POLYCYCLES AND CAGES IN MOLECULAR ALUMO-POLYSILOXANES—(Ph₂SiO)₈[Al(O)OH]₄ Used as a Supramolecular Target and “Auto-Condensation” Within the Molecule

Two new metal derivates of the alumosiloxane [Ph2SiO]8[AlO(OH)]4: [Ph2SiO]8[AlO2(Na)]4·5(THF) and [Ph2SiO]8[AlO(OH)]2[AlO2]2[Zn(OH)]2·2(OEt2)

“…With diamines of the general formula H 2 N-(CH 2 ) n -NH 2 intra-and intermolecular adducts can be formed opening a whole family of supra-molecular chemistry [9,10]. Metal compounds like LiNH 2 , LiPh or dicyclopentadienylegermanium or -tin can replace up to four acidic hydrogen atoms in [Ph 2 SiO] 8 [11,12].…”

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

“…3. Weaker bases like pyridine (proton affinity: 928 kJ/mol) seem to have less effect on the condensation within (Ph 2 SiO) 8 [AlO(OH)] 4 and instead, the adduct (Ph 2 SiO) 8 [Al-O(OH)] 4 Á4py is isolated without any noticeable side reaction (compare [16]); in the reaction with a mixture of pyridine and hexamethyldisilazane nevertheless in a minor fraction a condensation reaction is observed leading to the product (Ph 2 SiO) 8 [AlO 1.5 ] 4 Á2py [3]. The reaction of (Ph 2 SiO) 8 [AlO(OH)] 4 with H 2 AlClÁnmp (1) leads directly to the condensation product (Ph 2 SiO) 8 [AlO 1.5 ] 4 Á2nmp (2): here, the evolution of hydrogen and the disappearance of the chloro function indicate another pathway to the formally condensed product.…”

“…Furthermore, mechanistical questions can be addressed to more easily than in a solid. We have been interested in the hydrolysis of this alumosiloxane and have found that for example the compound (Ph 2 SiO) 12 [AlO(OH)] 6 [Al(OH) 3 ]Á3OEt 2 can be obtained in a crystalline form which contains in the centre of the polycyclic compound an [Al(OH) 6 ] 3À moiety [5]. On the other side, as the molecule (Ph 2 SiO) 8 [AlO(OH)] 4 contains several OH-groups which are bonded to the aluminum atoms, also condensation reactions may be envisaged.…”

“…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.…”

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

“…In Abhängigkeit der Basenstärke und Sterik der verwendeten organischen Base können zwei bis vier Moleküle über Wasserstoffbrückenbindungen an die vier Hydroxylgruppen des Alumopolysiloxans koordinieren. Zweizähnige Basen wie beispielsweise die Alkyldiamine können je nach Kettenlänge der Liganden sowohl intra‐ als auch intermolekular mit (Ph 2 SiO) 8 [AlO(OH)] 4 ( 1 ) wechselwirken, so dass entweder molekulare oder polymere Addukte entstehen 13,17…”