Crystal structure of the formal 20 electron zirconocene penta-fulvene complex Cp2Zr(η5,η1-adamantyl-idene-penta-fulvene):toluene:n-hexane = 1:0.125:0.125.

Malte Fischer,Rüdiger Beckhaus,Marc Schmidtmann

doi:10.1107/s2056989017015560

Malte Fischer, Rüdiger Beckhaus + Show 1 more

Open Access

https://doi.org/10.1107/s2056989017015560

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Abstract

The crystal structure of a solvated zirconocene penta-fulvene complex with a bulky adamantyl-idene substitution pattern, namely (η5,η1-adamantyl-idene-penta-fulvene)bis-(η5-cyclo-penta-dien-yl)zirconium(IV)-toluene-n-hexane (8/1/1), [Zr(C15H18)(C5H5)2]·0.125C7H8·0.125C6H14, 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 η5:η1 binding mode of the fulvene ligand to the central ZrIV atom. The asymmetric unit contains four independent mol-ecules of [η5:η1-adamantyl-idene-penta-fulvene]bis-[(η5)-cyclo-penta-dien-yl]zirconium(IV), together with half a mol-ecule of toluene disordered with half a mol-ecule of n-hexane (the solvent mol-ecules have no direct influence on the complex). In each of the four complex mol-ecules, the central ZrIV atom has a distorted tetra-hedral coordination environment. The measured crystal consisted of two domains with a refined ratio of 0.77:0.23.

Highlights

The crystal structure of a solvated zirconocene pentafulvene complex with a bulky adamantylidene substitution pattern, namely (5,1-adamantylidenepentafulvene)bis(5-cyclopentadienyl)zirconium(IV)–toluene–n-hexane
Single crystal X-ray diffraction proves the dianion-like 5:1 binding mode of the fulvene ligand to the central ZrIV atom
The asymmetric unit contains four independent molecules of [5:1-adamantylidenepentafulvene]bis[(5)-cyclopentadienyl]zirconium(IV), together with half a molecule of toluene disordered with half a molecule of n-hexane

Summary

Chemical context

Over the last few decades, pentafulvenes have found plenty of applications in organometallic chemistry (Preethalayam et al., 2017; Neuenschwander, 1989), one of which is their use as versatile ligands for a variety of early and late transition metals featuring a multitude of coordination modes and reactivity patterns The change of polarity at the exocyclic carbon atom of the pentafulvene ligand, resulting from its bonding to the central metal atom, enables a multitude of insertion reactions and C—H-activation reactions that are of great interest to our research group (Ebert et al, 2014; Manssen et al, 2015, 2017; Oswald et al., 2016). In this context we have recently reported the syntheses of the first zirconocene-based pentafulvene complexes and their reactivities (Jaroschik et al, 2017).

Structural commentary

Supramolecular features

Synthesis and crystallization

Refinement