Mechanism of Ziegler-Natta Polymerization of Acetylene: A Nutation NMR Study

摘要

Using nutation NMR spectroscopy the distance between adjacent 13C labels was measured in samples of polyacetylene prepared by polymerizing a dilute solution of double 13C-labelled acetylene in 12C-acetylene using titanium tetra-n-butoxide plus triethylaluminum as a catalyst. The experiments accord with expectation if the polymerization proceeds by a four-center insertion mechanism rather than by a metallacycle mechanism involving metal-carbenes. (Author)