Preparation and Structure of Two Highly Reactive Intermediates: [Li(thf) 4 ][Cu 5 Cl 4 R 2 ] and [Li(thf) 4 ][AlCl 3 R], R  Si(SiMe 3 ) 3

A SiCu 2 three‐center two‐electron bond with short CuCu distance is the prominent structural feature of the lithium silylcuprate Li(thf) 4 ‐ 1 mentioned in the title compound, the first compound of this type characterized by X‐ray crystallography (in the picture the SiMe 3 substituents have been omitted). The structure of the aluminate corresponds to a frozen intermediate from the reaction of (Me 3 Si)3SiLi and AlC1 3 . The two compounds are only stable at low temperatures.