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.

Cadmium(I) tetrachloroaluminate

Names
IUPAC name dicadmium(2+) bis( tetrachoridoaluminate(1−))
Identifiers
CAS Number	103823-00-3 Y
3D model (JSmol)	Interactive image
InChI InChI=1S/2Al.2Cd.8ClH/h;;;;8*1H/q2*+3;2*+1;;;;;;;;/p-8 Key: MVYUNQSYEKWWLE-UHFFFAOYSA-F
SMILES [Cd+][Cd+].Cl[Al-](Cl)(Cl)Cl.Cl[Al-](Cl)(Cl)Cl
Properties
Chemical formula	Cd2[AlCl4]2
Molar mass	562.4123 g/mol
Appearance	white crystal
Melting point	227 ° (decomp)[clarification needed]
Hazards
NIOSH (US health exposure limits):
PEL (Permissible)	[1910.1027] TWA 0.005 mg/m3 (as Cd)[1]
REL (Recommended)	Ca[1]
IDLH (Immediate danger)	Ca [9 mg/m3 (as Cd)][1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Preparation and properties

Cd₂[AlCl₄]₂ was originally prepared by dissolving Cd metal in molten CdCl₂ followed by the addition of AlCl₃.^[2]

CdCl₂ + Cd → Cd₂Cl₂

Cd₂Cl₂ + 2 AlCl₃ → Cd₂[AlCl₄]₂

Subsequent studies of the Raman vibrational spectrum indicated the presence of a cadmium–cadmium bond,^[3] which was confirmed by two separate X-ray diffraction studies of single crystals.^[4][5] The compound can therefore be compared to mercury(I) (mercurous) compounds (such as mercury(I) chloride), which contain Hg2+2. The Cd−Cd single bonds are part of ethane-like Cd₂Cl₆ units sharing vertices with AlCl₄ units, with a Cd−Cd bond length reported as 257.6 pm^[4] or 256.1pm.^[5]

Cd₂[AlCl₄]₂ is diamagnetic. It contains no unpaired electrons and reacts readily with water disproportionating to give Cd metal and Cd²⁺.

Thermal ellipsoid plot of a Cd₂Cl₆ unit