Bi−P Bond Homolysis as a Route to Reduced Bismuth Compounds and Reversible Activation of P 4

Direct synthesis of a semiconductive double-helical phosphorus allotrope in a metal-organic framework

There remains much ambiguity regarding the structure of red phosphorus. We report the adsorption and photo-polymerisation of P4 molecules encapsulated in an indium(III)-based metal-organic framework to afford a double-helical chain composite comprising of [P8] units. The similarity between the Raman spectrum of bulk red phosphorus and of the metal-organic framework - (P8)n adduct suggests the presence of such helical chains in the structure of amorphous red phosphorus. This provides crystallographic evidence of the structural building blocks of the red phosphorus allotrope stabilized within the pores of a metal-organic host. The (P8)n inclusion compound is an air-stable semiconductor with a band gap of 2.3 eV, which is relevant for gas detection and photo-catalysis. We demonstrate that this phosphorus adduct demonstrates a 10-fold increase in conversion in the oxidation of methyl orange dye compared with the parent metal-organic framework material.

P+ addition and transfer involving a tetraphosphenium ion

Triphospha[3]ferrocenophane Fe(C5H4-PTip)2PCl (Tip = 2,4,6-tri(isopropyl)phenyl) has been prepared and its suitability to generate the corresponding bisphosphanylphosphenium ion has been explored. By formal addition of P+ to the latter, an unprecedented tetraphosphenium ion forms which likewise is capable of P+ transfer and qualifies as Lewis superacid based on its computed fluoride ion affinity. As a solid, this species is stable and conveniently storable, featuring a remarkably long P-P bond (2.335(5) Å). From this tetraphosphenium ion, known and unprecedented triphosphenium ions have been generated via P+ transfer in solution, including a triphosphenium ion with P-H functionalities. Moreover, the latter has been obtained by tautomeric rearrangement from the corresponding hydrophosphane precursor. The bonding situation and details of the P+ transfer have been investigated by DFT calculations and experimental methods like multinuclear NMR spectroscopy and SC-XRD.

Bismuth as a Z-Type Ligand: an Unsupported Pt-Bi Donor-Acceptor Interaction and its Umpolung by Reaction with H2

Establishing unprecedented types of bonding interactions is one of the fundamental challenges in synthetic chemistry, paving the way to new (electronic) structures, physicochemical properties, and reactivity. In this context, unsupported element-element interactions are particularly noteworthy since they offer pristine scientific information about the newly identified structural motif. Here we report the synthesis, isolation, and full characterization of the heterobimetallic Bi/Pt compound [Pt(PCy3)2(BiMe2)(SbF6)] (1), bearing the first unsupported transition metal→bismuth donor/acceptor interaction as its key structural motif. 1 is surprisingly robust, its electronic spectra are interpreted in a fully relativistic approach, and it reveals an unprecedented reactivity towards H2.

Recent progress on the functionalization of white phosphorus in China

Direct synthesis of organophosphorus compounds from white phosphorus represents a significant but challenging subject, especially in the context of ongoing efforts to comprehensively improve the phosphorus-derived chemical industry driven by sustainability and safety concerns. China is the world's largest producer of white phosphorus, creating a significant demand for the green transformation of this crucial feedstock. This review provides an overview of advancements in white phosphorus activation by Chinese research teams, focusing on the direct construction of P‒C/N/O/S/M bonds from white phosphorus. Additionally, we offer some insights into prospective directions for the activation and transformation of white phosphorus in the future. This review paper aims to attract more researchers to engage in this area, stimulating follow-up exploration and fostering enduring advances.

Fusing Bismuth and Mercaptocarboranes: Design and Biological Evaluation of Low-Toxicity Antimicrobial Thiolato Complexes

This study proposes an innovative strategy to enhance the pharmacophore model of antimicrobial bismuth thiolato complex drugs by substituting hydrocarbon ligand structures with boron clusters, particularly icosahedral closo-dicarbadodecaborane (C2B10H12, carboranes). The hetero- and homoleptic mercaptocarborane complexes BiPh2L (1) and BiL3 (2) (L=9-S-1,2-C2B10H11) were prepared from 9-mercaptocarborane (HL) and triphenylbismuth. Comprehensive characterization using NMR, IR, MS, and XRD techniques confirmed their successful synthesis. Evaluation of antimicrobial activity in a liquid broth microdilution assay demonstrated micromolar to submicromolar minimum inhibitory concentrations (MIC) suggesting high effectiveness against S. aureus and limited efficacy against E. coli. This study highlights the potential of boron-containing bismuth complexes as promising antimicrobial agents, especially targeting Gram-positive bacteria, thus contributing to the advancement of novel therapeutic approaches.

Barium phosphidoboranes and related calcium complexes

The attempted synthesis of [{Carb}BaPPh2] (1) showed this barium-phosphide and its thf adducts, 1·thf and 1·(thf)2, to be unstable in solution. Our strategy to circumvent the fragility of these compounds involved the use of phosphinoboranes HPPh2·BH3 and HPPh2·B(C6F5)3 instead of HPPh2. This allowed for the synthesis of [{Carb}Ae{PPh2·BH3}] (Ae = Ba, 2; Ca, 3), [{Carb}Ca{(H3B)2PPh2}·(thf)] (4), [{Carb}Ba{PPh2·B(C6F5)3}] (5), [{Carb}Ba{O(B(C6F5)3)CH2CH2CH2CH2PPh2}·thf] (6), [Ba{O(B(C6F5)3)CH2CH2CH2CH2PPh2}2·(thf)1.5] (7) and [Ba{PPh2·B(C6F5)3}2·(thp)2] (8) that were characterised by multinuclear NMR spectroscopy (thp = tetrahydropyran). The molecular structures of 4, 6 and 8 were validated by X-ray diffraction crystallography, which revealed the presence of Ba⋯F stabilizing interactions (ca. 9 kcal mol-1) in the fluorine-containing compounds. Compounds 6 and 7 were obtained upon ring-opening of thf by their respective precursors, 5 and the in situ prepared [Ba{PPh2·B(C6F5)3}2]n. By contrast, thp does not undergo ring-opening under the same conditions but affords clean formation of 8. DFT analysis did not highlight any specific weakness of the Ba-P bond in 1·(thf)2. The instability of this compound is instead thought to stem from the high energy of its HOMO, which contains the non-conjugated P lone pair and features significant nucleophilic reactivity.

Bismuth in Radical Chemistry and Catalysis

Whereas indications of radical reactivity in bismuth compounds can be traced back to the 19th century, the preparation and characterization of both transient and persistent bismuth-radical species has only been established in recent decades. These advancements led to the emergence of the field of bismuth radical chemistry, mirroring the progress seen for other main-group elements. The seminal and fundamental studies in this area have ultimately paved the way for the development of catalytic methodologies involving bismuth-radical intermediates, a promising approach that remains largely untapped in the broad landscape of synthetic organic chemistry. In this review, we delve into the milestones that eventually led to the present state-of-the-art in the field of radical bismuth chemistry. Our focus aims at outlining the intrinsic discoveries in fundamental inorganic/organometallic chemistry and contextualizing their practical applications in organic synthesis and catalysis.

Direct Synthesis of Phosphoryltriacetates from White Phosphorus via Visible Light Catalysis

Organophosphorus compounds (OPCs) are widely used in many fields. However, traditional synthetic routes in the industry usually involve multistep and hazardous procedures. Therefore, it's of great significance to construct such compounds in an environmentally-friendly and facile way. Herein, a photoredox catalytic method has been developed to construct novel phosphoryltriacetates. Using fac-Ir(ppy)3 (ppy=2-phenylpyridine) as the photocatalyst and blue LEDs (456 nm) as the light source, white phosphorus can react with α-bromo esters smoothly to generate phosphoryltriacetates in moderate to good yields. This one-step approach features mild reaction conditions and simple operational process without chlorination.

Bismuth in Dynamic Covalent Chemistry: Access to a Bowl-Type Macrocycle and a Barrel-Type Heptanuclear Complex Cation

Dynamic covalent chemistry (DCvC) is a powerful and widely applied tool in modern synthetic chemistry, which is based on the reversible cleavage and formation of covalent bonds. One of the inherent strengths of this approach is the perspective to reversibly generate in an operationally simple approach novel structural motifs that are difficult or impossible to access with more traditional methods and require multiple bond cleaving and bond forming steps. To date, these fundamentally important synthetic and conceptual challenges in the context of DCvC have predominantly been tackled by exploiting compounds of lighter p-block elements, even though heavier p-block elements show low bond dissociation energies and appear to be ideally suited for this approach. Here we show that a dinuclear organometallic bismuth compound, containing BiMe2 groups that are connected by a thioxanthene linker, readily undergoes selective and reversible cleavage of its Bi-C bonds upon exposure to external stimuli. The exploitation of DCvC in the field of organometallic heavy p-block chemistry grants access to unprecedented macrocyclic and barrel-type oligonuclear compounds.

Photochemical Benzylation of White Phosphorus

Organophosphorus compounds (OPCs) have wide application in organic synthesis, material sciences, and drug discovery. Generally, the vast majority of phosphorus atoms in OPCs are derived from white phosphorus (P4). However, the large-scale preparation of OPCs mainly proceeds through the multistep and environmentally toxic chlorine route from P4. Herein, we report the direct benzylation of P4 promoted by visible light. The cheap and readily available benzyl bromide was used as a benzylation reagent, and tetrabenzylphosphonium bromide was directly synthesized from P4. In addition, the metallaphotoredox catalysis strategy was applied to functionalize P4 for the first time, which significantly improved the application range of the substituted benzyl bromide.

Insertion of CO2 and CS2 into Bi-N bonds enables catalyzed CH-activation and light-induced bismuthinidene transfer

The uptake and release of small molecules continue to be challenging tasks of utmost importance in synthetic chemistry. The combination of such small molecule activation with subsequent transformations to generate unusual reactivity patterns opens up new prospects for this field of research. Here, we report the reaction of CO₂ and CS₂ with cationic bismuth(iii) amides. CO₂-uptake gives isolable, but metastable compounds, which upon release of CO₂ undergo CH activation. These transformations could be transferred to the catalytic regime, which formally corresponds to a CO₂-catalyzed CH activation. The CS₂-insertion products are thermally stable, but undergo a highly selective reductive elimination under photochemical conditions to give benzothiazolethiones. The low-valent inorganic product of this reaction, Bi(i)OTf, could be trapped, showcasing the first example of light-induced bismuthinidene transfer.

Divalent metallocenes of the lanthanides - a guideline to properties and reactivity

Since the discovery in the early 1980s, the soluble divalent metallocenes of lanthanides have become a steadily growing field in organometallic chemistry. The predominant part of the investigation has been performed with samarium, europium, and ytterbium, whereas only a few reports dealing with other rare earth elements were disclosed. Reactions of these metallocenes can be divided into two major categories: (1) formation of Lewis acid-base complexes, in which the oxidation state remains +II; and (2) single electron transfer (SET) reductions with the ultimate formation of Ln(III) complexes. Due to the increasing reducing character from Eu(II) over Yb(II) to Sm(II), the plethora of literature concerning redox reactions revolves around the metallocenes of Sm and Yb. In addition, a few reactivity studies on Nd(II), Dy(II) and mainly Tm(II) metallocenes were published. These compounds are even stronger reducing agents but significantly more difficult to handle. In most cases, the metals are ligated by the versatile pentamethylcyclopentadienyl ligand: (C₅Me₅). Other cyclopentadienyl ligands are fully covered but only discussed in detail, if the ligand causes differences in synthesis or reactivity. Thus, the focus lays on three compounds: [(C₅Me₅)₂Sm], [(C₅Me₅)₂Eu] and [(C₅Me₅)₂Yb] and their solvates. We discuss the synthesis and physical properties of divalent lanthanide metallocenes first, followed by an overview of the reactivity rendering the full potential of these versatile reactants.

Synthesis, Isolation, and Characterization of Two Cationic Organobismuth(II) Pincer Complexes Relevant in Radical Redox Chemistry

Herein, we report the synthesis, isolation, and characterization of two cationic organobismuth(II) compounds bearing N,C,N pincer frameworks, which model crucial intermediates in bismuth radical processes. X-ray crystallography uncovered a monomeric Bi(II) structure, while SQUID magnetometry in combination with NMR and EPR spectroscopy provides evidence for a paramagnetic S = 1/2 state. High-resolution multifrequency EPR at the X-, Q-, and W-band enable the precise assignment of the full g- and 209Bi A-tensors. Experimental data and DFT calculations reveal both complexes are metal-centered radicals with little delocalization onto the ligands.

Heavy Chains: Synthesis, Reactivity and Decomposition of Interpnictogen Chains with Terminal Diaryl Bismuth Fragments

In this work, we report the preparation of multiple interpnictogen chain compounds with three consecutive pnictogen atoms and terminal Ar₂ Bi fragments (Ar=Ph, Mes). Symmetrical compounds of the form Ar₂ Bi-E(tBu)-Bi₂ Ar (1: Ar=Ph, E=P; 2: Ar=Ph, Mes, E=As) as well as ternary interpnictogen compounds of the form Ar₂ Bi-E¹ (tBu)-E² tBu₂ (Ar=Ph, Mes; 4: E¹ =P, E² =As; 5: E¹ =P, E² =Sb; 6: E¹ =As, E² =P) were prepared. The decomposition in solution at room temperature and under the influence of light was studied for compounds 1-6. The reactivity of 1_Ph and 2_Ph with the small N-heterocyclic carbene 1,3,4,5-tetramethylimidazol-2-ylidene (Me₂ IMe) was also studied. In the case of 1_Ph , the formation and consecutive decomposition of Me₂ IMe=PtBu (8) was observed in solution. Hence, it was shown that 1_Ph can react as a "masked phosphinidene". In the case of 2_Ph , no reaction with Me₂ IMe was observed. All isolated compounds were analysed by NMR and IR spectroscopy, mass spectrometry, elemental analysis and single-crystal X-ray diffraction.

Recent advances in stable main group element radicals: preparation and characterization

Radical species are significant in modern chemistry. Their unique chemical bonding and novel physicochemical properties play significant roles not only in fundamental chemistry, but also in materials science. Main group element radicals are usually transient due to their high reactivity. Highly stable radicals are often stabilized by π-delocalization, sterically demanding ligands, carbenes and weakly coordinating anions in recent years. This review presents the recent advances in the synthesis, characterization, reactivity and physical properties of isolable main group element radicals.

Binary interpnictogen compounds bearing diaryl bismuth fragments bound to all lighter pnictogens

Multiple interpnictogen compounds with covalent single bonds between a diarylbismuth fragment and all lighter pnictogens were prepared from the corresponding diarylhalido bismuthanes. The aminobismuthanes Ph₂BiNMe₂ (1) and Mes₂BiNMe₂ (2) (Mes = 2,4,6-trimethylphenyl-) have been obtained via a salt metathesis reaction and compound 2 was successfully reacted with tBuNH₂ in a condensation reaction to yield Mes₂BiNHtBu (3). The bismuthanyl phosphanes Ar₂BiPtBu₂ (Ar = Ph: 4 and Ar = Mes: 5) and arsanes Ar₂BiAstBu₂ (Ar = Ph: 8 and Ar = Mes: 9) were also obtained via salt metathesis. Through a trimethylsilyl halide abstraction reaction of the diaryl halido bismuthanes and EtBu(SiMe₃)₂ (E = P and As), the bismuthanyl phosphanes Ar₂BiPtBu(SiMe₃) (Ar = Ph: 6; Ar = Mes: 7) and the arsanes Ar₂BiAstBu(SiMe₃) (Ar = Ph: 10; Ar = Mes: 11) have been prepared. Bismuthanyl stibanes were accessed via a condensation reaction of Mes₂SbH with 1 or 2, respectively. The compound Ph₂BiSbMes₂ (12), which has different substituents at the bismuth and antimony atoms, was isolated and fully characterised. In contrast, the isolation of Mes₂BiSbMes₂ (13) was not possible due to a dynamic equilibrium with Mes₄Bi₂ and Mes₄Sb₂ which was investigated via low-temperature ¹H-NMR spectroscopy in solution. The isolated compounds with a single bond between bismuth and the heavy pnictogens arsenic and antimony are rare examples of their kind. All isolated compounds (1-12) were characterised by NMR and IR spectroscopy, mass spectrometry, elemental analysis and single crystal X-ray diffraction.

From a nanoparticular solid-state material to molecular organo-f-element-polyarsenides

A convenient pathway to new molecular organo-lanthanide-polyarsenides in general and to a f-element complex with the largest polyarsenide ligand in detail is reported. For this purpose, the activation of the solid state material As⁰ _nano (nanoscale gray arsenic) by the multi electron reducing agents [K(18-crown-6)][(Ln^+II)₂(μ-η⁶:η⁶-C₆H₆)] (Ln = La, Ce, Cp'' = 1,3-bis(trimethylsilyl)cyclopentadienyl anion) and [K(18-crown-6)]₂[(Ln^+II)₂(μ-η⁶:η⁶-C₆H₆)] (Ln = Ce, Nd) is shown. These non-classical divalent lanthanide compounds were used as three and four electron reducing agents where the product formation can be directed by variation of the applied reactant. The obtained Zintl anions As₃ ^3-, As₇ ^3-, and As₁₄ ^4- were previously not accessible in molecular 4f-element chemistry. Additionally, the corresponding compounds with As₁₄ ^4--moieties represent the largest organo-lanthanide-polyarsenides known to date.

Bismuth Redox Catalysis: An Emerging Main-Group Platform for Organic Synthesis

Bismuth has recently been shown to be able to maneuver between different oxidation states, enabling access to unique redox cycles that can be harnessed in the context of organic synthesis. Indeed, various catalytic Bi redox platforms have been discovered and revealed emerging opportunities in the field of main group redox catalysis. The goal of this perspective is to provide an overview of the synthetic methodologies that have been developed to date, which capitalize on the Bi redox cycling. Recent catalytic methods via low-valent Bi(II)/Bi(III), Bi(I)/Bi(III), and high-valent Bi(III)/Bi(V) redox couples are covered as well as their underlying mechanisms and key intermediates. In addition, we illustrate different design strategies stabilizing low-valent and high-valent bismuth species, and highlight the characteristic reactivity of bismuth complexes, compared to the lighter p-block and d-block elements. Although it is not redox catalysis in nature, we also discuss a recent example of non-Lewis acid, redox-neutral Bi(III) catalysis proceeding through catalytic organometallic steps. We close by discussing opportunities and future directions in this emerging field of catalysis. We hope that this Perspective will provide synthetic chemists with guiding principles for the future development of catalytic transformations employing bismuth.

Facile synthesis of cyclo-(P4tBu3)-containing oligo- and pnictaphosphanes

The cyclo-(P₄^tBu₃) synthon [Li{cyclo-(P₄^tBu₃)}(thf)(tmeda)] (1) (thf = tetrahydrofuran, tmeda = N,N,N',N'-tetramethylethane-1,2-diamine) is readily accessible in a one-pot synthesis from P₄ and Li^tBu. The use of 1 as a cyclo-(P₄^tBu₃) building block enables the rational synthesis of cyclo-(P₄^tBu₃)-containing oligophosphanes, namely {cyclo-(P₄^tBu₃)}₂ (2), {cyclo-(P₄^tBu₃)}₂P^tBu (3) and {cyclo-(P₄^tBu₃)}₂CH₂ (4), C_3v-symmetric pnictaphosphanes E{cyclo-(P₄^tBu₃)}₃ (E = Bi, Sb, As; 5-7) as well as AsCl{cyclo-(P₄^tBu₃)}₂ (8). Compounds 5 and 6 represent the first neutral homoleptic bismuthane and stibane that contain only bonds to phosphorus. All new compounds were isolated in moderate to good yields and fully characterised. The ³¹P{¹H} NMR spectral data of 1, 2, 4, and 8 have been determined by automated line-shape analysis.

Cationic Bismuth Aminotroponiminates: Charge Controls Redox Properties

The behavior of the redox‐active aminotroponiminate (ATI) ligand in the coordination sphere of bismuth has been investigated in neutral and cationic compounds, [Bi(ATI)₃] and [Bi(ATI)₂L_n][A] (L=neutral ligand; n=0, 1; A=counteranion). Their coordination chemistry in solution and in the solid state has been analyzed through (variable‐temperature) NMR spectroscopy, line‐shape analysis, and single‐crystal X‐ray diffraction analyses, and their Lewis acidity has been evaluated by using the Gutmann–Beckett method (and modifications thereof). Cyclic voltammetry, in combination with DFT calculations, indicates that switching between ligand‐ and metal‐centered redox events is possible by altering the charge of the compounds from 0 in neutral species to +1 in cationic compounds. This adds important facets to the rich redox chemistry of ATIs and to the redox chemistry of bismuth compounds, which is, so far, largely unexplored.

Bismuth Amides Mediate Facile and Highly Selective Pn-Pn Radical-Coupling Reactions (Pn=N, P, As)

The controlled release of well-defined radical species under mild conditions for subsequent use in selective reactions is an important and challenging task in synthetic chemistry. We show here that simple bismuth amide species [Bi(NAr2 )3 ] readily release aminyl radicals [NAr2 ]. at ambient temperature in solution. These reactions yield the corresponding hydrazines, Ar2 N-NAr2 , as a result of highly selective N-N coupling. The exploitation of facile homolytic Bi-Pn bond cleavage for Pn-Pn bond formation was extended to higher homologues of the pnictogens (Pn=N-As): homoleptic bismuth amides mediate the highly selective dehydrocoupling of HPnR2 to give R2 Pn-PnR2 . Analyses by NMR and EPR spectroscopy, single-crystal X-ray diffraction, and DFT calculations reveal low Bi-N homolytic bond-dissociation energies, suggest radical coupling in the coordination sphere of bismuth, and reveal electronic and steric parameters as effective tools to control these reactions.

Well-Defined, Molecular Bismuth Compounds: Catalysts in Photochemically Induced Radical Dehydrocoupling Reactions

A series of diorgano(bismuth)chalcogenides, [Bi(di-aryl)EPh], has been synthesised and fully characterised (E=S, Se, Te). These molecular bismuth complexes have been exploited in homogeneous photochemically-induced radical catalysis, using the coupling of silanes with TEMPO as a model reaction (TEMPO=(tetramethyl-piperidin-1-yl)-oxyl). Their catalytic properties are complementary or superior to those of known catalysts for these coupling reactions. Catalytically competent intermediates of the reaction have been identified. Applied analytical techniques include NMR, UV/Vis, and EPR spectroscopy, mass spectrometry, single-crystal X-ray diffraction analysis, and (TD)-DFT calculations.

Main-Group Metal Complexes in Selective Bond Formations Through Radical Pathways

Recent years have witnessed remarkable advances in radical reactions involving main-group metal complexes. This includes the isolation and detailed characterization of main-group metal radical compounds, but also the generation of highly reactive persistent or transient radical species. A rich arsenal of methods has been established that allows control over and exploitation of their unusual reactivity patterns. Thus, main-group metal compounds have entered the field of selective bond formations in controlled radical reactions. Transformations that used to be the domain of late transition-metal compounds have been realized, and unusual selectivities, high activities, as well as remarkable functional-group tolerances have been reported. Recent findings demonstrate the potential of main-group metal compounds to become standard tools of synthetic chemistry, catalysis, and materials science, when operating through radical pathways.

Synthesis of a Molecule with Five Different Adjacent Pnictogens

The first molecular compound with all five pnictogens was obtained by a multi-step reaction. Lithiation of the (bisamido)diazadiarsetidine (tBuNAs)2 (tBuNH)2 in aliphatic solvents leads to the dimeric metallated species [(tBuNAs)2 (tBuNLi)2 ]2 (12 ). Upon reactions with AsCl3 , SbCl3 and BiCl3 the polycyclic compounds [(tBuNAs)2 (tBuN)2 ]PnCl (Pn=As (2), Sb (3), Bi (4)) can be obtained. Conversion of 2-4 with [tBu2 SbP(tBu)Li(OEt2 )]2 leads to the remarkable interpnictogens [(tBuNAs)2 (tBuN)2 ]PnP(tBu)SbtBu2 (Pn=As (5), Sb (6), Bi (7)), whereby 7 is the first example of a molecule containing all five Group 15 elements. The compound with adjacent AsNBiPSb-chains is surprisingly stable and does not show high sensibility against light as the labile Bi-P bond might suggest.

Isolation of singlet carbene derived 2-arsa-1,3-butadiene radical cations and dications

2-Arsa-1,3-butadienes (L)As(cAACR) (L = PhC[double bond, length as m-dash]C{(NDipp)CH}2, Dipp = 2,6-iPr2C6H3; cAACR = C{(NDipp)CMe2CH2C(R)}, R = Me22a, R = cyclohexyl (Cy) 2b) and the corresponding radical cations [(L)As(cAACR)]GaCl4 (R = Me23a, Cy 3b) and dications [(L)As(cAACR)](GaCl4)2 (R = Me 4a, Cy 4b) featuring a C[double bond, length as m-dash]C-As[double bond, length as m-dash]C π-conjugated framework are reported.

Distibanes and Distibenes from Reduction of Sb(NONR )Cl by using MgI Reagents

The bis(amidodimethyl)disiloxane antimony chlorides Sb(NON^R )Cl (NON^R =[O(SiMe₂ NR)₂ ]^2- ; R=tBu, Ph, 2,6-Me₂ C₆ H₃ =Dmp, 2,6-iPr₂ C₆ H₃ =Dipp, 2,6-(CHPh₂ )₂ -4-tBuC₆ H₂ =tBu-Bhp) are reduced to Sb^II and Sb^I species by using Mg^I reagents, [Mg(BDI^R' )]₂ (BDI=[HC{C(Me)NR'}₂ ]^- ; R'=2,4,6-Me₃ C₆ H₂ =Mes, Dipp). Stoichiometric reactions with Sb(NON^R )Cl (R=tBu, Ph) form dimeric Sb^II stibanes [Sb(NON^R )]₂ , shown crystallographically to contain Sb-Sb single bonds. The analogous distibane with R=Dmp substituents has an exceptionally long Sb-Sb interaction and exhibits spectroscopic and reactivity properties consistent with radical character in solution. When R=Dipp, reductions with Mg^I reagents directly give distibenes [Sb(μ-NON^Dipp )Mg(BDI^R' )(THF)_n ]₂ (R'=Mes, n=1; R'=Dipp, n=0). Crystallographic analysis shows a trans-substitution of the Sb=Sb double bond, with bridging NON^Dipp -ligands between the Sb^I and Mg^II centres. An attempt to access the NON^Ph -analogue using the same protocol afforded the polystibide cluster Sb₈ [μ₄ ,η^2:2:2:2 -Mg(BDI^Mes )]₄ , which co-crystallized with the ligand transfer product, [Mg(BDI^Mes )]₂ (μ-NON^Ph ).

Direct functionalization of white phosphorus with anionic dicarbenes and mesoionic carbenes: facile access to 1,2,3-triphosphol-2-ides

A series of unique C₂P₃-ring compounds [(ADC^Ar)P₃] (4) are readily accessible in an almost quantitative yield by the direct functionalization of white phosphorus (P₄) with appropriate anionic dicarbenes [Li(ADC^Ar)].

A series of unique C₂P₃-ring compounds [(ADC^Ar)P₃] (ADC^Ar = ArC{(DippN)C}₂; Dipp = 2,6-iPr₂C₆H₃; Ar = Ph 4a, 3-MeC₆H₄4b, 4-MeC₆H₄4c, and 4-Me₂NC₆H₄4d) are readily accessible in an almost quantitative yield by the direct functionalization of white phosphorus (P₄) with appropriate anionic dicarbenes [Li(ADC^Ar)]. The formation of 1,2,3-triphosphol-2-ides (4a–4d) suggests unprecedented [3 + 1] fragmentation of P₄ into P₃⁺ and P^–. The P₃⁺ cation is trapped by the (ADC^Ar)^– to give 4, while the putative P^– anion reacts with additional P₄ to yield the Li₃P₇ species, a useful reagent in the synthesis of organophosphorus compounds. Remarkably, the P₄ fragmentation is also viable with the related mesoionic carbenes (iMICs^Ar) (iMIC^Ar = ArC{(DippN)₂CCH}, i stands for imidazole-based) giving rise to 4. DFT calculations reveal that both the C₃N₂ and C₂P₃-rings of 4 are 6π-electron aromatic systems. The natural bonding orbital (NBO) analyses indicate that compounds 4 are mesoionic species featuring a negatively polarized C₂P₃-ring. The HOMO–3 of 4 is mainly the lone-pair at the central phosphorus atom that undergoes σ-bond formation with a variety of metal-electrophiles to yield complexes [{(ADC^Ar)P₃}M(CO)_n] (M = Fe, n = 4, Ar = Ph 5a or 4-Me-C₆H₄5b; M = Mo, n = 5, Ar = Ph 6; M = W, n = 5, Ar = 4-Me₂NC₆H₄7).

A study of di(amino)stibines with terminal Sb(iii) hydrogen-ligands by X-ray- and neutron-diffraction

The bis(amidodimethyl)disiloxane ligands [O{SiMe2NR}2]2- (R = 2,6-Me2C6H3 (Ar') and 2,6-iPr2C6H3 (Ar), abbreviated [NONR]2-, are a stable support for Sb(iii) complexes of general formula Sb(NONR)X (X = Cl, H). The compounds are monomeric in the solid-state, with bidentate N,N'-coordination of the [NONR]2- and terminal chloride/hydrogen-ligands. Sb(NONAr')H was analyzed by single-crystal neutron diffraction, giving the first accurate parameters for the Sb-H bond to an antimony(iii) centre.

Samarium Polyarsenides Derived from Nanoscale Arsenic

Zintl phases of arsenic and molecular compounds containing Zintl-type polyarsenide ions are of fundamental interest in basic and applied sciences. Unfortunately, the most obvious and reactive arsenic source for the preparation of defined molecular polyarsenide compounds, yellow arsenic As₄ , is very inconvenient to prepare and neither storable in pure form nor easy to handle. Herein, we present the synthesis and reactivity of elemental As⁰ nanoparticles (As⁰ _Nano , d=7.2±1.8 nm), which were successfully utilized as a reactive arsenic source in reductive f-element chemistry. Starting from [Cp*₂ Sm] (Cp*=η⁵ -C₅ Me₅ ), the samarium polyarsenide complexes [(Cp*₂ Sm)₂ (μ-η² :η² -As₂ )] and [(Cp*₂ Sm)₄ As₈ ] were obtained from As⁰ _nano , thereby generating the largest molecular polyarsenide of the f-elements and circumventing the use of As₄ in preparative chemistry.

Synthesis and crystal structures of novel tertiary butyl substituted (pseudo-)halogen bismuthanes

The di-tertiary butyl substituted (pseudo-)halogen bismuthanes tBu₂BiX (X = Cl, Br, I, CN, N₃, SCN) were obtained by different synthetic strategies. They show secondary bonding interactions in the solid state and can be used for the synthesis of ternary group 15 element compounds.

Reduction vs. Addition: The Reaction of an Aluminyl Anion with 1,3,5,7-Cyclooctatetraene

The potassium aluminyl complex K[Al(NON^Ar )] (NON=NON^Ar =[O(SiMe₂ NAr)₂ ]^2- , Ar=2,6-iPr₂ C₆ H₃ ) reacts with 1,3,5,7-cyclooctatetraene (COT) to give K[Al(NON^Ar )(COT)]. The COT-ligand is present in the asymmetric unit as a planar μ₂ -η² :η⁸ -bridge between Al and K, with additional K⋅⋅⋅π-aryl interactions to neighboring molecules that generate a helical chain. DFT calculations indicate significant aromatic character, consistent with reduction to [COT]^2- . Addition of 18-crown-6 causes a rearrangement of the C₈ -carbocycle to form the isomeric 9-aluminabicyclo[4.2.1]nona-2,4,7-triene anion.

Catalytic oxidative coupling promoted by bismuth TEMPOxide complexes

Bismuth(iii) TEMPOxide complexes are active catalysts for oxidative coupling reactions to generate TEMPO silylethers.