A C2-symmetric, basic Fe(iii) carboxylate complex derived from a novel triptycene-based chelating carboxylate ligand

Abstract

A triptycene-based bis(benzoxazole) diacid ligand H₂2L2^Ph4Ph4 bearing sterically encumbering groups was synthesized. Treatment of H₂2L2^Ph4Ph4 with Fe(OTf)₃ afforded a C₂-symmetric trinuclear iron(III) complex, [NaFe₃(L2^Ph4Ph4Ph4)₂(μ₃-O)(μ-O₂CCPh₃)₂(H₂O)₃](OTf)₂ (8). The triiron core of this complex adopts the well known “basic iron acetate” structure where the heteroleptic carboxylates, comprising two Ph₃CCO₂⁻ and two (L2^Ph4Ph4Ph4)²⁻ ligands, donate the six carboxylate bridges. The (L2^Ph4Ph4Ph4)²⁻ ligand undergoes only minor conformational changes upon formation of the complex.