Si-H bond activation of a number of silanes via metal ligand cooperation in a carbene complex is reported. Thereby, the electronic flexibility of the carbene ligand allows for the activation via a unique mechanism with oxidative addition to an 18e species without a formal change in the number of valence electrons.

Cooperative B-H bond activation reactions with thio- and iminophosphoryl tethered ruthenium-carbene complexes are reported. The complexes show surprisingly different reactivities towards the commonly employed boranes CatBH, PinBH and BH ⋅LB as a result of different modes of metal-ligand cooperation. Although the iminophosphoryl system allows for selective 1,2-addition of the B-H bond across the Ru=C double bond, the sulfur analogue only delivers the 1,2-addition product for CatBH, whereas activation of BH and PinBH lead to further insertion reactions in one or more sides of the Ru-C-P-S-ring. The different reactivities can be explained by the differences in the electronics of the carbene complexes and the phosphoryl tether and by the Lewis acidities of the boranes. DFT calculations show that the mechanism of the reactions either proceeds by an addition across the Ru=C bond with different regioselectivities or across the Ru-S linkage.

The α‐metallated ylides [Ph3P−C−Z]−M+ (with Z=SO2Tol or CN and M=Na or K) were used as versatile nucleophiles for the facile access to ylide‐substituted compounds. Halogenations, alkylations, carbonylations and functionalization reactions with main group element halides were easily accomplished by simple trapping reactions with the appropriate electrophiles. X‐ray crystallographic studies of all compounds – including the first structures of α‐fluorinated P‐ylides – showed remarkable differences in the ylide backbone depending on the substituents. In the fluorinated compounds, a change from a fully planar to a pyramidalized ylidic carbon centre was observed despite the strongly anion‐stabilizing ability of the yldiide substituent. π‐Donation from the ylide substituent also resulted in geometric restrictions depending on the steric and electronic properties of the introduced substituents.

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