|
|
| | Bis(cyclopentadienyl)zirconium chloride hydride Basic information | | Reaction |
| | Bis(cyclopentadienyl)zirconium chloride hydride Chemical Properties |
| Melting point | 300 °C | | storage temp. | Keep in dark place,Inert atmosphere,2-8°C | | form | Powder | | color | off-white | | Water Solubility | reacts | | Sensitive | Light, Air & Moisture Sensitive | | Hydrolytic Sensitivity | 8: reacts rapidly with moisture, water, protic solvents | | Merck | 14,8396 | | Exposure limits | ACGIH: TWA 5 mg/m3; STEL 10 mg/m3
NIOSH: IDLH 25 mg/m3; TWA 5 mg/m3; STEL 10 mg/m3 | | CAS DataBase Reference | 37342-97-5(CAS DataBase Reference) |
| | Bis(cyclopentadienyl)zirconium chloride hydride Usage And Synthesis |
| Reaction |
- Reagent for the hydrozirconation of olefins.
- Reagent for the hydrozirconation of alkynes.
- Catalyst for the hydroboration of olefins.
- Mediates the reduction of tertiary amides to aldehydes, without reduction of cyano, nitro, ester, or α,β-unsaturated groups.
- Catalyst for the asymmetric vinylation and dienylation of ketones.
- Useful reagent for dimethylzinc mediated additions alkenylzirconocenes to aldimines.
- Useful reagent for the synthesis of oxidized amides from nitriles.
- Reagent for the hydrozirconation of propargylic alcohols.
| | Chemical Properties | Dicyclopentadienylzirconium hydride chloride, zirconocene hydride chloride, Schwartz’s reagent, Cp2ZrHCl (Cp = C5H5), is a white microcrystalline powder, mp >300℃(dec.). Under the influence of light or heat the color changes to pink, then gradually to dark red. The compound is sensitive to moisture; it is virtually insoluble in the usual organic solvents such as ethers, consistent with its polymeric character. It dissolves in halogenated solvents with evolution of heat, forming Cp2ZrClX, where X = Cl, Br, or I. | | Uses | Bis(cyclopentadienyl)zirconium hydridochloride is used in the conversion of amides to aldehydes. It is also used as a pharmaceutical intermediate. | | Uses | Functionalization of unsaturated systems via an organozirconium intermediate. Schwartz’s reagent is used in limited
amounts in organic synthesis for the selective
hydrozirconation of alkenes and alkynes. The
reaction takes place rapidly and quantitatively at
room temperature, forming zirconium alkyls or
alkenyls that may be converted into useful functionalized derivatives. For example, reaction with
carbon monoxide followed by removal of the
zirconium-containing part of the molecule yields
a variety of carbonyl compounds. | | Preparation | Schwartz’s reagent is produced by reaction of zirconocene dichloride (Cp2ZrCl2) with LiAlH4 or LiAlH[OC(CH3)3]3 in THF solution. The commercial product (Alfa Ventron, Aldrich) is slightly pink. | | Purification Methods | It is moisture and light sensitive. Determine its purity by reaction with a slight excess of Me2CO whereby the active H reacts to produce Cp2ZrClOPri and the integrals of the residual Me2CO in the 1H NMR will show its purity. The presence of Cp2ZrH2 can be determined because it forms Cp2Zr(OPri)2. For a very active compound, it is best to prepare it freshly from the dichloride (see below) by reduction with Vitride [LiAl(OCH2CH2OH)2H2], the white precipitate is filtered off, washed with tetrahydrofuran, then Et2O and dried in a vacuum. Store it dry in the dark. [Carr & Schwartz J Am Chem Soc 101 3521 1979, Negishi & Takahashi Synthesis 1 1988, Beilstein 16 IV 1770.] |
| | Bis(cyclopentadienyl)zirconium chloride hydride Preparation Products And Raw materials |
|