Synthesis and study of the structure of cage-like metallosiloxanes with pair combinations of 3d transition and alkaline earth metals

The selective replacement of Na ions in cage-like (Cu,Na) organosiloxanes in reactions with divalent metal halides was studied. The sandwich-like isomer [PhSiO2]6Cu4Na4[PhSiO2]6 forms the corresponding bimetallic complexes [PhSiO2]6Cu4M2[PhSiO2]6 (M = Cu, Zn, Mg, Sr, Ba) retaining a sandwich-like structure (in 60–90% yields) regardless of the metal ion size in MCl2. Under similar conditions, the reactions of the globular isomers [RSiO2]12Cu4Na4 (R = Ph, Me, Vin) with CuX2 (X = Cl or Br) afforded insoluble polymer products. The reaction in dioxane or THF in the presence of DMSO gave the crystalline globular-type metal complexes [RSiO2]12Cu4[CuX]4, in which Na ions are replaced by CuX groups. The compositions and structures of the synthesized metal complexes were studied by X-ray diffraction, elemental analysis, and destructive silylation combined with gel permeation chromatography and 1H NMR spectroscopy.