A computationally guided synthetic route to a free silanide derived from tris(3‐methylindol‐2‐yl)methane ([(tmim)Si]−) through nucleophilic substitution on the SiII precursor (Idipp)SiCl2 is reported (Idipp=2,3‐dihydro‐1,3‐bis(2,6‐diisopropylphenyl)‐1H‐imidazol‐2‐ylidene). This approach circumvents the need for strained tetrahedral silanes as synthetic intermediates. Computational investigations show that the electron‐donating properties of [(tmim)Si]− are close to those of PMe3. Experimentally, the [(tmim)Si]− anion is shown to undergo clean complexation to the base metal salts CuCl and FeCl2, demonstrating the potential utility as a supporting ligand.

A range of silanes was synthesized by the reaction of HSiCl3 with iminopyrrole derivatives in the presence of NEt3 . In certain cases, intramolecular hydrosilylation converts the imine ligand into an amino substituent. This reaction is inhibited by factors such as electron-donating substitution on Si and steric bulk. The monosubstituted ((Dipp) IMP)SiHMeCl ((Dipp) IMP=2-[N-(2,6-diisopropylphenyl)iminomethyl]pyrrolide), is stable towards hydrosilylation, but slow hydrosilylation is observed for ((Dipp) IMP)SiHCl2 . Reaction of two equivalents of (Dipp) IMPH with HSiCl3 results in the hydrosilylation product ((Dipp) AMP)((Dipp) IMP)SiCl ((Dipp) AMP=2-[N-(2,6-diisopropylphenyl)aminomethylene]pyrrolide), but the trisubsitituted ((Dipp) IMP)3 SiH is stable. Monitoring the hydrosilylation reaction of ((Dipp) IMP)SiHCl2 reveals a reactive pathway involving ligand redistribution reactions to form the disubstituted ((Dipp) AMP)((Dipp) IMP)SiCl as an intermediate. The reaction is strongly accelerated in the presence of chloride anions.

A convenient approach for the anchoring of S,S-BnTsDPEN ligands (S,S-N-tosyl-1,2-diphenylethylenediamine) to branched carbosilane scaffolds was investigated. It is based on a high-yielding reductive amination reaction between commercially available S,S-TsDPEN and readily accessible carbosilanes furnished with benzaldehyde terminal fragments. These molecularly enlarged ligands, bearing four S,S-BnTsDPEN units, and their simplified monomeric and ''dimeric'' analogues were evaluated in iron(III)-catalyzed asymmetric trans-stilbene epoxidation reactions using hydrogen peroxide as an environmentally benign oxidant. The catalytic investigations showed a large degree of variation in the activity and stereoselectivity of the series of DPEN catalysts. In combination with ESI-MS investigations, these data revealed an important role of the ligand orientation in determining the overall activity of the catalyst system. Accordingly, a suitable design of the molecularly enlarged ligands resulted in fully retained activity and selectivity in catalysis. Finally, a number of strategies for the recovery and reuse of the best performing carbosilane-tethered DPEN ligands were explored.

Reduced compounds of silicon, one of the constituting elements of quartz sand, are attracting attention as donor ligands for transition metals. In this Communication on page 12236 ff., a silicon(II) anion (silanide) was synthesized by direct substitution at the silicon(II) precursor (Idipp)SiCl2 by a tris‐indolide nucleophile. The free silanide was found to readily bind to the base metal salts FeCl2, CuCl and Cu(NCCH3)4PF6, illustrating its potential as a supporting ligand [Cover illustration: T. Ran and L. Witteman; 3D molecular plot produced using VMD software (http://www.ks.uiuc.edu/Research/vmd/)].