Bis(pentamethylcyclopentadienyl)magnesium: Unexpected Determination of the Until Now Unknown Molecular Structure of the Crystalline Compound

The structure of bis(pentamethylcyclopentadienyl)magnesium, Mg(C5Me5)2 (1), in the solid state has
been determined by X-ray diffraction. The experimental
results are described and discussed in comparison to
structural properties of the higher alkaline-earth metallocenes MCp*2 (M = Ca, Sr, Ba) as determined in the
gas phase or in the solid state. Structural trends of 1 in
comparison to the isoelectronic species [LiCp*2]-, BeCp*2,
and [AlCp*2]+ are also presented.