Reiner Willeke

Neutral Mononuclear and Binuclear Hexacoordinate Silicon Complexes withSiO5C Skeletons

Treatment of the silanes (EtO)3Si(CH2)2SCH2C(O)OSiMe3 and (EtO)3Si(CH2)3OSiMe3 with two molar equivalents of 1-hydroxy-2-pyridone in acetonitrile yielded the neutral hexacoordinate silicon complexes bis[μ-(3-thiapentanoato(2−)-C5,O′:C5′,O)]tetrakis[1-oxopyridin-2-olato(1−)]disilicon(IV) (6) and bis[1-oxopyridin-2-olato(1−)][propanolato(2−)-C3,O]silicon(IV) (8), respectively. The compounds 6·2CH3CN and 8 were characterized by solid-state 29Si VACP/MAS NMR spectroscopy, mass spectrometry (FAB MS), and single-crystal X-ray diffraction.

Macrocyclic Siloxanes with Two Exocyclictrans-Silanol and Two Exocyclictrans-Amino Functions − Stereoselective Syntheses and Structures

A simple preparative method for the stereoselective synthesis of ten- and twelve-membered cyclosiloxanes with two exocyclic trans-silanol and two exocyclic trans-amino functions has been developed. Thus, treatment of trimethoxy(morpholinomethyl)silane (5) with two molar equivalents of HOPh2Si−SiPh2OH and HOPh2Si−O−SiPh2OH, respectively, yielded trans-1,6-bis(2-hydroxy-1,1,2,2-tetraphenyldisilan-1-yloxy)-1,6-bis(morpholinomethyl)-3,3,4,4,8,8,9,9-octaphenyl-2,5,7,10-tetraoxa-1,3,4,6,8,9-hexasilacyclodecane (6, 10-membered ring) and trans-2,8-bis(3-hydroxy-1,1,3,3-tetraphenyldisiloxan-1-yloxy)-2,8-bis(morpholinomethyl)-4,4,6, 6,10,10,12,12-octaphenylcyclohexasiloxane (7, 12-membered ring). In contrast, treatment of 5 with two molar equivalents of HOPh2C−CPh2OH afforded (morpholiniomethyl)bis[tetraphenylethane-1,2-diolato(2−)]silicate (3), a zwitterionic spirocyclic λ5Si-silicate. Compounds 3, 6·EtOAc, and 7·PhMe were characterized by elemental analyses (C, H N), solid-state 29Si VACP/MAS NMR studies, solution NMR experiments (1H, 13C, 29Si; CDCl3), and crystal structure analyses.