STRUCTURAL INFLUENCE OF A SULFINYL GROUP IN 8-MEMBERED RINGS OF DIORGANOSILANES

The new monocyclic diorganosilanes OS(Me(2)C(6)H(2)O)(2)SiR(1)R(2), wh ere R(1) = R(2) = Me (1), R(1) = Me, R(2) = Ph (2), and R(1) = R(2) = Ph (3), were prepared by a condensation reaction of oxythiobis(4,6-dim ethylphenol), OS(Me(2)C(6)H(2)OH)(2) (4), with the appropriate diorgan odichlorosilane in CH2Cl2 solution in the presence of Et(3)N. X-ray cr ystallographic studies showed that the silanes had the eight-membered rings positioned in anti chairlike conformations. This precluded any a dditional coordination at silicon with the sulfinyl group that was pre sent as part of the ring system in each case. For silane 2 with two ty pes of acyclic organo substituents attached to silicon, two isomers fo rmed which differed in the position of these groups, cis or traits, re lative to the ring sulfinyl group. H-1, C-13, and Si-29 solution state NMR spectral data were recorded. Temperature-dependent H-1 NMR data s uggest a rigid ring conformation for 1.