cyclo-Stannasiloxanes Containing both Oxygen Atoms and Methylene Moieties within the Ring and Formation of Related Organotin Oxo Clusters

摘要

The syntheses of the 8-membered stannasiloxanes cyclo-[RR'SnOSi(Me-2)CH2](2), (5, R = R' = Ph; 6, R = R' = t-Bu; 7, R = Me2N(CH2)(3), R' = Ph) is reported. These react with organoelement oxides, providing the novel metallasiloxanes cyclo-[Me2SiCH2(RROSnOMO] (8, R = R' = Ph, M = t-Bu2Sn; 9, R = R' = t-Bu, M = t-Bu2Sn; 10, R = Me2N(CH2)(3), R' = Ph, M = t-Bu2Sn; 11, R = Me2N(CH2)(3), R' = Ph, M = Ph2Ge). Among these, compound 11 is the first example of such species being composed of four different group 14 elements in the 6-membered-ring skeleton. On contact with moist air compound 8 surprisingly undergoes Sn-Ph bond cleavage, giving the diorganotinoxo cluster [PhSn(CH2Me2SiO)Sn(mu(3)-O)(mu-OH)t-Bu-2](2) (12), which shows a ladder-type structure. The latter reacts with 2 molar equiv of t-Bu2SnO, affording the Sn-6-diorganotin oxo cluster [t-Bu-2(mu-OH)Sn(mu(3)-O)SnPh(CH2Me2SiO)Sn-t-Bu-2(mu(3)-O)](2) (13). The compounds have been characterized by NMR spectroscopy, electrospray mass spectrometry, and in the case of compounds 5-7, 12, and 13 also by single-crystal X-ray diffraction analysis.