key words: CLUSTER COMPOUND, CARBONYL COMPLEX, IRON COMPLEX, NITROGEN HETEROCYCLICS, SULFUR COMPOUNDS, METAL COMPLEX, CARBENE, CRYSTAL STRUCTURE, CRYSTAL STRUCTURE DETERMINATION, STRUCTURE CHARACTERISTICS