Synthesis, Crystal Structures, and Magnetic Properties
of Cyanide-Bridged W<sup>V</sup>Mn<sup>III</sup> Anionic Coordination
Polymers Containing Divalent Cationic Moieties: Slow Magnetic Relaxations
and Spin Crossover Phenomenon
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Abstract
Two trimetallic coordination
complexes were prepared by self-assembly
of [W(CN)<sub>8</sub>]<sup>3–</sup> and the Mn(III) Schiff
base followed by the addition of a Zn(II) or Fe(II) cationic unit.
The octacyanotungstate connects neighboring Mn(III) centers to form
a one-dimensional chain. The anionic chain requires cationic units
of Zn(II) or Fe(II) to maintain charge balance in the structure. The
Zn-containing complex shows ferrimagnetic behavior originating from
the antiparallel alignment of W(V) and Mn(III) spins within the chain,
which leads to slow magnetic relaxation at low temperatures. For the
Fe(II)-containing compound, Fe(II) moieties are integrated into the
ferrimagnetic chains, altering their spin states depending on the
temperature. It appears that the coexistence of high- and low-spin
states in the low temperature regime is responsible for the slower
and faster relaxations of the magnetization
