| Autor: |
Davies, Sian C., Henderson, Richard A., Hughes, David L., Oglieve, Kay E. |
| Zdroj: |
Journal of the Chemical Society, Dalton Transactions; February 7, 1998, Vol. 1998 Issue: 3 p425-432, 8p |
| Abstrakt: |
The reaction between anhydrous DCl and [Ni(Ph2PCH2CH2PPh2)2] in dichloromethane produced mixtures of HD and D2. The relative amounts of the dihydrogen isotopomers produced depends on the concentration of acid. Mechanistic investigations showed that the reaction involves initial formation of [NiD(Ph2PCH2CH2PPh2)2]+. This deuteriation labilises the nickel to phosphine dissociation. At low concentrations of acid, phosphine chelate ring opening produces [NiCl2(Ph2PCH2CH2PPh2)] (confirmed by X-ray crystallography) and free Ph2PCH2CH2PPh2 together with HD (65 ± 5) and D2 (35 ± 5%). The hydrogen atom of HD originates from a phosphine ligand. At high concentrations of acid the rate of attack of DCl at [NiD(Ph2PCH2CH2PPh2)2]+ becomes faster than phosphine chelate ring opening and results in the formation of [Ni(Ph2PCH2CH2PPh2)2]Cl2 and predominantly D2. Experimentally, the highest concentration of DCl that can be used without appreciable decomposition of the complex is 0.2 mol dm−3. At this concentration of acid the dihydrogen isotopomer distribution is HD (35 ± 5) and D2 (65 ± 5%); however, analysis of the product distribution indicates that at much higher acid concentrations D2 could be the exclusive isotopomer. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
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