Zirconocene dichloride is an organozirconium compound composed of a zirconium

Zirconium

Zirconium is a chemical element with the symbol Zr and atomic number 40. The name of zirconium is taken from the mineral zircon. Its atomic mass is 91.224. It is a lustrous, grey-white, strong transition metal that resembles titanium...

 central atom, with two cyclopentadienyl

Cyclopentadienyl

In organic chemistry, cyclopentadienyl is a cyclic group of atoms with the formula C5H5. Cyclopentadienyl are closely related to cyclopentadiene. Cyclopentadienyl have five carbon atoms bonded together in a pentagonal planar ring, all five of which are bonded to individual hydrogen atoms...

 and two chloro

Chlorine

Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...

 ligands. It is a colourless diamagnetic solid that is somewhat stable in air.

Preparation

Zirconocene dichloride may be prepared from zirconium(IV) chloride

Zirconium(IV) chloride

Zirconium chloride, also known as zirconium tetrachloride, is an inorganic compound frequently used as a precursor to other compounds of zirconium. This white high-melting solid hydrolyzes rapidly in humid air.-Structure:...

-THF

Tetrahydrofuran

Tetrahydrofuran is a colorless, water-miscible organic liquid with low viscosity at standard temperature and pressure. This heterocyclic compound has the chemical formula 4O. As one of the most polar ethers with a wide liquid range, it is a useful solvent. Its main use, however, is as a precursor...

 complex and sodium cyclopentadienide

Sodium cyclopentadienide

Sodium cyclopentadienide is an organosodium compound with the formula C5H5Na. The compound is often abbreviated as NaCp or CpNa, where Cp− is the cyclopentadienide anion. Cp is also used as an abbreviation for the cyclopentadienyl ligand in coordination chemistry.-Preparation:Sodium...

:

ZrCl₄(THF)₂ + 2 NaCp → Cp₂ZrCl₂ + 2 NaCl + 2 THF

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

Reactions

Zirconocene dichloride reacts with lithium aluminium hydride

Lithium aluminium hydride

Lithium aluminium hydride, commonly abbreviated to LAH or known as LithAl, is an inorganic compound with the chemical formula LiAlH4. It was discovered by Finholt, Bond and Schlesinger in 1947. This compound is used as a reducing agent in organic synthesis, especially for the reduction of esters,...

 to give Cp₂ZrHCl Schwartz's reagent

Schwartz's Reagent

Schwartz's reagent is the common name for the chemical compound with the formula 2ZrHCl, sometimes described zirconocene hydrochloride or zirconocene chloride hydride and is named after Jeffrey Schwartz, who is currently a professor in Chemistry at Princeton University...

:₂ZrCl₂ + ¹/₄ LiAlH₄ → (C₅H₅)₂ZrHCl + ¹/₄ "LiAlCl₄"

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