Crystal structure of the formal 20 electron zirconocene penta-fulvene complex CpZr(η,η-adamantyl-idene-penta-fulvene):toluene:-hexane = 1:0.125:0.125.

The crystal structure of a solvated zirconocene penta-fulvene complex with a bulky adamantyl-idene substitution pattern, namely (η,η-adamantyl-idene-penta-fulvene)bis-(η-cyclo-penta-dien-yl)zirconium(IV)-toluene--hexane (8/1/1), [Zr(CH)(CH)]·0.125CH·0.125CH, is reported. Reducing zirconocene dichloride with magnesium results in the formation of a low-valent zirconocene reagent that reacts readily with adamantyl-idene-penta-fulvene to give the aforementioned complex. Single crystal X-ray diffraction proves the dianion-like η:η binding mode of the fulvene ligand to the central Zr atom. The asymmetric unit contains four independent mol-ecules of [η:η-adamantyl-idene-penta-fulvene]bis-[(η)-cyclo-penta-dien-yl]zirconium(IV), together with half a mol-ecule of toluene disordered with half a mol-ecule of -hexane (the solvent mol-ecules have no direct influence on the complex). In each of the four complex mol-ecules, the central Zr atom has a distorted tetra-hedral coordination environment. The measured crystal consisted of two domains with a refined ratio of 0.77:0.23.