Cyclooligiomerization of Alkynlphosphazenes

Abstract

Abstract The cyclooligiomerization of the alkynl function in alkynlphosphazenes with various organometallic catalysts has been studied. The cyclization of N3P3F5(C≡CPh) with Fe2(CO)q yields a variety of products including the cyclodimer, cyclopentadienone and a unique cyclotrimer all coordinated to the Fe(CO)3 moiety. The cyclotrimerization of N3P3F5(C≡CPh) with CO2(CO)8 affords a dimetallated asymmetric hexasubstituted benzene derivative, C6(C6H5)3(N3P3F5)3. Due to the sterically hindered nature of the molecule, rotamers derived from restricted rotation about the phosphazene-central arene bond have been observed. Their intratransformations have been examined by VT 19F-NMR. Reactions involving CpCO(CO)2 lead to cyclodimer, cyclotrimer and cyclopentadienone products each coordinated to a CpCo fragment. Other organometallic catalysts capable of tetramerizing and polymerizing alkynlphosphazenes have been investigated.