The metal halide complexes ClAuPPh3 and ClHg(m) react in thf with [Fe6C(CO)16]2- affording the metal cluster compounds (NEt4)[Fe6C{μ3-AuPPh3}(CO)16] (1) and (NEt4)[Fe6C{Hg(m)}(CO)16] (m = Mo(CO)3Cp (2), W(CO)3Cp (3), and Mn(CO)5 (4)) in good yields. The cluster [{Fe6C(CO)16}2(Hg)]2- (5) is also isolated by reaction of this anion with Hg(NO3)2. The product obtained by treatment of 1 with NOBF4 depends on the stoichiometry of the reaction. Thus, with a 1:1 molar ratio the nitrosyl compound [Fe6C{AuPPh3}(CO)15(NO)] (6) was formed whereas the use of an excess of NOBF4 led to the pentametal cluster [Fe4C{AuPPh3}(CO)11(NO)] (7). The structures of 1 and 7 have been determined by X-ray diffraction methods. The electrochemical behavior of 2−5 has been investigated by cyclic voltammetry and coulometry. An extended Hückel molecular orbital study of the bonding capabilities of [Fe4C(CO)12]2- has been carried out in order to understand the structural differences between [Fe4C{AuPPh3}(CO)12]- and [HFe4C(CO)12]-.

The reaction of (NEt4)2[Fe6C(CO)16] and (AuCl)2(μ-L) (L = diphosphine) depends on the nature of the diphosphine. Unexpectedly, for L = dppm (dppm = bis(diphenylphosphino)methane), the cluster [Fe4Au2C(CO)12(dppm)] (1) was formed, whereas for L = dppe (dppe = 1,2-bis(diphenylphosphino)ethane) the reaction gave the 14-metal cluster (Et4N)2[{Fe6AuC(CO)16}2(μ-dppe)], in which two Fe6CAu fragments are linked by the bridging ligand. Remarkably, 1 is a skeletal isomer of the previously published [Fe4Au2C(CO)12(PEt3)2].

The synthesis of soluble carbosilane dendrimers terminated with AuFe2 and AuFe3 carbonyl cluster units is reported.

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