Novel motifs for magnetic exchange interactions as exemplified in one dimensional magnets based on the FeCl3-α-di-imine system: Nuclear gamma resonance evidence of slow paramagnetic relaxation and 3D-ordering

The extremes of single ion slow paramagnetic relaxation and cooperative 3D-antiferromagnetic order are exemplified in a series of structurally characterized complexes based on the anhydrous FeCl3-α-di-imine system. “Soft” Cl−Cl contacts, C−C (π-π) and hydrogen bonding interactions are found to lead to surprisingly strong magnetic exchange among five and six coordinate high-spin iron III monomers. The latter form the building blocks of novel “double chain” polymer magnets held together via the preceding “weak” interactions.