A new route to incompletely-condensed silsesquioxanes: base-mediated cleavage of polyhedral oligosilsesquioxanes
Abstract
Readily available R8Si8O12 frameworks react selectively with aqueous Et4NOH to afford discrete incompletely-condensed silsesquioxanes: reaction of R8Si8O12 (2a, R = c-C6H11; 2b, R = Bui) with Et4NOH first produces endo-D2-R8Si8O11(OH)2 (3a, R = c-C6H11; 3b, R = Bui), which reacts further with Et4NOH to produce endo-C2-R8Si8O10(OH)4 (5a and 5b) and endo-C3-R7Si7O9(OH)3 (4a, R = c-C6H11; 4b, R = Bui); the reactions of Et4NOH with Me8Si8O12 (2c), (c-C6H11)7(H)Si8O12 (2d) and (c-C6H11)7(OH)Si8O12 (2d) also produce the corresponding trisilanols (i.e. endo-C3-R7Si7O9(OH)3 (4a, R = c-C6H11; 4c, R = Me).