Embryonic brass: pseudo two electron Cu/Zn clusters

The isoelectronic M(7) clusters [Cu(3)Zn(4)](Cp*)(5) (1) and {[Cu(2)Zn(5)](Cp*)(5)}(+) (2) are described. While 1 can be isolated only as a minor side product from the reaction of Cu(CH(3)CO(2)) with equimolar amounts of [Zn(2)Cp*(2)] with the trigonal cluster [CuZn(2)](Cp*)(3) as the major product, 2 is available in acceptable yields from the reaction of [CuZn(2)](Cp*)(3) with the Cp*Zn(2)-transfer-reagent [Cp*Zn(2)(Et(2)O)(3)][BAr(4)(F)]. The trigonal bipyramidal Cu/Zn-clusters exhibit exceptional bonding situations: with formally only one skeleton electron pair they can be regarded as highly electron deficient. However, a detailed DFT analysis reveals that the cluster bonding is supported by 3d orbital contributions of the trigonal metal base unit. The data contribute to the development of an advanced tool-box for synthesis of Hume-Rothery intermetallic (e.g. brass) inspired clusters.