Syntheses and Structures of Platinum Siloxides Bridged by a Sulfur or Selenium Atom and a Unique 1,3-Aryl Migration from Silicon to Platinum through the Si−O−Pt Linkages

Platinum siloxides bridged by a sulfur or selenium atom, [Tbt(Mes)Si(μ-O)(μ-E)Pt(PPh3)2] (1a: E = S, 1b: E = Se), were synthesized by utilizing hydroxysilanechalcogenols, Tbt(Mes)Si(OH)(EH) (2a: E = S, 2b: E = Se), which were kinetically stabilized by an effective combination of steric protection groups, 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl (Tbt) and mesityl (Mes), as key building blocks. Platinum siloxide 1 underwent a unique 1,3-migration of the Mes group from the silicon atom to the platinum center on treatment with chloride ion in the presence of a Brønsted acid, affording the corresponding chloro(hydroxysilane)chalcogenolatoplatinums, [TbtSi(OH)(Cl)(μ-E)Pt(Mes)(PPh3)2] (3a: E = S, 3b: E = Se), in moderate yields.