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Past one decade has witnessed a tremendous growth in the field of carbene stabilized low‐valent silicon compounds unravelling very exciting properties of these molecules. Herein, we have employed a bicyclic (alkyl)(amino)carbene, (MeBICAAC) to explore the low‐valent chemistry of silicon. The reduction of bicyclic (alkyl)(amino)carbene‐SiCl4 complex, [(MeBICAAC)SiCl4] (1) with KC8 afforded low‐valent Si complexes, including Si(III) radical [(MeBICAAC)SiCl3] (2) and a complex with silicon center in a formal zero‐valent state, [(MeBICAAC)2Si] (3). Similarly, the reduction of in‐situ generated MeBICAAC adduct of Me2SiCl2 with one equivalent of KC8 led to the formation of [(MeBICAAC)SiMe2Cl] (4) complex having an unpaired electron. These complexes have been characterized by IR, UV‐Vis. NMR, HRMS, EPR and their solid‐state structures were also elucidated by single crystal X‐ray crystallography. Further, DFT calculations revealed the lower energy singlet state for complexes 1, 3 and doublet state for complexes 2, 4. [ABSTRACT FROM AUTHOR]

BICAAC (bicyclic (alkyl)(amino)carbene) as ambiphilic carbene has been utilized to prepare stable neutral tetrahydrodiborane [BICAAC→ ${\to }$ (H2)B−B(H2)← ${\leftarrow }$ BICAAC] and dihydrodiborene [BICAAC→(H)B=B(H) ← ${\leftarrow }$ BICAAC] compounds. The Lewis base stabilized dihydrodiborene is isoelectronic and isolobal to conventional olefins and therefore offers the possibility to explore the formation of π‐complexes with transition metals. Reaction of the diborene with coinage metal salts (CuCl, AgBr and CuI) leads to the formation of π‐diborene metal complexes via η2 side‐on coordination. These are first examples of dihydrodiborene coinage metal complexes. Interestingly, coordination of two CuCl units to the diborene has been observed for the first time with a considerable lengthening of >B=B< and B- ${-}$ CBICAAC bonds manifesting the key role of the BICAAC combined with small steric requirements of hydride substituents in stabilizing these complexes. The energy decomposition analysis (EDA) calculations reveal the interaction between the diborene and Cu(I)/Ag(I) is mainly electrostatic in nature. [ABSTRACT FROM AUTHOR]

Hydride abstraction from the borane adduct, (BICAAC) ⋅ BH3 afforded the hydride bridged dinuclear borenium ion equivalent complexes 1 and 2 that have been characterized by various spectroscopic and spectrometric techniques followed by the assessment of Lewis acidity using the Gutmann‐Beckett method. The single crystal X‐ray structure of complex 2 revealed the presence of discrete ions in the solid state. The complex (BICAAC) ⋅ BH2(OTf) (3), obtained from the reaction of (BICAAC) ⋅ BH3 with MeOTf, formed the corresponding boronium cations [(BICAAC) ⋅ BH2(L)]+(OTf)− on reaction with Lewis bases (L= pyridine (4) and DMAP (5)). Complexes 1 and 2 demonstrated notable catalytic activity in the hydrosilylation of a diverse array of carbonyls using 1.0 mol % catalyst loading (achieving the highest turnover frequency (TOFmax) of up to 1200 h−1 with benzaldehyde. A broad substrate scope has been presented for aldehydes and ketones decorated with various electron‐donating and withdrawing substituents along with this the hydrosilylation of a few para‐quinone methides has also been presented. [ABSTRACT FROM AUTHOR]

Herein, we report extended π‐conjugated arylazopyrazole and arylazoisoxazole photoswitches towards tuning and modulation of their intrinsic properties. In this regard, we systematically introduced phenyl, styryl, (triphenylvinyl)styryl, phenylethynyl groups at ortho, meta, and para positions relative to the azo unit to extend the π‐conjugation and vary the electronic coupling. In addition, the heterocyclic substituents were also modified. Overall, 20 photoswitches with modular substituents have been synthesized and studied for the photoswitching ability and thermal relaxations of Z isomers in the solution phase and solid state. Besides deciphering the importance of extending conjugation in photoswitching characteristics, intriguing properties such as mechanochromism and reversible bidirectional photochromism in the solid state were also unravelled. Through extensive spectroscopic studies, we envisage the effect of electronic coupling due to π‐conjugation and its impact on longer wavelength light‐induced photoswitching that holds several application potentials. [ABSTRACT FROM AUTHOR]

Past one decade has witnessed a tremendous growth in the field of carbene stabilized low-valent silicon compounds unravelling very exciting properties of these molecules. Herein, we have employed a bicyclic (alkyl)(amino)carbene, ( Me BICAAC) to explore the low-valent chemistry of silicon. The reduction of bicyclic (alkyl)(amino)carbene-SiCl 4 complex, [( Me BICAAC)SiCl 4 ] (1) with KC 8 afforded low-valent Si complexes, including Si(III) radical [( Me BICAAC)SiCl 3 ] (2) and a complex with silicon center in a formal zero-valent state, [( Me BICAAC) 2 Si] (3). Similarly, the reduction of in-situ generated Me BICAAC adduct of Me 2 SiCl 2 with one equivalent of KC 8 led to the formation of [( Me BICAAC)SiMe 2 Cl] (4) complex having an unpaired electron. These complexes have been characterized by IR, UV-Vis., NMR, HRMS, EPR and their solid-state structures were also elucidated by single crystal X-ray crystallography. Further, DFT calculations revealed the lower energy singlet state for complexes 1, 3 and doublet state for complexes 2, 4., (© 2024 Wiley-VCH GmbH.)