Unusual Magnetic Behaviors and Electronic Configurations Driven by Diverse Co(II) or Mn(II) MOF Architectures

Five novel metal organic frameworks were obtained by hydro-solvothermal
reactions using the hexafluorisopropylidenebis­(benzoic) acid (H2hfipbb) as linker and Co­(II) or Mn­(II) ions as connectors.
[Co2(Hhfipbb)­(TEA)], compound 1 (TEA = triethanolamine
trianion) with a three-dimensional (3D) framework, and a tpu net; [Co1.5(hfipbb)2]·HN­(CH2CH3)3 and [Co3(hfipbb)2]·2­{HN­(CH2CH3)3}, compounds 2 and 2-a, respectively, both with two-dimensional
structure, sql topologies, and different layer packings.
Compounds 3 and 4, having the general formula
[M2(hfipbb)2]·C7H8, where M = Co (3) or Mn (4), have 3D frameworks
with an sqc topology. A deep analysis of the magnetic
measurements reveals different striking magnetic behaviors resulting
from diverse secondary building unit and framework architectures.
Compound 1 presents canted antiferromagnetic chains,
compound 2 contains ferromagnetic linear trimeric clusters,
and compound 3 exhibits ferromagnetic chains. For the
three compounds, a 3D canted antiferromagnetic structure takes place
at ∼8 K by means of weak magnetic interactions between the
mentioned magnetic units. Such long-range magnetic order is precluded
with the application of a high enough magnetic field. Compound 4 evidenced intrachain antiferromagnetic interactions.