Tin silicate species have shown good catalytic activity in various oxidation reactions. In an attempt to mimic surface tin species, several tin containing silsesquioxanes have been synthesized. Incompletely condensed silsesquioxanes (
c-C
5H
9)
7Si
7O
9(OH)
3 and (
c-C
5H
9)
7Si
7O
9(OSiMe
3)(OH)
2 were reacted with common tin-precursors, which afforded several silsesquioxane ligated tin compounds. Divalent stannasilsesquioxanes form dimers of the type [(
c-C
5H
9)
7Si
7O
11(OX)Sn]
2
(X = H, SiMe
3) with three-coordinated tin centers. The three-coordinated tin(
II) are hydrolytically unstable whereas the octahedrally surrounded tetravalent stannasilsesquioxanes [(
c-C
5H
9)
7Si
7O
11(OX)]Sn(acac)
2
(X = H, OSiMe
3) are hydrolytically robust. An unprecedented anionic trimeric cluster, {[(
c-C
5H
9)
7Si
7O
12Sn]
3(μ
2-OH)
3(μ
3-OH)}
−{HNEt
3}
+, stabilized by bridging hydroxyl groups was formed when the product formed upon reacting (
c-C
5H
9)
7Si
7O
9(OH)
3 with SnCl
4 was slowly hydrolyzed. The stannasilsesquioxanes showed no catalytic activity in oxidation reactions.
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