Synthesis and characterization of T[Ni(CN)4]·2pyz with T=Fe, Ni; pyz=pyrazine: Formation of T–pyz–Ni bridges

The formation of T–pyz–Ni bridges (pyz=pyrazine) in the T[Ni(CN)4]·2pyz series is known for T=Mn, Zn, Cd and Co but not with T=Fe, Ni. In this contribution the existence of such bridges also for T=Fe, Ni is discussed. The obtained pillared solids, T[Ni(CN)4]·2pyz, were characterized from XRD, TG, UV–Vis, IR, Raman, Mössbauer and magnetic data. Their crystal structures were refined in the orthorhombic Pmna space group from XRD powder patterns. The structural behavior of these solids on cooling down to 77 K was also studied. In the 180–200 K temperature range the occurrence of a structural transition to a monoclinic structure (P21/c space group) was observed. No temperature induced spin transition was observed for Fe[Ni(CN)4]·2pyz. The iron (II) was found to be in high spin electronic state and this configuration is preserved on cooling down to 2 K. The magnetic data indicate the occurrence of a low temperature weak anti-ferromagnetic interaction between T metal centers within the T[Ni(CN)4] layer. In the paramagnetic region for Ni[Ni(CN)4]·2pyz, a reversible temperature induced spin transition for the inner Ni atom was detected.

Rippled sheets structure for the pillared solids T[Ni(CN)4]·2pyz. The pyrazine molecule is found forming T–pyz–Ni bridges between neighboring layers.Figure optionsDownload as PowerPoint slideHighlights
► Pillared 2D solids.
► Inorganic–organic solids.
► Assembling of molecular blocks.
► From 1D and 2D building blocks to 3D solids.