Synthese und Struktur von achtgliedrigen Titan- und Zirkon-haltigen Siloxanringen / Synthesis and Structure of Eight-Membered Titanium and Zirconium Containing Siloxane Rings

Abstract

Reaction of (tBu)2Si(OH)2 with TiCl4, TiBr4, TiI4, and ZrCl4 affords eight-membered rings 2a-2d. The X-ray structural analysis of 2a, 2b and 2d reveals in 2a and 2b tetrahedral and in 2d octahedral coordination at the transition metal atoms. The octahedral geometry in 2d is due to two additional coordinated solvent molecules. The Ti—O bond lengths in 2a and 2b are short indicating multiple bonding. Compounds 2a-2d are thermodynamically very stable having melting points above 250 °C.