Reactivity of (p-MeOC6H4)2TeO toward t-Bu2Si(OH)2. Synthesis of a 12-Membered Tellurasiloxane Ring, cyclo-[(p-MeOC6H4)2TeOSit-Bu2O]3

Condensation of t-Bu2Si(OH)2 with (p-MeOC6H4)2TeO in a Si/Te ratio of 1:1.2 exclusively produced the 12-membered tellurasiloxane ring cyclo-[(p-MeOC6H4)2TeOSit-Bu2O]3 (1), whose molecular structure was determined by X-ray crystallography. At larger Si/Te ratios, the open-chain tellurasiloxanes HOt-Bu2SiOR2TeOSit-Bu2OH (2, R = p-MeOC6H4) and HOt-Bu2SiOR2TeOSit-Bu2OR2TeOSit-Bu2OH (3, R = p-MeOC6H4) were identified in solution by 29Si and 125Te NMR spectroscopy along with 1 and unreacted t-Bu2Si(OH)2. The analogous reaction of Ph2Si(OH)2 with (p-MeOC6H4)2TeO did not provide tellurasiloxanes, but led to the formation of the known siloxanes rings cyclo-(Ph2SiO)3 and cyclo-(Ph2SiO)4.