Copper/sodium-directed hydrolytic condensation of methyltriethoxysilane: Self-assembly of polyhedral Cu/Na-methylsiloxane. Synthesis and properties of new stereoregular macrocyclosiloxane

A hydrolytic condensation of methyltriethoxysilane was performed in the presence of sodium and copper ions. A crystalline copper/sodium-methylsiloxane of a general formula {Na4[(MeSi(O)O)12Cu4]} · 6(n-BuOH) (1a) was obtained as the only product in a high yield. X-ray analysis of a single crystal obtained after recrystallization of 1a by slow diffusion of methanol vapours into its ethanol solution was characterised as {Na4[(MeSi(O)O)12Cu4]} · 4(MeOH) · 4(EtOH) (1b). In the crystal molecules are assembled into zig-zag chains by O–H⋯O bonds. Removal of metal ions by a reaction of 1a or 1b with Me3SiCl gave a new siloxane macrocycle tris-cis-tris-trans-dodecamethyldodecatrimethylsiloxycyclododecasiloxane, [MeSi(O)OSiMe3]12 (2), in a high yield.