Synthesis, structure, and some reactions of the cluster complex [(μ-H)2Fe5(μ3-Se)2(CO)14]

In the reaction of Na2Se with [Fe(CO)5] in isopropanol with subsequent acidification with HCl, which is used to synthesize [(μ-H)2Fe3(μ3-Se)(CO)9] (II), the cluster [(μ-H)2Fe5(μ3-Se)2(CO)14] (I) was detected. In assumption that compound I could serve as a suitable synthon for preparing the bulky heterometallic clusters, its reactions with the Rh-containing complexes were studied. The reaction of I with [Rh(CO)2Cp*] (Cp* is pentamethylcyclopentadienyl) was found to give a mixture of the products. The main reaction products were isolated and their structures were determined: [Fe2Rh(μ3-Se)2(CO)6Cp*], [Fe2Rh(μ3-Se)(μ3-CO)(CO)6Cp*], [FeRh2(μ3-Se)(μ-CO)(CO)3Cp2*], [Fe2Rh2(μ4-Se)(μ-CO)4(CO)2Cp2*]. Potassium hydride treatment of II with subsequent addition of [Cp*Rh(CH3CN)3](CF3SO3)2 leads to the well-known cluster complex [Fe3Rh(μ4-Se)(CO)9Cp*]. A set of the reaction products indicates that the {Fe5Se2} core cannot be used as one-piece “building block” in the synthesis of heterometallic clusters.