The reaction of ferriohydridosilanes Cp(CO)(L)Fe -SiRzH (R = Me, t-But Ph, o-Tolyl; L = CO, Ph3P) l a -e with dimethyldioxirane (as an acetone solution) leads directly to the corresponding ferriosilanols Cp(CO)(L)Fe -SiRzOH 2a -e in moderate to excellent yields.Organosilanols play an important role as intermediates in the technical synthesis of silicones[21. In contrast to the chemistry of organosilanols, which has been intensively studiedI31, there is only limited knowledge on derivatives L,M -SiR3 -.(OH), (x = 1 -3), in which an organometallic fragment is attached to silicon.In context with systematic studies on exchange reactions at the silicon atom of ferriohalosilanes we found that the ferrio-substituted silanols of the type C5RS(C0)2Fe-SiR'R20H (R = H, Me) can be obtained in good yields by the conventional method of silanol formation, which involves the hydrolysis of the corresponding ferriochlorosilanes in the presence of an auxiliary base[',41. This route, however, cannot be applied to ferriochlorosilanes which bear an electron-rich organoiron fragment like Cp(CO)(Ph3P)Fe or sterically demanding organo groups at the silicon atom.Another potentially convenient way to prepare silanols is by direct oxidation of the corresponding silanes. Recently dimethyldioxirane was shown to be an ideal oxidant for numerous electron-rich as well as electron-poor e.g. the epoxidation of TCsystems, oxidation of heteroatoms, and oxygen insertion into C -H bonds. Relevant for the present study is the selective transformation of organosilanes into their silanols [6] by dimethyldioxirane without any condensation to disiloxanes. Furthermore, the fact that ruthenium thiolates with electron-rich metal centers can be selectively oxidized by dimethyldioxirane at the sulfur atom to afford the sulfone ligand"], encouraged us to use this novel oxidant for the synthesis of ferriosilanols from their silanes. Scheme 3 2Indeed, the reaction of dimethyldioxirane (as an acetone solution) with the ferriohydridosilanes l a -e (Scheme 1) led to the corresponding silanols 2a-e in moderate to excellent yields. The results of these transformations are summarized in Table 1, in which the reaction parameters and yields are stated. The preparative procedure consisted of adding rapidly the required amount of oxidant to the dissolved substrates 1 a-e at low temperature. After removal of the solvents, purification by column chromatography afforded the silanols 2a-e in good yields. The ferriosilanols 2a-e crystallize from pentane as pale yellow or light brown solids. They show no tendency for self-condensation to the disiloxanes during the preparation nor on standing in solution. The structure assignment of the silanols 2a-e rests on the $-OH vibration at 3700-3600 cm-' in the IR spectrum and the signals for this functional group at 6 = 1.63-2.50 in the 'H-NMR spectrum. From the doubling of the higher 0-CO band the existence of two conformational isomers is evident for 2bLg1. In the case of the ortho-tolyl derivative 2e two 'H-and 13C-NMR resonances for ...

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Synthesis and Reactivity of Silicon‐Transition Metal Complexes, 31 — Metallosilanols and Metallosiloxanes, 6. — The First Hydroxysilanediyl‐Bridged Binuclear Complexes: Selective Oxofunctionalization of the Silicon Bridge in Silanediyliron Complexes with Dimethyldioxirane Oxygenation of [μ‐(R)(H)Si][Fe(CO)2Cp]2 [R = Me (1a), pTol (1b)] with dimethyldioxirane (2) yields the μ‐(hydroxysilanediyl)bisiron complexes [μ‐(R)(HO)Si][Fe(CO)2Cp]2 [R = Me (3a), pTol (3b)]. In an analogous manner the cyclic complex (μ‐OC)[μ‐(Mes)(H)Si][Fe(CO)Cp]2(Fe‐Fe) (6) obtained by photochemical reaction of Cp(OC)2Fe‐Me (4) with MesSiH3, (5) is converted into (μ‐OC)[μ‐(Mes)(HO)Si][Fe(CO)Cp]2‐(Fe‐Fe) (7). 6 and 7 are obtained as a mixture of cis(Mes), cis(H or OH), and trans isomers.

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