New types of alumosiloxanes by the reaction of the bicyclic compound Al2[(OPh2Si)2O]3·2 Et2O with water in the presence of donor ligands – A status report

Abstract

The selective synthesis of new types of alumosiloxanes can be achieved by the reaction of the bicyclic compound Al 2 [(OPh 2 Si) 2 O] 3 $2 Et 2 O (3) with water in donor solvents like acetone or THF, leading to the polycyclic THF adduct [(Ph 2 SiO) 8 (AlO 1,5 ) 4 ]$2 THF, (7), and to the polycyclic alumosiloxane [(Ph 2 SiO) 8 (AlO(OH)) 4 ]$4 Me 2 C]O (8), respectively. In the presence of the base triethylamine, the starting compound 3 gives rise to two other condensation products. At medium temperatures (50-60 C) in toluene the dispiro ''alumosilicate'' [(Ph 2 SiO) 2 O] 2 {Al[(Ph 2 SiO) 2 OH$NEt 3 ]} 2 (9) is formed and at higher temperatures under reflux in toluene, the product [(Ph 2 SiO) 2 O]Al[(Ph 2 SiO) 2 OH$NEt 3 ] (10) is generated. The spirocyclic compounds 9 and 10 present the first isolated ''alumosilicates'' with six-membered O(SiO) 2 Al cycles. These new types of alumosiloxanes and ''alumosilicates'' have been characterised by spectroscopic methods as well as by single crystal X-ray analyses.

Acid‐Base Interactions of Pyrazine, Ethyl Acetate, Di‐alcohols, and Lysine with the cyclic Alumosiloxane (Ph2SiO)8[Al(O)OH]4 in View of Mimicking Al2O3(H2O) Surface Reactions

“…[13] The mean Al-O value (in the ring) in 2 is comparable for the one found in the acetone adduct (Ph 2 SiO) 8 [Al(O)OH] 4 • 4(H 3 C) 2 C=O, which has a value of 1.794(4) Å and a proton affinity of 812 kJ•mol -1 . [14,13] The other bond lengths and angles compare well with other base adducts of Ph 2 SiO) 8 [Al(O)OH] 4 : so the mean Al-O(Si) bond length in 2 is 1.696(5) Å and consequently shorter than the Al-O bond lengths in the eight membered ring (compare Figure 3). [6] The NMR spectra taken in benzene are not compatible with a pseudo C 2 symmetry (for example the 29 Si NMR has only one signal) which means that the structure in the crystal is not representative for the molecule in solution.…”

“…[ 13 ] The mean Al–O value (in the ring) in 2 is comparable for the one found in the acetone adduct (Ph 2 SiO) 8 [Al(O)OH] 4 · 4(H 3 C) 2 C=O, which has a value of 1.794(4) Å and a proton affinity of 812 kJ · mol –1 . [ 14,13 ]…”

Aluminum‐Doped Hafnium Oxynitride: Effect of Cation Doping on Oxygen‐Reduction‐Reaction Activity in Acid Media

“…To Al 2 [O‐SiPh 2 ‐O‐ SiPh 2 ‐O] 2 ·2 OEt 2 10 (0.513 g, 0.356 mmol) in toluene (10 mL), water (2 drops) was added, which led to clouding. The reaction mixture was stirred for some hours and heated until the solution became clear.…”

“…The bicyclic compound (O‐SiPh 2 ‐O‐SiPh 2 ‐O) 3 Al 2 , which can be obtained as a diethyl etherate adduct (O‐SiPh 2 ‐O‐SiPh 2 ‐O) 3 Al 2 ·2Et 2 O, when smoothly hydrolyzed in donor solvents (THF, triethylamine/toluene) either converts to the condensation product [(Ph 2 SiO) 8 (AlO 1,5 ) 4 ]·2THF or to the spiro compounds [(Ph 2 SiO) 2 O] 2 {Al[(Ph 2 SiO) 2 OH·NEt 3 ]} 2 and [(Ph 2 SiO) 2 O]Al[(Ph 2 SiO) 2 OH·NEt 3 ] 10. Using no donor in the reaction mixture and adding a drop of water to the toluene solution of (O‐SiPh 2 ‐O‐SiPh 2 ‐O) 3 Al 2 ·2Et 2 O gives rise to a new product 2 (Equation (1)).…”

Reaktionen des Alumopolysiloxans (Ph2SiO)8[AlO(OH)]4 mit 4,4′‐Bipyridin und Azobipyridinen

“…Die längstenAl–O‐Bindungsabstände findet man erwartungsgemäß am Sauerstoffatom O(3), da hier aufgrund der im Vergleich zu Stickstoff schwächeren Sauerstoffbase ein relativ geringer Protonenabzug stattfindet (vgl. Abbildung 6) 10,16,26,27. Die übrigen Al–O‐Bindungslängen betragen im Mittel 1.779(9) Å und liegen damit ein wenig über den Al–O‐Bindungslängen, welche mit dem Liganden Pyridin beobachtet wurden und die einen Al–O‐Bindungsabstand von 1.768(2) Å aufweisen 11.…”