Bis{[diphenyl(piperidinomethyl)silyl]methyl}cadmium and ‐magnesium

The homoleptic and monomeric metal alkyls bis{[di­phenyl(piperidino­methyl)­silyl]­methyl}cadmium, [Cd(C₁₉H₂₄­NSi)₂] or [Cd{CH₂SiPh₂(CH₂NC₅H₁₀)}₂], (I), and bis{[di­phenyl­(piperidino­methyl)­silyl]­methyl}magnesium, [Mg(C₁₉H₂₄NSi)₂] or [Mg{CH₂SiPh₂(CH₂NC₅H₁₀)}₂], (II), (CH₂NC₅H₁₀ is piperidino­methyl) are isostructural, and the mol­ecules exhibit crystallographically imposed C₂ symmetry. The metal centres are located on special positions and, for each structure, half of the mol­ecule is located in the asymmetric unit. The metal centres are intramolecularly coordinated and stabilized by two piperidino­methyl groups (side‐arm donation). The Si—C and M—C bonds (M is Cd or Mg) are shortened compared with the corresponding non‐metallated compounds, indicating stabilization by the diffuse polarizable Si centres (α effect). The C—M—C angle is 140.53 (12)° in (I) and 123.39 (11)° in (II).