The amino imidazolin-2-imine ligand [HAmIm, 1,2-(DippNH)–C6H4–NC(NiPrCMe)2] is employed in the synthesis of the paramagnetic cobalt(I) arene complex Co(AmIm)(η 6 -C6H6). The latter was found to be a highly efficient (pre)catalyst in H/D exchange reactions with deuterium (D2) in hydrosilanes. The scope comprises primary to tertiary silanes at a low catalyst loading of 1 mol %. Additionally, the same cobalt(I) arene complex was able to catalyze hydrosilylation reactions of terminal olefins with primary to tertiary silanes at low catalyst loadings of 0.5 mol %. The scope of hydrosilylation includes intramolecular hydrosilylation to produce silacarbocycles and multiple hydrosilylation with primary silanes. The mechanistic investigation includes numerous control experiments for both H/D exchange and hydrosilylation. Isolated (trapped) cobalt(III) hydride silyl complexes (including X-ray crystallographic authentication) are presented for primary to tertiary Si–H entities, which demonstrates a wide scope of Si–H bond activation by the low-valent Co(AmIm) core. The experimental results are strongly corroborated by density functional theory calculations, which explore the possible reaction mechanisms of studied reactions.

Boron reluctantly forms B=X (X=O, S, Se, Te) moieties, which has stimulated the quest for such species in the past few years. Based on the N,N′‐chelating β‐diketiminato ligand (HNacNac), a new amido imidazoline‐2‐imine ligand system (HAmIm) is presented, giving rise to the isolation of an exhaustive series of Lewis acid free, monomeric chalcogen B=X boranes with documented π‐bond character between boron and the chalcogen. The chalcogenoboranes are isoelectronic and isolobal to the respective ketones. The chemical behavior of the oxoborane (B=O) strongly resembles the classical carbonyl reactivity in C=O bonds. The improved stability provided by HAmIm arises from the formation of more‐stable five‐membered boron chelates versus the six‐membered NacNac analogues and from the imidazoline‐2‐imine moiety providing enhanced σ‐ and π‐donation. The HAmIm ligand class may supersede the widely employed NacNac system in certain applications.

We present the first cyclic five-membered triel(I) carbenoides E(AmIm) for E = Ga, In, Tl; AmIm = amido imidazoline-2-imine, which fill the current gap between four- and six-membered triel(I) carbenoides...

We present facile access to an alumaborane species with electron precise AlÀ B σ-bond. The reductive rearrangement of 1-(AlI 2 ), 8-(BMes 2 ) naphthalene (Mes = 2,4,6-Me 3 C 6 H 2 ) affords the alumaborane species cyclo-(1,8-C 10 H 6 )-[1-Al(Mes)(OEt 2 )-8-B(Mes)] with a covalent AlÀ B σ-bond. The AlÀ B σ-bond performs the reductive scission of multiple bonds: S=C(NiPrCMe) 2 affords the naphthalene bridged motif BÀ SÀ Al(NHC), NHC = N-heterocyclic carbene, while O=CPh 2 is deoxygenated to afford an BÀ OÀ Al bridged species with incorporation of the remaining �CPh 2 fragment into the naphthalene scaffold. The reaction with isonitrile Xyl-N�C (Xyl = 2,6-Me 2 C 6 H 4 ) proceeds via a proposed (amino boryl) carbene species; which adds a second equivalent of isonitrile to ultimately form the AlÀ NÀ B bridged species cyclo-(1,8-C 10 H 6 )-[1-Al(Mes)-N(Xyl)-8-B{C(Mes)=CÀ NÀ Xyl}] with complete scission of the C�N triple bond. The latter reaction is supported with isolated intermediates and by DFT calculations.

Boron reluctantly forms B=X (X=O, S, Se, Te) moieties, which has stimulated the quest for such species in the past few years. Based on the N,N′‐chelating β‐diketiminato ligand (HNacNac), a new amido imidazoline‐2‐imine ligand system (HAmIm) is presented, giving rise to the isolation of an exhaustive series of Lewis acid free, monomeric chalcogen B=X boranes with documented π‐bond character between boron and the chalcogen. The chalcogenoboranes are isoelectronic and isolobal to the respective ketones. The chemical behavior of the oxoborane (B=O) strongly resembles the classical carbonyl reactivity in C=O bonds. The improved stability provided by HAmIm arises from the formation of more‐stable five‐membered boron chelates versus the six‐membered NacNac analogues and from the imidazoline‐2‐imine moiety providing enhanced σ‐ and π‐donation. The HAmIm ligand class may supersede the widely employed NacNac system in certain applications.

Alkynyl functionalized boron compounds are versatile intermediates in the areas of medicinal chemistry, materials science, and optical materials. In particular, alkynyl boronate esters [R1−C≡C−B(OR2)2] are of interest since they provide reactivity at both the alkyne entity, with retention of the B−C bond or alkyne transfer to electrophilic substrates with scission of the latter. The boron atom is commonly well stabilized due to (i) the extraordinary strength of two B−O bonds, and (ii) the chelate effect exerted by a bifunctional alcohol. We reasoned that the replacement of a B−O for a B−S bond would lead to higher reactivity and post-functionalization in the resulting alkynyl boronate thioesters [R1−C≡C−B(S2X)]. Access to this poorly investigated class of compounds starts form chloro dithioborolane cyclo-Cl−B(S2C2H4) as a representative example. Whereas syntheses of three coordinate alkynyl boronate thioesters [R1−C≡C−B(S2X)] proved to be ineffective, the reactions of NHC-adducts (NHC = N-heterocyclic carbene) of cyclo-Cl-B(S2C2H4) afforded the alkyne substituted thioboronate esters in good yield. The products NHC−B(S2C2H4)(C≡C-R1) are remarkably stable towards water and air, which suggests their use as boron-based building blocks for applications akin to oxygen-based boronate esters.

aza-)BODIPY dyes (boron dipyrromethene dyes) are well-established fluorophores due to their large quantum yields, stability, and diversity,which led to promising applications including imagingt echniques, sensors, organic (opto)electronic materials, or biomedical applications. Although the control of the optical properties in (aza-)BODIPY dyes by peripheral functional groups is well studied, we herein present an ovel approach to modify the 12 p-electron core of the dipyrromethene scaffold.T he replacemento ft wo carbon atoms in the b-positiono faBODIPYd ye by two nitrogen atoms affordeda14 p-electron system, which was termed BODIIM( boron diimidazolylmethene)i ns ystematic analogyt ot he BODIPYd yes. Remarkably,t he BODIIM dye was obtained with aB H 2 -rigidifying entity,w hich is currently elusive and highly sought after for the BODIPY dye class. DFT-Calculations confirmt he [12+ +2] p-electron relationship between BODIPY and BODIIM and reveal as trong shapec orrelationbetween LUMO in the BODIPY and the HOMO of the BODIIM.The modification of the p-system leads to ad ramatic shifto ft he optical properties, of whicht he fluorescent emissioni smost noteworthy and occurs at much larger Stokess hift, that is, % 500 cm À1 in BODIPY versus > 4170 cm À1 in BODIIM system in all solvents investigated. Nucleophilic reactivity was found at the meso-carbona tom in the formation of stable borane adducts with as ignificant shift of the fluorescent emission, and this behavior contrasts the reactivity of conventional BODIPY systems. In addition, the reversedecomplexation of the borane adducts was demonstrated in reactions with ar epresentative N-heterocyclic carbene to retain the strongly fluorescent BODIIM compound, which suggestsa pplications as fully reversible fluorescent switch.

Benzyl‐substituted boronates and borates are widely employed as mild sources in radical or anionic transfer reactions of benzyl entities. In this process the B−C bond to the benzyl moiety is essentially ruptured. In contrast, reactions with retention of the B−C bond are poorly investigated although several other reactive sites in benzyl–boron systems are clearly inherent. In this respect, the novel reactivity of the representative borane adduct IiPr−BH2Bn [IiPr=:C{N(iPr)CH}2, Bn=CH2C6H5] is demonstrated. Dihalogenation of the BH2 entity is observed with BCl3 and BBr3, whereas BI3 either affords IiPr−BHI2 or proceeds with borylation of the aromatic phenyl ring to give a hydride‐bridged bisborylated species. The photochemical mono‐ and dihalogenation of the benzylic CH2 group was demonstrated with elemental bromine Br2. The brominated product IiPr−BBr2−CHBr−C6H5 was borylated at the benzylic carbon atom in an umpolung event with BI3 to afford the zwitterion IiPr−BI−CH(BI3)−C6H5.