Synthesis of bis(η-1,3,5-tri-t-butylbenzene) sandwich complexes of yttrium(0) and gadolinium(0); the X-ray crystal structure of the first authentic lanthanide(0) complex, [Gd(η-Bu t 3 C 6 H 3 ) 2 ]

The vapours of yttrium and gadolinium react with 1,3,5-tri-t-butylbenzene to afford the metal(0) complexes [(M(η-But3C6H3)2], M = Y, Gd; the X-ray crystal structure of the gadolinium complex shows the molecule to possess the parallel ring sandwich structure.