An Al₄(OH)₄ Eight‐Membered Ring in a Molecular Aluminopolysiloxane and Its Behavior with Bases

Abstract

12] EHMO calculations were carried out using standard programs and parameters a)

Syntheses and Structures of Acetyl‐Acetonato‐Alumo‐Diphenylsilanolates with Magnesium(II), Iron(II), Iron(III), Cobalt(II), and Nickel(II)

“…The acetyl-acetonate hydrates of Mg, Fe, Co, and Ni are first dissolved in diethyl ether and then slowly added to a solu- (1) (M = Mg, Fe, Co, Ni) The solutions become colored when the iron, cobalt, and nickel salts are used. The hydroxides described in the equation cannot be isolated, but seem to coordinate to the original alumosiloxane, as we have found by analyzing the side-products of the reaction with Ni(acac) 2 (H 2 O) 2 (see Experimental Section).…”

“…Curiously, the oxygen bridge of OH between the two aluminum atoms is maintained like in the starting material [O-Ph 2 Si-O-SiPh 2 -O] 4 Al 4 (OH) 4 . [1] …”

“…The tetrameric alumosiloxane [1] [O-Ph 2 Si-O-SiPh 2 -O] 4 Al 4 -(OH) 4 , which we first described in 1997, can be considered as a molecular counterpart of alumosilicates, [2] which have found a wide range of applications. [3][4][5][6] In contrast to the naturally occurring zeolites, in which each AlO 4 tetrahedron is separated by SiO 4 tetrahedra, in [O-Ph 2 Si-O-SiPh 2 -O] 4 Al 4 (OH) 4 , the four AlO 4 tetrahedra are connected through oxygen corners, thus hurting the Loewenstein rule.…”

“…[3][4][5][6] In contrast to the naturally occurring zeolites, in which each AlO 4 tetrahedron is separated by SiO 4 tetrahedra, in [O-Ph 2 Si-O-SiPh 2 -O] 4 Al 4 (OH) 4 , the four AlO 4 tetrahedra are connected through oxygen corners, thus hurting the Loewenstein rule. [7] Similarly to the solid alumosilicates the highly acidic protons in the molecular alumooligosiloxane may be displaced by cations like Li + , Na + ,Ge 2+ , Sn 2+ , Pb 2+ (see literature [8][9][10][11] ), but until now only one example with a transition metal (Zn 2+ ) could be obtained, characterized, and isolated. [12] In view of the potential use of these molecular transition metal alumosilicates as templates to study reactions on special sites of zeolites, especially in the field of catalysis, [13,14] we have looked for new synthetic routes to obtain such compounds.…”

Condensation reaction through base assistance within (Ph2SiO)8[AlO(OH)]4

“…The polycyclic alumosiloxane (Ph 2 SiO) 8 [AlO(OH)] 4 , which may be obtained by treatment of diphenylsilanediol, Ph 2 Si(OH) 2 , with tert-butoxyalane, [H 2 AlO t Bu] 2 [1], is a representative of a molecular alumosilicate with hydrogen atoms in the place of metallic elements [2][3][4]. Molecular alumosilicates are of general interest because one can mimic reactions of solid alumosilicates, like ion exchange reactions, in an organic solvent.…”