Collect. Czech. Chem. Commun. 1986, 51, 753-762

Interactions of tungsten hexachloride with esters of carboxylic acids

Hynek Balcar, Alena Dosedlová and Bohumír Matyska

The J. Heyrovský Institute of Physical Chemistry and Electrochemistry, Czechoslovak Academy of Sciences, 121 38 Prague 2


The interactions of tungsten chlorides and oxychlorides with methyl 10-undecenoate, methyl palmitate and methyl acetate, respectively, have been investigated by UV-VIS, IR and EPR spectroscopic methods. The primary complex formed by coordination of the carbonyl group to WCl6 is converted successively to an analogical, very stable complex WOCl4.ester under the simultaneous formation of acyl chloride and methyl chloride. In the case of methyl undecenoate, the coordination reaction is accompanied by a partial reduction of WCl6 to WCl5. The latter reacts with the ester in excess to give a complex characterized by a broad EPR single line at g = 1.767 (ΔH = 7.8 mT). At higher ester-to-tungsten molar ratios, this complex undergoes deeper reduction to products containing tungsten in a lower oxidation state, and competitively, a parallel oxygen abstraction reaction yielding WOCl3, acyl chloride and methyl chloride. The participation of these reactions in the formation of active WCl6-based catalysts for methathesis of unsaturated esters is discussed.