Crystal structure of [{[Ni(C10H24N4)][Ni(CN)4]}·2H2O]n, a one-dimensional coordination polymer formed from the [Ni(cyclam)]2+ cation and the [Ni(CN)4]2– anion

Abstract

The asymmetric unit of the title compound, catena-poly[[[(1,4,8,11-tetraazacyclotetradecane-κ4N1,N4,N8,N11)nickel(II)]-μ-cyanido-κ2N:C-[bis(cyanido-κC)nickel(II)]-μ-cyanido-κ2C:N] dihydrate], {[Ni2(CN)4(C10H24N4)]·2H2O]n or [{[Ni(C10H24N4)][Ni(CN)4]}·2H2O]n, consists of a pair of crystallographically non-equivalent macrocyclic cations and anions. The nickel(II) ions (all with site symmetry \overline{1}) are coordinated by the four secondary N atoms of the macrocyclic ligands, which adopt the most energetically stable trans-III conformation, and the mutually trans N atoms of the tetracyanonickelate anion in a slightly tetragonally distorted NiN6 octahedral coordination geometry. The [Ni(CN)4)]2– anion exhibits a bridging function, resulting in the formation of parallel polymeric chains running along the [1\overline{1}0] direction. The water molecules of crystallization play a pivotal role in the three-dimensional supramolecular organization of the crystal. Acting as acceptors, they form N—H...Ow (w = water) hydrogen bonds with the secondary amino groups of the macrocycles, forming layers oriented parallel to the (001) plane. At the same time, as donors, they interact with the non-coordinated cyano groups of the anion via Ow—H...Nc (c = cyanide) hydrogen bonds, giving two-dimensional layers oriented parallel to the (100) plane and thus generating a three-dimensional network.

Keywords

• crystal structure
• coordination polymer
• cyclam
• nickel
• hydrogen bonds