Modulated one-dimensional structure of [Cd(NH3)3Ni(CN)4]

Abstract

The crystal structure of [Cd(NH3)3Ni(CN)4] has been solved and refined as an incommensurate structure in four-dimensional superspace. The Xcalibur point-detector diffractometer was used for data collection up to the third-order satellites. The structure was refined from 3496 observed reflections to a final R value of 0.0371. The modulation strongly affects all the atoms of the structure. The dominating feature of the modulation is the incommensurate alternation between octahedrally and tetrahedrally coordinated Cd atoms in the electroneutral chains [—Cd(NH3) n —NC—Ni(CN)2—CN—]∞ (n alternates between 2 and 4). The chain is propagated along the a axis, in which the [Cd(NH3) n ]2+ cations are linked by square [Ni(CN)4]2− anions. The atomic positional modulations, having mainly a transversal character in the c-direction, exhibit a switching character that can be described by the crenel and sawtooth functions. The effectively pentagonal coordinated cadmium positions were detected in the intermediate regions.