Syntheses, Structures, and Magnetic Properties of Three Manganese(II)-Octacyanotungstate(V) Bimetallic Compounds with Linear Ligands

Three
manganese­(II)-octacyanotungstate­(V) bimetallic compounds, [Mn­(H2O)2(dpe)]3­[W­(CN)8]2­·2dpe­·7H2O (dpe = trans-1,2-di­(4-pyridyl)­ethene) (1), [Mn­(H2O)2(azpy)]3­[W­(CN)8]2­·3azpy­·4H2O (azpy = 4,4′-azopyridine)
(2), and [Mn­(H2O)3(azpy)]2­[Mn­(CH3CN)2­(azpy)]­[W­(CN)8]2­·5azpy­·2H2O
(3) were prepared by in situ or secondary assembly methods.
Compounds 1 and 2 show three-dimensional
(3D) networks through the cross-link of one-dimensional (1D) infinite
3,2-chains or rope-ladder chains with linear ligands (dpe, azpy),
while compound 3 adopts a 1D ribbon-like structure by
the connection of pentanuclear repeating units with azpy linkers.
Magnetic studies reveal that compounds 1–3 show intramolecular antiferromagnetic coupling between Mn­(II)
and W­(V) centers, which produce the typical ferrimagnetic chain behaviors
for compounds 1 and 2 but paramagnetic properties
for compound 3. Notably, field-induced metamagnetic behavior
was detected for compound 2, indicating it undergoes
a transition from the antiferromagnetic ground state to ferrimagnetic
phase above critical dc field.