Functionalization of MCM-41 and SBA-1 with titanium(iv) (silyl)amides

Abstract

The surface organometallic chemistry (SOMC) of Ti(NMe₂)₄ and Ti(NMe₂)₃[N(SiHMe₂)₂] on periodic mesoporous silica (PMS) materials MCM-41 and SBA-1 was examined. While the smaller titanium amide gave the highest titanium loadings (e.g., Ti(NMe₂)₄@MCM-41: 12.1 wt%), a ligand-promoted silylation reaction competes effectively with Ti–N bond protonolysis for the tailor-made complex Ti(NMe₂)₃[N(SiHMe₂)₂]. Pre-functionalized materials SiMePh₂@PMS and [Mg{N(SiHMe₂)₂}₂]₂@SBA-1 were employed for further control of the titanium load. Amido ligand exchange with R-(+)-1,1′-bi-2-naphthol (R-H₂BINOL) was observed only on channel-like material Ti(NMe₂)₄@MCM-41, whereas size-selective grafting seems to be prominent on cage-like Ti(NMe₂)₄@SBA-1. All materials were characterized by DRIFT spectroscopy, nitrogen physisorption and elemental analysis.