hide
Free keywords:
-
Abstract:
The reaction of Bi, BiCl3, and CuCl in the ionic liquid [BMIm]Cl4AlCl(3) (BMIm=1-n-butyl-3-methylimidazolium) at 180 degrees C yielded air-sensitive shiny black crystals of (CuBi8)[AlCl4](2)[Al2Cl7] and (CuBi8)[AlCl4](3). For both compounds X-ray diffraction on single crystals revealed monoclinic structures that contain the intermetalloid cluster (CuBi8)(3+). It is the first pure bismuth cluster with a 3d metal and the first with a metal that does not form binary intermetallics with bismuth under ambient pressure. The cluster can be interpreted either as a copper(I) cation, eta(4)-coordinated by a square-antiprismatic Bi-8(2+) polycation (Bi-Cu 267 pm), or as a nine-atomic intermetalloid nido-cluster with 22 skeletal electrons and the C-4v symmetry. One of the chloride ions of a tetrahedral [AlCl4](-) group coordinates the copper atom (Cu-Cl 228 pm) and thereby completes its 18 electron count. DFT-based calculations, followed by real-space bonding analysis, revealed a multicenter bonding situation between copper and bismuth atoms with about seven shared electrons.
