Zirconocene

Zirconocene dichloride

Identifiers
CAS Number	1291-32-3 Y
3D model (Jmol)	Interactive image
ChemSpider	29081433 N
ECHA InfoCard	100.013.697
PubChem CID	10891641
InChI InChI=1S/2C5H5.2ClH.Zr/c2*1-2-4-5-3-1;;;/h2*1-5H;2*1H;/q2*-1;;;+4/p-2 N Key: QMBQEXOLIRBNPN-UHFFFAOYSA-L N InChI=1/2C5H5.2ClH.Zr/c2*1-2-4-5-3-1;;;/h2*1-5H;2*1H;/q2*-1;;;+4/p-2 Key: QMBQEXOLIRBNPN-NUQVWONBAX
SMILES [cH-]1cccc1.[cH-]1cccc1.[Cl-].[Cl-].[Zr+4]
Properties
Chemical formula	C10H10Cl2Zr
Molar mass	292.31 g·mol−1
Appearance	white solid
Solubility in water	Soluble (Hydrolysis)
Hazards
Safety data sheet	CAMEO Chemicals MSDS
Related compounds
Related compounds	Titanocene dichloride Hafnocene dichloride Vanadocene dichloride Vanadocene dichloride Niobocene dichloride Tanatalocene dichloride Tungstenoocene dichloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YN ?)
Infobox references

Zirconocene dichloride is an organozirconium compound composed of a zirconium central atom, with two cyclopentadienyl and two chloro ligands. It is a colourless diamagnetic solid that is somewhat stable in air.

Zirconocene dichloride may be prepared from zirconium(IV) chloride-THF complex and sodium cyclopentadienide:

The closely related compound Cp₂ZrBr₂ was first described by Birmingham and Wilkinson.

The compound is a bent metallocene: the Cp rings are not parallel, the average Cp(centroid)-M-Cp angle being 128°. The Cl-Zr-Cl angle of 97.1° is wider than in niobocene dichloride (85.6°) and molybdocene dichloride (82°). This trend helped to establish the orientation of the HOMO in this class of complex.

Zirconocene dichloride reacts with lithium aluminium hydride to give Cp₂ZrHCl Schwartz's reagent:

Since lithium aluminium hydride is a strong reductant, some over-reduction occurs to give the dihydrido complex, Cp₂ZrH₂; treatment of the product mixture with methylene chloride converts it to Schwartz's reagent.

Zirconocene dichloride can also be used to prepare the Negishi reagent, Cp₂Zr(η²-butene) which is used as a source for Cp₂Zr in oxidative cyclisation reactions. This reagent is prepared by treating zirconacene dichloride with n-BuLi leading to replacement of the two chloride ligands with butyl. The dibutyl compound subsequently undergoes beta-hydrogen abstraction to give one η2-butene ligand, eliminating the other butyl ligand as butane.