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The development of ligands capable of effectively stabilizing highly reactive main‐group species has led to the experimental realization of a variety of systems with fascinating properties. In this work, we computationally investigate the electronic, structural, energetic, and bonding features of proximity‐enforced group 13–15 homodimers stabilized by a rigid expanded pincer ligand based on the 1,8‐naphthyridine (napy) core. We show that the redox‐active naphthyridine diimine (NDI) ligand enables a wide variety of structural motifs and element‐element interaction modes, the latter ranging from isolated, element‐centered lone pairs (e.g., E = Si, Ge) to cases where through‐space π bonds (E = Pb), element‐element multiple bonds (E = P, As) and biradical ground states (E = N) are observed. Our results hint at the feasibility of NDI‐E2 species as viable synthetic targets, highlighting the versatility and potential applications of napy‐based ligands in main‐group chemistry.

Using the AlI precursor Cp3tAl in conjunction with triphosphiranes (PAr)3 (Ar=Mes, Dip, Tip) we have succeeded in preparing Lewis base‐free cyclic diphosphadialanes with both the Al and P atoms bearing three substituents. Using the sterically more demanding Dip and Tip substituents the first 1,2‐diphospha‐3,4‐dialuminacyclobutanes were obtained, whereas with Mes substituents [Cp3tAl(μ‐PMes)]2 is formed. This divergent reactivity was corroborated by DFT studies, which indicated the thermodynamic preference for the 1,2‐diphospha‐3,4‐dialuminacyclobutane form for sterically more demanding groups on phosphorus. Using Cp*Al we could extend this concept to the corresponding cyclic diarsadialanes [Cp*Al(μ‐AsAr)]2 (Ar=Dip, Tip) and additionally add the phosphorus variants [Cp*Al(μ‐PAr)]2 (P=Mes, Dip, Tip). The reactivity of one variant [Cp3tAl(μ‐PPh)]2 towards NHCs was tested and resulted in double NHC‐stabilised [Cp3t(IiPr2)Al(μ‐PPh)]2., Pnictaalenes with a pnictogen−aluminium double bond are inherently unstable and prone to dimerization. The synthesis of Lewis‐base‐free dipnictadialenes is revealed. It is shown that depending on the steric profile of the substituents either the alternating [Cp x Al(μ‐PAr)]2 dimers or the head‐to‐head species [ArPnAlCp3t]2 are formed. DFT studies corroborate that the different outcomes are thermodynamically driven.

The B-nucleophilic 9H-9-borafluorene dianion reacts with 9-chloro-9-silafluorene to afford air- and moisture-stable silylborate salts M[Ar

The reaction of a cyclic alkyl(amino)carbene (CAAC)-stabilized thiazaborolo[5,4-d]thiazaborole (TzbTzb) with strong Brønsted acids, such as HCl, HOTf (Tf=O

Die 1:2-Reaktion von [μ-(dmpm)Pt(nbe)]\(_{2}\) (dmpm=Bis(dimethylphosphino)methan, nbe=Norbornen) mit Cl\(_{2}\)BNR(SiMe\(_{3}\)) (R=tBu, SiMe\(_{3}\)) führt durch eine B-N-Kupplung über eine ClSiMe\(_{3}\)-Eliminierung zu unsymmetrischen (N-Aminoboryl)aminoboryl-Pt\(^{I}\)\(_{2}\)-Komplexen. Eine anschließende intramolekulare ClSiMe\(_{3}\)-Eliminierung des tBu-Derivats führt zu einer Cyclisierung der BNBN-Einheit unter Bildung eines einzigartigen 1,3,2,4-Diazadiboretidin-2-yl-Liganden. Im Gegensatz hierzu steht die analoge Reaktion mit Br\(_{2}\)BN(SiMe\(_{3}\))\(_{2}\), die über eine zweifache BrSiMe\(_{3}\)-Eliminierung zu einem Pt\(^{II}\)\(_{2}\)-A-Frame-Komplex führt, der von einem linearen Isoster des Butatriens verbrückt wird. Strukturelle und theoretische Daten bestätigen eine π-Elektronen-Delokalisierung über die gesamte BNBN-Einheit.

The NHC-stabilised diboryne (B\(_2\)(SIDep)\(_2\); SIDep=1,3-bis(2,6-diethylphenyl)imidazolin-2-ylidene) undergoes a high-yielding P−P bond activation with tetraethyldiphosphine at room temperature to form a B\(_2\)P\(_2\) heterocycle via a diphosphoryldiborene by 1,2-diphosphination. The heterocycle can be oxidised to a radical cation and a dication, respectively, depending on the oxidant used and its counterion. Starting from the planar, neutral 1,3-bis(alkylidene)-1,3-diborata-2,4-diphosphoniocyclobutane, each oxidation step leads to decreased B−B distances and loss of planarity by cationisation. X-ray analyses in conjunction with DFT and CASSCF/NEVPT2 calculations reveal closed-shell singlet, butterfly-shaped structures for the NHC-stabilised dicationic B\(_2\)P\(_2\) rings, with their diradicaloid, planar-ring isomers lying close in energy.

Boron tribromide and aryldihaloboranes were found to undergo 1,3-haloboration across one W-N≡N moiety of a group 6 end-on dinitrogen complex (i.e. trans-[W(N2 )2 (dppe)2 ]). The N-borylated products consist of a reduced diazenido unit sandwiched between a WII center and a trivalent boron substituent (W-N=N-BXAr), and have all been fully characterized by NMR and IR spectroscopy, elemental analysis, and single-crystal X-ray diffraction. Both the terminal N atom and boron center in the W-N=N-BXAr unit can be further derivatized using electrophiles and nucleophiles/Lewis bases, respectively. This mild reduction and functionalization of a weakly activated N2 ligand with boron halides is unprecedented, and hints at the possibility of generating value-added nitrogen compounds directly from molecular dinitrogen.

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Geringe HOMO-LUMO-Abstände und eine hohe Ladungsträgermobilität prädestinieren die höheren Acene für Anwendungen im Bereich der Organoelektronik. Die Leistungsfähigkeit derartiger Verbindungen steigt hierbei dramatisch mit der Anzahl anellierter Benzolringe. Größere Acenmengen sind synthetisch bisher jedoch nur für Acene bis Heptacen verlässlich zugänglich. Theoretischen Studien zufolge besitzen (Oligo)acene offenschalige Singulettbiradikal- und (Poly)acene polyradikalische Grundzustände. Eindeutige experimentelle Belege für diese Vorhersagen sind hingegen äußerst selten. Durch den Einbau von zwei Boratomen in das Anthracengrundgerüst konnten wir den HOMO-LUMO-Abstand von Acenen dramatisch verringern und zwar ohne die Notwendigkeit einer Ausweitung des konjugierten π-Systems. Stabilisierung der Borzentren durch cyclische (Alkyl)(amino)carbene lieferte hierbei neutrale 9,10-Diboraanthracene mit disjunkten, offenschaligen Singulettbiradikal-Grundzuständen.

Narrow HOMO–LUMO gaps and high charge‐carrier mobilities make larger acenes potentially high‐efficient materials for organic electronic applications. The performance of such molecules was shown to significantly increase with increasing number of fused benzene rings. Bulk quantities, however, can only be obtained reliably for acenes up to heptacene. Theoretically, (oligo)acenes and (poly)acenes are predicted to have open‐shell singlet biradical and polyradical ground states, respectively, for which experimental evidence is still scarce. We have now been able to dramatically lower the HOMO–LUMO gap of acenes without the necessity of unfavorable elongation of their conjugated π system, by incorporating two boron atoms into the anthracene skeleton. Stabilizing the boron centers with cyclic (alkyl)(amino)carbenes gives neutral 9,10‐diboraanthracenes, which are shown to feature disjointed, open‐shell singlet biradical ground states., 9,10‐diboraanthracenes (DBAs) stabilized by cyclic (alkyl)(amino)carbenes (cAACs) are prepared. EPR spectroscopy and quantum chemistry established disjointed singlet biradical ground states for these molecules, which provides experimental evidence for the predicted open‐shell configurations of larger acenes. The incorporation of two boron atoms is a suitable way to lower the HOMO–LUMO band gaps of acene‐type species.

Double ruthenium(II)-catalyzed alkyne annulations of quinones were accomplished. Thus, a strategy is reported that provides step-economical access to valuable quinones with a wide range of applications. C-H/N-H activations for alkyne annulations of naphthoquinones provided challenging polycyclic quinoidal compounds by forming four new bonds in one step. The singular power of the thus-obtained compounds was reflected by their antileukemic activity.

Herein we describe the first examples of isolable electron‐precise diboranes(4) that bear azide moieties: the acyclic 1,2‐diazido‐1,2‐bis(dimethylamino)diborane(4) and the cyclic 1,4‐diaryl‐2,3‐diazido‐1,4‐diaza‐2,3‐diborinines (aryl=mesityl, 2,6‐xylyl, 4‐tolyl). The reported examples are not only stable enough to be observed and isolated (putative transient diborane(4) azides previously reported by our group spontaneously decompose even below room temperature), but some of them are even robust enough to undergo controlled pyrolysis without explosive decomposition at temperatures well above 100 °C. In two cases, the controlled pyrolysis allows the isolation of complex diazaboretidines, which are the apparent dimerization products of endocyclic boryl‐iminoboranes., Potentially explosive yet mild‐mannered! The synthesis and reactivity of diamino‐substituted diborane(4) diazides, the first diborane(4) azides, is reported. Despite the presence of energetic and oxidizing azide groups and of reactive B−B bonds, they are astonishingly robust. The species do not decompose below 100 °C. Two diazides could be pyrolyzed in a controlled manner to diazadiboretidines, the dimerization product of transient iminoboranes.

The reduction of a cyclic alkyl(amino)carbene (CAAC)‐stabilized organoberyllium chloride yields the first neutral beryllium radical, which was characterized by EPR, IR, and UV/Vis spectroscopy, X‐ray crystallography, and DFT calculations., The reduction of a cyclic alkyl(amino)carbene (CAAC)‐stabilized organoberyllium chloride yields the first neutral beryllium radical, which was characterized by EPR, IR, UV/Vis spectroscopy and X‐ray crystallography. DFT calculations show significant spin density at beryllium and confirm donor–acceptor bonding between an alkylberyllium radical fragment and a neutral CAAC ligand.