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Recent advances in luminescent materials highlight the significant impact of hydrogen isotope effects on improving optoelectronic properties. However, the research on the influence of the boron isotope effects on photophysical properties remains underdeveloped. This study focused on exploring the boron isotope effects in boron‐cluster‐based luminogens. In doing so, we designed and synthesized carborane‐based luminogens containing 98 % 10B and 95 % 11B, respectively, and observed distinct photophysical behaviors. Compared to the 10B‐enriched luminogens, the 11B‐enriched counterparts can significantly enhance luminescence efficiency, prolong emission lifetime, and reduce full‐width at half‐maximum. Additionally, increased thermal stability, redshifted B−H vibrations, and a fourfold enhanced electrochemiluminescence intensity have also been observed. On the other hand, the biological assessments of a 10B‐enriched luminogen reveals low cytotoxicity, high boron uptake, and excellent fluorescence imaging capability, indicating the potential application in boron neutron capture therapy (BNCT). This work presents the first comprehensive exploration on the boron isotope effects in boron clusters, and provides valuable insights into the rational design of organic luminogens for advanced optoelectronic and biomedical applications. [ABSTRACT FROM AUTHOR]

A dearomative addition of readily available carboranyllithium reagents to isoquinolinium salts gave a series of carborane cage C‐substituted 1,2‐dihydroisoquinolines in 43–85 % yields. Subsequent hydrogenation enabled the facile synthesis of corresponding carboranyl 1,2,3,4‐tetrahydroisoquinolines in 65–95 % yields. The addition‐reduction pathway is applicable to a wide range of substituted isoquinolinium salts and o‐carborane or m‐carborane. [ABSTRACT FROM AUTHOR]

In this work, we present our improved protocols for the single batch syntheses of approximately 32 g of [NHMe3][CB11H12] and 10 g of Na[CHB11F11] as well as salt metathesis reactions, granting access to useful starting materials to introduce the [CHB11F11]− anion. This includes the trityl cation [Ph3C]+ and the bis‐1,2‐difluorobenzene‐silver(I)‐complex [Ag(odfb)2]+, as well as some applications of the shown compounds. The described methodology allows the synthesis of large amounts of both the [CB11H12]− and the [CHB11F11]− anion and therefore making them accessible for further reactions. To facilitate the reproducibility, we present video tutorials of the synthetic steps towards Na[CHB11F11]. [ABSTRACT FROM AUTHOR]

Carborane compounds, known for their exceptional thermal stability and non‐toxic attributes, have garnered widespread utility in medicine, supramolecular design, coordination/organometallic chemistry, and others. Although there is considerable interest among chemists, the integration of suitable carborane molecules into ferroelectric materials remains a formidable challenge. In this study, we employ the quasi‐spherical design strategy to introduce functional groups at the boron vertices of the o‐carborane cage, aiming to reduce molecular symmetry. This approach led to the successful synthesis of the pioneering ferroelectric crystals composed of cage‐like carboranes: 9‐OH‐o‐carborane (1) and 9‐SH‐o‐carborane (2), which undergo above‐room ferroelectric phase transitions (Tc) at approximately 367 K and 347 K. Interestingly, 1 and 2 represent uniaxial and multiaxial ferroelectrics respectively, with 2 exhibiting six polar axes and as many as twelve equivalent polarization directions. As the pioneering instance of carborane ferroelectric crystals, this study introduces a novel structural archetype for molecular ferroelectrics, thereby providing fresh insights into the exploration of molecular ferroelectric crystals with promising applications. [ABSTRACT FROM AUTHOR]

Herein, we report the unique multiple‐stimuli responsiveness of anthracene‐tethered o‐carborane derivatives. We designed and synthesized anthracene derivatives with different substitution positions and numbers of the o‐carborane units. Two compounds had characteristic crystal structures involving the columnar π‐stacking structures of the anthracene units. From the analysis of crystalline‐state structure–property relationships, it was revealed that the crystals exhibited the photosalient effect accompanied by photochemical [4+4] cycloaddition reactions and temperature‐dependent photophysical dual‐emission properties including excimer emission of anthracene. Those properties were considered as non‐radiative and radiative deactivation pathways through the excimer formation in the excited state and the formation of excimer species was facilitated by the π‐stacking structure of anthracene units. Moreover, we found unusual temperature dependency on the occurrence of the photosalient effect. According to the data from variable temperature X‐ray crystallography, a strong correlation between lattice shrinkage and strain accumulation is suggested. [ABSTRACT FROM AUTHOR]

Several ortho‐carboranes bearing a phenoxy or a phenylamino group in the B9 position were prepared employing various protection and deprotection strategies. Following established protocols, dendritic compounds were synthesized from a hexachlorocyclotriphosphazene or thiophosphoryl chloride core, and possible anchoring options for the B9‐substituted ortho‐carboranes were investigated experimentally and theoretically (DFT). Furthermore, 1‐ or 1,2‐phosphanyl‐substituted carborane derivatives were obtained. The resulting diethyl‐, diisopropyl‐, di‐tert‐butyl‐, diphenyl‐ or diethoxyphosphines bearing a tunable ortho‐carborane moiety are intriguing ligands for future applications in homogeneous catalysis or the medicinal sector. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: This work describes a general method for the synthesis of a series of sulfenylated and selenylated carboranes at room temperature using readily available iodocarboranes as starting materials via boron‐centered carboranyl radicals. Such hypervalent boron radicals are generated by a visible‐light‐promoted Pd(0)/Pd(I) pathway. They are useful intermediates and can be trapped by disulfides and phenylselenyl chloride for the convenient construction of B—S/Se bonds. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: This work describes a general method for the synthesis of a series of sulfenylated and selenylated carboranes at room temperature using readily available iodocarboranes as starting materials via boron‐centered carboranyl radicals. Such hypervalent boron radicals are generated by a visible‐light‐promoted Pd(0)/Pd(I) pathway. They are useful intermediates and can be trapped by disulfides and phenylselenyl chloride for the convenient construction of B—S/Se bonds. [ABSTRACT FROM AUTHOR]

Derivatives of the nido‐7,8‐C2B9H12(1‐) (dicarbollide ion) and [3,3′‐Co‐(1,2‐C2B9H11)2](1‐) cobalt sandwich (COSAN) ion represent groups of extremely chemically and thermally stable abiotic compounds. They are being investigated in many research areas, that is, medicinal chemistry, material sciences, analytical chemistry, and electrochemistry. The chirality of these compounds remains still grossly overlooked, what is also reflected in limited number of reports on their chiral separations. Continued progress depends on reliable, fast, and cost‐effective methods for such separations. Recently, chiral separations of COSAN derivatives were achieved in liquid chromatography and supercritical fluid chromatography. Only five anionic derivatives of nido‐7,8‐C2B9H12(1‐) were successfully enantioseparated in liquid chromatography. Efforts to separate anionic nido‐7,8‐C2B9H12(1‐) in supercritical chromatography have failed, and only a few dicarbollide ions were separated using liquid chromatography. Generally, all chiral separations in liquid chromatography took about 30 min. Herein, we identify a versatile column capable of separating both COSAN and nido‐7,8‐C2B9H12(1‐) derivatives and achieve faster analyses times employing commercially available superficially porous chiral stationary phases. The semisynthetic hydroxypropyl β‐cyclodextrin‐based column (CDShell‐RSP) is identified as the column of choice from the tested columns by separating 19 of 27 compounds from each structural motifs tested mainly in less than 10 min. The dihydroxyalkyl, oxygen‐bridged hydroxyalkyl, and bisphenylene‐bridged COSAN derivatives were baseline separated in less than 5 min exceeding the results of supercritical fluid chromatography. Methods developed herein will aid synthetic chemists without the possession of a supercritical fluid chromatograph to achieve fast chiral separations of COSAN and derivatives of nido‐7,8‐C2B9H12(1‐) on a common liquid chromatograph without the need of dedicated instrumentation. [ABSTRACT FROM AUTHOR]

Due to their limited capacity for π‐backdonation, isolation of π‐complexes of main‐group elements remains a great challenge. We report herein the synthesis of a homoleptic diphosphene lead complex (2) from the degradation of P4 with a bis(germylene)‐stabilized Pb(0) complex. Structural and computational studies showed that 2 possesses significant π bonding interactions between Pb atom and diphosphene ligands, which is reminiscent of transition‐metal diphosphene complexes. Consistent with its unique electronic structure, complex 2 can deliver Pb(0) atoms to perform redox reaction with an iminoquinone to produce a cyclic plumbylene (4) and perform 2,5‐dimethyl‐3,4‐dimethylimidazol‐1‐ylidene (IMe2Me2) induced phosphorus cation abstraction to give an anionic PbP3 complex (6). [ABSTRACT FROM AUTHOR]

Multi‐metallic multivariate (MTV) rare earth (RE) metal−organic frameworks (MOFs) are of interest for the development of multifunctional materials, however examples with more than three RE cations are rare and obstructed by compositional segregation during synthesis. Herein, this work demonstrates the synthesis of a multi‐metallic MTV RE MOF incorporating two, four, six, or eight different RE ions with different sizes and in nearly equimolar amounts and no compositional segregation. The MOFs are formed by a combination of RE cations (La, Ce, Eu, Gd, Tb, Dy, Y, and Yb) and a 1,7‐di(4‐carboxyphenyl)‐1,7‐dicarba‐closo‐dodecaborane (mCB‐L) linker. The steric bulkiness and acidity of mCB‐L is crucial for the incorporation of different size RE ions into the MOF structure. Demonstration of the incorporation of all RE cations is performed via compositional and structural characterization. The more complex MTV MOF, including all eight RE ions (mCB‐8RE), are also characterized using optical, thermal, and magnetic techniques. Element‐selective X‐ray absorption spectroscopy and X‐ray Magnetic Circular Dichroism measurements allow us to characterize spectroscopically each of the eight RE ions and determine their magnetic moments. This work paves the way for the investigation of MTV MOFs with the possibility to combine RE ions à la carte for diverse applications. [ABSTRACT FROM AUTHOR]

The synthesis of monocarborane sulfonamides is reported. The methodology relies on coupling of the anionic {CB11} boron cluster to sulfonyl azides. Under rhodium catalysis and with the assistance of a pyridine or pyrimidine directing group at the C1 position, the cluster undergoes B−H activation. Conditions have been identified that lead to B2‐selective mono‐sulfonamidation with concomitant loss of N2. The protocol requires no additional ligand, oxidant or base and enables B−N bond formation with various monocarborane and sulfonyl azide inputs. The new products possess the structure [1‐(heteroaryl)‐2‐(NHSO2Ar)−CB11H10]− and have been fully characterized by NMR spectroscopy and mass spectrometry. In addition, three solid state structures confirm the particular B2 substitution pattern. Furthermore, the stoichiometric reaction of the pyridinyl monocarborane precursor with Rh(III) affords a cyclometalated complex with a direct B−Rh bond that has also been characterized by X‐ray crystallography. [ABSTRACT FROM AUTHOR]

This study reports unique luminescent properties of pyrene‐substituted nido‐carborate anion (PYnCA) with two counter cations, tetrabutylammonium (NBu4+) and tetraphenylphosphonium (PPh4+). It is revealed that PYnCA shows twisted intramolecular charge transfer (TICT) emission by the change of the dihedral angle between pyrene and the CcageCcage bond in the carborane unit in the excited state. Although the structure of nCA is almost same as that of ortho‐carborane (oC), the photophysical processes of both pyrene‐substituted compounds are completely different. The study also succeeds in modulating the luminescence species by counter cations in both solution and solid states. To the best of the current knowledge, this is the first report that anion‐based luminescent materials can show the different luminescent species not only in solution but also in the mechanochromic behaviors depending on the type of counter cations. This fundamental research on nCA demonstrates anion‐based emitters as a new platform for stimuli‐responsive materials. [ABSTRACT FROM AUTHOR]

Luminochromic behaviors regarding mechanochromic luminescence (MCL) of o‐carborane‐modified anthracene derivatives are reported. We have previously synthesized bis‐o‐carborane‐substituted anthracene and found that its crystal polymorphs show dual‐emission properties composed of excimer and charge transfer (CT) emission bands in the solid state. Initially, we observed the bathochromic MCL behavior from 1 a originating from emission mechanism alteration from dual emission to CT emission. By inserting the ethynylene spacers between anthracene and o‐carboranes, compound 2 was obtained. Interestingly, 2 showed hypsochromic MCL originating from the emission mechanism alteration from CT to excimer emission. Furthermore, luminescent color of ground 1 a can be recovered to the initial state by allowing to stand at room temperature, meaning that self‐recovery proceeds. Detailed analyses are described in this study. [ABSTRACT FROM AUTHOR]

Visible‐light‐induced photoreaction of carboranes is an effective approach to prepare carborane‐containing compounds. While several methods involving boron‐centered carboranyl radicals have been established, those for carbon‐centered carboranyl radicals are underdeveloped, except for the UV‐light‐promoted photohomolysis. Herein, we describe a simple but effective approach to access carbon‐centered carboranyl radicals by photoreduction of carborane phosphonium salts under blue light irradiation without using transition metals and photocatalysts. The utility of the method was demonstrated by successfully preparing a range of carborane‐oxindole‐pharmaceutical hybrids by radical cascade reactions. Computational and experimental studies suggest that the carbon‐centered carboranyl radicals are generated by single‐electron transfer of the photoactive charge‐transfer complexes between the salts and the additive potassium acetate. [ABSTRACT FROM AUTHOR]

Reaction of B(4)‐acylmethyl o‐carborane with 2‐azido‐1,3‐dimethylimidazolinium hexafluorophosphate (ADMP) in the presence of 1,8‐diazabicyclo[5.4.0]‐undec‐7‐ene (DBU) in acetonitrile at 25 °C for 3 h produced a wide range of o‐carboranyl‐acyl‐substituted diazo compounds in high yields with good functional group tolerance. [ABSTRACT FROM AUTHOR]

Reexamination of the co‐pyrolysis reactions of B2Cl4 with C2Cl4 at 350 °C and of B2Br4 with CBr4 at 300 °C in vacuo confirmed the carboranes C2B5Cl7 (1), C2B7Cl9 (2), and C2B5Br7 (3) as low‐yield products. While 1 only could be concentrated by repeated vacuum fractionation, 2 and 3 could now be isolated from the conglomerate mixtures for a full spectroscopic characterization and the compounds were verified in their geometries by detailed DFT computations. Surprisingly, the perhalogenated carboranes do not adopt the expected "all‐endo"‐geometries with cluster sizes derived by the sum of the n boron and two carbon atoms (n+2) as known from the syntheses of the parent closo‐carboranes C2BnHn+2. Instead, DFT/GIAO(ZORA)/NMR (GIAO for X=Cl, ZORA for X=Br) computations revealed that the perhalogenated carboranes favor structures with BX2 groups as exo‐skeletal ligands attached to both cage‐carbon atoms yielding the five‐vertex closo‐1,5‐(CBX2)2B3X3 (1: X=Cl; 3: X=Br) and the seven‐vertex closo‐2,4‐(CBCl2)2B5Cl5 for 2. In contrast to these perhalogenated carboranes, analogous computations on the hydrogen substituted carboranes C2BnHn+2, silaboranes Si2BnHn+2 and Si2BnXn+2 (n=5, 7) show in all cases a thermodynamic favorization of structures where all boron atoms of the formula are endo‐skeletally incorporated into the cluster frameworks. [ABSTRACT FROM AUTHOR]

Direct insertion of unsaturated substrates into a five‐membered borole ring is a useful method to obtain valuable heterocycles containing one or more three‐coordinate boron atoms. A highly Lewis acidic 9‐o‐carboranyl‐9‐borafluorene, in which the o‐carboranyl substituent is connected via one of the cluster carbon atoms to the boron atom of the 9‐borafluorene unit, was found to react with a vast array of unsaturated molecules, such as alkynes, aldehydes and various organic azides, to form larger boraheterocyclic products. The ring expansion reactions of the central borole ring proceed rapidly at room temperature, cementing the role of the o‐carboranyl substituent in enhancing the insertion reactivity of 9‐borafluorenes. [ABSTRACT FROM AUTHOR]

The syntheses of the first B9‐connected carboranylphosphines (B9‐Phos) featuring two carboranyl moieties as well as access to B9‐Phos ligands with bulky electron‐donating substituents, previously deemed unattainable, is reported. The electrochemical properties of the B9‐Phos ligands were investigated, revealing the ability of the mesityl derivatives to form stabilized phosphoniumyl radical cations. The B9‐Phos ligands display an extremely electron‐releasing character surpassing that of alkyl phosphines and commonly used N‐heterocyclic carbenes. This is demonstrated by their very small Tolman electronic parameters (TEPs) as well as extremely low P−Se coupling constants. Cone angles and buried volumes attest to the high steric demand exerted by the (di)carboranyl phosphines. The dicarboranyl phosphine AuI complexes show superior catalytic performance in the hydroamination of alkynes compared to the monocarboranyl phosphine analogs. [ABSTRACT FROM AUTHOR]

Closo‐carborane anions are prominent, whereas the cations of the same are less abundant in the literature. As these ions have similar size and are weakly coordinating, the ionic liquids of these two ions could have important applications in many areas of chemistry. In view of limited number of polyhedral carborane cations available, we revisited the rearrangement of dicarboranyl methyl cation (7‐CH2 7,9‐nido‐C2B9H10+) using ab initio molecular dynamics calculations with metadynamics. Our simulations confirmed the concerted mechanism of the rearrangement. We believe this work will resume the interest in its synthesis and carborane cations in general. [ABSTRACT FROM AUTHOR]

We report herein the synthesis of a stable plumbylone (3) by reduction of a bromodigermylplumbylene (2) with 2.2 equiv of potassium graphite (KC8). The molecular structure of 3 was established by a single‐crystal X‐ray diffraction study and features a two‐coordinated Pb center with an acute Ge−Pb−Ge bond angle. Computational studies showed that this complex (3) possesses a singlet electronic ground state with a Pb0 center. Its high thermal stability can be most likely ascribed to the delocalization of π electrons over the Ge−Pb−Ge moiety. A preliminary reactivity study demonstrates that complex 3 can deliver Pb0 atoms to an organic azide producing a tetrameric imido complex [(PbNDipp)4] (Dipp=2,6‐iPr‐C6H3, 4) and perform a metathesis reaction with GeCl2⋅dioxane to produce a bis(germylene)‐stabilized germylone (5), highlighting the synthetic utility of 3. [ABSTRACT FROM AUTHOR]

Herein, we report the unique solid‐state excimer emission of three types of acridine‐tethered o‐carboranes with variable degrees of methylation at the o‐carborane unit. They all showed columnar packing structures based on dimer formation, and two types of π‐overlapping motifs were alternately stacked. From the photoluminescence (PL) measurements on the crystalline samples, it was found that three types of luminescence bands can simultaneously appear: monomer emission, excimer emission from the moderately π‐stacked intra‐dimer unit, and excimer emission from the widely π‐stacked inter‐dimer unit. Consequently, the PL colors were drastically changed by the steric effect of the methyl groups, with a strong correlation found between the π‐overlapping and excimer character. In addition, variable‐temperature PL measurements revealed that these PL species should be in thermal equilibrium at room temperature, with the intensity ratios sensitive toward temperature changes. [ABSTRACT FROM AUTHOR]

Carboranes, a three‐dimensional class of carbon‐boron molecular clusters with remarkable electronic, physical, chemical characteristics, have proved as useful building blocks in boron neutron capture therapy agents, supramolecular design, optoelectronics, nanomaterials and organometallic/coordination chemistry. Thus, various organic modifications of the B−H and C−H functionalities in carboranes have been developed. These methods with great success utilize directing groups, such as carboxylic acids, to achieve a selective B−H functionalization of carboranes. The carboxyl group can be easily introduced to carboranes and then be removed after reactions. On the other hand, assisted by the carboxyl group a highly regioselective electrophilic attack at the electron‐rich positions B(4) and B(5) of the cage generates five‐membered metallacyclic intermediates, which then undergo further transformation. In this review, we show that transition metal‐catalyzed decarboxylation cross coupling reactions offer an opportunity for the selective and direct B−H activation of carboranes. [ABSTRACT FROM AUTHOR]

Realization of practical sodium metal batteries (SMBs) is hindered due to lack of compatible electrolyte components, dendrite propagation, and poor understanding of anodic interphasial chemistries. Chemically robust liquid electrolytes that facilitate both favorable sodium metal deposition and a stable solid‐electrolyte interphase (SEI) are ideal to enable sodium metal and anode‐free cells. Herein we present advanced characterization of a novel fluorine‐free electrolyte utilizing the [HCB11H11]1− anion. Symmetrical Na cells operated with this electrolyte exhibit a remarkably low overpotential of 0.032 V at a current density of 2.0 mA cm−2 and a high coulombic efficiency of 99.5 % in half‐cell configurations. Surface characterization of electrodes post‐operation reveals the absence of dendritic sodium nucleation and a surprisingly stable fluorine‐free SEI. Furthermore, weak ion‐pairing is identified as key towards the successful development of fluorine‐free sodium electrolytes. [ABSTRACT FROM AUTHOR]

The synthesis of tris(ortho‐carboranyl)borane (BoCb3), a single site neutral Lewis superacid, in one pot from commercially available materials is achieved. The high fluoride ion affinity (FIA) confirms its classification as a Lewis superacid and the Gutmann‐Beckett method as well as adducts with Lewis bases indicate stronger Lewis acidity over the widely used fluorinated aryl boranes. The electron withdrawing effect of ortho‐carborane and lack of pi‐delocalization of the LUMO rationalize the unusually high Lewis acidity. Catalytic studies indicate that BoCb3 is a superior catalyst for promoting C−F bond functionalization reactions than tris(pentafluorophenyl)borane [B(C6F5)3]. [ABSTRACT FROM AUTHOR]

Herein, we report the structures of chiral‐at‐cage carborane derivatives bearing carbazole chromophores that emit circularly polarized luminescence (CPL) and aggregation‐induced electrochemiluminescence (AIECL). By adjusting the substituent positions on the carborane derivatives, two chiral luminescent molecules, Cb1 and Cb2, with different properties were obtained. The photoluminescence dissymmetry factors |gPL| of both (R/S)‐Cb1 and (R/S)‐Cb2 enantiomers in neat films were as high as 6.24×10−3 and 7.38×10−3, respectively. Cb1 showed a deep blue emission peak at 434 nm in n‐pentane. Interestingly, distinct fluorescence and CPL spectra were observed in solvents of different polarities due to the twisted intramolecular charge transfer effect, suggesting its potential use in solvent recognition. Meanwhile, Cb2 exhibited good AIECL property, excellent ECL stability and could be used for determining dopamine concentrations, suggesting its potential applications in biology and diagnosis. [ABSTRACT FROM AUTHOR]

Functionalization of carboranes in a vertex‐specific manner is a perennial challenge. Here, we report a photocatalytic B−C coupling for the selective functionalization of carboranes at the boron site which is most distal to carbon. This reaction was achieved by the photo‐induced decarboxylation of carborane carboxylic acids to generate boron vertex‐centered carboranyl radicals. Theoretical calculations also demonstrate that the reaction more easily occurs at the boron site bearing higher electron density owing to the lower energy barrier for a single‐electron transfer to generate a carboranyl radical. By using this strategy, a number of functionalized carboranes could be accessed through alkylation, alkenylation, and heteroarylation under mild conditions. Moreover, both a highly efficient blue emitter with a solid‐state luminous efficiency of 42 % and a drug candidate for boron neutron capture therapy (BNCT) containing targeting and fluorine units were obtained. [ABSTRACT FROM AUTHOR]

Herein, we report the facile synthesis of a three‐dimensional (3D) inorganic analogue of 9,10‐diazido‐9,10‐dihydrodiboraantracene, which turned out to be a monomer in both the solid and solution state, and thermally stable up to 230 °C, representing a rare example of azido borane with boosted Lewis acidity and stability in one. Apart from the classical acid‐base and Staudinger reactions, E−H bond activation (E=B, Si, Ge) was investigated. While the reaction with B−H (9‐borabicyclo[3.3.1]nonane) led directly to the 1,1‐addition on Nα upon N2 elimination, the Si−H (Et3SiH, PhMe2SiH) activation proceeded stepwise via 1,2‐addition, with the key intermediates 5int and 6int being isolated and characterized. In contrast, the cooperative Ge−H was reversible and stayed at the 1,2‐addition step. [ABSTRACT FROM AUTHOR]

Density functional theory was used to investigate the possible migration mechanism of the B−H activation on carboranes. The effects of inducing groups, mediating atoms and ligands were clarified, and the specific reaction process and driving force of transition metal migration in carboranes were explored. The study of thermodynamics, dynamics, wave function analysis and bond order showed that hydrogen atoms and ligands had remarkable effects on metal migration in carboranes. Results indicated that the transition metal complexes can migrate between B/B or C/B mediated by H‐atom, which contributes to the regioselective B−H activation of carboranes. [ABSTRACT FROM AUTHOR]

The classical aggregation‐induced emission (AIE)‐active luminogens (AIEgens) usually include two‐dimensional aromatic systems such as tetraphenylethenes, which are synthesized in several steps by using toxic additives. Here, we proposed a new molecular design strategy for the realization of AIE properties by combining three‐dimensional aromatic boron clusters of carboranes with vinyl group(s). To obtain a library of the boron cluster‐based AIEgens, a Pd‐catalyzed hydroboration of alkynes with carboranes is reported. This reaction protocol proceeds in one step under mild conditions with rapid reaction rate, excellent yields and regioselectivity. Photophysical property studies demonstrate that the facile molecular motions in solution can be inhibited in the solid state for these molecules, which leads to interesting AIE properties. This work provides not only a general design principle for AIEgens but also an efficient methodology to synthesize boron cluster‐based photo‐functional molecules. [ABSTRACT FROM AUTHOR]

Subtle tailoring of gold nanoclusters (NCs) could significantly change their physicochemical properties. However, direct comparison of the catalytic performance of gold NCs with identical metal cores but distinct ligand shells is rarely elucidated. In this work, a novel gold NC, Au28(C2B10H11S)12(tht)4Cl4 (Au28‐S), was isolated by a facile self‐reducing synthesis. Au28‐S adopts an identical Au28 metal framework to that of the reported alkynyl‐protected Au28‐C. The different protective layers lead to distinctions in their electronic structure and optical properties. Furthermore, Au28‐S shows better catalytic activity for the electrochemical reduction of CO2 to CO. Theoretical calculations identified the active sites and shed light on the catalytic mechanism to elucidate the different catalytic performances. This work provides an ideal platform to study the protective layer‐activity relationship of gold NCs, and may also provide guidance in the design of metal NC‐based catalysts. [ABSTRACT FROM AUTHOR]

The nucleophilic aromatic BH substitution reaction of carboranes is uncommon, compared to the electrophilic one. This work reported a pyridine‐enabled transition‐metal‐free regioselective nucleophilic aromatic cage B(4)‐H amination of 1,2‐diaryl‐o‐carboranes with magnesium bisamides, giving a series of B(4)‐aminated o‐carboranes. DFT calculations showcased a stepwise B−N formation/B−H cleavage process, in which Mg−H formation/cage closure is the rate‐determining step. Unprecedentedly, in the presence of 4,4′‐di‐tert‐butyl‐2,2′‐dipyridyl (dtbpy), a tandem B(4)‐amination/cage isomerization reaction of o‐carboranes was discovered for the facile preparation of B(2)‐aminated m‐carboranes. Control experiments indicated that magnesium complex, bidentate ligand (dtbpy) and reaction temperature were crucial in the cage isomerization process. This direct nucleophilic aromatic cage B−H amination reaction offers an alternative strategy for selective amination of o‐ and m‐carboranes. [ABSTRACT FROM AUTHOR]

A family of fully sandwiched arachno‐lanthanacarborane complexes formulated as {η6‐[μ‐1,2‐[o‐C6H4(CH2)2]‐1,2‐C2B10H10]2Ln}{Li5(THF)10} (Ln=Tb, Dy, Ho, Er, Y) is successfully synthesized, where the "carbons‐adjacent" carboranyl ligand (arachno‐R2‐C2B10H104−) bears four negative charges and coordinates to the central lanthanide ions using the hexagonal η6C2B4 face. Thus, the central lanthanide cations are pseudo‐twelve‐coordinate and have an approximate pseudo‐D6h symmetry or hexagonal‐prismatic geometry. As the crystal field effect imparted by this geometry is still unknown, we thoroughly investigated the magnetic properties of this series of complexes and found that the crystal field imposed by this ligand causes a relation of Tb>Dy>Ho>Er for the energy gaps between the ground and the first excited states, which is of striking resemblance to the ferrocenophane and phthalocyanine ligands although the latter two ligands give disparate local coordination geometries. Moreover, the effective energy barrier to magnetization reversal of 445(10) K, the observable hysteresis loop up to 4 K and the relaxation time of the yttrium‐diluted sample reaching 193(17) seconds at 2 K under an optimized field for the Tb analogue of this family of arachno‐lanthanacarborane complexes, render a new benchmark for Tb3+‐based single‐molecule magnets. [ABSTRACT FROM AUTHOR]

New types of metal‐free white phosphorus (P4) activation are reported. While the phosphine‐silylene‐substituted dicarborane 1, CB‐SiP (CB=ortho‐C,C′‐C2B10H10, Si=PhC(tBuN)2Si, P=P[N(tBu)CH2]2), activates white phosphorus in a 2 : 1 molar ratio to yield the P5‐chain containing species 2, the analogous bis(silylene)‐substituted compound 3, CB‐Si2, reacts with P4 in the molar ratio of 2 : 1 to furnish the first isolable 1,3‐diphospha‐2,4‐disilabutadiene (Si=P−Si=P‐containing) compound 4. For the latter reaction, two intermediates having a CB‐Si2P4 and CB‐Si2P2 core could be observed by multinuclear NMR spectroscopy. The compounds 2 and 4 were characterized including single‐crystal X‐ray diffraction analyses. Their electronic structures and mechanisms were investigated by density functional theory calculations. [ABSTRACT FROM AUTHOR]

A robust method for the selective labeling of peptides via manganese(I) catalysis was devised to achieve the C‐2 alkenylation of tryptophan containing peptides with 1‐ethynyl‐o‐carboranes. The manganese‐catalyzed C−H activation was accomplished with high catalytic efficiency, and featured low toxicity, high functional group tolerance and excellent E‐stereoselectivity. This approach unravels a promising tool for the assembly of o‐carborane with structurally complex peptides of relevance to applications in boron neutron capture therapy. [ABSTRACT FROM AUTHOR]

We developed o‐carborane as a new mechanophore by showing that the o‐carborane cluster is the preferred scission site in chain‐centered polymers through ultrasonication mechanochemistry. Mechanistic studies are consistent with a predominately homolytic mechanism of chain scission. The mechanically generated monocarbaborane fragments are highly reactive toward alcohol nucleophiles. By contrast, carborane with a different regiochemistry (m‐carborane) maintained its high mechanical stability. DFT simulations provide insights into the origins of carborane's mechanical lability. This fundamental research provides a new stimulus for carborane cage activation. [ABSTRACT FROM AUTHOR]

The primary phosphines MesPH2 and tBuPH2 react with 9‐iodo‐m‐carborane yielding B9‐connected secondary carboranylphosphines 1,7‐H2C2B10H9‐9‐PHR (R=2,4,6‐Me3C6H2 (Mes; 1 a), tBu (1 b)). Addition of tris(pentafluorophenyl)borane (BCF) to 1 a, b resulted in the zwitterionic compounds 1,7‐H2C2B10H9‐9‐PHR(p‐C6F4)BF(C6F5)2 (2 a, b) through nucleophilic para substitution of a C6F5 ring followed by fluoride transfer to boron. Further reaction with Me2SiHCl prompted a H−F exchange yielding the zwitterionic compounds 1,7‐H2C2B10H9‐9‐PHR(p‐C6F4)BH(C6F5)2 (3 a, b). The reaction of 2 a, b with one equivalent of R'MgBr (R'=Me, Ph) gave the extremely water‐sensitive frustrated Lewis pairs 1,7‐H2C2B10H9‐9‐PR(p‐C6F4)B(C6F5)2 (4 a, b). Hydrolysis of the B−C6F4 bond in 4 a, b gave the first tertiary B‐carboranyl phosphines with three distinct substituents, 1,7‐H2C2B10H9‐9‐PR(p‐C6F4H) (5 a, b). Deprotonation of the zwitterionic compounds 2 a, b and 3 a, b formed anionic phosphines [1,7‐H2C2B10H9‐9‐PR(p‐C6F4)BX(C6F5)2]−[DMSOH]+ (R=Mes, X=F (6 a), R=tBu, X=F (6 b); R=Mes, X=H (7 a), R=tBu, X=H (7 b)). Reaction of 2 a, b with an excess of Grignard reagents resulted in the addition of R' at the boron atom yielding the anions [1,7‐H2C2B10H9‐9‐PR(p‐C6F4)BR'(C6F5)2]− (R=Mes, R'=Me (8 a), R=tBu, R'=Me (8 b); R=Mes, R'=Ph (9 a), R=tBu, R'=Ph (9 b)) with [MgBr(Et2O)n]+ as counterion. The ability of the zwitterionic compounds 3 a, b to hydrogenate imines as well as the Brønsted acidity of 3 a were investigated. [ABSTRACT FROM AUTHOR]

The discovery of colossal barocaloric effects in organic plastic crystals has significantly advanced the development of solid‐state refrigerant techniques. Adapting to the real application, a tradeoff of various barocaloric performances has to be achieved. Here, it is reported a novel plastic crystal system, that is, carboranes (C2B10H12), including three positional isomers: ortho‐carborane, meta‐carborane, and para‐carborane, which are characterized by C2v, C2v, D5d point groups, respectively. They all undergo an orthorhombic‐to‐tetragonal phase transition around room temperature. Compared to the previously reported organic plastic crystals, this system exhibits a combination of large pressure‐normalized entropy changes, the high‐pressure sensitivity of the transition temperature, small thermal hysteresis, and so forth. Their barocaloric performances are positional‐isomerism dependent, and the best performances are obtained in para‐carborane with maximum entropy changes of about 106.2 J kg−1 K−1 achieved under pressure changes below 30 MPa. This study not only suggests that carboranes would be a considerably promising working material for barocaloric refrigeration at room temperature but also indicates that delicate tuning of molecular isomerism is an effective strategy to enhance barocaloric performances. [ABSTRACT FROM AUTHOR]

Carboranes are boron–carbon molecular clusters that possess unique properties, such as their icosahedron geometry, high boron content, and delocalized three‐dimensional aromaticity. These features render carboranes valuable building blocks for applications in supramolecular design, nanomaterials, optoelectronics, organometallic coordination chemistry, and as boron neutron capture therapy (BNCT) agents. Despite tremendous progress in this field, stoichiometric chemical redox reagents are largely required for the oxidative activation of carborane cages. In this context, electrosyntheses represent an alternative strategy for more sustainable molecular syntheses. It is only in recent few years that considerable progress has been made in electrochemical cage functionalization of carboranes, which are summarized in this Minireview. We anticipate that electrocatalysis will serve as an increasingly powerful stimulus within the current renaissance of carborane electrochemistry. [ABSTRACT FROM AUTHOR]

It is still challenging to realize a dual‐emission system, in which two luminescent bands simultaneously appear by photoexcitation, in solid with organic dyes due to the difficulty in regulation of electronic properties in the excited state and concentration quenching. o‐Carborane is known to be a versatile platform for constructing solid‐state emitters since the sphere boron cluster is favorable for suppressing intermolecular interactions and subsequently concentration quenching. Here, we show solid‐state dual‐emissive o‐carborane derivatives. We prepared 4 types of o‐carborane derivatives and found dual‐emission behaviors both in solution and solid states. By regulating the rotation at the o‐carborane unit with the intramolecular CcageH⋅⋅⋅O interaction, the dual‐emission intensity ratios were changed. Finally, it was demonstrated that the overall photoluminescence spectra can be estimated using the binding energy of intramolecular interactions. [ABSTRACT FROM AUTHOR]

Invited for the cover of this issue are the groups and colleagues of Anne‐Marie Caminade at the CNRS and University of Toulouse, Evamarie Hey‐Hawkins at Leipzig University, and Agustí Lledós from the Autonomous University of Barcelona. The image depicts birds crowned by a carborane competing for access to food, to illustrate the steric hindrance encountered when grafting carboranes to dendrimers (artwork by Dr. Christoph Selg). Read the full text of the article at 10.1002/chem.202303867. [ABSTRACT FROM AUTHOR]

During the Search for a relationship between boranes and allotropes of elemental boron, several chemical problems came up: mechanism of 1,2‐shift in vinyl cations, relative stability of polyhedral boranes, carboranes, pyramidal cations, Non‐planar 2π aromaticity, pseudo π* aromaticity, sequential dehydrogenation and polycondensation of polyhedral boranes, design of stuffed boron fullerenes and C−C bond making and breaking processes belong to this group. A common thread that runs through these projects is the use of frontier molecular orbitals to design, control and explain chemical observations. Such manipulation of molecular orbitals as a design element is introduced here as Orbital Engineering which continues to help in 2D boron also. [ABSTRACT FROM AUTHOR]

Fluorescent nanohybrids, based on π‐extended hydroxyoxophosphole ligands grafted onto ZnO nanoparticles, are designed and studied. The restriction of the intramolecular motions of the organic fluorophore, through either aggregates' formation in solution or processing into thin films, forms highly emissive materials due to a strong aggregation induced emission effect. Theoretical calculations and XPS analyses were performed to analyze the interactions between the organic and inorganic counterparts. Preliminary results on the use of these nanohybrids as solution‐processed emissive layers in organic light emitting diodes (OLEDs) illustrate their potential for lighting applications. [ABSTRACT FROM AUTHOR]

The reaction of the known closo‐ruthenacarborane 3‐H‐3‐Cl‐3,3‐(PPh3)2‐closo‐3,1,2‐RuC2B9H11 with tridentade nitrogen‐based ligands of the general formula (C5NH4CH2)2NR (R=H, Me, Et, iPr, But) in benzene solution at 60 °C allowed us to isolate novel ruthenacarborane clusters 3,3,3‐(2'‐NC5H4CH2)2NR‐pseudocloso‐3,1,2‐RuC2B9H11. According to the performed X‐ray study, the obtained compounds are the first examples of pseudocloso‐metallacarboranes bearing unsubstituted C2B92−nido‐carborane ligand. In spite of the determined pseudocloso structure of the complexes in the solid state, the recorded 11B{1H} NMR spectra indicate that some of them are converted into the closo isomers in solution. The conducted quantum‐chemical calculations have confirmed the subtle difference between two configurations and possible rearrangement in solution. The performed electrochemical investigations show the ability of the formed ruthenacarboranes to undergo reversible oxidation to Ru(III) species. [ABSTRACT FROM AUTHOR]

The aryltellurenyl cation [2‐(tBuNCH)C6H4Te]+, a Lewis super acid, and the weakly coordinating carborane anion [CB11H12]−, an extremely weak Brønsted acid (pKa=131.0 in MeCN), form an isolable ion pair complex [2‐(tBuNCH)C6H4Te][CB11H12], in which the Brønsted acidity (pKa 7.4 in MeCN) of the formally hydridic B−H bonds is dramatically increased by more than 120 orders of magnitude. The electrophilic activation of B−H bonds in the carborane moiety gives rise to a proton transfer from boron to nitrogen at slightly elevated temperatures, as rationalized by the isolation of a mixture of the zwitterionic isomers 12‐ and 7‐[2‐(tBuN{H}CH)C6H4Te(CB11H11)] in ratios ranging from 62 : 38 to 80 : 20. [ABSTRACT FROM AUTHOR]

Main observation and conclusion: The steric and electronic properties of N‐heterocyclic carbenes (NHCs) can be modified by the exocyclic substituents at the nitrogen atoms, by 1—3 atoms' replacements of the five‐membered imidazolium skeleton and by the changes of the backbones. Herein, we report the usage of nido‐C2B9 carborane anions as the backbones of NHCs. Stirring the mixture of secondary amino o‐carboranes (1b—1e), triethyl orthoformate and HBF4∙Et2O results in the unexpected cage‐opening of o‐carboranes to afford the nido‐C2B9 carborane anions supported N‐heterocyclic carbene precursors (4b—4e). Deprotonation of 4b with sodium hexamethyldisilazide at −78 oC affords the N‐heterocyclic carbene ligand, which was used to form an Au(I) NHC complex (5). DFT calculations revealed a high‐lying lone pair orbitals of the carbene ligands, predicting their strong σ‐donating abilities. [ABSTRACT FROM AUTHOR]

An efficient synthesis of an acid‐free neutral oxoborane of the type carboranyl‐B(carbene)=O has been developed via a serendipitous discovery from the reaction of 1,2‐[BBr(carbene)]‐o‐carborane with AgOTf. This represents a new type of oxoborane. The stabilization of this oxoborane may be attributed to 1) kinetic stabilization provided by a bulky 3D carboranyl ligand and 2) thermodynamic stabilization offered by a carbene ligand. Crystallographic analyses support the presence of the shortest terminal B=O double bond ever reported thus far. Its reactivity has also been examined. [ABSTRACT FROM AUTHOR]

Using the chelating C,C′‐bis(silylenyl)‐ortho‐dicarborane ligand, 1,2‐(RSi)2‐1,2‐C2B10H10 [R=PhC(NtBu)2], leads to the monoatomic zero‐valent Ge complex ("germylone") 3. The redox non‐innocent character of the carborane scaffold has a drastic influence on the reactivity of 3 towards reductants and oxidants. Reduction of 3 with one molar equivalent of potassium naphthalenide (KC10H8) causes facile oxidation of Ge0 to GeI along with a two‐electron reduction of the C2B10 cluster core and subsequent GeI‐GeI coupling to form the dianionic bis(silylene)‐supported Ge2 complex 4. In contrast, oxidation of 3 with one molar equivalent of [Cp2Fe][B{C6H3(CF3)2}4] as a one‐electron oxidant furnishes the dicationic bis(silylene)‐supported Ge2 complex 5. The Ge0 atom in 3 acts as donor towards GeCl2 to form the trinuclear mixed‐valent Ge0→GeII←Ge0 complex 6, from which dechlorination with KC10H8 affords the neutral Ge2 complex 7 as a diradical species. [ABSTRACT FROM AUTHOR]

We report the novel single‐step 1,2‐dicarbofunctionalization of an arylacetylene with an allylsilane and tris(pentafluorophenyl)borane [B(C6F5)3] involving C−C bond formation with C−H bond scission at the β‐position to the silicon atom of an allylsilane and B→C migration of a C6F5 group. The 1,2‐carbopentafluorophenylation occurs smoothly without the requirement for a catalyst or heating. Mechanistic studies suggest that the metallomimetic "pull‐push" reactivity of B(C6F5)3 imparts consecutive electrophilic and nucleophilic characteristics to the benzylic carbon of the arylacetylene. Subsequent photochemical 6π‐electrocyclization affords tetrafluoronaphthalenes, which are important in the pharmaceutical and materials sciences. Owing to the unique reactivity of B(C6F5)3, the 1,2‐carbopentafluorophenylation using 2‐substituted furan proceeded with ring opening, and the reaction using silyl enolates formed a C−C bond with C−O bond scission at the silyloxy‐substituted carbon. [ABSTRACT FROM AUTHOR]

The weakly coordinating dianion [B12Cl12]2− originates from a family of carboranes typically reserved for application in coordination chemistry. Herein, we show that its readily accessible Ag(I) salt, [Ag]2[B12Cl12], can be used as a catalyst in the PhICl2 mediated chlorination of arenes, alkenes, and alkynes. The promising activity displayed by [Ag]2[B12Cl12] over a variety of commercially available Ag(I) sources merits its incorporation to the toolkit of commonly screened silver catalysts in synthesis. [ABSTRACT FROM AUTHOR]