Novel iron carbonyl complexes from thiophene-2-carboxaldehyde thiosemicarbazone

The reaction of thiophene-2-carboxaldehyde thiosemicarbazone (2-C4H3SCHNNHC(S)NH2) (1) with diiron nonacarbonyl under mild conditions in anhydrous benzene yields three iron carbonyl organometallic clusters: (i) Fe2S2 square-base pyramidal cluster 2 ([Fe(CO)3]3(μ3-S)2), (ii) Fe2S2 square-base pyramidal metal carbene cluster 3 ([Fe(CO)3]2Fe(CO)2(μ3-S)2(C(NH2)NHNCH (2-C4H3S)), and (iii) double butterfly cluster 4 ([Fe(CO)3]3Fe(CO)2(μ4-S)(C,N; C(NH2)NHNCH(2-C4H3S) (μ2-S, N; SC(NH2)NNCH(2-C4H3S)), and an octahedral complex 5 (Fe(CO)2(S, N; SC(NH2)NNCH (2-C4H3S))2. These products were fully characterized spectrally. The molecular structures of 1, 3, 4, and 5 have been determined by single-crystal X-ray diffraction.