Cadmium(I) tetrachloroaluminate

Cadmium(I) tetrachloroaluminate is the inorganic compound with the formula Cd2(AlCl4)2, a tetrachloroaluminate of cadmium(I). It was the first compound reported (1961) that contained cadmium in the +1 oxidation state and features a cadmium–cadmium bond.
Preparation and properties.
Cd2(AlCl4)2 was originally prepared by dissolving Cd metal in molten CdCl2 followed by the addition of AlCl3.
Subsequent studies of the Raman vibrational spectrum indicated the presence of a cadmium–cadmium bond, which was confirmed by two separate X-ray diffraction studies of single crystals. The compound can therefore be compared to mercury(I) (mercurous) compounds (such as mercury(I) chloride), which contain . The Cd–Cd bonds are part of ethane-like Cd2Cl6 units sharing vertices with AlCl4 units, with a Cd–Cd bond length reported as 257.6 pm or 256.1pm.
Cd2(AlCl4)2 is diamagnetic. It contains no unpaired electrons and reacts readily with water disproportionating to give Cd metal and Cd2+.