Synthesis, crystal structure and electrospray ionisation mass spectrometry of a novel one-dimensional cyano-bridged Ni(II)–Au(I) polymer

Abstract

Reaction of nickel(II) acetate with tren [tren=tris(2-aminoethyl)amine] and K[Au(CN)₂] produced [Ni(tren)Au(CN)₂][Au(CN)₂] (1), which consists of cis-[Ni(tren)]²⁺ units linked by Au(CN)₂⁻ to form infinite zig-zag chains. The complex obeys the Curie–Weiss law throughout the temperature range 4–300 K, with a Curie constant of 1.10 cm³ K mol⁻¹ and a Weiss temperature, θ, of 0.62 K. The electrospray mass spectrum of 1 in H₂O–CH₃OH shows peaks that can be described by the general formulae {[Ni(tren)]_n[Au(CN)₂]_2n−1}⁺ (n=1–4) and {[Ni(tren)]_n[Au(CN)₂]_2n−2}²⁺ (n=2–9). Based on the crystal structure of the polymer, these ions are best described as composed of an oligomeric cation that may be associated with one or more Au(CN)₂⁻ counter ions.