Aggregation of dinuclear {Fe2hpdta} units to form polynuclear oxy/hydroxy-bridged Fe(iii) coordination complexes

Abstract

An approach for the preparation of oxy/hydroxy briged Fe^III clusters that takes advantage of hydrolytic condensations of well defined {Fe₂hpdta(H₂O)₄} building units is presented. Co-ligands such as tripodal H₃tea or bidentate organic bases such as ethylenediamine (enH₂) can be used to complete the coordination spheres of the Fe^III centres and stabilise unsymmetrical iron-oxo clusters with non-zero magnetic ground spin-states. This strategy led to the isolation of a pentanuclear complex [Fe₅(μ₃-O)(hpdta)(H₂tea)(Htea)₂)(tea)]·{N(C₂H₄OH)₃}·2EtOH·7H₂O (1) and a nonanuclear coordination complex [Fe₉(μ₃-O)₅(μ-OH)₅(en)₆(hpdta)₂](NO₃)₂·7H₂O (2).