SYNTHESIS AND CRYSTAL-STRUCTURES OF THE CYCLOSILOXYTIN(IV) COMPLEXES [CL2SN(O(SIPH(2)O)(2))(2)]-MU-(LI(THF)(2))(2)] AND [THF2SN((OSIPH(2))(3)O)(2)]CENTER-DOT-TOLUENE

The reaction between the lithium compound [{Ph(2)SiOLi}O-2] and SnCl4 gave the lithium-bridged chlorostannasiloxane [Cl2Sn{O(SiPh(2)O)2}2]-mu-(Li(THF)(2))(2)] (1) containing six-membered stannasiloxane rings. A similar reaction between the corresponding sodium compound [{Ph(2)SiONa}(2)}O] and SnCl4 surprisingly gave the stannasiloxane [THF2Sn{(OSiPh(2))(3)O}(2)] (2), which crystallised as the mono-toluene solvate) containing eight-membered stannasiloxane rings. Compounds 1 and 2 were obtained in reactions in which the relative molar ratio of the lithium or sodium reagents to SnCl4 was varied from 1:1 to 3:1. Compounds 1 and 2 were characterised by H-1 and Si-29 NMR spectroscopy, elemental analysis and single-crystal X-ray diffraction studies.