Ligand-directed synthesis of {Mn III5} twisted bow-ties

Abstract

Two isostructural polymetallic complexes [Mn^III₅(μ₃-O)₂(CH₃COO)₄(L1)₄]⁻ and [Mn^III₅(μ₃-O)₂(CH₃COO)₄(L2)₄]⁻ have been synthesised by using two Schiff base ligands derived from 3,5-diamino-1,2,4-triazole, following two different preparative routes, either using the pre-formed ligand (for L1) or via a metal-mediated template synthesis (for L2). The {Mn^III₅} structure is unusual, being based on two corner-sharing perpendicular {Mn₃} triangles forming a twisted bow-tie. The magnetic studies reveal antiferromagnetic coupling between Mn(III) ions while electrochemical experiments are consistent with a quasi-reversible Mn(III)↔Mn(IV) redox process at the central manganese ion.