Comparison of the Reactivity of the Low Buried-Volume Carbene Complexes (ITMe)2Pd(PhC≡CPh) and (ITMe)2Pd(PhN═NPh)

Synthesis of trans-Mono(silyl)palladium(II) Bromide Complexes

The stoichiometric reaction of cis-[Pd(ITMe)₂(SiR₃)₂], where (SiR₃ = SiMe₃ and SiMe₂Ph and ITMe = 1,3,4,5-tetramethylimidazol-2-ylidene) with allyl bromide affords the corresponding allylsilanes along with complexes of the type trans-[Pd(ITMe)₂(SiR₃)(Br)]. The structure of trans-[Pd(ITMe)₂(SiMe₂Ph)Br] 2b has been determined in the solid state and displays a slightly distorted square-planar geometry with the two N-heterocyclic carbene ligands in a trans-configuration.

Tetryl-Tetrylene Addition to Phenylacetylene

Phenylacetylene adds [Ar*GeH2 -SnAr'], [Ar*GeH2 -PbAr'] and [Ar'SnH2 -PbAr*] at rt in a regioselective and stereoselective reaction. The highest reactivity was found for the stannylene, which reacts immediately upon addition of one equivalent of alkyne. However, the plumbylenes exhibit addition to the alkyne only in reaction with an excess of phenylacetylene. The product of the germylplumbylene addition reacts with a second equivalent of alkyne and the product of a CH-activation, a dimeric lead acetylide, were isolated. In the case of the stannylplumbylene the trans-addition product was characterized as the kinetically controlled product which isomerizes at rt to yield the cis-addition product, which is stabilized by an intramolecular Sn-H-Pb interaction. NMR chemical shifts of the olefins were investigated using two- and four-component relativistic DFT calculations, as spin-orbit effects can be large. Hydride abstraction was carried out by treating [Ar'SnPhC=CHGeH2 Ar*] with the trityl salt [Ph3 C][Al(OC{CF3 })4 ] to yield a four membered ring cation.

Activation of the Si–B interelement bond related to catalysis

Covering the past seven years, this review comprehensively summarises the latest progress in the preparation and application of Si–B reagents, including the discussion of relevant reaction mechanisms.