Giant Metal−Cyanide Coordination Clusters: Tetracapped Edge-Bridged Cubic Cr12Ni12(CN)48 and Double Face-Centered Cubic Cr14Ni13(CN)48 Species

Abstract
The crystal structures of two new metal−cyanide clusters with record high nuclearities are reported. A direct assembly reaction involving [(Me3tacn)Cr(CN)3] (Me3tacn = N,N,N-trimethyl-1,4,7-triazacyclononane), NiI2, and KCN in aqueous solution affords [(Me3tacn)12Cr12Ni12(CN)48]12+. The structure of this 24-metal cluster features a cube of eight CrIII centers linked along the edges by 12 trans-coordinated [Ni(CN)4]2- units, and capped on four faces by [(Me3tacn)Cr]3+ moieties. Its metal−cyanide cage encloses a 900 Å3 cavity that is accessible through the two noncapped cube faces. A still larger cluster, [(Me3tacn)14Cr14Ni13(CN)48]20+, was obtained from a related reaction excluding the addition of KCN. This 27-metal species possesses a highly anisotropic geometry in which two face-centered cubic units are fused through a common NiII vertex.