An efficient synthesis of the first electroactive phosphorus-containing bisferrocene macrocycles

Abstract

Condensation reactions of the phosphodihydrazide XP(Ph)(NMeNH₂)₂(X = O 1a, S 1b) with ferrocene-1,1′-dicarboxaldehyde 2 afford in good yield the first examples of phosphorus ferrocenyl macrocycles Fe[C₅H₄CHNNMeP(X)PhNMeNCHC₅H₄]₂Fe (X = O 3a, S 3b) and 3b can be converted to the new compounds Fe[C₅H₄CH₂NHNMeP(S)PhNMeNHCH₂C₅H₄]₂Fe 5 and [Fe{C₅H₄CHNNMeP(S)(Me)PhNMeNCHC₅H₄}₂Fe][CF₃SO₃]₂6 by reaction with, respectively, LAH and CF₃SO₃Me; 5 represents a novel prototype of an anion receptor which electrochemically recognises the H₂PO₄^–, HSO₄^– and Cl^– anions.