Formation of a Propeller-Shaped Ni4Ga3 Cluster Supported by Transmetalation of Cp* from Ga to Ni

The reactivity of GaCp* toward different Ni-0 olefin complexes is investigated. The reaction of GaCp* with [Ni(cdt)] (cdt = all-trans-1,5,9-cyclododecatriene) leads to simple adduct formation and the 18 valence electron (ye) compound [Ni(GaCp*)(cdt)] (1). In contrast, [Ni-2(dvds)(3)] (dvds = 1,1,3,3-tetramethyl-1,3-divinyldisiloxane) is converted to the undercoordinated and highly reactive 16 ve complex [Ni(GaCp*)(dvds)] (2), which represents an intermediate in the formation of the propeller-shaped M-7 cluster [Ni4Ga3](Cp*)(3)(dvds)(2) (3). Extensive characterization of the latter compound by experimental and computational means reveals the Cp* transfer from Ga to Ni. Therefore, the title compound can be best expressed by the structural formula [(mu(2)-GaCp*)(Ni-2)(mu(2)-GaNiCp*)(2) (dvds)(2)]. The flexible dvds ligands stabilize this arrangement via alkene-Ni and O-Ga. interactions. Furthermore, compound 2 exhibits a fast GaCp* ligand exchange with external GaCp*, which is rather unexpected for the [TM(ECp*)(a)] compounds; they usually do not undergo substitution reactions with two electron donor ligands like CO, phosphines, or GaCp*.