P- and S-substituted vinylidene complexes, [Ru{CC(R)(E)}(dppe)Cp]BArF
4 [E = PO(OMe)2, PO(OEt)2, POPh2, SPh,
and SO2Ph], were found to be active for retro-vinylidene
rearrangements to add new entries of reversible systems of vinylidene/alkyne
isomerization. Isotope labeling experiments revealed that PO(OMe)2- and POPh2-substituted complexes underwent the
retro-vinylidene rearrangement via selective 1,2-migration of the
P-substituents. In contrast, in the case of a SPh-substituted complex,
both the SPh and the R groups served as migrating groups during the
reversible alkyne/vinylidene isomerization, though the migration of
the SPh group was still the major reaction path. These findings would
deepen the mechanistic understanding of alkyne/vinylidene rearrangements
of heteroatom-substituted internal alkynes.
The coordinatively unsaturated manganase(II) bis(supersilyl) complex Mn[Si(SiMe3)3]2(THF)2 (2) was synthesized in one step via the reaction of MnBr2 with two equivalents of KSi(SiMe3)3 in THF. Complex 2 acts as an effective precatalyst for the catalytic hydrosilylation of aldehydes and ketones with 1,1,3,3‐tetramethyldisiloxane (TMDS). The catalytic efficiency can be improved by combining 2 and adamantyl isocyanide (CNAd). The stoichiometric reaction of 2 and two equivalents of CNAd led to the isolation of Mn[Si(SiMe3)3]2(CNAd)2 (3) in high yield. Complex 3 shows superior catalytic performance than 2 in the hydrosilylation of relatively unreactive ketones.
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