New Polyhedral Zinc Siloxanes: Synthesis and X-ray Crystal Structures of Zn8Me7(dioxane)2(O3SiR)3 and [Zn7Me2(THF)5(O3SiR)4] [R = (2,6-i-Pr2C6H3)N(SiMe3)]

In continuation of our previous work on the synthesis of zinc siloxanes to understand the influence of stoichiometry in the assembly of polyhedral zinc siloxanes, we have carried out two different reactions between RSi(OH) 3 [R = (2,6- i -Pr 2 C 6 H 3 )N(SiMe 3 )] and ZnMe 2 in molar ratios of 1:3 and 1:1.75. In these reactions, we have isolated an octanuclear Zn 8 Me 7 (dioxane) 2 (O 3 SiR) 3 ( 5 ) and a heptanuclear zinc siloxane [Zn 7 Me 2 (THF) 5 (O 3 SiR) 4 ] ( 6 ), respectively. Compound 5 is a complex cage structure and can be understood as being a derivative of a drum-shaped species containing a Zn 7 Si 3 O 9 core. In contrast, 6 consists of a Zn 4 Si 4 O 12 unit with zinc and silicon atoms occupying alternate corners of the cube; three contiguous faces of this cube are capped by zinc atoms, leaving the other three faces open.