Felipe Fantuzzi - Academia.edu (original) (raw)

Papers by Felipe Fantuzzi

Research paper thumbnail of Platinum‐Templated Coupling of B=N Units: Synthesis of BNBN Analogues of 1,3‐Dienes and a Butatriene

Angewandte Chemie International Edition, 2021

The 1:2 reaction of [m-(dmpm)Pt(nbe)] 2 (dmpm = bis(dimethylphosphino)methane, nbe = norbornene) ... more The 1:2 reaction of [m-(dmpm)Pt(nbe)] 2 (dmpm = bis(dimethylphosphino)methane, nbe = norbornene) with Cl 2 BNR(SiMe 3) (R = tBu, SiMe 3) yields unsymmetrical (Naminoboryl)aminoboryl Pt I 2 complexes by BÀN coupling via ClSiMe 3 elimination. A subsequent intramolecular ClSiMe 3 elimination from the tBu-derivative leads to cyclization of the BNBN unit, forming a unique 1,3,2,4-diazadiboretidin-2-yl ligand. In contrast, the analogous reaction with Br 2 BN(SiMe 3) 2 leads, via a twofold BrSiMe 3 elimination, to a Pt II 2 A-frame complex bridged by a linear BNBN isostere of butatriene. Structural and computational data confirm p electron delocalization over the entire BNBN unit.

Research paper thumbnail of Understanding, Modulating, and Leveraging Transannular M Z Interactions

Density functional theory calculations have been performed on metallatranes featuring a group 13 ... more Density functional theory calculations have been performed on metallatranes featuring a group 13 elements at the bridgehead position to understand the factors that influence the nature of the M···Z (M = Fe, Co, Ni; Z = Al, Ga, In) interaction present in these complexes and the resultant reactivity at the metal center. The strength of the M···Z interaction increases with the increase in the size and polarizability of the bridgehead group 13 elements. The calculated reaction free energies (ΔG° values) for binding of different Lewis bases to the metallatranes are found to be significantly more exergonic for the larger In(III) ions. Quantum theory of atoms in molecules calculations reveal the covalent nature of the M···Z interactions, while the EDA-NOCV analysis indicates the strong binding ability of these metallatranes not only to different σ-donor and π-acceptor ligands but also to relatively inert species, such as N2.

Research paper thumbnail of Fragmentation of isocyanic acid, HNCO, following core excitation and ionization

The Journal of Chemical Physics, 2021

We report a study on the fragmentation of core-ionized and core-excited isocyanic acid, HNCO, usi... more We report a study on the fragmentation of core-ionized and core-excited isocyanic acid, HNCO, using Auger-electron/photoion coincidence spectroscopy. Site-selectivity is observed both for normal and resonant Auger electron decay. Oxygen 1s ionization leads to the CO+ + NH+ ion pairs, while nitrogen 1s ionization results in three-body dissociation and an efficient fragmentation of the H-N bond in the dication. Upon 1s → 10a' resonant excitation, clear differences between O and N sites are discernible as well. In both cases, the correlation between the dissociation channel and the binding energy of the normal Auger electrons indicates that the fragmentation pattern is governed by the excess energy available in the final ionic state. High-level multireference calculations suggest pathways to the formation of the fragment ions NO+ and HCO+, which are observed although the parent compound contains neither N-O nor H-C bonds. This work contributes to the goal to achieve and understand site-selective fragmentation upon ionization and excitation of molecules with soft x-ray radiation.

Research paper thumbnail of Gas-phase spectroscopic characterization of neutral and ionic polycyclic aromatic phosphorus heterocycles (PAPHs)

Monthly Notices of the Royal Astronomical Society, 2020

Polycyclic aromatic hydrocarbons (PAHs) constitute an essential family of compounds in interstell... more Polycyclic aromatic hydrocarbons (PAHs) constitute an essential family of compounds in interstellar (ISM) and circumstellar (CSM) media. Recently, formation routes for the corresponding polycyclic aromatic phosphorus heterocycles (PAPHs) in astrophysical environments have been proposed. In order to contribute to a better understanding of the phosphorus chemistry in the ISM, infrared (IR) spectra and selected properties of PAPHs were computed at the density functional theory level for neutral, cationic, and anionic species. Our results reveal that several protonated PAPHs do not have planar backbones, and all species have permanent dipole moments between 2D and 4D. Closed-shell PAPHs have similar ionization potentials compared to the parent PAHs, below the Lyman threshold limit. In addition, all PAPHs show positive electron affinities higher than those of PAHs. Protonation preferably occurs on the heteroatom but with lower proton affinities than those of the corresponding nitrogen an...

Research paper thumbnail of A Neutral Beryllium(I) Radical

Angewandte Chemie International Edition, 2021

Abstract The reduction of a cyclic alkyl(amino)carbene (CAAC)‐stabilized organoberyllium chloride... more Abstract The reduction of a cyclic alkyl(amino)carbene (CAAC)‐stabilized organoberyllium chloride yields the first neutral beryllium radical, which was characterized by EPR, IR, and UV/Vis spectroscopy, X‐ray crystallography, and DFT calculations.

Research paper thumbnail of Controlled Synthesis of Oligomers Containing Main‐Chain B(sp2)‐B(sp2) Bonds

Chemistry – A European Journal, 2021

A number of novel alkynyl-functionalized diarylbis(dimethylamino)diboranes(4) are prepared by sal... more A number of novel alkynyl-functionalized diarylbis(dimethylamino)diboranes(4) are prepared by salt metathesis, and the appended alkynyl groups are subjected to hydroboration. Their reactions with monohydroboranes lead to discrete boryl-appended diborane(4) species, while dihydroboranes induce their catenation to oligomeric species, the first known examples of well-characterized macromolecular species with B-B bonds. The oligomeric species were found to comprise 4-19 repeat units and are soluble in common organic solvents. Some of the oligomeric species have good air stability and all were characterized by NMR and vibrational spectroscopy and size exclusion chromatography techniques.

Research paper thumbnail of Platinum‐Templated Coupling of B=N Units: Synthesis of BNBN Analogues of 1,3‐Dienes and a Butatriene

Angewandte Chemie International Edition, 2021

The 1:2 reaction of [m-(dmpm)Pt(nbe)] 2 (dmpm = bis(dimethylphosphino)methane, nbe = norbornene) ... more The 1:2 reaction of [m-(dmpm)Pt(nbe)] 2 (dmpm = bis(dimethylphosphino)methane, nbe = norbornene) with Cl 2 BNR(SiMe 3) (R = tBu, SiMe 3) yields unsymmetrical (Naminoboryl)aminoboryl Pt I 2 complexes by BÀN coupling via ClSiMe 3 elimination. A subsequent intramolecular ClSiMe 3 elimination from the tBu-derivative leads to cyclization of the BNBN unit, forming a unique 1,3,2,4-diazadiboretidin-2-yl ligand. In contrast, the analogous reaction with Br 2 BN(SiMe 3) 2 leads, via a twofold BrSiMe 3 elimination, to a Pt II 2 A-frame complex bridged by a linear BNBN isostere of butatriene. Structural and computational data confirm p electron delocalization over the entire BNBN unit.

Research paper thumbnail of Understanding, Modulating, and Leveraging Transannular M Z Interactions

Density functional theory calculations have been performed on metallatranes featuring a group 13 ... more Density functional theory calculations have been performed on metallatranes featuring a group 13 elements at the bridgehead position to understand the factors that influence the nature of the M···Z (M = Fe, Co, Ni; Z = Al, Ga, In) interaction present in these complexes and the resultant reactivity at the metal center. The strength of the M···Z interaction increases with the increase in the size and polarizability of the bridgehead group 13 elements. The calculated reaction free energies (ΔG° values) for binding of different Lewis bases to the metallatranes are found to be significantly more exergonic for the larger In(III) ions. Quantum theory of atoms in molecules calculations reveal the covalent nature of the M···Z interactions, while the EDA-NOCV analysis indicates the strong binding ability of these metallatranes not only to different σ-donor and π-acceptor ligands but also to relatively inert species, such as N2.

Research paper thumbnail of Cyclo‐Dipnictadialanes

Angewandte Chemie International Edition, 2021

Abstract Using the AlI precursor Cp3tAl in conjunction with triphosphiranes (PAr)3 (Ar=Mes, Dip, ... more Abstract Using the AlI precursor Cp3tAl in conjunction with triphosphiranes (PAr)3 (Ar=Mes, Dip, Tip) we have succeeded in preparing Lewis base‐free cyclic diphosphadialanes with both the Al and P atoms bearing three substituents. Using the sterically more demanding Dip and Tip substituents the first 1,2‐diphospha‐3,4‐dialuminacyclobutanes were obtained, whereas with Mes substituents [Cp3tAl(μ‐PMes)]2 is formed. This divergent reactivity was corroborated by DFT studies, which indicated the thermodynamic preference for the 1,2‐diphospha‐3,4‐dialuminacyclobutane form for sterically more demanding groups on phosphorus. Using Cp*Al we could extend this concept to the corresponding cyclic diarsadialanes [Cp*Al(μ‐AsAr)]2 (Ar=Dip, Tip) and additionally add the phosphorus variants [Cp*Al(μ‐PAr)]2 (P=Mes, Dip, Tip). The reactivity of one variant [Cp3tAl(μ‐PPh)]2 towards NHCs was tested and resulted in double NHC‐stabilised [Cp3t(IiPr2)Al(μ‐PPh)]2.

Research paper thumbnail of Unexpected formation of a dodecanuclear {CoII6CuII6} nanowheel under ambient conditions: magneto-structural correlations

Dalton Transactions, 2021

An unexpected heterobimetallic ring {CoII6CuII6} was synthesised by slow diffusion in water under... more An unexpected heterobimetallic ring {CoII6CuII6} was synthesised by slow diffusion in water under ambient conditions and its dc magnetic properties were analysed through an effective Hamiltonian in the light of DFT type calculations.

Research paper thumbnail of The Dimethylbismuth Cation: Entry into Dative Bi–Bi Bonding and Unconventional Methyl Exchange

Angewandte Chemie, 2021

The isolation of simple, fundamentally important, and highly reactive organometallic compounds re... more The isolation of simple, fundamentally important, and highly reactive organometallic compounds remains among the most challenging tasks in synthetic chemistry. The detailed characterization of such compounds is key to the discovery of novel bonding scenarios and reactivity. The dimethylbismuth cation, [BiMe 2 (SbF 6 )] ( 1 ), has been isolated and characterized. Its reaction with BiMe 3 gives access to an unprecedented dative bond, a Bi→Bi donor/acceptor interaction. The exchange of methyl groups (arguably the simplest hydrocarbon moiety) between different metal atoms is among the most principal types of reactions in organometallic chemistry. The reaction of 1 with BiMe 3 enables an S E 2(back) type methyl exchange, which is for the first time investigated in detail for isolable, (pseudo-)homoleptic main group compounds.

Research paper thumbnail of Isolierung neutraler, mono‐ und dikationischer B 2 P 2 ‐Ringe durch Addition eines Diphosphans an eine Bor‐Bor‐Dreifachbindung

Angewandte Chemie, 2021

Das NHC-stabilisierte Diborin B 2 (SIDep) 2 (SIDep = 1,3-Bis(2,6-diethylphenyl)imidazolin-2-ylide... more Das NHC-stabilisierte Diborin B 2 (SIDep) 2 (SIDep = 1,3-Bis(2,6-diethylphenyl)imidazolin-2-yliden) unterzieht sich bei Raumtemperatur einer P-P-Bindungsaktivierung mit Tetraethyldiphosphan, wobei mittels 1,2-Diphosphinierung über ein Diphosphoryldiboren in hohen Ausbeuten B 2 P 2-Heterocyclen gebildet werden. In Abhängigkeit vom verwendeten Oxidationsmittel und Gegenion kann dieser Heterocyclus zu einem Radikalkation beziehungsweise Dikation oxidiert werden. Beginnend mit dem planaren, neutralen 1,3-Bis(alkyliden)-1,3-diborata-2,4-diphosphoniocyclobutan führt jeder Oxidationsschritt zu einer verminderten B-B-Bindungslänge und dem Verlust der Planarität durch die Kationisierung. Rçntgenstrukturanalysen in Kombination mit DFT-und CASSCF/NEVPT2-Rechnungen offenbaren für die NHC-stabilisierten dikationischen B 2 P 2-Ringe geschlossenschalige, schmetterlingsartige Strukturen, wovon die diradikaloiden Isomere mit planarem Ring in energetischer Nähe liegen. Cyclische Bor-und Phosphorverbindungen ziehen seit Dekaden die Aufmerksamkeit von Hauptgruppenchemikern auf sich. [1] Die ersten Entdeckungen auf diesem Gebiet haben sich auf Oligomere von Phosphinoboranen, R 2 PBR 2 , fokussiert. [2] Im Vergleich zu ihren leichteren Vertretern, den Aminoboranen R 2 NBR 2 , führt die Abneigung von Phosphor, planare Geometrien sowie p-Bindungen mit Bor einzuneh-men beziehungsweise auszubilden, zu einer hçheren Tendenz für intermolekulare B-P-Systeme und der Bildung vier-und sechsgliedriger (A, Schema 1) Heterocyclen sowie sogar von Polymeren. [3] Ebenso wurde eine Reihe an viergliedrigen 1,3-Diphospha-2,4-diboretanen (B) berichtet, [4] die zum Großteil aus erfolglosen Versuchen, monomere RP=BR-Spezies herzustellen, resultierten. [5] Diese Verbindungen enthalten pyramidalisierte Phosphoratome, die als Liganden für Übergangsmetalle dienen kçnnen. [4e, 6] Die Mehrheit der Entwicklungen von P-B-Ringsystemen bezog sich in den letzten zwei Dekaden auf die Synthese des Diradikaloids 1,3-Diphospha-2,4-diboretandiyl (C, Schema 1) von Bertrand und Mitarbeitern. [7] Das erste Beispiel für solche Verbindungen, cyclo-(BtBu) 2 (PiPr 2) 2 , wurde durch die Reaktion des Diborans(4) 1,2-B 2 Cl 2 tBu 2 mit LiPiPr 2 erhalten. Das angenommene 1,2-Diphosphinodiboran-Intermediat durchläuft eine Umlagerung unter Spaltung der B-B-s-Bindung und Bildung des Vierrings. Trotz des großen Abstands der beiden Boratome (2.57) besitzt diese Verbindung einen p-Einfachbindungscharakter sowie ein tiefliegendes antibindendes LUMO. Theoretische Studien [8] an den Diradikaloiden C offenbarten große Singulett-Triplett-Abstände zwischen + 23.4 und + 33.7 kcal mol À1 , während die Besetzung Schema 1. Oben: Relevante Verbindungsklassen von Bor-Phosphor-Ringen. Mitte: Synthese eines B 2 P 2-Diradikaloids. Unten: Hydrophosphinierung eines Diborins.

Research paper thumbnail of Intensiv farbige Bor‐dotierte Thiazolthiazole durch reduktive Dimerisierung von Borisothiocyanaten

Research paper thumbnail of Oxidation, Coordination, and Nickel‐Mediated Deconstruction of a Highly Electron‐Rich Diboron Analogue of 1,3,5‐Hexatriene

Angewandte Chemie, 2020

Abstract The reductive coupling of an N‐heterocyclic carbene (NHC) stabilized (dibromo)vinylboran... more Abstract The reductive coupling of an N‐heterocyclic carbene (NHC) stabilized (dibromo)vinylborane yields a 1,2‐divinyldiborene, which, although isoelectronic to a 1,3,5‐triene, displays no extended π conjugation because of twisting of the C2B2C2 chain. While this divinyldiborene coordinates to copper(I) and platinum(0) in an η2‐B2 and η4‐C2B2 fashion, respectively, it undergoes a complex rearrangement to an η4‐1,3‐diborete upon complexation with nickel(0).

Research paper thumbnail of cAAC‐stabilisierte 9,10‐Diboraanthracene – offenschalige Singulettbiradikale

Angewandte Chemie, 2020

Geringe HOMO-LUMO-Abstände und eine hohe Ladungsträgermobilitätp r ädestinieren die hçheren Acene... more Geringe HOMO-LUMO-Abstände und eine hohe Ladungsträgermobilitätp r ädestinieren die hçheren Acene für Anwendungen im Bereichd er Organoelektronik. Die Leistungsfähigkeit derartiger Verbindungen steigt hierbei dramatisch mit der Anzahl anellierter Benzolringe.G rçßere Acenmengen sind synthetischb isher jedochn ur fürA cene bis Heptacen verlässlichzugänglich. Theoretischen Studien zufolge besitzen (Oligo)acene offenschalige Singulettbiradikal-und (Poly)acene polyradikalische Grundzustände.E indeutige experimentelle Belege fürd iese Vorhersagen sind hingegen äußerst selten. Durchd en Einbau von zwei Boratomen in das Anthracengrundgerüst konnten wir den HOMO-LUMO-Abstand von Acenen dramatisch verringern und zwar ohne die Notwendigkeit einer Ausweitung des konjugierten p-Systems. Stabilisierung der Borzentren durch cyclische (Alkyl)-(amino)carbene lieferte hierbei neutrale 9,10-Diboraanthracene mit disjunkten, offenschaligen Singulettbiradikal-Grundzuständen. Einleitung Acene sind eine der wichtigsten Unterklassen polycyclischer aromatischer Kohlenwasserstoffe (PAKs), deren Struk-tur durch eine lineare Verkettung anellierter Benzolringe charakterisiert ist (Abbildung 1). [1] Die ungewçhnlichen elektronischen Eigenschaften derartiger Moleküle haben nicht nur bei Theoretikern eine kontrovers diskutierte Debatte nach sich gezogen, [2] sondern auch die Aufmerksamkeit experimenteller und anwendungsorientierter Forschungsgruppen geweckt. [1] Theoretische Studien haben in diesem Zusammenhang gezeigt, dass (Oligo)acene von Hexacen (n = 2) bis Decacen (n = 6) anstelle einer geschlossenen Elektronenkonfiguration einen offenschaligen Singulettbiradikal-Grundzustand mit disjunktem Charakter besitzen, [3] was auf die Verkleinerung der HOMO-LUMO-Abstände und Singulett-Triplett-Aufspaltungen bei steigender Länge des konjugierten p-Systems zurückgeführt wurde.D em selben Tr end folgend sinkt auch die fürd as Aufbrechen der Acen-p-Bindungen bençtigte Energie in deren KekulØ-Darstellung (I). FürA cene mit n = 2-6 kann diese letztendlich durch Beimischen von biradikalischem Charakter zum elektronischen Grundzustand überkompensiert werden, wodurch die offenschaligen Resonanzstrukturen (II)m it einem zusätzlichen Clar-Sextett energetisch zugänglich und begünstigt werden (Abbildung 1). [2c] Der Grundzustand grçßerer Systeme (n ! 8) besitzt der Theorie nach indes eher polyradikali-Abbildung 1. Geschlossenschalige und biradikalische Resonanzstrukturen von (Oligo)acenen (oben; n = 1-6) und neutraler Diboraacenen (unten). Clar-Sextetts sind in lila hervorgehoben. NHC = N-heterocyclisches Carben;cAAC = cyclisches (Alkyl)(amino)carben.

Research paper thumbnail of Functionalization of N 2 via Formal 1,3‐Haloboration of a Tungsten(0) σ‐Dinitrogen Complex

Chemistry – A European Journal, 2020

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

Research paper thumbnail of Hydrogenated Benzene in Circumstellar Environments: Insights into the Photostability of Super-hydrogenated PAHs

The Astrophysical Journal, 2018

Polycyclic aromatic hydrocarbons (PAHs), comprised of fused benzene (C 6 H 6) rings, emit infrare... more Polycyclic aromatic hydrocarbons (PAHs), comprised of fused benzene (C 6 H 6) rings, emit infrared radiation (3-12 μm) due to the vibrational transitions of the C-H bonds of the aromatic rings. The 3.3 μm aromatic band is generally accompanied by the band at 3.4 μm assigned to the vibration of aliphatic C-H bonds of compounds such as PAHs with an excess of peripheral H atoms (H n-PAHs). Herein we study the stability of fully hydrogenated benzene (or cyclohexane, C 6 H 12) under the impact of stellar radiation in the photodissociation region (PDR) of NGC 7027. Using synchrotron radiation and time-of-flight mass spectrometry, we investigated the ionization and dissociation processes at energy ranges of UV (10-200 eV) and soft X-rays (280-310 eV). Density Functional Theory (DFT) calculations were used to determine the most stable structures and the relevant low-lying isomers of singly charged C 6 H 12 ions. Partial Ion Yield (PIY) analysis gives evidence of the higher tendency toward dissociation of cyclohexane in comparison to benzene. However, because of the high photoabsorption crosssection of benzene at the C1s resonance edge, its photodissociation and photoionization cross-sections are enhanced, leading to a higher efficiency of dissociation of benzene in the PDR of NGC 7027. We suggest that a similar effect is experienced by PAHs in X-ray photon-rich environments, which ultimately acts as an auxiliary protection mechanism of super-hydrogenated polycyclic hydrocarbons. Finally, we propose that the single photoionization of cyclohexane could enhance the abundance of branched molecules in interstellar and circumstellar media.

Research paper thumbnail of Bond-Strengthening Backdonation in Aminoborylene-Stabilized-Aminoborylenes: at the Intersection of Borylenes and Diborenes

Angewandte Chemie International Edition, 2019

Singly NHC-coordinated diamino(boryl)borenium salts react with Na2[Fe(CO)4] to yield the first st... more Singly NHC-coordinated diamino(boryl)borenium salts react with Na2[Fe(CO)4] to yield the first stable coordination complexes of 'animoborylene-stabilized-aminoborylenes', which exhibit exceptional σ-donor properties. Upon photolytic CO extrusion from the metal center, the diboron ligand adopts a novel η 3-BBN coordination mode, where bond-strengthening backdonation from the metal centre into the vacant B-B π-orbital is observed; a bonding situation which can be equivalently described as a Fediaminodiborene complex. In a related reduction of CAAC-stabilized diaminodihalodiborane with KC8, the reduced species can be captured with nucleophiles to form three coordinate (diaminoboryl)borylenes, where both amino groups have migrated to the distal boron. Collectively, these reactions illustrate the isomeric flexibility imparted by amino groups on this reduced diboron system, allowing for multiple avenues of novel reactivity.

Research paper thumbnail of Mechanistic Insights into the Formation of Lithium Fluoride Nanotubes

Chemistry - A European Journal, 2019

Born-Oppenheimer molecular dynamics (BOMD) and periodic density functional theory (DFT) calculati... more Born-Oppenheimer molecular dynamics (BOMD) and periodic density functional theory (DFT) calculations have been applied for describing the mechanism of formation of lithium fluoride (LiF) nanotubes with cubic, hexagonal, octagonal, decagonal, dodecagonal, and tetradecagonal cross-sections. It has been shown that high energy structures, such as nanowires, nanorings, nanosheets, and nanopolyhedra are transient species for the formation of stable nanotubes. Unprecedented (LiF) n clusters (n 12) were also identified, some of them lying less than 10 kcal mol À[1] above their respective global minima. Such findings indicate that stochastic synthetic techniques, such as laser ablation and chemical vapor deposition, should be combined with a template-driven procedure in order to generate the nanotubes with adequate efficiency. Apart from the stepwise growth of LiF units, the formation of nanotubes was also studied by rolling up a planar square sheet monolayer, which could be hypothetically produced from the exfoliation of the FCC crystal structure. It was shown that both pathways could lead to the formation of alkali halide nanotubes, a still unprecedented set of one-dimensional materials.

Research paper thumbnail of Doubly and Triply Charged Species Formed from Chlorobenzene Reveal Unusual C-Cl Multiple Bonding

Journal of the American Chemical Society, Mar 28, 2018

In free-radical halogenation of aromatics, singly charged ions are usually formed as intermediate... more In free-radical halogenation of aromatics, singly charged ions are usually formed as intermediates. These stable species can be easily observed by time-of-flight mass spectrometry (TOF-MS). Here we used electron and proton beams to ionize chlorobenzene (CHCl) and investigate the ions stability by TOF-MS. Additionally to the singly charged parent ion and its fragments, we find a significant yield of doubly and triply charged parent ions not previously reported. In order to characterize these species, we used high-level theoretical methods based on density functional theory (DFT), coupled-cluster (CC), and generalized valence bond (GVB) to calculate the structure, relative stabilities, and bonding of these dications and trications. The most stable isomers exhibit unusual carbon-chlorine multiple bonding: a terminal C═Cl double bond in a formyl-like CHCl moiety (1, r = 1.621 Å) and a ketene-like C═C═Cl cumulated species (2, r = 1.542 Å). The calculations suggest that an excited state o...

Research paper thumbnail of Platinum‐Templated Coupling of B=N Units: Synthesis of BNBN Analogues of 1,3‐Dienes and a Butatriene

Angewandte Chemie International Edition, 2021

The 1:2 reaction of [m-(dmpm)Pt(nbe)] 2 (dmpm = bis(dimethylphosphino)methane, nbe = norbornene) ... more The 1:2 reaction of [m-(dmpm)Pt(nbe)] 2 (dmpm = bis(dimethylphosphino)methane, nbe = norbornene) with Cl 2 BNR(SiMe 3) (R = tBu, SiMe 3) yields unsymmetrical (Naminoboryl)aminoboryl Pt I 2 complexes by BÀN coupling via ClSiMe 3 elimination. A subsequent intramolecular ClSiMe 3 elimination from the tBu-derivative leads to cyclization of the BNBN unit, forming a unique 1,3,2,4-diazadiboretidin-2-yl ligand. In contrast, the analogous reaction with Br 2 BN(SiMe 3) 2 leads, via a twofold BrSiMe 3 elimination, to a Pt II 2 A-frame complex bridged by a linear BNBN isostere of butatriene. Structural and computational data confirm p electron delocalization over the entire BNBN unit.

Research paper thumbnail of Understanding, Modulating, and Leveraging Transannular M Z Interactions

Density functional theory calculations have been performed on metallatranes featuring a group 13 ... more Density functional theory calculations have been performed on metallatranes featuring a group 13 elements at the bridgehead position to understand the factors that influence the nature of the M···Z (M = Fe, Co, Ni; Z = Al, Ga, In) interaction present in these complexes and the resultant reactivity at the metal center. The strength of the M···Z interaction increases with the increase in the size and polarizability of the bridgehead group 13 elements. The calculated reaction free energies (ΔG° values) for binding of different Lewis bases to the metallatranes are found to be significantly more exergonic for the larger In(III) ions. Quantum theory of atoms in molecules calculations reveal the covalent nature of the M···Z interactions, while the EDA-NOCV analysis indicates the strong binding ability of these metallatranes not only to different σ-donor and π-acceptor ligands but also to relatively inert species, such as N2.

Research paper thumbnail of Fragmentation of isocyanic acid, HNCO, following core excitation and ionization

The Journal of Chemical Physics, 2021

We report a study on the fragmentation of core-ionized and core-excited isocyanic acid, HNCO, usi... more We report a study on the fragmentation of core-ionized and core-excited isocyanic acid, HNCO, using Auger-electron/photoion coincidence spectroscopy. Site-selectivity is observed both for normal and resonant Auger electron decay. Oxygen 1s ionization leads to the CO+ + NH+ ion pairs, while nitrogen 1s ionization results in three-body dissociation and an efficient fragmentation of the H-N bond in the dication. Upon 1s → 10a' resonant excitation, clear differences between O and N sites are discernible as well. In both cases, the correlation between the dissociation channel and the binding energy of the normal Auger electrons indicates that the fragmentation pattern is governed by the excess energy available in the final ionic state. High-level multireference calculations suggest pathways to the formation of the fragment ions NO+ and HCO+, which are observed although the parent compound contains neither N-O nor H-C bonds. This work contributes to the goal to achieve and understand site-selective fragmentation upon ionization and excitation of molecules with soft x-ray radiation.

Research paper thumbnail of Gas-phase spectroscopic characterization of neutral and ionic polycyclic aromatic phosphorus heterocycles (PAPHs)

Monthly Notices of the Royal Astronomical Society, 2020

Polycyclic aromatic hydrocarbons (PAHs) constitute an essential family of compounds in interstell... more Polycyclic aromatic hydrocarbons (PAHs) constitute an essential family of compounds in interstellar (ISM) and circumstellar (CSM) media. Recently, formation routes for the corresponding polycyclic aromatic phosphorus heterocycles (PAPHs) in astrophysical environments have been proposed. In order to contribute to a better understanding of the phosphorus chemistry in the ISM, infrared (IR) spectra and selected properties of PAPHs were computed at the density functional theory level for neutral, cationic, and anionic species. Our results reveal that several protonated PAPHs do not have planar backbones, and all species have permanent dipole moments between 2D and 4D. Closed-shell PAPHs have similar ionization potentials compared to the parent PAHs, below the Lyman threshold limit. In addition, all PAPHs show positive electron affinities higher than those of PAHs. Protonation preferably occurs on the heteroatom but with lower proton affinities than those of the corresponding nitrogen an...

Research paper thumbnail of A Neutral Beryllium(I) Radical

Angewandte Chemie International Edition, 2021

Abstract The reduction of a cyclic alkyl(amino)carbene (CAAC)‐stabilized organoberyllium chloride... more Abstract The reduction of a cyclic alkyl(amino)carbene (CAAC)‐stabilized organoberyllium chloride yields the first neutral beryllium radical, which was characterized by EPR, IR, and UV/Vis spectroscopy, X‐ray crystallography, and DFT calculations.

Research paper thumbnail of Controlled Synthesis of Oligomers Containing Main‐Chain B(sp2)‐B(sp2) Bonds

Chemistry – A European Journal, 2021

A number of novel alkynyl-functionalized diarylbis(dimethylamino)diboranes(4) are prepared by sal... more A number of novel alkynyl-functionalized diarylbis(dimethylamino)diboranes(4) are prepared by salt metathesis, and the appended alkynyl groups are subjected to hydroboration. Their reactions with monohydroboranes lead to discrete boryl-appended diborane(4) species, while dihydroboranes induce their catenation to oligomeric species, the first known examples of well-characterized macromolecular species with B-B bonds. The oligomeric species were found to comprise 4-19 repeat units and are soluble in common organic solvents. Some of the oligomeric species have good air stability and all were characterized by NMR and vibrational spectroscopy and size exclusion chromatography techniques.

Research paper thumbnail of Platinum‐Templated Coupling of B=N Units: Synthesis of BNBN Analogues of 1,3‐Dienes and a Butatriene

Angewandte Chemie International Edition, 2021

The 1:2 reaction of [m-(dmpm)Pt(nbe)] 2 (dmpm = bis(dimethylphosphino)methane, nbe = norbornene) ... more The 1:2 reaction of [m-(dmpm)Pt(nbe)] 2 (dmpm = bis(dimethylphosphino)methane, nbe = norbornene) with Cl 2 BNR(SiMe 3) (R = tBu, SiMe 3) yields unsymmetrical (Naminoboryl)aminoboryl Pt I 2 complexes by BÀN coupling via ClSiMe 3 elimination. A subsequent intramolecular ClSiMe 3 elimination from the tBu-derivative leads to cyclization of the BNBN unit, forming a unique 1,3,2,4-diazadiboretidin-2-yl ligand. In contrast, the analogous reaction with Br 2 BN(SiMe 3) 2 leads, via a twofold BrSiMe 3 elimination, to a Pt II 2 A-frame complex bridged by a linear BNBN isostere of butatriene. Structural and computational data confirm p electron delocalization over the entire BNBN unit.

Research paper thumbnail of Understanding, Modulating, and Leveraging Transannular M Z Interactions

Density functional theory calculations have been performed on metallatranes featuring a group 13 ... more Density functional theory calculations have been performed on metallatranes featuring a group 13 elements at the bridgehead position to understand the factors that influence the nature of the M···Z (M = Fe, Co, Ni; Z = Al, Ga, In) interaction present in these complexes and the resultant reactivity at the metal center. The strength of the M···Z interaction increases with the increase in the size and polarizability of the bridgehead group 13 elements. The calculated reaction free energies (ΔG° values) for binding of different Lewis bases to the metallatranes are found to be significantly more exergonic for the larger In(III) ions. Quantum theory of atoms in molecules calculations reveal the covalent nature of the M···Z interactions, while the EDA-NOCV analysis indicates the strong binding ability of these metallatranes not only to different σ-donor and π-acceptor ligands but also to relatively inert species, such as N2.

Research paper thumbnail of Cyclo‐Dipnictadialanes

Angewandte Chemie International Edition, 2021

Abstract Using the AlI precursor Cp3tAl in conjunction with triphosphiranes (PAr)3 (Ar=Mes, Dip, ... more Abstract Using the AlI precursor Cp3tAl in conjunction with triphosphiranes (PAr)3 (Ar=Mes, Dip, Tip) we have succeeded in preparing Lewis base‐free cyclic diphosphadialanes with both the Al and P atoms bearing three substituents. Using the sterically more demanding Dip and Tip substituents the first 1,2‐diphospha‐3,4‐dialuminacyclobutanes were obtained, whereas with Mes substituents [Cp3tAl(μ‐PMes)]2 is formed. This divergent reactivity was corroborated by DFT studies, which indicated the thermodynamic preference for the 1,2‐diphospha‐3,4‐dialuminacyclobutane form for sterically more demanding groups on phosphorus. Using Cp*Al we could extend this concept to the corresponding cyclic diarsadialanes [Cp*Al(μ‐AsAr)]2 (Ar=Dip, Tip) and additionally add the phosphorus variants [Cp*Al(μ‐PAr)]2 (P=Mes, Dip, Tip). The reactivity of one variant [Cp3tAl(μ‐PPh)]2 towards NHCs was tested and resulted in double NHC‐stabilised [Cp3t(IiPr2)Al(μ‐PPh)]2.

Research paper thumbnail of Unexpected formation of a dodecanuclear {CoII6CuII6} nanowheel under ambient conditions: magneto-structural correlations

Dalton Transactions, 2021

An unexpected heterobimetallic ring {CoII6CuII6} was synthesised by slow diffusion in water under... more An unexpected heterobimetallic ring {CoII6CuII6} was synthesised by slow diffusion in water under ambient conditions and its dc magnetic properties were analysed through an effective Hamiltonian in the light of DFT type calculations.

Research paper thumbnail of The Dimethylbismuth Cation: Entry into Dative Bi–Bi Bonding and Unconventional Methyl Exchange

Angewandte Chemie, 2021

The isolation of simple, fundamentally important, and highly reactive organometallic compounds re... more The isolation of simple, fundamentally important, and highly reactive organometallic compounds remains among the most challenging tasks in synthetic chemistry. The detailed characterization of such compounds is key to the discovery of novel bonding scenarios and reactivity. The dimethylbismuth cation, [BiMe 2 (SbF 6 )] ( 1 ), has been isolated and characterized. Its reaction with BiMe 3 gives access to an unprecedented dative bond, a Bi→Bi donor/acceptor interaction. The exchange of methyl groups (arguably the simplest hydrocarbon moiety) between different metal atoms is among the most principal types of reactions in organometallic chemistry. The reaction of 1 with BiMe 3 enables an S E 2(back) type methyl exchange, which is for the first time investigated in detail for isolable, (pseudo-)homoleptic main group compounds.

Research paper thumbnail of Isolierung neutraler, mono‐ und dikationischer B 2 P 2 ‐Ringe durch Addition eines Diphosphans an eine Bor‐Bor‐Dreifachbindung

Angewandte Chemie, 2021

Das NHC-stabilisierte Diborin B 2 (SIDep) 2 (SIDep = 1,3-Bis(2,6-diethylphenyl)imidazolin-2-ylide... more Das NHC-stabilisierte Diborin B 2 (SIDep) 2 (SIDep = 1,3-Bis(2,6-diethylphenyl)imidazolin-2-yliden) unterzieht sich bei Raumtemperatur einer P-P-Bindungsaktivierung mit Tetraethyldiphosphan, wobei mittels 1,2-Diphosphinierung über ein Diphosphoryldiboren in hohen Ausbeuten B 2 P 2-Heterocyclen gebildet werden. In Abhängigkeit vom verwendeten Oxidationsmittel und Gegenion kann dieser Heterocyclus zu einem Radikalkation beziehungsweise Dikation oxidiert werden. Beginnend mit dem planaren, neutralen 1,3-Bis(alkyliden)-1,3-diborata-2,4-diphosphoniocyclobutan führt jeder Oxidationsschritt zu einer verminderten B-B-Bindungslänge und dem Verlust der Planarität durch die Kationisierung. Rçntgenstrukturanalysen in Kombination mit DFT-und CASSCF/NEVPT2-Rechnungen offenbaren für die NHC-stabilisierten dikationischen B 2 P 2-Ringe geschlossenschalige, schmetterlingsartige Strukturen, wovon die diradikaloiden Isomere mit planarem Ring in energetischer Nähe liegen. Cyclische Bor-und Phosphorverbindungen ziehen seit Dekaden die Aufmerksamkeit von Hauptgruppenchemikern auf sich. [1] Die ersten Entdeckungen auf diesem Gebiet haben sich auf Oligomere von Phosphinoboranen, R 2 PBR 2 , fokussiert. [2] Im Vergleich zu ihren leichteren Vertretern, den Aminoboranen R 2 NBR 2 , führt die Abneigung von Phosphor, planare Geometrien sowie p-Bindungen mit Bor einzuneh-men beziehungsweise auszubilden, zu einer hçheren Tendenz für intermolekulare B-P-Systeme und der Bildung vier-und sechsgliedriger (A, Schema 1) Heterocyclen sowie sogar von Polymeren. [3] Ebenso wurde eine Reihe an viergliedrigen 1,3-Diphospha-2,4-diboretanen (B) berichtet, [4] die zum Großteil aus erfolglosen Versuchen, monomere RP=BR-Spezies herzustellen, resultierten. [5] Diese Verbindungen enthalten pyramidalisierte Phosphoratome, die als Liganden für Übergangsmetalle dienen kçnnen. [4e, 6] Die Mehrheit der Entwicklungen von P-B-Ringsystemen bezog sich in den letzten zwei Dekaden auf die Synthese des Diradikaloids 1,3-Diphospha-2,4-diboretandiyl (C, Schema 1) von Bertrand und Mitarbeitern. [7] Das erste Beispiel für solche Verbindungen, cyclo-(BtBu) 2 (PiPr 2) 2 , wurde durch die Reaktion des Diborans(4) 1,2-B 2 Cl 2 tBu 2 mit LiPiPr 2 erhalten. Das angenommene 1,2-Diphosphinodiboran-Intermediat durchläuft eine Umlagerung unter Spaltung der B-B-s-Bindung und Bildung des Vierrings. Trotz des großen Abstands der beiden Boratome (2.57) besitzt diese Verbindung einen p-Einfachbindungscharakter sowie ein tiefliegendes antibindendes LUMO. Theoretische Studien [8] an den Diradikaloiden C offenbarten große Singulett-Triplett-Abstände zwischen + 23.4 und + 33.7 kcal mol À1 , während die Besetzung Schema 1. Oben: Relevante Verbindungsklassen von Bor-Phosphor-Ringen. Mitte: Synthese eines B 2 P 2-Diradikaloids. Unten: Hydrophosphinierung eines Diborins.

Research paper thumbnail of Intensiv farbige Bor‐dotierte Thiazolthiazole durch reduktive Dimerisierung von Borisothiocyanaten

Research paper thumbnail of Oxidation, Coordination, and Nickel‐Mediated Deconstruction of a Highly Electron‐Rich Diboron Analogue of 1,3,5‐Hexatriene

Angewandte Chemie, 2020

Abstract The reductive coupling of an N‐heterocyclic carbene (NHC) stabilized (dibromo)vinylboran... more Abstract The reductive coupling of an N‐heterocyclic carbene (NHC) stabilized (dibromo)vinylborane yields a 1,2‐divinyldiborene, which, although isoelectronic to a 1,3,5‐triene, displays no extended π conjugation because of twisting of the C2B2C2 chain. While this divinyldiborene coordinates to copper(I) and platinum(0) in an η2‐B2 and η4‐C2B2 fashion, respectively, it undergoes a complex rearrangement to an η4‐1,3‐diborete upon complexation with nickel(0).

Research paper thumbnail of cAAC‐stabilisierte 9,10‐Diboraanthracene – offenschalige Singulettbiradikale

Angewandte Chemie, 2020

Geringe HOMO-LUMO-Abstände und eine hohe Ladungsträgermobilitätp r ädestinieren die hçheren Acene... more Geringe HOMO-LUMO-Abstände und eine hohe Ladungsträgermobilitätp r ädestinieren die hçheren Acene für Anwendungen im Bereichd er Organoelektronik. Die Leistungsfähigkeit derartiger Verbindungen steigt hierbei dramatisch mit der Anzahl anellierter Benzolringe.G rçßere Acenmengen sind synthetischb isher jedochn ur fürA cene bis Heptacen verlässlichzugänglich. Theoretischen Studien zufolge besitzen (Oligo)acene offenschalige Singulettbiradikal-und (Poly)acene polyradikalische Grundzustände.E indeutige experimentelle Belege fürd iese Vorhersagen sind hingegen äußerst selten. Durchd en Einbau von zwei Boratomen in das Anthracengrundgerüst konnten wir den HOMO-LUMO-Abstand von Acenen dramatisch verringern und zwar ohne die Notwendigkeit einer Ausweitung des konjugierten p-Systems. Stabilisierung der Borzentren durch cyclische (Alkyl)-(amino)carbene lieferte hierbei neutrale 9,10-Diboraanthracene mit disjunkten, offenschaligen Singulettbiradikal-Grundzuständen. Einleitung Acene sind eine der wichtigsten Unterklassen polycyclischer aromatischer Kohlenwasserstoffe (PAKs), deren Struk-tur durch eine lineare Verkettung anellierter Benzolringe charakterisiert ist (Abbildung 1). [1] Die ungewçhnlichen elektronischen Eigenschaften derartiger Moleküle haben nicht nur bei Theoretikern eine kontrovers diskutierte Debatte nach sich gezogen, [2] sondern auch die Aufmerksamkeit experimenteller und anwendungsorientierter Forschungsgruppen geweckt. [1] Theoretische Studien haben in diesem Zusammenhang gezeigt, dass (Oligo)acene von Hexacen (n = 2) bis Decacen (n = 6) anstelle einer geschlossenen Elektronenkonfiguration einen offenschaligen Singulettbiradikal-Grundzustand mit disjunktem Charakter besitzen, [3] was auf die Verkleinerung der HOMO-LUMO-Abstände und Singulett-Triplett-Aufspaltungen bei steigender Länge des konjugierten p-Systems zurückgeführt wurde.D em selben Tr end folgend sinkt auch die fürd as Aufbrechen der Acen-p-Bindungen bençtigte Energie in deren KekulØ-Darstellung (I). FürA cene mit n = 2-6 kann diese letztendlich durch Beimischen von biradikalischem Charakter zum elektronischen Grundzustand überkompensiert werden, wodurch die offenschaligen Resonanzstrukturen (II)m it einem zusätzlichen Clar-Sextett energetisch zugänglich und begünstigt werden (Abbildung 1). [2c] Der Grundzustand grçßerer Systeme (n ! 8) besitzt der Theorie nach indes eher polyradikali-Abbildung 1. Geschlossenschalige und biradikalische Resonanzstrukturen von (Oligo)acenen (oben; n = 1-6) und neutraler Diboraacenen (unten). Clar-Sextetts sind in lila hervorgehoben. NHC = N-heterocyclisches Carben;cAAC = cyclisches (Alkyl)(amino)carben.

Research paper thumbnail of Functionalization of N 2 via Formal 1,3‐Haloboration of a Tungsten(0) σ‐Dinitrogen Complex

Chemistry – A European Journal, 2020

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

Research paper thumbnail of Hydrogenated Benzene in Circumstellar Environments: Insights into the Photostability of Super-hydrogenated PAHs

The Astrophysical Journal, 2018

Polycyclic aromatic hydrocarbons (PAHs), comprised of fused benzene (C 6 H 6) rings, emit infrare... more Polycyclic aromatic hydrocarbons (PAHs), comprised of fused benzene (C 6 H 6) rings, emit infrared radiation (3-12 μm) due to the vibrational transitions of the C-H bonds of the aromatic rings. The 3.3 μm aromatic band is generally accompanied by the band at 3.4 μm assigned to the vibration of aliphatic C-H bonds of compounds such as PAHs with an excess of peripheral H atoms (H n-PAHs). Herein we study the stability of fully hydrogenated benzene (or cyclohexane, C 6 H 12) under the impact of stellar radiation in the photodissociation region (PDR) of NGC 7027. Using synchrotron radiation and time-of-flight mass spectrometry, we investigated the ionization and dissociation processes at energy ranges of UV (10-200 eV) and soft X-rays (280-310 eV). Density Functional Theory (DFT) calculations were used to determine the most stable structures and the relevant low-lying isomers of singly charged C 6 H 12 ions. Partial Ion Yield (PIY) analysis gives evidence of the higher tendency toward dissociation of cyclohexane in comparison to benzene. However, because of the high photoabsorption crosssection of benzene at the C1s resonance edge, its photodissociation and photoionization cross-sections are enhanced, leading to a higher efficiency of dissociation of benzene in the PDR of NGC 7027. We suggest that a similar effect is experienced by PAHs in X-ray photon-rich environments, which ultimately acts as an auxiliary protection mechanism of super-hydrogenated polycyclic hydrocarbons. Finally, we propose that the single photoionization of cyclohexane could enhance the abundance of branched molecules in interstellar and circumstellar media.

Research paper thumbnail of Bond-Strengthening Backdonation in Aminoborylene-Stabilized-Aminoborylenes: at the Intersection of Borylenes and Diborenes

Angewandte Chemie International Edition, 2019

Singly NHC-coordinated diamino(boryl)borenium salts react with Na2[Fe(CO)4] to yield the first st... more Singly NHC-coordinated diamino(boryl)borenium salts react with Na2[Fe(CO)4] to yield the first stable coordination complexes of 'animoborylene-stabilized-aminoborylenes', which exhibit exceptional σ-donor properties. Upon photolytic CO extrusion from the metal center, the diboron ligand adopts a novel η 3-BBN coordination mode, where bond-strengthening backdonation from the metal centre into the vacant B-B π-orbital is observed; a bonding situation which can be equivalently described as a Fediaminodiborene complex. In a related reduction of CAAC-stabilized diaminodihalodiborane with KC8, the reduced species can be captured with nucleophiles to form three coordinate (diaminoboryl)borylenes, where both amino groups have migrated to the distal boron. Collectively, these reactions illustrate the isomeric flexibility imparted by amino groups on this reduced diboron system, allowing for multiple avenues of novel reactivity.

Research paper thumbnail of Mechanistic Insights into the Formation of Lithium Fluoride Nanotubes

Chemistry - A European Journal, 2019

Born-Oppenheimer molecular dynamics (BOMD) and periodic density functional theory (DFT) calculati... more Born-Oppenheimer molecular dynamics (BOMD) and periodic density functional theory (DFT) calculations have been applied for describing the mechanism of formation of lithium fluoride (LiF) nanotubes with cubic, hexagonal, octagonal, decagonal, dodecagonal, and tetradecagonal cross-sections. It has been shown that high energy structures, such as nanowires, nanorings, nanosheets, and nanopolyhedra are transient species for the formation of stable nanotubes. Unprecedented (LiF) n clusters (n 12) were also identified, some of them lying less than 10 kcal mol À[1] above their respective global minima. Such findings indicate that stochastic synthetic techniques, such as laser ablation and chemical vapor deposition, should be combined with a template-driven procedure in order to generate the nanotubes with adequate efficiency. Apart from the stepwise growth of LiF units, the formation of nanotubes was also studied by rolling up a planar square sheet monolayer, which could be hypothetically produced from the exfoliation of the FCC crystal structure. It was shown that both pathways could lead to the formation of alkali halide nanotubes, a still unprecedented set of one-dimensional materials.

Research paper thumbnail of Doubly and Triply Charged Species Formed from Chlorobenzene Reveal Unusual C-Cl Multiple Bonding

Journal of the American Chemical Society, Mar 28, 2018

In free-radical halogenation of aromatics, singly charged ions are usually formed as intermediate... more In free-radical halogenation of aromatics, singly charged ions are usually formed as intermediates. These stable species can be easily observed by time-of-flight mass spectrometry (TOF-MS). Here we used electron and proton beams to ionize chlorobenzene (CHCl) and investigate the ions stability by TOF-MS. Additionally to the singly charged parent ion and its fragments, we find a significant yield of doubly and triply charged parent ions not previously reported. In order to characterize these species, we used high-level theoretical methods based on density functional theory (DFT), coupled-cluster (CC), and generalized valence bond (GVB) to calculate the structure, relative stabilities, and bonding of these dications and trications. The most stable isomers exhibit unusual carbon-chlorine multiple bonding: a terminal C═Cl double bond in a formyl-like CHCl moiety (1, r = 1.621 Å) and a ketene-like C═C═Cl cumulated species (2, r = 1.542 Å). The calculations suggest that an excited state o...