Renzo Arias-Ugarte

Dehydrogenative Dimerization of Di‐tert‐butyltin Dihydride Photochemically and Thermally Catalyzed by Iron and Molybdenum Complexes

Dehydrogenative coupling of tertiary stannanes, R3SnH, catalyzed by a transition metal is known to produce distannanes, R3Sn SnR3, whereas a mixture of cyclic and linear oligoor polystannanes is obtained from the analogous dehydrogenative coupling of secondary stannanes, R2SnH2. [2–4] 1,2-Dihydrodistannanes are of significant interest as bifunctional model compounds to mimic the properties of polystannanes and they are excellent precursors for further derivatization. However, until a report by Uhlig et al. there were no well-defined methodologies for the synthesis of 1,2dihydrodistannanes. The Uhlig synthesis involves a two-step reaction sequence that starts with the reaction of tertbutylmagnesium chloride with tin tetrachloride in an overall yield of 2.5%. We now report the photochemical and thermal dehydrogenative dimerization of tBu2SnH2 (1) to tBu2HSn SnHtBu2 (2), catalyzed by the iron catalysts 3 and 4 and their molybdenum analogues 5 and 6.

Platinum-Catalyzed Reduction of DMF by 1,1,3,3-Tetramethyldisiloxane, HMeSi2OSiMe2H: New Intermediates HSiMe2OSiMe2OCH2NMe2 and HSiMe2(OSiMe2)3OCH2NMe2 and Their Further Chemical Reactivity

The use of Karstedt’s catalyst to study the reduction of Me2NCHO (DMF) by the popular “dual SiH”-containing tetramethyldisiloxane, HMe2SiOSiMe2H (1), has revealed that the first step in the process involves an initial single hydrosilylation to form HSiMe2OSiMe2OCH2NMe2 (3). This intermediate is readily isolated and purified via distillation. In the continued presence of the catalyst, 3 transforms to the transient tetrasiloxane HMe2SiOSiMe2OSiMe2OSiMe2OCH2NMe2 (4), along with the formation of Me3N. The tetrasiloxane 4 itself transforms to Me3N and (Me2SiO)n (n = 4–6). Despite the demonstrated reactivity of 3, it can also be used to perform the expected metal-catalyzed hydrosilylation chemistry of the SiH group as well as reactions of the SiOCH2NMe2 functionality involving siloxane chain extension and is thus an important new reagent for siloxane chemistry.

Methyl transfer from Fe (and Mo) to Sn: formation of (eta(5)-C(5)H(5))M(CO)(n)Sn(t)Bu(2)Me (M = Fe, n = 2; M = Mo, n = 3) complexes from photochemical irradiation of (eta(5)-C(5)H(5))M(CO)(n)Me and (t)Bu(2)SnH(2).

Formation of an Sn-CH(3) bond, concomitantly with an Sn-M (M = Fe, Mo), is readily achieved from the photochemical reactions of (t)Bu(2)SnH(2) with (eta(5)-C(5)H(5))M(CO)(n)Me (M = Fe, n = 2; M = Mo, n = 3) via the intermediacy of (eta(5)-C(5)H(5))M(CO)(n)Sn(t)Bu(2)H.