Exploring Cu/Al cluster growth and reactivity: from embryonic building blocks to intermetalloid, open-shell superatoms

International audienceCluster growth reactions in the system [Cu](Mes) + [Al](Cp*) (Mes = mesitylene, Cp* = pentamethylcyclopentadiene) were explored and monitored by LIFDI-MS and H-NMR. Feedback into experimental design allowed for an informed choice and precise adjustment of reaction conditions and led to isolation of the intermetallic cluster [CuAl](Cp*)(Mes) (). Cluster reacts with excess 3-hexyne to yield the triangular cluster [CuAl](Cp*) (). The two embryonic [CuAl](Cp*)(Mes) and [CuAl](Cp*) clusters and , respectively, were shown to be intermediates in the formation of an inseparable composite of the closely related clusters [CuAl](Cp*) (), [HCuAl](Cp*) () and [CuAl](Cp*) (), which just differ by one Cu core atom. The radical nature of the open-shell superatomic [CuAl](Cp*) cluster is reflected in its reactivity towards addition of one Cu core atom leading to the closed shell superatom [CuAl](Cp*) (, and as well by its ability to undergo σ(C-H) and σ(Si-H) activation reactions of CHCH (toluene) and (TMS)SiH (TMS = tris(trimethylsilyl))