Herein, we describe the first synthesis of anionic silaketenimines and the coupling product with an isocyanide. Treatment of boryl silanorcaradienyllithium [CH2(L)­N]2BSiLi (where L = B­[N­(Ar)­CH]2 and Ar = 2,6-iPr2C6H3) with isocyanides afforded silaketenimine anions [CH2(R)­N]2BSi­(Li)CNR featuring a SiCN allenic structure. X-ray diffraction studies and density functional theory calculations strongly support the presence of an anionic silicon atom and a strong π bond between the silicon and carbon atoms. One of the silaketenimine anions underwent a formal [2 + 2] cycloaddition reaction with a second molecule of isocyanide to give a novel silacyclopropyl anion with a delocalized anionic skeleton. These reactions demonstrated that the bonding nature of the boryl lithiosilylene was distinct from that of common silylenes.

Herein we report the first synthesis of a 1-magnesium-2,3-disilacyclopropene and a related bis­(disilenide). Reduction of (boryl)­tribromosilane (1, boryl = (HCArN)2B, Ar = 2,6-iPr2C6H3) with magnesium in THF afforded boryl-substituted magnesium complex [(boryl)­Si]2Mg­(THF)3 (2) in good yield, whereas reduction of (boryl)­trichlorosilane (3) with KC8 in THF led to the isolation of bridged alkoxy alkyl bis­(disilenide) (THF)­K­(boryl)­SiSi­(boryl)­O­(CH2)4(boryl)­SiSi­(boryl)­K­(THF) (4) via ring opening of a THF molecule. X-ray diffraction analysis of 2 confirmed the presence of the novel Si2Mg three-membered ring as well as the SiSi double bond, which existed in a noticeably twisted B–Si–Si–B array. Complex 2 also represents the first reported example of a stable disilyne dianion.

Reduction of (boryl)dibromosilane (boryl)SiHBr 2 (1; boryl = B(NArCH) 2 , Ar = 2,6-iPr 2 C 6 H 3 ) with 2 equiv of potassium graphite in DME at low temperature led to the isolation of bis(boryl)disilane (boryl)SiH 2 SiH 2 (boryl) (3) as a colorless solid, whereas reduction of (boryl)SiPhBr 2 (2) in THF gave the boryl-substituted disilene (boryl)-PhSiSiPh(boryl) (4) as a yellow solid. The reaction of 1 with 1,3diisopropyl-4,5-dimethylimidazol-2-ylidene (IiPr) unexpectedly led to the formation of the cationic species [(boryl)SiHBr(IiPr)] + Br − (6). These products were characterized by spectroscopic methods as well as by X-ray single-crystal analysis.

A series of novel bis-BN-naphthalene-fused oxepin derivatives were synthesized via a Pd-catalyzed tandem reaction from brominated 2,1-borazaronaphthalenes and cis-bis­(boryl)­alkenes. X-ray crystallographic analysis revealed that bis-BN-naphthalene-fused oxepins feature a planar framework. The electronic and photophysical properties of the novel BN-naphthalene-fused oxepins were investigated by UV–vis and fluorescence spectroscopies and density functional theory (DFT) calculations, which disclosed the distinct electronic and photophysical properties of the analogous hydrocarbon system. Interestingly, dual-fluorescent emissions were observed upon dissolving N-substituted derivatives 10–14 in dimethyl sulfoxide. Tunable emission colors especially for white-light emissions can be achieved by controlling the ratio of solvents, concentration, or temperature using only a single-molecule compound.

The first examples of cyclic (alkyl)­(amino)­carbene (CAAC) lanthanide (Ln) complexes were synthesized from the reaction of CAAC with Yb­[N­(SiMe3)2]2 and Eu­[N­(SiMe3)2]2(THF)2 (THF = tetrahydrofuran). The structures of (CAAC)­Yb­[N­(SiMe3)2]2 (2) and (CAAC)­Eu­[N­(SiMe3)2]2(THF) (3) were determined by X-ray diffraction analysis. Density functional theory calculations of 2 revealed the predominantly ionic bond between the Ln ion and CAAC. Complex 3 enabled catalytic hydrosilylation of aryl- and silylalkenes with primary and secondary silanes in high yields and Markovnikov selectivity.