Syntheses and Characterization of Half-Sandwich Zirconium Complexes with Dichalcogenolate o-Carborane Ligands

Metallocene complex Cp tt 2ZrCl 2 (Cp tt =η 5 1,3 t Bu 2 C 5 H 3 ) (1) has been prepared from the reaction of LiCp tt with ZrCl 4 in good yield. Reactions of 1 with dilithium dichalcogenolate o carboranes afforded new type of half sandwich compounds with dichalcogenolate o carboranyl ligands, [Li(THF) 4 ][Cp tt Zr(E 2 C 2 B 10 H 10 ) 2 ] (E=S, 2a; E=Se, 2b) in which only one cyclopentadienyl ring ligand existed. Complexes 1 and 2a were structurally characterized by X ray analyses. In complex 2a, the Zr(IV) ion is η 5 bound to one 1,3 di tert cyclopentadienyl ring and σ bound to four μ 2 sulfur atoms of two dithio carboranes. The zirconium atom and four sulfur atoms form a distorted pyramid. The coordination sphere around the zirconium atom resembles in a piano stool structure with four legs of sulfur atoms and the fulcrum at the zirconium atom.