A Two-Dimensional Manganese(II) Carboxylato Polymer. Structure, Magnetism, and EPR Study

The synthesis, crystal structure, and properties of
[MnII(MCPA)2(H2O)2]n
(MCPA = 2-methyl-4-chlorophenoxyacetic acid), 1, a 2-D manganese carboxylato
polymer is reported. The synthesis of 1 has been
achieved via the
reaction of MCPA with MnCl2·2H2O and
NaHCO3 in methanol. Crystal structure data: 
[C18H20Cl2O8Mn];
orthorhombic; space group Pbca; a =
7.811(6) Å; b = 34.67(3) Å; c =
7.481(6) Å; Z = 4. The compound
has
a two-dimensional structure with Mn2+ atoms in an
octahedral environment and mixed water/carboxylate
coordination. The metal atoms are segregated in planes which are
perpendicular to the b axis and are spaced
17.73 Å apart. Variable-temperature magnetic susceptibility
measurements indicate the presence of antiferromagnetic behavior. The EPR spectra of polycrystalline samples at 4
K show that the intensity of the signal
decreases significantly with decreasing temperature and below ∼4 K
becomes EPR silent.