Embryonic brass: Pseudo two electron Cu/Zn clusters

Abstract

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 4F ]. 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.