The Clusters [Ma(ECp)b] (M=Pd, Pt; E=Al, Ga, In): Structures, Fluxionality, and Ligand Exchange Reactions

The synthesis and structural characterization of the novel homoleptic cluster complexes [Pd2(GaCp*)2(μ2‐GaCp*)3] (1 c), [Pd3(GaCp*)4(μ2‐GaCp*)4] (2 b) and [Pd3(AlCp*)2(μ2‐AlCp*)2(μ3‐AlCp*)2] (3) (Cp*=C5Me5) are presented. Furthermore, ligand exchange reactions of these cluster complexes are explored. In contrast to the electronically and sterically saturated complexes [M(ECp*)4] (M=Ni, Pd, Pt), the new unsaturated analogues [Ma(ER)b] (E=Al, Ga, In) react with a variety of typical ligands (Cp*Al, CO, phosphines, isonitriles) to give new di‐ and tri‐substituted compounds like [Pt2(GaCp*)2(μ2‐AlCp*)3] (1 d), [PdPt(GaCp*)(PPh3)(μ2‐GaCp*)3] (4 b), or [Pd3(PPh3)3(μ2‐InCp*)(μ3‐InCp*)2] (8). The trends of the reactivity of [Ma(ER)b] as well as their fluxional behavior in solution has been elucidated by NMR spectroscopy, resulting in a mechanistic rationale for the ligand exchange reactions as well as the fluxional processes. The successful synthesis of the homoleptic cluster compounds [Ma(ECp*)b] (M=Pd, Pt; E=Al, Ga, In; an example of which is shown here) is highly dependent on the conditions and the particular combination of the starting compounds [MLn] and EICp*. The reactivity of [M2(ECp*)5] and [M3(ECp*)8] towards ligand substitution is studied in detail.