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.

Simple and readily accessible lithium compounds such as 2,6-di-tert-butyl phenolate lithium (1a), 1,1' dilithioferrocene (1b) and nacnac lithium (1c) are found to be efficient single site catalysts for hydroboration of a range of aldehydes and ketones with HBpin at room temperature. The efficacy of 1a-1c as catalysts is extended to the cyanosilylation of aldehydes and ketones with Me3SiCN.

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Ever increasing demand for green and sustainable chemical processes has set up a drive to replace transition metals with earth-abundant, nontoxic, and environmentally benign alternatives. In this regard, the alkaline earth metal complexes have attracted significant attention. Herein, we have used a β-diketiminato ligand with methyl-pyridine side arm to synthesize magnesium (1) and calcium (2) compounds. The constitutions of 1 and 2 have been confirmed by single crystal X-ray studies, which show that the magnesium and calcium atom in 1 and 2 possesses octahedral geometry. Subsequently, we have used them as catalysts (1 mol %) for hydroboration of a wide range of aldehydes using pinacolborane (HBpin) at room temperature. The strategy has further been extended to ketones with 2 mol % catalyst loading. DFT calculations have been performed to understand the mechanism.

The transition metal free catalytic hydroboration of aldehydes and ketones is very limited and has not been reported with a well-defined silicon(iv) compound. Therefore, we chose to evaluate the previously reported silicon(iv) hydride [PhC(NtBu)SiHCl], (1) as a single component catalyst and found that it catalyzes the reductive hydroboration of a range of aldehydes with pinacolborane (HBpin) under ambient conditions. In addition, compound 1 can catalyze imine hydroboration. DFT calculation was carried out to understand the mechanism.

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.

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.

Readily accessible lithium compounds have been employed to catalyze the hydroboration of alkene and alkynes including terpenes using HBpin with anti-Markovnikov selectivity. The mechanism is proposed on the basis of experimental and DFT studies.