Abstract Cycloaddition reactions of the kinetically stabilized phosphaalkynes 1 with the imidovanadium (V) trihalides 9 furnish the 1, 2, 4-azaphosphavanada (V) cyclobutenes 10. The stability of these novel metallacyclic compounds depends solely on the substitutents of the imido unit. Thus, the imidovanadium (V) species 9 with tertiary alkyl groups on the N atom form stable addition products with 1 while in the cases of compounds 9 with a lower ...
