Synthesis and Structures of Salen-Supported Borates Containing Siloxides

The ligand N,N‘ ‘-bis(2-hydroxybenzylidene)diethylenetriamine (SalenN3H3) was used to prepare the compound SalenN3H{B(OMe2)}2 (1) which could, in turn, be used in the formation of SalenN3H{B(OSiPh3)2}2 (2). For comparative purposes, the compounds Salben{B(OSiPh3)2}2 (3) (Salben = N,N‘-butylenebis(2-hydroxybenzylideneamine), Salen(tBu){B(OSiPh3)2}2 (4) (Salen(tBu) = N,N‘-ethylenebis(3,5-di-tert-butyl-2-hydroxybenzylideneamine) and Salben(tBu){B(OSiPh3)2}2 (5) (Salben(tBu) = N,N‘-butylenebis(3,5-di-tert-butyl-2-hydroxybenzylideneamine) were prepared. In reactions where the siloxide is (HO)2SiPh2, unique dimeric siloxide-bridged compounds result, [Salpten(tBu){B(O2SiPh2}]2 (6) and [SalenN3H{B(O2SiPh2)}]2 (7). Compound 6 possesses a zeolite-like cavity having a volume of 157 Å3. All of the compounds were characterized by physical (mp, analyses) and spectroscopic techniques (1H and 11B NMR, IR) and, in the case of 1, 3, 4, and 6, by X-ray crystallography.