A 2D Hofmann-type cyano-bridged coordination polymer Mn(H₂O)₂[Ni(CN)₄]•4H₂O (1) has been synthesized by self-assembly based on [Ni(CN)₄]^2－ and Mn^2＋ as building blocks. The single crystals were obtained successfully by slow solution diffusion method and the crystal structure has been solved. 1 belongs to orthorhombic system, space group Cmcm, cell parameters: a＝0.73080(5) nm, b＝1.21372(8) nm, c＝1.40875(9) nm, α＝β＝γ＝90°. Ni and Mn centers are connected by cyano-bridges alternately, resulting in 2D undulate sheets. A series of powder samples M(H₂O)₂[Ni(CN)₄]•xH₂O (M＝Mn, Fe, Co, Ni, Cd) have been synthesized by quick mixing method, which are isostructural with 1 confirmed by PXRD patterns. VT-PXRD and TG analysis indicate that these coordination polymers are of high stability. A 3D porous coordination polymer has been constructed with dehydrated sample of Mn(H₂O)₂[Ni(CN)₄]•xH₂O and pillared ligand pyrazine, which exhibits gas storage property.

Key words: Hofmann-type, coordination polymer, [Ni(CN)₄]^2－, crystal structure, adsorption