The bis(trimethylsilyl)amides and -phosphanides of the heavier alkaline earth metals gain increasing interest due to easy access by metathesis or transmetalation reactions. The structural and solution properties display amazing similarities between these derivatives and similar compounds of early transition metals and the lanthanoids. Of special interest is the pyramidal coordination of the metal atoms in the solvent-free dimeric amides R₂N-M(μ-NR₂)₂M-NR₂ as well as the triply bridged phosphanides with a central moiety of the type R₂P-M(μ-PR₂)₃M. Both these compound classes show a fluxionality which leads to an exchange of terminal and bridging ligands in toluene or benzene solution as can be observed by temperature-dependent D-NMR spectroscopy.