The reaction of benzylpotassium with anhydrous calcium diiodide and 2,2,6,6-tetramethylpiperidine (Tmp-H) in a molar ratio of 2:1:2 in toluene in the presence of tetramethylethylenediamine yields colorless [(tmeda)Ca(Tmp)(2)] (1) with an average Ca-N-amide bond length of 227.5 pm. The metathesis reaction of Cal(2) with 2 equiv of KN(Ph)iPr in tetrahydrofuran (THF) gives [(thf)(3)Ca{N(Ph)iPr}(2)] (2) with a Ca-N distance of 234.9 pm. An excess of KN(Ph)R (R = Me, iPr) in the metathesis reaction with Cal(2) leads to the formation of calciates of the type K2Ca[N(Ph)R)4 regardless of the applied stoichiometry. The THF-free compound [K2Ca{N(Ph)Me}(4)](infinity) (3) forms a three-dimensional net structure, whereas the amides with the larger isopropyl group lead to the formation of molecular [{(thf)(2)K(mu-N(Ph)iPr)(2)}(2)Ca] (4). In both of these heterobimetallic compounds, the potassium atoms bind to the pi systems of the phenyl groups. Heterobimetallic calciates [K2Ca(NPh2)(4)(thf)(3)](infinity) (5) with R = Ph crystallize with a chain structure. In all of these calciates, the tetra-coordinate calcium atoms are in distorted tetrahedral environments.