Transition metal complexes of cubic (T8) oligo-silsesquioxanes

Acid hydrolysis of (EtO)3Si(CH2)3NH2 in the presence of ZnCl2 affords the silsesquioxane derivative [Si8O12((CH2)3NH3)8]8+·2.8[ZnCl4]2−·2.4[Cl]−, which has been characterized by X-ray crystallography. Direct reaction of [Si8O12((CH2)3NH3)8]Cl8 with the chlorides of Co(II), Cu(II) and Cd(II) in methanol gave the compounds [Si8O12((CH2)3NH3)8][MCl4]4 (M = Co, Cu, Cd) but of insufficient crystal quality for X-ray study. The octaimide Si8O12[(CH2)3N(COMe)2]8 was obtained by reacting [Si8O12((CH2)3NH3)8]Cl8 with acetic anhydride and X-ray crystallography shows it to have a slightly flattened structure rather than having the eight pendant groups pointing to the corners of a cube. Metal complexes of the silsesquioxane Si8O12((CH2)3NH2)8 (L) of stoichiometry L(MX2)2 with some salts of Ni, Cu, Zn, and Cd are also reported.