Question

Using some of the materials listed below, come up with a reasonable synthesis for the preparation of Cp2TiMe2.

TiCl4, Cp-H, KH, PhBr, Mg, dicyclopentadiene, Li, hexane, THF, MeI, table salt, urea, dihydrogen monoxide, CO, CO2, SO2, KI, UI4, VCl5

Answer 1

Reasonable synthesis for the preparation of Cp2TiMe2 we require TiCl4, Cp-H, Mg, dicyclopentadiene, THF, MeI.Li, hexane,

Cp2TiMe2 is commonly known as Petasis reagent .The Petasis reagent is an organotitanium compound with the formula Cp₂Ti(CH₃)₂. It is an orange-colored solid. The compound is used for transforming carbonyl groups to terminal alkenes. In terms of reactivity, it resembles the Tebbe reagent and Wittig reaction. Unlike the Wittig reaction, the Petasis reagent can react with a wide range of carbonyls, including aldehydes, ketones and esters. The Petasis reagent is also more air stable than the Tebbe reagent, and can be isolated as a pure solid, or used directly as a solution in THF.

Cp₂TiCl₂ can also be prepared by using freshly distilled cyclopentadiene:

2 C₅H₆ + TiCl₄ → (C₅H₅)₂TiCl₂ + 2 HCl

This reaction is conducted under a nitrogen atmosphere and by using THF as solvent. The product is purified by soxhlet extraction using toluene as solvent.

The complex is pseudotetrahedral. Each of the two Cp rings are attached as η⁵ ligands. Viewing the Cp ligands as tridentate, the complex has a coordination number of 8.

It prepared by the salt metathesis reaction of methylmagnesium chloride or methyllithium with titanocene dichloride.

Cp₂TiCl₂ + 2 CH₃MgCl → Cp₂Ti(CH₃)₂ + 2 MgCl₂