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CO2 fixation and reduction to value‐added products is of utmost importance in the battle against rising CO2 levels in the Earth's atmosphere. An organoaluminum complex containing a formal aluminum double bond (dialumene), and thus an alkene equivalent, was used for the fixation and reduction of CO2. The CO2 fixation complex undergoes further reactivity in either the absence or presence of additional CO2, resulting in the first dialuminum carbonyl and carbonate complexes, respectively. Dialumene (1) can also be used in the catalytic reduction of CO2, providing selective formation of a formic acid equivalent via the dialuminum carbonate complex rather than a conventional aluminum–hydride‐based cycle. Not only are the CO2 reduction products of interest for C1 added value products, but the organoaluminum complexes isolated represent a significant step forward in the isolation of reactive intermediates proposed in many industrially relevant catalytic processes. [ABSTRACT FROM AUTHOR]

Heterodiatomic multiple bonds have never been observed within Group 13. Herein, we disclose a method that generates [(CAAC)PhB=AlCp3t] (1), a complex featuring π bonding between boron and aluminum through the association of singlet fragments. We present the properties of this multiple bond as well as the reactivity of the complex with carbon dioxide, which yields a boron CO complex via an unusual metathesis reaction. [ABSTRACT FROM AUTHOR]

Heterodiatomic multiple bonds have never been observed within Group 13. Herein, we disclose a method that generates [(CAAC)PhB=AlCp3t] (1), a complex featuring π bonding between boron and aluminum through the association of singlet fragments. We present the properties of this multiple bond as well as the reactivity of the complex with carbon dioxide, which yields a boron CO complex via an unusual metathesis reaction. [ABSTRACT FROM AUTHOR]

The olefinic C−H bond functionalization of (NHC)CHPh (NHC=IPr=C{(NAr)CH}21; SIPr=C{(NAr)CH2}22; Ar=2,6‐iPr2C6H3), derived from classical N‐heterocyclic carbenes (NHCs), with PCl3 affords the dichlorovinylphosphanes {(NHC)C(Ph)}PCl2 (NHC=IPr 3, SIPr 4). Two‐electron reduction of 3 and 4 with magnesium leads to the formation of the divinyldiphosphenes [{(NHC)C(Ph)}P]2 (NHC=IPr 5, SIPr 6) as crystalline solids. Unlike literature‐known diphosphenes, which are mostly yellow or orange, 5 is a green whereas 6 is a purple solid. Although the P=P bond lengths of 5 (2.062(1)) and 6 (2.055(1) Å) are comparable to those of the known diphosphenes (2.02–2.08 Å), the C−P bond lengths of 5 (1.785(1)) and 6 (1.797(1) Å) are, however, considerably shorter than a Csp2 −P single bond length (1.85 Å), indicating a considerable π‐conjugation between C=C and P=P moieties. The HOMO–LUMO energy gap for 5 (4.15) and 6 (4.52 eV) is strikingly small and thus the narrowest among the diphosphenes (>4.93 eV) reported as yet. Consequently, 5 readily undergoes P=P bond cleavage at room temperature on treatment with sulfur to form the unique dithiophosphorane {(IPr)C(Ph)}P(S)27. Interestingly, reaction of 5 with selenium gives the selenadiphosphirane [{(IPr)C(Ph)}P]2Se 8 with an intact P−P bond. [ABSTRACT FROM AUTHOR]

The lability of B=B, B−P, and B–halide bonds is combined in the syntheses of the first diiododiborenes. In a series of reactivity tests, these diiododiborenes undergo cleavage of all six of their central bonds in different ways, leading to products of B=B hydrogenation and dihalogenation as well as halide exchange. The lability of B=B, B−P, and B–halide bonds is combined in the synthesis of the first diiododiborenes. In a series of reactivity tests, these diiododiborenes undergo cleavage of all six of their central bonds in different ways. [ABSTRACT FROM AUTHOR]

The diboration of the C≡N bond in organic nitriles, and the N=N bond in azobenzene and pyridazine, by the highly Lewis‐acidic tetra(o‐tolyl)diborane(4) are reported. In the reactions with nitriles, azobenzene, and pyridazine, the addition of diborane(4) to the C≡N and N=N bonds was observed. Conversely, the N=N bond in phthalazine was cleaved by an addition/rearomatization sequence. Double down: The diboration of the C≡N bond in organic nitriles, and the N=N double bond in azobenzene and pyridazine, by the highly Lewis‐acidic (o‐tol)2BB(o‐tol)2 are reported. In the reactions with nitriles, azobenzene, and pyridazine, the addition of the diborane(4) to the C≡N and N=N bonds was observed. Conversely, the N=N bond in phthalazine was cleaved by an addition‐rearomatization sequence. [ABSTRACT FROM AUTHOR]

In all likelihood the first synthesis of the phosphaethynolate anion, PCO−, was performed in 1894 when NaPH2 was reacted with CO in an attempt to make Na(CP) accompanied by elimination of water. This reaction was repeated 117 years later when it was discovered that Na(OCP) and H2 are the products of this remarkable transformation. Li(OCP) was synthesized and fully characterized in 1992 but this salt proved to be too unstable to allow for a detailed investigation of its chemistry. It was not until the heavier analogues of this lithium salt were isolated, Na(OCP) and K(OCP) (both of which are remarkably stable and can be even dissolved in water), that the chemistry of this new functional group could be explored. Here we review the chemistry of the 2‐phosphaethynolate anion, a heavier phosphorus‐containing analogue of the cyanate anion, and describe the wide breadth of chemical transformations for which it has been thus far employed. Its use as a ligand, in decarbonylative and deoxygenative processes, and as a building block for novel heterocycles is described. In the mere twenty‐six years since Becker first reported the isolation of this remarkable anion, it has become a fascinating reagent for the synthesis of a vast library of, often unprecedented, molecules and compounds. Round about NaOCP: The chemistry of the 2‐phosphaethynolate anion, a heavier phosphorus‐containing analogue of the cyanate anion, is comprehensively reviewed. This simple anion allows a wide breadth of chemical transformations leading to heterocycles, π‐conjugated molecules, and metal phosphides. [ABSTRACT FROM AUTHOR]

The synthesis and isolation of stable main group compounds featuring multiple bonds has been of great interest for several decades. A plethora of such multiply bonded complexes have been obtained by using sterically demanding substituents that provide both kinetic and thermodynamic stability. Most of these compounds have unusual structural and electronic properties that challenge the classical concept of covalent multiple bonding. In contrast, analogous aluminium compounds are scarce in spite of its high natural abundance. The parent dialumene (Al2H2) has been calculated to be extremely unstable, thus making compounds containing Al multiple bonds a challenging synthetic target. This Review provides an overview of the recent advances in the cutting edge synthetic approaches and the careful ligand design used to obtain aluminium homo‐ and heterodiatomic multiply bonded complexes. In addition, the reactivity of these novel compounds towards various small molecules and reagents will be discussed herein. Experimentally challenging and intellectually intriguing, the field of aluminium homo‐ and heterodiatomic multiply bonded complexes and their reactivity has made signficant progress in recent years. This Review outlines some of the cutting edge synthetic approaches and careful ligand design that have paved the way for this success. [ABSTRACT FROM AUTHOR]

Abstract: A series of monomeric rare‐earth metal silyl‐thiophosphinoyl‐alkylidene complexes [LLn{C(SiR3)PPh2S}] (5: Ln=Lu, R=Me; 6: Ln=Lu, R=Ph; 7: Ln=Y, R=Me; 8: Ln=Y, R=Ph; 9: Ln=Sm, R=Ph; 10: Ln=Sm, R=Me; 11: Ln=La, R=Ph; L=[MeC(NDIPP)CHC(Me)(NCH2CH2N(Me)2)]−, DIPP=2,6‐(iPr)2C6H3) have been synthesized and structurally characterized. The influences of rare‐earth metal ions, ancillary ligands, and alkylidene groups on the reactivity of complexes 5–11 and the related scandium complexes [LSc{C(SiR3)PPh2S}] (1: R=Me; 2: R=Ph) and [L′Sc{C(SiR3)PPh2S}] (3: R=Me; 4: R=Ph; L′=[MeC(NDIPP)CHC(Me)(NCH2CH2N(iPr)2)]−) have been studied. Reactions of these rare‐earth metal alkylidene complexes with PhCN give four kinds of products, the formation of which is dependent on the rare‐earth metal ions, ancillary ligands, and alkylidene groups of the complexes. In the reactions with tBuNC, unusual C−P bond cleavage of the alkylidene group and C≡C triple bond formation occur. Complexes 10 and 11 also react with PhSiH3 to form hydrides, which subsequently undergo Ln−H addition to the C=N bond of the ancillary ligand L. DFT calculations have been used to analyze the bonding in complex 10, which exhibits a polarized three centers Sm−C−P π interaction, and to rationalize the reactivity by computing reaction mechanisms. The difference in reactivity of PhCN and tBuNC is due to the electron density delocalization that is enabled by the phenyl group rather than the tBu group. [ABSTRACT FROM AUTHOR]

The reactions of two equivalents of LGa {L = HC[C(Me)N(2,6‐iPr2C6H3)]2} with SbX3 (X = Br, I, OEt) proceed with elimination of LGaX2 and formation of Ga‐substituted distibenes [L(X)GaSb]2 [X = Br (1), I (2), OEt (3)]. Compounds 1 to 3 were characterized by heteronuclear NMR (1H, 13C), IR and UV/Vis spectroscopy, elemental analysis, and single‐crystal X‐ray diffraction. [ABSTRACT FROM AUTHOR]

The reactions of two equivalents of LGa {L = HC[C(Me)N(2,6‐iPr2C6H3)]2} with SbX3 (X = Br, I, OEt) proceed with elimination of LGaX2 and formation of Ga‐substituted distibenes [L(X)GaSb]2 [X = Br (1), I (2), OEt (3)]. Compounds 1 to 3 were characterized by heteronuclear NMR (1H, 13C), IR and UV/Vis spectroscopy, elemental analysis, and single‐crystal X‐ray diffraction. [ABSTRACT FROM AUTHOR]

Abstract: Transition‐metal carbene complexes and their reactivities are a key topic of chemistry. They are an integral part of researches in catalysis, organic synthesis, coordination chemistry, and numerous other areas. In this context, we report the synthesis of a low‐valent bis(η5:η1‐(di‐p‐tolyl)‐pentafulvene)niobium chloride. Owing to the π‐η5:σ‐η1 coordination mode of the pentafulvenes and the resulting high nucleophilic character of the exocyclic carbon atom of the ligand, the bis(η5:η1‐pentafulvene)niobium complex is able to achieve the umpolung of a coordinated vinyl unit and the resulting formation of the first η5:η1 cyclic niobium Schrock carbene complex. This new synthetic route is, in comparison to classical α‐hydrogen elimination reactions or thermolysis of diazo compounds, completely unprecedented. The reactivity of the cyclic carbene function and the remaining fulvene ligand is demonstrated by double N−H bond activation of primary amines to niobium imido complexes. [ABSTRACT FROM AUTHOR]

Abstract: Grafting Ti(=NtBu)(Me2Pyr)2(py)2 (Me2Pyr= 2,5‐dimethylpyrrolyl, py=pyridine) onto the surface of silica partially dehydroxylated at 700 °C gives the well‐defined silica‐supported Ti imido complex (≡SiO)Ti(=NtBu)(Me2Pyr)(py)2, which is fully characterized by IR and solid‐state NMR spectroscopy as well as elemental and mass balance analyses. While stoichiometric imido‐transfer reactivity is typical for Ti imides, the obtained surface complex is unique in that it enables catalytic transformations involving Ti imido and oxo intermediates. In particular, it efficiently catalyzes imidation of carbonyl compounds with N‐sulfinylamines by oxo/imido heterometathesis. [ABSTRACT FROM AUTHOR]

Abstract: The hydrogenation reaction of multiple bonds that is mediated by geminal aminoborane‐based frustrated Lewis pairs (FLPs) has been explored by means of density functional theory calculations. It was found that the release of the activated dihydrogen occurred in a concerted, yet highly asynchronous, manner. The physical factors that control the transformation were quantitatively described in detail by using the activation strain model of reactivity in combination with the energy decomposition analysis method. This approach suggested a cooperative double hydrogen‐transfer mechanism, which involves the initial migration of the protic (N)H followed by the nucleophilic attack of the (B)H hydride to the carbon atom of the multiple bond. The influence of both the substituents directly attached to the boron atom of the initial FLP and the nature of the multiple bond on the transformation was also investigated. [ABSTRACT FROM AUTHOR]

The first pyrroloazaphosphinines with nitrogen at the junction, 7a and 7b, have been prepared by a special route involving the collapse of the phosphorus bridges of appropriate 7-phosphanorbornenes. The parent molecule 7a has a strictly planar azaphosphinine ring with some electronic delocalization according to DFT computations. Its P=C double bond does not react with 2,3-dimethylbutadiene unless P is coordinated toMo(CO)5. Compound 7a reacts with CuI to give a new type of polymeric complex [–Cu-μ2-7a–]n in which P acts as a bridging ligand and the ligand planes are antiparallel. The benzo-annulated and bromo-substituted 7b displays a skewed ring according to DFT computations and its P=C double bond is reactive toward 2,3-dimethylbutadiene without complexation. [ABSTRACT FROM AUTHOR]

Abstract: Cyclic diboranes(4) based on a chelating monoanionic benzylphosphine linker were prepared through boron–silicon exchange between arylsilanes and B2Br4. Coordination of Lewis bases to the remaining sp2 boron atom yielded unsymmetrical sp3‐sp3 diboranes, which were reduced with KC8 to their corresponding trans‐diborenes. These compounds were studied with a combination of spectroscopic methods, X‐ray diffraction, and DFT calculations. PMe3‐stabilized diborene 6 was found to undergo thermal rearrangement to gem‐diborene 8. DFT calculations on 8 reveal a polar boron–boron bond, and indicate that the compound is best described as a borylborylene. [ABSTRACT FROM AUTHOR]

Abstract: The catalytic activation of small neutral molecules followed by the formation of C−C bonds is a highly important method to increase the complexity and/or value of simple starting materials. Reported is an isolable digermyne, a compound with a Ge≡Ge bond, which acts as a precatalyst for the cyclotrimerization of terminal arylacetylenes to afford the corresponding 1,2,4‐triarylbenzenes with absolute regioselectivity. The results demonstrate that bespoke main‐group‐element compounds can catalytically activate and transform small neutral organic molecules and induce the formation of C−C bonds. [ABSTRACT FROM AUTHOR]

The noble gas compound containing a double bond of xenon and transition metal atoms (i.e. F 2 XeWF 2 ) is predicted by using quantum-chemical calculations. At the MP2 level of theory, the predicted Xe W bond length of 2.45 Å is comparable to the corresponding standard double bond length of 2.55 Å (i.e. the sum of double bond radii of Xe and W atoms). Natural bond orbital analysis indicates that the Xe W double bond consists of a σ-bond and a π-bond, which is also supported by Atoms in Molecules (AIM) analysis. [ABSTRACT FROM AUTHOR]

The base-stabilized borylene [Cp(OC)2Mn=B tBu(IMe)] readily reacts with elemental chalcogens in an insertion reaction that yields borachalcone complexes [Cp(OC)2Mn-E=B tBu(IMe)] (E=S, Se, Te). The tellurium example features the first double bond between boron and tellurium, making Te the heaviest main-group element to make multiple bonds with boron. This unprecedented interaction has been fully investigated both experimentally and computationally. [ABSTRACT FROM AUTHOR]

The complexes (C5Me5)2Th(EHTipp)2, (E=P or As; Tipp=2,4,6-triisopropylphenyl), provide a ligand framework that results in facile access to rare Th-E multiple bonds. The reaction of (C5Me5)2Th(EHTipp)2 with KN(SiMe3)2, proceeds cleanly to the desired bridging phosphinidiide or arsinidiide complex, [{(C5Me5)2Th(μ2-ETipp)(μ2-EHTipp)}K]2 under ambient conditions. In the absence of a chelating agent, the potassium cation of one monomeric unit interacts with the aryl ring of a second monomer to form a bridged dimer. In the presence of 2,2,2-cryptand, the terminal phosphinidene complex, [(C5Me5)2Th=PTipp(PHTipp)][K(2,2,2-cryptand)] is isolated. Using X-ray crystallographic analysis, we have determined these complexes display the shortest Th−P and Th−As bond lengths reported. [ABSTRACT FROM AUTHOR]

A triaminotriborane(3) was isolated as purple crystals through the reduction of (TMP)BCl2 (TMP=2,2,6,6-tetramethylpiperidino) by sodium naphthalenide. Single-crystal X-ray diffraction and computational studies of the obtained triaminotriborane(3) revealed a bent structure of the [B(NR2)]3 chain. The bond lengths between the central and terminal boron atoms were similar to those observed in neutral diborene species. The multiple-bonding character may be best described by a three-center two-electron π-bond along the B3 chain. The distance between the two terminal boron atoms (2.177 Å) in the solid-state structure implies a weak interaction between them. When an excess amount of Li was used as the reducing agent, the reaction yielded an unusual dianionic species. The isolation and characterization of these two reduction products are reported herein. [ABSTRACT FROM AUTHOR]

Boroles are important motifs within functional materials. With the aim to prepare a pinacolboryl-substituted derivative, the metallacycle transfer from corresponding zirconium and tin precursors has been explored. We show that the reaction of 1,1-dimethyl-2,3,4,5-tetrapinacolborylstannole with dichloro(phenyl)borane does not provide the desired borole, but instead a stannyl-substituted 1-chloroboracyclopent-3-ene. Spectroscopic and structural details of this highly functionalized boracycle indicate that intramolecular interactions between the tin and oxygen atoms of the boryl substituents may account for the unexpected outcome of the tin-boron exchange reaction. [ABSTRACT FROM AUTHOR]

In the present work an in depth deep electronic study of multicenter XBs (FX)n/NH3 (X = Cl, Br and n = 1-5) is conducted. The ways in which X...X lateral contacts affect the electrostatic or covalent nature of the X...N interactions are explored at the CCSD(T)/aug-cc-pVTZ level and in the framework of the quantum theory of atoms in molecules (QTAIM). Calculations show that relatively strong XBs have been found with interaction energies lying between -41 and -90 kJ mol-1 for chlorine complexes, and between -56 and -113 kJ mol-1 for bromine complexes. QTAIM parameters reveal that in these complexes: (i) local (kinetics and potential) energy densities measure the ability that the system has to concentrate electron charge density at the intermolecular X...N region; (ii) the delocalization indices [δ(A,B)] and the exchange contribution [VEX(X,N)] of the interacting quantum atoms (IQA) scheme, could constitute a quantitative measure of the covalence of these molecular interactions; (iii) both classical electrostatic and quantum exchange show high values, indicating that strong ionic and covalent contributions are not mutually exclusive. [ABSTRACT FROM AUTHOR]

Benzodisilacyclobutadienes 2 a- c were isolated as blue to green crystalline solids from the reaction of stable disilyne 1 and 1,2-dibromobenzenes in the presence of potassium graphite. In the solid state, substantial bond alternation was observed within the benzene rings of 2 a- c. In hexane, 2 a- c showed remarkable bathochromic shifts of the π→π* (HOMO→LUMO) absorption bands at 625-670 nm. NMR spectra and theoretical calculations indicated that the diamagnetic ring currents of the benzene rings of 2 a- c are considerably reduced by contributions from the antiaromatic 1,2-disilacyclobutadienes. In their entirety, the obtained results indicate that 2 a- c represent 8π-electron systems that contain an antiaromatic 1,2-disilacyclobutadiene. [ABSTRACT FROM AUTHOR]

The encumbered tetraisocyanide dianion Na2[Fe(CNAr [ABSTRACT FROM AUTHOR]

The formation of a hitherto unknown 4-center, 6 π-conjugated trigonal-planar complex, [Bi{Cr(CO)5}3]− ( 1), is reported, in which the oxidation state of the Bi atom is +3, as evidenced by XAS, XPS, and DFT calculations. The BiIII atom in 1 has dual donor and acceptor properties in its bonding mode. In contrast to the mild Lewis acidity of BiIII, the central Bi in 1 functions as a prodigious Lewis acid site to exhibit strong affinity toward F− ions, unique solvatochromic properties, intriguing etherification through the C−O bond cleavage of alcohols, and surprising semiconducting characteristics with an ultra-narrow optical band gap of 1.02 eV, which can be attributed to the intermolecular Bi⋅⋅⋅O and O⋅⋅⋅O interactions in the solid state. The tetrahedral Fe(CO)4-adduct [{Fe(CO)4}Bi{Cr(CO)5}3]3− ( 1-Fe) allowed the selective demetallation to afford the isoelectronic multiply bonded BiCr3-complex 1 and the BiCr2Fe-complex, [Bi{Cr(CO)5}2{Fe(CO)4}]− ( 2), which may open a novel pathway for the design of the heterometal-incorporated trigonal-planar Bi-Cr complexes. [ABSTRACT FROM AUTHOR]

Formal exchange of C=C units with isoelectronic B=N or B=P units can provide access to molecules with unique electronic or chemical properties. Herein, we report the simple solution-phase generation of highly reactive phosphaborenes, RP=BR, and demonstrate their use for the introduction of P=B units into organic systems. Ring opening of a P−B-containing cyclobutene isostere provided access to unique 1,4-boraphosphabutadiene systems with conjugated main-group multiple bonds. [ABSTRACT FROM AUTHOR]

A zwitterionic boraalkenyl boronium 3 was synthesized by reduction of cyclic (alkyl)(amino)carbene (cAAC) and trimethylphosphine (PMe3)-coordinated tetrabromodiborane 2 with KC8 in the presence of PMe3. Further reduction of 3 led to the formation of neutral allenic diborene 4. X-ray diffraction and computational studies revealed that 4 features the cumulated C=B and B=B double bonds. The reaction of 4 with four isonitrile molecules afforded a heterocycle 5 with the B2C3 five-membered ring, via a complete scission of the B=B bond of 4. [ABSTRACT FROM AUTHOR]

Despite its electron deficiency, boron is versatile in forming multiple bonds. Transition-metal–boron double bonding is known, but boron–metal triple bonds have been elusive. Two bismuth boron cluster anions, BiB2O− and Bi2B−, containing triple and double B−Bi bonds are presented. The BiB2O− and Bi2B− clusters are produced by laser vaporization of a mixed B/Bi target and characterized by photoelectron spectroscopy and ab initio calculations. Well-resolved photoelectron spectra are obtained and interpreted with the help of ab initio calculations, which show that both species are linear. Chemical bonding analyses reveal that Bi forms triple and double bonds with boron in BiB2O− ([Bi≡B−B≡O]−) and Bi2B− ([Bi=B=Bi]−), respectively. The Bi−B double and triple bond strengths are calculated to be 3.21 and 4.70 eV, respectively. This is the first experimental observation of Bi−B double and triple bonds, opening the door to design main-group metal–boron complexes with multiple bonding. [ABSTRACT FROM AUTHOR]

Despite its electron deficiency, boron is versatile in forming multiple bonds. Transition-metal-boron double bonding is known, but boron-metal triple bonds have been elusive. Two bismuth boron cluster anions, BiB2O− and Bi2B−, containing triple and double B−Bi bonds are presented. The BiB2O− and Bi2B− clusters are produced by laser vaporization of a mixed B/Bi target and characterized by photoelectron spectroscopy and ab initio calculations. Well-resolved photoelectron spectra are obtained and interpreted with the help of ab initio calculations, which show that both species are linear. Chemical bonding analyses reveal that Bi forms triple and double bonds with boron in BiB2O− ([Bi≡B−B≡O]−) and Bi2B− ([Bi=B=Bi]−), respectively. The Bi−B double and triple bond strengths are calculated to be 3.21 and 4.70 eV, respectively. This is the first experimental observation of Bi−B double and triple bonds, opening the door to design main-group metal-boron complexes with multiple bonding. [ABSTRACT FROM AUTHOR]

Despite its electron deficiency, boron is versatile in forming multiple bonds. Transition-metal–boron double bonding is known, but boron–metal triple bonds have been elusive. Two bismuth boron cluster anions, BiB2O− and Bi2B−, containing triple and double B−Bi bonds are presented. The BiB2O− and Bi2B− clusters are produced by laser vaporization of a mixed B/Bi target and characterized by photoelectron spectroscopy and ab initio calculations. Well-resolved photoelectron spectra are obtained and interpreted with the help of ab initio calculations, which show that both species are linear. Chemical bonding analyses reveal that Bi forms triple and double bonds with boron in BiB2O− ([Bi≡B−B≡O]−) and Bi2B− ([Bi=B=Bi]−), respectively. The Bi−B double and triple bond strengths are calculated to be 3.21 and 4.70 eV, respectively. This is the first experimental observation of Bi−B double and triple bonds, opening the door to design main-group metal–boron complexes with multiple bonding. [ABSTRACT FROM AUTHOR]

Despite its electron deficiency, boron is versatile in forming multiple bonds. Transition-metal-boron double bonding is known, but boron-metal triple bonds have been elusive. Two bismuth boron cluster anions, BiB2O− and Bi2B−, containing triple and double B−Bi bonds are presented. The BiB2O− and Bi2B− clusters are produced by laser vaporization of a mixed B/Bi target and characterized by photoelectron spectroscopy and ab initio calculations. Well-resolved photoelectron spectra are obtained and interpreted with the help of ab initio calculations, which show that both species are linear. Chemical bonding analyses reveal that Bi forms triple and double bonds with boron in BiB2O− ([Bi≡B−B≡O]−) and Bi2B− ([Bi=B=Bi]−), respectively. The Bi−B double and triple bond strengths are calculated to be 3.21 and 4.70 eV, respectively. This is the first experimental observation of Bi−B double and triple bonds, opening the door to design main-group metal-boron complexes with multiple bonding. [ABSTRACT FROM AUTHOR]

Solvothermal and microwave-assisted methods have been used to prepare several amidate and carboxylate complexes of the type [Ru2X(µ-NHOCC6H3-3,5-(OMe)2)4]n [X = Cl (1), Br (2), I (3)] and [Ru2X(µ-O2CC6H3-3,5-(OMe)2)4]n [X = Cl (4), Br (5), I (6)]. Complexes 4-6 have also been obtained by conventional synthesis which is ineffective to prepare the amidate compounds. However, single crystals of complexes 1-5 were obtained using the solvothermal method. The single crystal X-ray structure determination of compounds 1-5 have been carried out. All complexes display a paddlewheel-type structure with the metal atoms connected by four bridging amidate or carboxylate ligands. Chloride, bromide, or iodide anions connect the dimetallic units, producing one-dimensional zigzag chains. The magnetic properties of all compounds were studied. The magnetic moment at room temperature are in accordance with an electronic configuration with three unpaired electrons σ²π4δ2(π*δ*)³ per dimer unit. The fit of the magnetic data suggests the existence, in these complexes, of a weak antiferromagnetic intermolecular interaction between the diruthenium units mediated by the halide ligand and an appreciable zero-field splitting in the diruthenium moieties. [ABSTRACT FROM AUTHOR]

The synthesis of the unprecedented monomeric SiII selenide complex (bis-NHC)Si=Se→GaCl3 2 (bis-NHC=bis-N heterocyclic carbene, H2C[{NC(H)=C(H)N(Dipp)}C:]2, Dipp=2,6-iPr2C6H3), bearing the elusive SiSe ligand as a heavy CO homologue by the reaction of the silylone-GaCl3 adduct (bis-NHC)Si→GaCl3 1 with elemental selenium in acetonitrile, is reported. The similar conversion of 1 with excess selenium conducted in THF afforded the SiSe2 complex (bis-NHC)Si(=Se)Se→GaCl3 3. Remarkably, the reaction of 1 with Te=P( nBu)3 as a gentle Te transfer reagent led to the isolation of the monomeric SiTe2 complex (bis-NHC)SiTe2 4, the first structurally characterized Lewis acid free heavy CO2 homologue complex. The isolated compounds 2, 3, and 4 have been fully characterized, including single-crystal X-ray diffraction analyses. Their electronic structures and spectroscopic data have also been studied by quantum-chemical calculations. [ABSTRACT FROM AUTHOR]

There is growing interest in compounds containing functionalized E=E multiple bonds (E=Si, Ge, Sn, Pb) because of their potential to exhibit novel physical and chemical properties. However, compounds containing multiple functionalizations are rare, with scarcity increasing with increasing degree of substitution. The first ditetrelene R2E=ER2 in which the E=E bond is substituted by four heteroatoms (other than Si) is described. The tetraphosphadisilene {(Mes)2P}2Si=Si{P(Mes)2}2 ( 7) is readily isolated from the reaction between SiBr4 and [(Mes)2P]Li, the latter of which acts as a sacrificial reducing agent. The structure of 7 is presented, while the bonding in, and stability of 7 were probed using DFT calculations. [ABSTRACT FROM AUTHOR]

Among the variety of isolable compounds with multiple bonds involving silicon, examples of compounds that contain silicon-boron double bonds (borasilenes) still remain relatively rare. Herein, we report the synthesis of the potassium salt of a chloride adduct of borasilene 1 ([ 2]−), which was obtained as an orange crystalline solid. Single-crystal X-ray diffraction analysis and reactivity studies on [ 2]− confirmed the double-bond character of the Si=B bond as well as the reduced Lewis acidity, which is due to the coordination of Cl− to the boron center. A thermal reaction of [ 2]− afforded a bicyclic product by formal intramolecular C−H insertion across the Si=B bond of 1, which was corroborated by a theoretical study. [ABSTRACT FROM AUTHOR]