The solid state structures of the high and low temperature phases of dimethylcadmium.

The solid state structure of dimethylcadmium, a classic organometallic compound with a long history, has remained elusive for almost a century. X-ray crystallography and density functional theory reveal similar phase behaviour as in dimethylzinc. The high temperature tetragonal phase, α-Me2Cd, exhibits two-dimensional disorder, while the low temperature monoclinic phase, ß-Me2Cd, is ordered. Both phases contain linearly coordinated cadmium atoms. While the methyl groups are staggered in the α-phase, they are eclipsed in the ß-phase.