Coordination polymers with [Au(CN)4]- building blocks: a 1-d chain of molecular NiII 2AuIII 2 squares

A new coordination polymer utilizing the neglected cyanoaurate anion [Au(CN)4]- building block is reported. Reaction of a Ni(II) salt, diethylenediamine (dien) and K[Au(CN)4] yields Ni(dien)[Au(CN)4]2, which consists of a unique bimetallic Ni(II)2/Au(III)2 supramolecular square through cis N(cyano) bridging of the [Au(CN)4]- building block to [Ni(dien)]2+ cations. These squares further aggregate into a 1-D chain via Au-N(cyano) interactions; no Au(III)-Au(III) interactions are observed. Within the square, the magnetic coupling between the Ni(II) centres is very weak, indicating that the [Au(CN)4]- unit is a poor mediator of magnetic exchange in this system.