Reaction of Other Pentacarbonylcarbene Complexes with Boron Trihalides

REACTION OF OTHER PENTACARBONYLCARBENE COMPLEXES WITH BORON TRIHALIDES 

It was also of interest to us how changes in the organic residue of the carbyne ligand influence the stability and the behavior of carbyne complexes. Hence, we treated with boron tribromide a series of pentacarbonyl-[methoxy (aryl) carbene tungsten (0) complexes which were substituted at 

Also here 13C NMR spectroscopy should be suitable as a probe for electronic changes. The chemical shifts of the carbyne-carbon atoms of the trans-(brorno) tetraearbonyl (arylcarbyne) tungsten (0) complexes obtained are presented in Table II (87, 91). 

Contrary to expectation, in this series one finds for the p-CF3 derivative the lowest 5-value, i.e., the strongest screening of the carbyne-carbon atom, whereas for the 2,4,6-trimcthyl derivative, by comparison, the screening is distinctly weaker. For an exact interpretation of these results, it is apparent to us that further experiments (currently in progress) are necessary. 

13C Nuclear Magnetic Resonance Shifts for the Ccarbyne Atom in Several trans-Br(CO)4WC-Ar Complexes0  

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