Controlled hydrolysis of [Ti(O-2,4,6-Br 3C 6H 2) 2(O- iPr) 2] 2: Synthesis, structural characterization and studies on bulk polymerization of cyclic esters and lactide

• Published in: Inorganic chemistry communications 2011-11, Vol.14 (11), p.1777-1782
• Main Authors: Gowda, Ravikumar R., Chakraborty, Debashis, Ramkumar, Venkatachalam
• Format: Article
• Language: English
• Subjects: L-Lactide; rac-Lactide; Ti-oxo cluster; δ-Valerolactone; ε-Caprolactone
• ISSN: 1387-7003; 1879-0259
• DOI: 10.1016/j.inoche.2011.08.008

Controlled hydrolysis of [Ti(O-2,4,6-Br 3C 6H 2) 2(O- iPr) 2] 2 with water results in the formation of the Ti-oxo cluster Ti 8O 24C 66H 58Br 24 ( 1). This compound has a very interesting cage structure. The crystal structure consists of centrosymmetric neutral octamers containing two planar Ti 4 layers, interlinked by four linear oxo-bridges. The four independent Ti atoms have three different coordination environments. The four unique Ti centers are rigidly coplanar, giving a unique configuration. The bridging oxygen atoms linking the two inversion-center related Ti atoms give a novel assemblage reminiscent of an inverse “cake-plate”. Compound 1 is an active initiator for the polymerization of cyclic ester monomers and lactide resulting in polymers with moderate number average molecular weights ( M n) and close to narrow molecular weight distribution (MWD). Structure of a titanium cluster Ti 8O 24C 66H 58Br 24 along with polymerization studies described. [Display omitted] ► Ti 8O 24C 66H 58Br 24 has a cage structure. ► Ti centers are rigidly coplanar. ► Active initiator for the polymerization of cyclic esters and lactide.