A kinetic study of the generation of terminal phosphinidene complexes from 7-phosphanorbornadiene complexes. X-ray crystal structure analysis of the dimers of terminal phosphinidene complexes

Article abstract of DOI:10.1021/om00131a012

A kinetic study of the thermal decomposition of a 7-phenyl-7-phosphanorbornadiene P-W(CO)₅ complex in the presence of aniline, tolan, and cyclooctene has been performed at 105, 115, 117, and 125°C. The kinetics of this decomposition are first order in the concentration of the phosphanorbornadiene complex and do not depend on the concentration and nature of the trapping reagent. These results give additional support to the intermediacy of a terminal phosphinidene complex, [PhP=W(CO)₅], in such a decomposition. The activation energy of the process is calculated to be 33 ± 1 kcal mol^-1. The thermolysis of the same 7-phosphanorbornadiene at 55°C in the presence of CuCl as a catalyst gives a dimeric complex, [PhP= PPh][W(CO)₅]₃, in which both the phosphorus atoms and the P=P double bond are complexed by the three W(CO)₅ units as shown by X-ray crystal structure analysis.