Tungsten dichloride dioxide is a thin yellow-colored crystalline with the chemical formula of WO2Cl2, and CAS No. of 13520-76-8. It is used as a precursor to other tungsten compounds.
Physical Properties
1. Stable at normal temperature and pressure.
2. Dissolvable in cold water, decomposed in hot water, soluble in ammonia and alkali, and insoluble in ethanol.
3. Like other tungsten halides, sensitive to moisture in the atmosphere, so the reaction tube must be opened in a dry nitrogen atmosphere and stored under vacuum or in dry inert gas.
Structure
The compound is a polymer consisting of distorted octahedral W centers. The monomer is characterized by two short W-O distances, typical for a multiple W-O bond, and two long W-O distances more typical of a single or datice W-O bond.
Preparation
WO2Cl2 is prepared by ligand redistribution reaction from tungsten trioxide (WO3) and tungsten hexachloride (WCl6):
2 WO3 + WCl6 → 3 WO2Cl2
Using a two-zone tube furnace, a vacuum-sealed tube containing these solids is heated to 350°C. The yellow product sublimes to the cooler end of the reaction tube. No redox occurs in this process. An alternative route highlights the oxophilicity of tungsten:
WCl6 + 2 O(Si(CH3)3)2 → 3 WO2Cl2 + 4 ClSi(CH3)3
This reaction, like the preceding one, proceeds via the intermediacy of WOCl4.
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