Search

Aromaticity is a key concept that underpins the behavior and applications of a wide range of chemical compounds. Its impact on stability, reactivity, biological functions, material properties, and environmental persistence underscores the importance of understanding and harnessing aromaticity in chemistry and materials sciences. We have been pioneers in the field of silylene chemistry and recently, our silylene molecules have been used to synthesize several inorganic aromatic ring compounds. Aromaticity in inorganic compounds is not commonly observed; hence, inorganic aromatic rings derived from silylene would further enhance our understanding of aromaticity and stability. Herein, we discuss the inorganic aromatic rings which have been synthesized from amidinato silylene. [ABSTRACT FROM AUTHOR]

Silylenes, divalent silicon(II) compounds, once considered highly reactive and transient species, are now widely employed as stable synthons in main-group and coordination chemistry for myriad applications. The synthesis of stable silylenes represents a major breakthrough, which led to extensive exploration of silylenes in stabilizing low-valent main-group elements and as versatile ligands in coordination chemistry and catalysis. In recent years, the exploration of transition metal complexes stabilized with silylene ligands has captivated significant research attention. This is due to their robust σ-donor characteristics and capacity to stabilize transition metals in low valent states. It has also been demonstrated that the transition metal complexes of silylenes are effective catalysts for hydroboration, hydrosilylation, hydrogenation, hydrogen isotope exchange reactions, and small molecule activation chemistry. This review article focuses on the recent progress in the synthesis and catalytic application of transition metal complexes of silylenes. [ABSTRACT FROM AUTHOR]

Silicon compounds containing silicon–silicon bond with a variety of unusual oxidation states are quite important, because their high reactivity leads to the formation of a variety of silicon compounds. The isolation of such compounds with unusual oxidation states requires a resilient synthetic strategy. Herein, we report the synthesis of a silicon based spirocyclic compound containing a hyper-valent silicon atom and a silicon–silicon bond. The computational calculations employing natural bond orbital (NBO) analysis and energy decomposition analysis–natural orbitals for chemical valence (EDA–NOCV) reveal that the nature of bonding between the silicon atoms is of an electron sharing nature. [ABSTRACT FROM AUTHOR]

Herein, we report the synthesis of a rare bis‐silylene, 1, in which two SiIIatoms are bridged by a SiIV atom. Compound 1 contains an unusual SiII−SiIV−SiII bonding arrangement with SiII−SiIV bond distances of 2.4212(8) and 2.4157(7) Å. Treatment of 1 with Fe(CO)5 afforded a dinuclear Fe0 complex 2 with two unusually long Si−Si bonds (2.4515(8) and 2.4488(10) Å). We have also carried out a detailed computational study to understand the nature of the Si−Si bonds in these compounds. Natural bond orbital (NBO) and energy decomposition analysis–natural orbital for chemical valence (EDA‐NOCV) analyses reveal that the Si−Si bonds in 1 and 2 are of an electron‐sharing nature. [ABSTRACT FROM AUTHOR]

Herein, we report the synthesis of a rare bis-silylene, 1, in which two Si II atoms are bridged by a Si IV atom. Compound 1 contains an unusual Si II -Si IV -Si II bonding arrangement with Si II -Si IV bond distances of 2.4212(8) and 2.4157(7) Å. Treatment of 1 with Fe(CO) 5 afforded a dinuclear Fe 0 complex 2 with two unusually long Si-Si bonds (2.4515(8) and 2.4488(10) Å). We have also carried out a detailed computational study to understand the nature of the Si-Si bonds in these compounds. Natural bond orbital (NBO) and energy decomposition analysis-natural orbital for chemical valence (EDA-NOCV) analyses reveal that the Si-Si bonds in 1 and 2 are of an electron-sharing nature., (© 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

The synthesis of the first inorganic four-membered neutral 2π-aromatic compound 2 is reported. This unique ring has been synthesized from a simple and straightforward reaction of amidinato-silylene with dichlorophenylborane, followed by the reduction with KC 8 in THF. Compound 2 has been fully characterized by single-crystal X-ray diffraction (SC-XRD), NMR spectroscopy, and mass spectrometry. The computational calculations reveal that the Si 2 B 2 ring is a π-delocalized system resulting from the interaction of p π orbital of B and Si-N σ* orbitals having pseudo π symmetry. Compound 2 is the first known example of a neutral planar inorganic analogue of cyclobutenyl dication.

The donor ligand bonded singlet (L) 2 Si 2 C containing a bent Si 2 C unit in the middle has been studied by theoretical quantum mechanical calculations (NBO, QTAIM, EDA-NOCV analyses) [L = cAAC, NHC, Me 3 P]. EDA-NOCV analysis suggests that this Si 2 C is possible to stabilize by a pair of donor base ligands. The bond dissociation energy of the Si 2 C fragment is endothermic (85-45 kcal/mol) with a sufficiently high intrinsic interaction energy (Δ E int = -89 to -48 kcal/mol). Fifty percent of the total stabilization energy arises from electrostatic interactions, and nearly 45% is contributed by covalent orbital interaction between Si 2 C and (L) 2 fragments in their singlet states. 75-80% of the orbital interaction energy is contributed by two sets of σ-donation L → SiCSi ← L. The π-back-donation is only 15-10%. The dispersion energy is not negligible (3-5%). The interaction energy is highest for 1 (L = cAAC) among three compounds. Additionally, (cAAC) 2 Si 2 C-Ni(CO) 3 ( 4 ) has been studied. The interaction energy between 1 and Ni(CO) 3 is nearly 61 kcal/mol with the major contribution coming from donation of electron cloud from electron rich Si 2 C backbone to empty hybrid orbital of Ni(CO) 3 fragment. A sufficiently strong π-back-donation from (OC) 3 Ni to Si 2 C has also been identified.

A robust tetrameric nickel complex [Ni 4 ((O al - ) 2 L-Me) 4 (s) 4 ] (3) (s = solvent) with cubane-like Ni 4 O 4 core topology was isolated as a light greenish-orange crystalline solid in excellent yield. The mechanism of formation of 3 involving the two chloride-containing precursors [Ni 4 ((O al - ) 2 L-Me) 4 (s) 4 ]·2MeOH (1) and [Ni 4 ((O - ) 2 L-Me) 3 ((O al - )(OH)L-Me)Cl] (2) was studied by ESI mass spectrometry and confirmed by the solid state isolation and single-crystal X-ray diffraction. The challenging ligand fields containing mono/di-anionic O 2 N donating atoms and/or chloride ions stabilized the pentacoordinate Ni(ii) ions in 1-2 upon controlling the experimental conditions. Complexes 1-3 have been characterized by NMR, UV-Vis and mass spectrometric analysis. Complex 3 was found to be redox active by cyclic voltammetry (CV) studies. Theoretical calculations were carried out to shed light on the effects of ligand fields on the stability of complexes 1-3. Complex 3 was found to be a potential catalyst for the diastereoselective cyclopropanation of heteroarenes with good to excellent yields. The ESI mass spectrometric analysis revealed the existence of solution dynamics and oligomerization of 3 in solution. Mechanistic investigation of the catalytic cycle revealed that complex 3 and its various oligomers bind to the diazoester employed, followed by dissociative insertion of the respective carbene moieties to the C2-C3 double bond of the involved aromatic heterocycle, leading to the diastereoselective cyclopropanation., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)