Controlled hydrolysis of [Ti(O-2,4,6-Br3C6H2)2(O-iPr)2]2: Synthesis, structural characterization and studies on bulk polymerization of cyclic esters and lactide

Controlled hydrolysis of [Ti(O-2,4,6-Br3C6H2)2(O-iPr)2]2 with water results in the formation of the Ti-oxo cluster Ti8O24C66H58Br24 (1). This compound has a very interesting cage structure. The crystal structure consists of centrosymmetric neutral octamers containing two planar Ti4 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 (Mn) and close to narrow molecular weight distribution (MWD).

Graphical abstractStructure of a titanium cluster Ti8O24C66H58Br24 along with polymerization studies described.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Ti8O24C66H58Br24 has a cage structure. ► Ti centers are rigidly coplanar. ► Active initiator for the polymerization of cyclic esters and lactide.