Electrophilic Additions of Mercury and Gold Species to the Anion Carbide Cluster [Fe5C(CO)14]2-. X-ray Crystal Structures of (NEt4)[Fe5C(CO)14{μ-HgW(CO)3Cp}] and (NEt4)2[μ4-Hg{Fe5C(CO)14}2

Abstract

The reaction of the carbide carbon anion [Fe5C(CO)14]2- with ClHgM in tetrahydrofuran gives the new heptametallic clusters (NEt4)[Fe5C(CO)14{μ-HgM}] (M = Mo(CO)3Cp (1a), W(CO)3Cp (1b), Mn(CO)5 (1c), Co(CO)4 (1d), Fe(CO)2Cp (1e)). The spiro species (NEt4)2[μ4-Hg{Fe5C(CO)14}2] (2) has been isolated by reaction of the pentairon carbide carbon dianion with Hg(NO3)2. The structures of 1b and 2 have been determined by X-ray diffraction methods. The anion of 1b has an Fe5 square-pyramidal metal skeleton in which a basal edge is bridged by the HgW(CO)3Cp moiety. For the cluster anion 2, the metal core consists of a four-coordinate mercury atom bridging the bond edges of two square-based-pyramidal pentairon units. The electrochemical behavior of these compounds has been investigated by cyclic voltammetry and coulometry. The 57Fe Mossbauer spectroscopy of complexes 1b,e reveals the existence of three and four types of iron sites, respectively. This study has been extended by reacting the new species (NEt4)[Fe5C(CO)...