Rational Design of Tetranuclear Complexes Employing N‐Imidoylamidine Based Ligands.

Ligands such as N‐2‐pyrimidylimidoyl‐2‐pyrimidylamidine (Pm2ImAm) possess both a bidentate and tridentate coordination site within a single ligand framework. Taking advantage of this, two tetranuclear complexes with manganese ([MnIIIMnII3(Pm2ImAm)3Cl6]) and iron ([FeIII4(Pm2ImAm)3Cl9]) have been isolated, characterized by single‐crystal X‐ray analysis, and their magnetic properties have been investigated through SQUID magnetometry and Mössbauer spectroscopy. As well, a mononuclear ([FeIII(Pm2ImAm)Cl3]) and binuclear ([MnII2(µ‐Cl)2(Pm2ImAm)2Cl2]) complex employing this ligand framework were also isolated, characterized by single‐crystal X‐ray analysis and their magnetic properties were investigated. For comparison purposes, the previously reported mononuclear complexes [MnIII(Py2ImAm)3] and [FeIII(Py2ImAm)3] were also probed here via SQUID magnetometry due to the similarities between these mononuclear systems and fragments of the tetranuclear complexes. Through this approach, clear interpretation of the magnetic properties in [MnIIIMnII3(Pm2ImAm)3Cl6] and [FeIII4(Pm2ImAm)3Cl9] was achieved. These results reveal that employing our N‐imidoylamidine ligands facilitates the rational design of polynuclear complexes with differing metal ion spin states. Rational design of tetranuclear complexes with manganese and iron was achieved by employing N‐imidoylamidine ligands. Evaluation via SQUID magnetometry and Mössbauer spectroscopy reveal a unique combination of low and high spin states for the metal centers within these cluster aggregates. [ABSTRACT FROM AUTHOR]