New Organically Templated Copper(I) Sulfites: the Role of Sulfite Anion as Both Soft and Hard Ligand

Two new organically templated layered copper(I) sulfites, namely, {H2pip}{Cu3(CN)3(SO3)} (1) and {H2pip}{NaCu2(SO3)2Br(H2O)}·2H2O (2) (pip = piperazine), have been synthesized by hydrothermal reactions of copper(I) cyanide or copper(I) bromide with NaHSO3 and piperazine. Both compounds exhibit a layered structure. The 2D
layer of {Cu3(CN)3(SO3)}2- in 1 is composed of 1D chains of copper(I) cyanide interconnected by sulfite anions
via both Cu−S and Cu−O bonds, whereas the 2D layer of {NaCu2(SO3)2Br}2- in 2 is formed by 1D chains of
copper(I) bromide and 1D sodium(I) aqua chains that are interconnected by sulfite anions via Na−O, Cu−S, and
Cu−O bonds. Chemical bonding in 1 and 2 has been also investigated by theoretical calculations based on DFT
methods.