New Insight into Titanium-Magnesium Ziegler-Natta Catalysts Using Photoluminescence Spectroscopy.

This paper presents the results of study of titanium-magnesium catalysts often used in polymerization processes, by photoluminescence spectroscopy (PL) in combination with diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The interaction of dibutyl phthalate (DBP) with MgCl was studied at DBP/Mg = 0-1 (mol/mol). The luminescence spectra with excitation at 278 nm and the excitation spectra for main emission bands were recorded.

Substitution of fluorine in M[CFBF] with organolithium compounds: distinctions between O- and N-nucleophiles.

Borates M[CFBF] (M = K, Li, BuN) react with organolithium compounds, RLi (R = Me, Bu, Ph), in 1,2-dimethoxyethane or diglyme to give M[4-RCFBF] and M[2-RCFBF]. When R is Me or Bu, the nucleophilic substitution of the fluorine atom at the position to boron is the predominant route. When R = Ph, the ratio M[4-RCFBF]/M[2-RCFBF] is ca.

Weakly nucleophilic potassium aryltrifluoroborates in palladium-catalyzed Suzuki-Miyaura reactions: relative reactivity of K[4-RC6F4BF3] and the role of silver-assistance in acceleration of transmetallation.

Small differences in the reactivity of weakly nucleophilic potassium aryltrifluoroborates are revealed in the silver-assisted Pd-catalyzed cross-coupling of K[4-RC6F4BF3] (R = H, Bu, MeO, EtO, PrO, iPrO, BuO, t-BuO, CH2=CHCH2O, PhCH2O, PhCH2CH2O, PhO, F, pyrazol-1-yl, pyrrol-1-yl, and indol-1-yl) with ArX (4-BrC6H4CH3, 4-IC6H4F and 3-IC6H4F). An assumed role of silver(I) compounds Ag m Y (Y = O, NO3, SO4, BF4, F) consists in polarization of the Pd-X bond in neutral complex ArPdL n X with the generation of the related transition state or formation of [ArPdL n ][XAg m Y] with a highly electrophilic cation and subsequent transmetallation with the weakly nucleophilic borate. Efficiency of Ag m Y as a polarizing agent decreases in order Ag2O > AgNO3 ≈ Ag2SO4 > Ag[BF4] > AgF.