Complexes Derived from the Reaction of Manganese(III) Schiff Base Complexes and Hexacyanoferrate(III): Syntheses, Multidimensional Network Structures, and Magnetic Properties

The reaction between the
[Mn(BS)(H2O)]+ monomeric and
[Mn2(μ-BS)2(H2O)2]2+
dimeric cations and
[Fe(CN)6]3- gave rise to
cation−anion interaction via the formation of
[FeC⋮NMn] bridges. Depending on the
nature of the Schiff base and regardless of the stoichiometry used,
either the trimeric anion
[{Mn(BS)}2{Fe(CN)6}]-
(BS = 3-MeOsalen, 6; 5-Clsalen, 7; 5-Brsalen,
8; salcy, 10) or the pentameric cation
[{Mn(BS)}4{Fe(CN)6}]+
(BS
= saltmen, 9) is formed, which has been assembled by the
K+ cation or the ClO4- anion,
respectively. The X-ray
analysis of 6 revealed a two-dimensional network layer
structure. The magnetic measurements showed its
metamagnetic behavior, where the ferromagnetic interaction operates
within each layer and the antiferromagnetic
interaction operates between the layers. The Neel temperature,
TN, is 9.2 K, and the critical field at 2 K is
300 Oe.
The temperature dependent magnetic susceptibilities of
7 and 8 are in agreement with a discrete,
symmetrical, trinuclear
structure Mn(III)Fe(III)Mn(III)
(SMn = 2, SFe = 1/2,
SMn = 2) with a ferromagnetic spin coupling
between the
Mn(III) and Fe(III) ions, a small antiferromagnetic
intertrimer interaction, and a large zero-field splitting of
the
Mn(III) ion. The structure of 9 consists of a
two-dimensional layer containing as the repeating unit a cyclic
dodecamer.
The layers stack along the c axis, and
ClO4- anions are positioned between the
layers. The magnetic measurements
showed this compound's ferromagnetic behavior. There are, in
fact, two kinds of intralayer magnetic interactions,
the interaction between the Fe(III) and Mn(III) ions bridged
by CN groups and the interaction between two Mn(III)
ions in the dimer [Mn2(saltmen)2], both
being ferromagnetic. The interlayer magnetic interaction is
ferromagnetic.
All of the interactions render to 9 an overall
ferromagnetic behavior.