Stabilization of an amidinatosilylene with a bulky tris(trimethylsilyl)silyl substituent was realized with the preparation of PhC(NtBu) 2 Si{Si(SiMe 3 ) 3 } (1) from PhC-(NtBu) 2 SiHCl 2 with K{Si(SiMe 3 ) 3 } in more than 90% yield. The highly deshielded 29 Si NMR resonance (δ = 76.91 ppm) can be attributed to the absence of a π-donating substituent. The molecular structure of 1 shows a trigonal-planar geometry around the Si II center with a Si II −Si IV bond length of 2.4339(13) Å. A series of reactions of 1 with Me 3 NO, S, Se, and Te were performed. While siloxane derivatives (2 and 3) are obtained from reactions with Me 3 NO, silachalcogenones (4− 6) are formed with other chalcogens. The presence of SiE (E = S, Se, and Te) bonds in 4−6 have been confirmed by singlecrystal X-ray studies. Silaoxirane (7) formation was observed when 1 was treated with acetone, demonstrating the importance of the tris(trimethylsilyl)silyl group to kinetically and thermodynamically protect the silaoxirane derivative with less bulky substituents on the C atom.

Cations and dications of heavier group 14 elements in their low oxidation state have received widespread attention in recent years. The journey started with the isolation of a series of cations of the composition [(C5Me5)E:](+) [E = Si-Pb], followed by the more recent isolation of a Ge(ii) dication encapsulated within a cryptand, a carbodiphosphorane stabilized [GeCl](+) monocation with a two coordinate Ge atom, Si(ii) cations and dications stabilized by N-heterocyclic carbenes (NHCs), which highlights the ongoing growth and interest in the chemistry of tetrel(ii) cations. This is presumably because the central atom (E) in these compounds contains two or three unoccupied valence orbitals as well as holds a lone pair of electrons. Such an electronic description represents ambiphilicity, which is of great interest for catalysis. The successful synthesis of divalent group 14 cations requires new synthetic strategies based on the sterically demanding neutral or monoanionic ligands, utilization of counter anions, and solvents with low nucleophilicity in order to minimize the degree of interactions with the cations. An alternative approach for the realization of divalent cations of group 14 elements is their coordination to the transition metals. This synthetic approach was successfully applied for the isolation of a range of transition metal coordinated divalent cations of group 14 elements. Apart from arousing academic interest some of these cations have found application as activators in the Ziegler-Natta polymerization of alkenes.

Phosphorus ylides are 1,2-dipolar compounds with a negative charge at the carbon atom. This charge is stabilized by the neighboring onium moiety, but can also be shifted towards other substituents...

The recently reported hypersilylsilylene PhC-(NtBu) 2 SiSi(SiMe 3 ) 3 (1) reacts with BH 3 , 9-BBN, and PhBCl 2 to yield the respective Lewis acid base adducts 2−4, respectively. Compound 4 undergoes isomerization to form a ring expansion product 5. The same silylene was found to initially form an adduct with HBpin (6) and subsequently isomerized to 7 via the rupture of the B−H bond of HBpin ( 7), where the hydride was bound to the carbon atom of the amidinate ligand and the Bpin unit was attached to the silicon center. Surprisingly, the reaction of 1 with HBcat results in PhC(NtBu) 2 Bcat (8). Subsequently, we have shown that HBcat forms the same product when it reacts with related silylene PhC(NtBu) 2 SiN(SiMe 3 ) 3 (1′). With all of these reactions in hand, we ponder if silylene can activate two small molecules at one time. In this work, we delineate the three-component reactions of silylenes 1 and 1′ with 4-fluorobenzaldehyde and HBpin, which afforded unusual coupling products, 9 and 10, respectively. Note that 9 and 10 were prepared from the cleavage of the B−H and CO bonds by silylene in a single reaction and are the first structurally attested Si−C−O−B coupled products.

This study demonstrates the preparation and structural characterization of a Si(iv) hydride (PhC(NtBu)SiH(CH)Cl) (1) and its use as a catalyst for the cyanosilylation of a variety of aldehydes. Compound 1 represents the first neutral penta-coordinate silicon(iv) species that catalyzes cyanosilylation of aldehydes under mild conditions.

Silylene [PhC(NtBu)SiN(SiMe)] (1) cleaves the C(sp)-H and C-F bonds of acetophenone and 1,1,1-trifluoroacetophenone, respectively, under mild conditions. The reaction is initiated via a nucleophilic attack from the oxygen to the silicon atom followed by C-F/H bond cleavage. The scope of C-F bond activation has further been extended with CF and CFCF.

Silylene mediated B–H and aldehyde C–H bond splitting were realized under ambient conditions.

A nacnac-based tridentate ligand containing a picolyl group (L) was employed to isolate a chlorogermylene (1). The reaction of 1 with another equivalent of GeCl2•dioxane surprisingly gave a pyridylpyrrolide based...