The facile assembly of bis-, tris- and poly-(triazaphosphole) systems using click chemistry

Uncatalysed 1,3-dipolar cycloaddition reactions between two phosphaalkynes, P CR (R = Bu-t or Me), and a series of di-, tri- and poly-azido precursor compounds have given very high yields of a range of triazaphosphole substituted systems. These comprise the 1,1'-bis(triazaphosphole)ferrocenes, [Fe-{C5H4(N3PCR)}(2)], the tris(triazaphosphole)cyclohexane, cis-1,3,5-C6H9(N3PCBut)(3), and the poly(allyltriazaphosphole)s, {C3H5(N3PCR)}(infinity). Electrochemical studies on the 1,1'-bis(triazaphosphole)ferrocenes reveal the compounds to undergo reversible 1-electron oxidation processes, at significantly more positive potentials than ferrocene itself. Attempts to chemically oxidise one 1,1'-bis(triazaphosphole)ferrocene with a silver salt, Ag[Al{OC(CF3)(3)}(4)] were not successful, and led to the formation of a silver coordination complex, [{Fe[mu-C5H4(N3PCBut)](2)(mu-Ag)}(2)][Al{OC(CF3)(3)}(4)](2), thereby demonstrating the potential the reported triazaphosphole substituted systems possess as novel ligands in coordination chemistry.